George A Michael
email: george.michael@univ-lyon2.fr

Jean-Michel Dorey

Romain Rey

Thierry D'amato

Delphine Fabre

Sophie Brunet

Catherine Padovan

Attention in schizophrenia: impaired inhibitory control, faulty attentional resources, or both?

Keywords: schizophrenia, attention, resistance to interference, inhibition, attentional resources, divided attention

While the literature regarding the existence of difficulties in inhibition in schizophrenia is relatively consistent, it is not clear whether these difficulties reflect any specific deficit in an inhibitory control process or whether they are the result of deficits in the systems that regulate inhibitory control, such as attentional resources. This also raises the issue of attentional resources in schizophrenia, which offers a somewhat puzzling and sometimes contradictory picture. In this study, these issues were investigated by means of a paradigm in which the need for inhibitory control and the need for correct allocation of attentional resources varied parametrically. Twenty-six outpatients with a diagnosis of schizophrenia and 26 matched controls completed a visual search task during which distractors were presented and had to be inhibited. At the same time, they also completed an auditory target detection task of varying difficulty. The results show that the patients had difficulties both in inhibiting distractors and in correctly allocating attention to the two tasks. The results also show that these two difficulties were not related. This leads to the conclusion that schizophrenia involves both defective inhibitory control and faulty management of attentional resources, and that the former does not result from the latter. Furthermore, these effects seem to be neither dependent on processing speed, nor related to medication.

INTRODUCTION

Schizophrenia is a chronic mental disorder with attention deficits being some of its most pervasive neurocognitive features. Attention deficits can predict functional outcomes [START_REF] Green | Neurocognitive deficits and functional outcome in schizophrenia: are we measuring the "right stuff[END_REF][START_REF] Nuechterlein | Neurocognitive predictors of work outcome in recent-onset schizophrenia[END_REF]. This comes as no surprise because, as a central mechanism for the control of information processing, attention operates to activate processes that enhance the processing of relevant signals, inhibits irrelevant signals in a way that strengthens resistance to interference and distractibility, and coordinates the realization of concurrent tasks by distributing processing resources [START_REF] Michael | Dissociable yet tied inhibitory processes: The structure of inhibitory control[END_REF]. These processes are critical for learning and other complex everyday activities, and their malfunctioning may have serious consequences.

Decreased inhibition of interfering information seems to be a hallmark of cognitive disturbances in schizophrenia. Taken individually, recent studies provide a rather puzzling picture of inhibitory control in schizophrenia. Indeed, some have found no differences between patients with schizophrenia and controls (e.g., [START_REF] Birkett | Control of attention in schizophrenia[END_REF], while others have found poorer performance in patients [START_REF] Caprile | Mixing apples with oranges: Visual attention deficits in schizophrenia[END_REF][START_REF] Galaverna | Attention in patients with chronic schizophrenia: Deficit in inhibitory control and positive symptoms[END_REF][START_REF] Laurenson | Cognitive control and schizophrenia: The greatest reliability of the Stroop task[END_REF], and yet others have reported that inhibitory control in schizophrenia might be reduced only under certain circumstances (Boucart et al., 1998). Such discrepancies may be due to the clinical and biological heterogeneity of schizophrenic disorders, or to specific features of individual studies rather than to schizophrenia per se. A meta-analysis has shown that patients with schizophrenia are not only slower than controls, but that they also produce more errors in tasks involving inhibitory control [START_REF] Westerhausen | Impaired cognitive inhibition in schizophrenia: a meta-analysis of the Stroop interference effect[END_REF].

Despite this finding, a question still persists: is inhibitory control disturbed in schizophrenia, or is decreased performance in tasks involving inhibitory control an epiphenomenon of another disturbance? [START_REF] Henik | Schizophrenia and the Stroop effect[END_REF] suggested that patients with schizophrenia can adequately activate inhibitory control, but only if sufficient attentional resources are available.

Patients could, however, face difficulties when multiple attentional demands occur. Indeed, theoretical models suggest that inhibitory control requires cognitive resources if it is to reach high levels of efficiency, and this assumption is supported by studies showing that decreased resource availability (e.g., due to performing a secondary task) reduces efficiency in such a way that distracting signals have a greater effect [START_REF] Michael | The ventral premotor cortex (vPM) and resistance to interference[END_REF]2014). This naturally points to the desirability of studying attentional resource availability and dual-tasking in schizophrenia.

Conversely, little has been done to investigate the management of attentional resources and, to our knowledge, no meta-analysis has ever been published on this issue. This leaves us with scarce and in some ways contradictory evidence. For instance, it has been suggested that as cognitive load increases, patients with schizophrenia exhibit poorer performance than controls and that this indicates resource limitations [START_REF] Schwartz | Reaction time impairment in schizophrenia and affective illness: The role of attention[END_REF][START_REF] Nuechterlein | Information processing and attentional functioning in the developmental course of schizophrenic disorders[END_REF].

There is indeed evidence that the availability of attentional resources or the ability to allocate them to multiple tasks is weakened in this disorder [START_REF] Ahlers | Smoking improves divided attention in schizophrenia[END_REF][START_REF] Granholm | Dual-task performance operating characteristics, resource limitations, and automatic processing in schizophrenia[END_REF][START_REF] Gray | Relationships between divided attention and working memory impairment in people with schizophrenia[END_REF][START_REF] Lin | Dual-task performance involving hand dexterity and cognitive tasks and daily functioning in people with schizophrenia: A pilot study[END_REF][START_REF] Shen | Neurocognitive pattern analysis reveals classificatory hierarchy of attention deficits in schizophrenia[END_REF]. The idea of the existence of difficulties in correctly allocating attentional resources was also supported by the findings of [START_REF] Fuller | Concurrent performance of motor tasks and processing capacity in patients with schizophrenia[END_REF]. These authors asked their participants to perform two simultaneous motor tasks and showed that, compared to the controls, the performance of patients with schizophrenia increased in the first task while it decreased in the second one. This probably suggests that the patients diverted an excessive quantity of resources away from the second task and allocated more than required to the first one, thus resulting in unbalanced patterns of performance compared to the controls. It has also been suggested that there is a possible failure to regulate attentional resources over time in schizophrenia in situations in which significant time constraints are present and when it is necessary to process a relatively large number of items (Michael et al., 2016). However, this is only a part of the picture. [START_REF] Allen | Dichotic monitoring and focused versus divided attention in schizophrenia[END_REF] and [START_REF] Huang | Disrupted modulation of thalamus activation and thalamocortical connectivity during dual task performance in schizophrenia[END_REF] found that patients with schizophrenia performed worse than controls in a divided attention task, without any proportional fall-off in performance compared to controls. This may suggest that poorer performance may have its origin in globally slower information processing [START_REF] Knowles | Processing speed deficits in schizophrenia: Reexamining the evidence[END_REF] rather than in the limited availability of attentional resources. Finally, a small increase in performance under dualtasking conditions was also reported by [START_REF] Birkett | Control of attention in schizophrenia[END_REF]. This seems to indicate that performing multiple tasks may sometimes help mobilize available but otherwise dormant attentional resources. It is thus difficult to draw any clear conclusions from these inconsistent findings.

The aim of the present study was to investigate the issues left unresolved by the abovementioned literature, namely (i) whether inhibitory control per se is weakened in schizophrenia, or (ii) whether inefficient inhibitory control might be due to some form of faulty management of attentional resources, or (iii) whether there are problems involving both inhibitory control and the management of resources, in which case deficiencies in the latter can hardly be considered responsible for the efficiency of the former. A visual search task was carried out during which participants searched for a target among a varying number of items.

In half the trials, a salient distractor was present in order to assess resistance to interference and hence inhibitory control. This task was performed simultaneously with an auditory target detection task of varying difficulty in order to assess limitations in attentional resources. The influence of the latter on the former indicated the way attentional resources regulated inhibitory control. Finally, two companion reaction time tasks (simple and choice reaction time tasks, i.e. SRT and CRT) were also completed in order to control for a general slowing of information processing (methodological and statistical details about the companion tasks are presented as supplementary material).

On the basis of theoretical models suggesting a hierarchical organization of attentional resources and inhibitory control (with inhibition depending on the availability of attentional resources; Kane & Engel, 2003;[START_REF] Michael | The ventral premotor cortex (vPM) and resistance to interference[END_REF], three distinct and mutually exclusive hypotheses can be formulated (summarized in Table 1):

1. If inhibitory control is impaired but attentional resources are not faulty, then the effect of the distractor would be larger in patients than in controls (i.e., significant group X distractor condition interaction). This would be due to difficulties in resisting to interference from the irrelevant distracting item. However, the normal availability of attentional resources would not modulate inhibitory control because of the latter's impairment. Therefore, the falloff in performance as the difficulty of the concurrent auditory task increases would follow the same pattern as in controls (i.e., no group X auditory task difficulty interaction and no group X distractor condition X auditory task difficulty interaction).

2. If attentional resources are faulty but inhibitory control is normal, then the fall-off in performance as the difficulty of the concurrent auditory task increases would be steeper in patients than in controls (i.e., significant group X auditory task difficulty interaction). Indeed, mobilizing the necessary amount of resources in order to complete the secondary task would withdraw the already diminished resource pool away from the primary visual task, resulting in difficulty managing both concurrent tasks. And the greater the difficulty of the secondary task, the greater the failure would be. Yet, the outlined theoretical models suggest a hierarchical dependence of inhibition on resources. This predicts that, in case of faulty resources, inhibitory control would also suffer since available resources would not be sufficient for it to be fully operational. As a consequence, the distractor effect would globally be larger than in controls due to the non-availability of resources to manage it (i.e., significant group X distractor condition interaction). The hierarchical dependence of inhibition on resources also predicts a third effect in case of faulty resources and normal inhibition. The greater the need for resources, the more difficult would be to modulate inhibition. Therefore, the distractor effect in patients would increasingly depart from that of the controls as the difficulty of the concurrent auditory task increases (i.e., significant group X distractor condition X auditory task difficulty interaction). This would show that the greater the need for resources, the greater the difficulty in modulating inhibition. All interactions involving group would therefore be significant.

3. If inhibitory control is impaired and attentional resources are faulty, then the effect of the distractor would be larger in patients than in controls (i.e., significant group X distractor condition interaction), and the fall-off in performance as the difficulty of the concurrent auditory task increases would be steeper in patients than in controls (i.e., significant group X auditory task difficulty interaction). The reasons are the same as those presented in hypotheses 1 and 2. However, the non-availability of attentional resources would not be a cause of faulty inhibitory control and could not modulate an already impaired inhibitory process. There would therefore be no relation between them (i.e., no significant group X distractor condition X auditory task difficulty interaction).

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METHODS

2.1. Participants: (a) Twenty-six outpatients (9 females, 17 males; Table 1) who met DSM-V criteria for schizophrenia and were clinically stable. They were recruited at the Centre Hospitalier Le Vinatier, Lyon, France. Their mean age was 31.4±10.4 (range: 20 to 51), their mean level of education (not available for 3 patients) was 13.1±1.9 years and the average duration of illness was 12.9±6.8 years. Their mean total score on the Positive and Negative Symptoms Scale (PANSS) was 56.9±12.3. They were all receiving long-term neuroleptic treatment, administered in a standard dose, with the mean chlorpromazine equivalent being 644mg/day ± 578 (range: 20 to 2100; [START_REF] Woods | Chlorpromazine equivalent doses for the newer atypical antipsychotics[END_REF]. The mean Verbal Comprehension Index and the mean Perceptual Reasoning Index obtained on the Wechsler Adult Intelligence Scale (WAIS-IV; [START_REF] Wechsler | WAIS-IV administration and scoring manual[END_REF] were 99.9 ±17.8 and 94.5 ± 18.1, respectively. None of the patients had any history of known neurological disorders. (b) Twenty-six control participants (9 females, 17 males) with a mean age of 31.1±10.4 years (range: 18 to 59) and a mean level of education (not available for 6 controls) of 13.1±1.3 years. They had no history of current or past psychiatric treatment, no history of diagnosable substance abuse, and no history of neurological disorders. The two groups did not differ on age (t(50)=.13; p > .90, bicaudal) or on mean level of education (t(41)=.1; p > .94, bicaudal). All participants reported normal or corrected-to-normal vision and hearing and gave their written informed consent for their participation. We complied with the APA ethical standards, and this research on human subjects was approved by the Comité de Protection des Personnes Sud-Est VI (N° AU863-AFSSAPS : 2010-A00980-39), France. The research was also conducted in accordance with the Helsinki Declaration.

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Stimuli and apparatus

The task used in the present study is illustrated in Figure 1.

Primary visual search task: The stimuli were white outlined squares (luminance 37.37 cd/m 2 ) presented on a black background (luminance 0.034 cd/m 2 ). At a viewing distance of 30 cm, the angular size of each square was 0.5°x0.5°. Each square had a gap and was rotated clockwise through 0°, 90°, 180° or 270°. The target orientations were 90° or 270°, while that of non-targets was 0° or 180°. To make the target salient, it was placed inside a white outlined 1°x1° diamond (luminance 37.37 cd/m 2 ). To make a non-target (i.e., the critical distractor) salient, it was placed inside a white outlined circle (luminance 37.37 cd/m 2 ) with a radius of 1°. The same apparatus and software as before were used.

Concurrent auditory task: The stimuli in the auditory task were the numbers 0 to 9. They were recorded as an mp3 file and played back using speakers at a rate of 1 per second. The stimuli were arranged in series of 10 numbers, with all the numbers being presented randomly and once only within each series. Each new series started only when the previous series had ended, but there was no indication in the mp3 file to signal the end of one series and the beginning of the next. Instead, a continuous flow was perceived. This arrangement prevented participants from developing detection and response strategies. The mp3 file was played through a second ACER Extensa 7630 computer equipped with two 572703 Dacomex speakers.

Procedure

Diagnostic interviews were carried out by a senior psychiatrist according to the DSM-V criteria (French version of the 4th edition; American Psychiatric Association, 2015) for schizophrenia. Psychotic symptomatology was assessed using the Positive And Negative Symptoms Scale (PANSS). After giving their written informed consent, the patients completed two separate sessions. During the first one, the WAIS-IV was completed in order to assess the Verbal Comprehension Index and the Perceptual Reasoning Index. During the second session, they completed the computerized tasks. They had to sit on a chair facing a computer monitor. The SRT and CRT tasks were completed first, followed by the main Experiment. The controls completed only the computerized tasks once they had given their written informed consent. Instructions were given for each task, followed by a short training session for each of them.

Visual Search Task with Auditory Background: The stimuli were randomly distributed inside an imaginary 7.8° x 7.8° square, and the search display remained visible until a response was given. The whole session started with 10 training trials showing all possible conditions. A trial started with the appearance of a central fixation point displayed for 1000 ms. Then, the search display was presented. Two conditions were manipulated throughout the study, each occurring with equal probability: (a) in the baseline condition, only the target was placed in the center of the salient surround (diamond); (b) in the distractor condition, in addition to the salient distractor, one of the non-target items was placed in the center of the salient surround (circle) in order to indicate a critical distractor to be avoided. The display consisted of either 6 or 10 items, including the target (and the distractor, in the corresponding conditon). The presence of the distractor (present vs. absent) and the display size (6 vs. 10 items) varied randomly from trial to trial. The participants were asked to indicate the location of the target's gap (right or left) by pressing one of two pre-defined response keys on the computer keyboard as quickly as possible. The next trial started 500 ms after a response had been given. RTs and errors were recorded by the computer. Overall, the visual task consisted of 240 trials (3 identical blocks of 20 trials per condition and display size). The subdivision into 3 blocks was related to the concurrent auditory task. The participants had to complete this concurrent auditory task, the difficulty of which varied: (a) they had to listen to the auditory list but without responding to it (i.e., 0 targets); (b) they had to detect a single target (the number 2) by making a verbal response ("stop" response; i.e., 1 target condition); (c) they had to detect three targets (numbers 2, 4 and 6) by making the same verbal response (i.e., 3 targets condition). The auditory target(s) was (were) presented in a completely random and unpredictable order. The three degrees of difficulty were presented in three separate blocks during which the participants performed the same visual task (i.e., the visual task remained constant, since the aim was to assess the effects of a secondary task). The three blocks were balanced in a Latin-square design across participants. To optimize time-sharing between the visual and auditory tasks, the auditory items were played continuously from the beginning of the block right through to the end, without interruption. Furthermore, the high presentation rate of the auditory items (1 per second) was intended to make the task demanding in terms of resources, because it has been shown that if one stream of stimuli is presented at a high rate, another stream cannot be handled efficiently at the same time. This method [START_REF] Michael | Dissociable yet tied inhibitory processes: The structure of inhibitory control[END_REF] was therefore a straightforward means of drawing resources away from the visual task and observing the effects of reduced resource availability. The participants were informed that the two tasks (visual and auditory) were equally important, and that one should not be favored over the other. Their responses were recorded by the experimenter, who was sitting at some distance from the participant and had the full list of auditory stimuli. Based on the results of a pilot study as well as on previous research [START_REF] Michael | Dissociable yet tied inhibitory processes: The structure of inhibitory control[END_REF], target detections were considered correct if the response was given within 2 seconds. The participants were fully informed of these criteria.

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RESULTS

3.1. Auditory task: a detection accuracy score was computed by subtracting the percentage of false positives (erroneous detections) from the percentage of hits (correctly detected targets).

This score was subjected to an analysis of variance (ANOVA), with the number of targets to be detected (1 vs. 3) as the within-subjects factor, and the group (controls vs. patients) as the between-groups factor. The main effect of group was significant (F(1,50) = 9.2, p < .004, η 2 p = .16), with patients performing less well than controls (89% vs 95%). The main effect of the number of targets to be detected was significant (F(1,50) = 59.1, p < .0001, η 2 p = .54), with detection accuracy being higher when 1 target had to be detected (97.6%) rather than 3 (87.4%). From these results, it is apparent that, as expected, increasing the number of auditory targets increased the task demands in terms of the required resources and therefore resulted in poorer performance. The group X number of targets to be detected interaction was also significant (F(1,50) = 7.8, p < .007, η 2 p= . 14; Figure 2). Bonferroni-corrected comparisons (the threshold p-value for four comparisons is .013) showed that performance decreased as the number of targets to be detected increased both in controls (1 target 98.6% vs 3 targets 91.4%, difference = 7.2%, p < .001, Cohen's d = .76) and patients (1 target 96.7% vs 3 targets 81.3%, difference = 15.4%, p < .0001, Cohen's d = 1.32). It should be noted that the patients' performance fell by more than twice as much as that of the controls when passing from 1 to 3 targets to be detected, with a ratio of ≈2.14. No difference was found between the groups when 1 target had to be detected (patients 96.7% vs controls 98.6%, p = .11), whilst a difference was observed for 3 targets (patients 81.3% vs controls 91.4%, p < .003, Cohen's d = .86).

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Visual Search Task:

The number of errors and medians of correct RTs were analyzed. Medians were preferred to means because of the intra-subject and between-participants variability in RTs classically observed in detection and visual search tasks.

Errors: The mean percentage of errors was 2% for the controls and 2.4% for the patients. This low percentage is not surprising since the stimuli remained on the screen until a response was given. The percentage of correct responses was subjected to an analysis of variance (ANOVA), with the distractor condition (absent vs. present), display size (6 items vs. 10 items) and auditory task difficulty (0, 1 or 3 targets for detection) as within-participants factors, and group (controls vs. patients) as the between-groups factor. The Greenhouse-Geisser correction was applied since the assumption of sphericity was not met. No significant result was found.

Response Times: Response times shorter than 100 ms and longer than 2000 ms were discarded. Discarded trials accounted for less than 0.5% of the total number of trials. Since both the simple and choice RT tasks revealed that patients took longer overall to respond than controls, it was necessary to eliminate any interference in this slowing-down of information processing. Response Times obtained in both these tasks were averaged and then subtracted from the median RT for correct responses obtained in each visual search task condition. This excludes all processes involved in both tasks from the analyses, i.e. central and peripheral detection of signals, orienting toward them, decision processes that make it possible to choose the correct response, and giving a response. The remaining time thus reflects visual search and attentional processes. An analysis of variance (ANOVA) was carried out on visual search times, with the distractor condition (absent vs. present), display size (6 items vs. 10 items) and auditory task difficulty (0, 1 or 3 targets for detection) as within-participants factors, and group (controls vs. patients) as the between-groups factor. The Greenhouse-Geisser correction was applied since the assumption of sphericity was not met. Only significant effects involving group will be reported. The main effect of group was significant (F(1, 50) = 10.3, p < .002, η 2 p = .17), with patients exhibiting slower visual search times than controls (patients 353 ms vs controls 263 ms, respectively). The group X distractor condition interaction was significant (F(1, 50) = 5.2, p < .026, η 2 p = .10). The presence of the distractor increased visual search times in both groups, but this increment was much larger in patients (247 ms) than in controls (195 ms), giving a ratio of ≈1.27. The group X auditory task difficulty interaction was also significant (F(2, 100) = 8.3, p < .003, η 2 p = .14; Figure 3 left panel). Bonferroni-corrected comparisons (the threshold p-value for 3 comparisons being .016) showed that the patients did not differ from controls when 0 (patients 284 ms vs controls 234 ms) or 1 (patients 310 ms vs controls 257 ms) auditory targets had to be detected (p = .022 and p = .046, respectively), but that their visual search times were much longer than those of the controls when 3 auditory targets had to be detected (patients 465 ms vs controls 299 ms; p < .002, Cohen's d = .96).

When the difference in visual search times between 1 and 3 targets was inspected, it was found to be quite disproportionate in the patients (155 ms) as compared to the controls (42 ms), giving a ratio of ≈3.7. The group X distractor condition X auditory task difficulty interaction was not significant (F(2, 100) = .32, p > .61). No other effects involving the group were observed.

Complementary analyses

Since some cognitive models posit that inhibitory control is hierarchically dependent on available attentional resources, two indices were computed on the basis of the visual search task data in order to further investigate this link. The Inhibition Difficulty Index (ID) was derived by computing the main effect of the presence of a distractor (i.e., difference between distractor-absent and distractor-present trials) on RT and proportions of errors, z-transforming these effects, and then averaging the z-scores in order to obtain a single value. The higher the score, the weaker inhibition was. The Resources Difficulty Index (RD) was derived by computing the main effect of the number of auditory targets on RT and proportions of errors in the visual task, and proportions of errors in the auditory task. The α regression slope1 was used to obtain a single value for each of these dependent variables. These values were then ztransformed and averaged in order to obtain a single value. The higher the score, the greater the difficulty became as the number of auditory targets for detection increased. A simple linear regression analysis confirmed that, in line with the cognitive models, the RD was indeed predictive of the ID only for controls (β = .47, SEM = .18; t(24) = 2.6, p < .016; Adj.

R 2 = .19). No such relationship was found in the performance of patients with schizophrenia (β = .18, SEM = .166; t(24) =.90, p > .37; Adj. R 2 = .007). The results are presented in Figure 3 (right panel).

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Correlation analyses

Pearson correlations were conducted on the patients' results to identify correlations between medication, on one hand, and performance in the SRT and CRT tasks, and the ID and the RD indices, on the other. No correlation was observed.

DISCUSSION

Even if inhibitory control and attentional resources are usually assessed separately from each other on the basis of different paradigms, theoretical models of attention suggest that inhibition needs resources if it is to be fully efficient [START_REF] Michael | The ventral premotor cortex (vPM) and resistance to interference[END_REF]2014). Whilst the literature concerning the existence of difficulties in inhibition in schizophrenia is fairly consistent [START_REF] Westerhausen | Impaired cognitive inhibition in schizophrenia: a meta-analysis of the Stroop interference effect[END_REF], it is not clear whether these difficulties reflect any specific deficit in a process of inhibitory control, or whether they are the result of faulty systems that regulate inhibitory control, such as attentional resources [START_REF] Henik | Schizophrenia and the Stroop effect[END_REF].

This also raises the issue of attentional resources in schizophrenia, which offers a somewhat puzzling and sometimes contradictory picture. The aim of the present study was to investigate these issues by means of a single paradigm in which the need for inhibitory control and the correct allocation of attentional resources varied parametrically.

The results provide a largely direct and clear picture. First, task-irrelevant visual distractors occurring randomly during the visual search task produced effects of attentional capture that were as much as 27% larger in patients with schizophrenia than in controls. This is suggestive of decreased inhibitory control and tallies quite well with the large body of scientific literature and with those meta-analyses that have shown that inhibitory control is, indeed, weakened in schizophrenia [START_REF] Caprile | Mixing apples with oranges: Visual attention deficits in schizophrenia[END_REF][START_REF] Galaverna | Attention in patients with chronic schizophrenia: Deficit in inhibitory control and positive symptoms[END_REF][START_REF] Laurenson | Cognitive control and schizophrenia: The greatest reliability of the Stroop task[END_REF][START_REF] Westerhausen | Impaired cognitive inhibition in schizophrenia: a meta-analysis of the Stroop interference effect[END_REF].

Second, a secondary auditory target detection task slowed visual search times in both patients and controls. No difference between the two groups was observed when 0 or 1 auditory targets were to be detected, even though performance was poorer for 1 target (easy dual task) than for 0 targets (single task). Similarly, the two groups did not differ in their ability to detect only 1 target in the auditory task. As suggested in a previous investigation using a similar experimental protocol [START_REF] Michael | Dissociable yet tied inhibitory processes: The structure of inhibitory control[END_REF], a single predefined target can be detected entirely using perceptual information (i.e., reacting to a specific sound) without further processing. This demands only a small amount of attentional resources, as reflected in the slowing in performance [START_REF] Kahneman | Attention and effort[END_REF]. It seems that, in schizophrenia, performing such a simple activity is not a problem, thus suggesting that patients have sufficient attentional resources to allow them to perform both tasks correctly, and that they seemingly mobilize and allocate resources adequately. However, increasing the difficulty of the secondary task to 3 targets produced a disproportionate slowing in the patients with schizophrenia as compared to the controls. Detecting 3 predefined targets can therefore no longer result from simple perceptual information. Some extra cognitive processing is needed in order to determine whether each new item is one of the targets or not. Here, mobilizing the amount of resources required in order to complete the secondary task withdraws very large quantities away from the primary visual task. It is also interesting to note that this disproportionate slowing in visual search time in patients was also accompanied by a similarly disproportionate fall-off in detection accuracy in the auditory task. Indeed, passing from 1 to 3 targets for detection produced a decline in performance in the patients that was twice as large as that observed in the controls. This clearly suggests that allocating attentional resources to the auditory task did not result in perfect performance in that task, while performance in the visual task was also impaired. The patients performed both tasks less well than the controls, suggesting a deficit in their attentional resources. Taken together, these results may help explain the inconsistencies reported in the literature. As mentioned earlier, some dual-task investigations [START_REF] Allen | Dichotic monitoring and focused versus divided attention in schizophrenia[END_REF][START_REF] Huang | Disrupted modulation of thalamus activation and thalamocortical connectivity during dual task performance in schizophrenia[END_REF] have found no difference between patients with schizophrenia and controls apart from a general slowing-down of processing speed, while others [START_REF] Ahlers | Smoking improves divided attention in schizophrenia[END_REF][START_REF] Fuller | Concurrent performance of motor tasks and processing capacity in patients with schizophrenia[END_REF][START_REF] Granholm | Dual-task performance operating characteristics, resource limitations, and automatic processing in schizophrenia[END_REF][START_REF] Gray | Relationships between divided attention and working memory impairment in people with schizophrenia[END_REF][START_REF] Lin | Dual-task performance involving hand dexterity and cognitive tasks and daily functioning in people with schizophrenia: A pilot study[END_REF][START_REF] Shen | Neurocognitive pattern analysis reveals classificatory hierarchy of attention deficits in schizophrenia[END_REF]) have reported a disproportionate decline in performance. In our study, no group difference was found in easy dual tasks, whilst a large difference was found in more difficult dual tasks, with general processing speed being controlled for at all times. It is possible that those investigations that failed to find any difference may have used tasks that were much too easy to manage, even with faulty and residual attentional resources, whilst those that did find such a difference used tasks that were more likely to mobilize large quantities of attentional resources. In such cases, residual resources would not be sufficient to perform the tasks adequately. Now that we have described the existence of both impaired inhibitory control and faulty attentional resources in our schizophrenia sample, we turn to the million-dollar question: does the former result from the latter? Some empirical data and cognitive models assume that inhibitory control needs resources to operate (Kane & Engel, 2003;[START_REF] Michael | The ventral premotor cortex (vPM) and resistance to interference[END_REF]2014). If this were the case, then faulty resources would impact inhibition in such a way that it would also be weakened. In the field of schizophrenia research, such a hypothesis has indeed been proposed on the basis of a review of the Stroop effect [START_REF] Henik | Schizophrenia and the Stroop effect[END_REF]. This hypothesis states that inhibitory control is not disturbed in schizophrenia. It is weakened only when attentional resources are missing. However, any hierarchical dependence of inhibition on resources, in addition to weakened inhibition and weakened resources, also predicts that the distractor effect in patients would become increasingly pronounced as the difficulty of the auditory task increases (i.e., significant group X distractor condition X auditory task difficulty interaction), thus showing that the greater the need for resources, the more difficult it is to modulate inhibition (this corresponds to hypothesis 2 as detailed in the introduction). This was not found, and the interaction of interest was far from being significant. Such a finding does not permit us to infer that problems in inhibitory control are due to faulty attentional resources. On the contrary, the whole pattern of results observed here corresponds better to the idea of a deficit of both inhibition and attentional resources (hypothesis 3 as detailed in the introduction). In fact, the non-availability of attentional resources would not be a cause of faulty inhibitory control and there is therefore no relation between them. Indeed, our complementary analyses showed that the effect of the difficulty of the auditory task was not predictive of the distractor effect in patients with schizophrenia, whilst it was in controls, as had been expected on the basis of cognitive models.

Taking all the results into account, we may safely conclude that our sample of schizophrenia patients did indeed exhibit impaired inhibitory control and faulty attentional resources.

However the former does not result from the latter. These effects are not dependent on processing speed and, in patients with schizophrenia, are seemingly not related to medication.

Future research could use dual tasks of varying difficulties when investigating attentional resources in schizophrenia. Such a manipulation could help bring about an understanding of the way faulty inhibition and resources may contribute to symptomatology and to the cognitive diagnostic classification of schizophrenia. a salient distractor was presented and was located inside a circle. This task was completed three times, each time with an auditory background consisting of random numbers. In one block, the participants had to ignore the auditory background (i.e., 0 targets, single task), in another they had to detect the number 2 (i.e., 1 target, easy dual task), and in another the numbers 2, 4 and 6 (i.e., 3 targets, difficult dual task). The three blocks were counter-balanced across participants in a Latin-square design.

Figure 1 :

 1 Figure 1: Illustration of the visual search task with concurrent auditory detection task used in the present study. Participants searched for a target placed inside a diamond. In half the trials,

Figure 2 :

 2 Figure 2: Results (mean detection accuracy ± SEM) from the auditory target detection task as a function of the group.

Figure 3 :

 3 Figure 3: Left panel. Mean visual search times (± SEM) as a function of the group and the

Table 1 .

 1 Three mutually exclusive hypotheses concerning inhibitory control and attentional resources in schizophrenia.

		Impaired	Preserved	Impaired inhibition,
		inhibition,	inhibition, faulty	faulty resources
		preserved	resources
		resources
	group x distractor	expected	expected	expected
	condition
	group x auditory task	not expected	expected	expected
	difficulty
	group x distractor	not expected	expected	not expected
	condition x auditory
	task difficulty

Table 2 .

 2 Characteristics of the two groups.

			Controls	Schizophrenia
				patients
	N (men/women)	26 (17/9)	26 (17/9)
	Age in years		31.1 (10.4)	31.4 (9.5)
	Years of education	13.1 (1.3)	13.1 (1.9)
	Duration of illness in		12.9 (6.8)
	years
	PANSS Positive		13.3 (3.6)
	PANSS Negative		15.7 (5.03)
	PANSS Psychopathology		27.96 (6.6)
	PANNS Total			56.9 (12.3)
	WAIS-IV			99.9 (17.8)
	Verbal Comprehension
	Index
	WAIS-IV			94.5 (18.1)
	Perceptual	Reasoning
	Index
	Suicide attempt (N)		8/26
	Addictive behavior (N)		20/26
	PANSS, Positive and Negative Symptoms Scale; WAIS-IV, Wechsler Adult Intelligence
	Scale IV.

α = covariance(x,y)/variance(x), where x is the number of targets to be detected (0, 1 or 3) and y is the visual search time.

Acknowledgments

This study received funding support from the CH Le Vinatier Conseil de Recherche (EVINAT project n° CSR Y03). It was also supported by the LABEX CORTEX (ANR-11-LABX-0042) of Université de Lyon, within the program "Investissements d'Avenir" (ANR-11-IDEX-0007) operated by the French National Research Agency (ANR).

Conflict of interest: None.

Data linking: https://recherche.univ-lyon2.fr/etmeco/data/ Michael-et-alSchz.xls.zip


Damien Vasseur

Dr Jonathan Lopez
email: jonathan.lopez@chu-lyon.fr

Sabrina Croce

Garance Tondeur

Lucie Bonin

Françoise Descotes

François Golfier

Mojgan Devouassoux-Shisheboran

Transcriptome profiling of gastric-type endocervical adenocarcinomas identifies key signaling pathways for tumor progression

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

First described by [START_REF] Kojima | Gastric Morphology and Immunophenotype Predict Poor Outcome in Mucinous Adenocarcinoma of the Uterine Cervix[END_REF] [START_REF] Kojima | Gastric Morphology and Immunophenotype Predict Poor Outcome in Mucinous Adenocarcinoma of the Uterine Cervix[END_REF], endocervical adenocarcinoma of gastric-type (G-ECA) has been introduced into the 2014 edition of the World Health Organization (WHO) classification under the category of mucinous endocervical adenocarcinomas [START_REF] Kurman | WHO classification of tumours of female reproductive organs[END_REF]. This category also includes intestinal-type adenocarcinoma (I-ECA) and signet ring cell adenocarcinoma. The intestinal-type is a mucin-producing adenocarcinoma showing tumor glands lined by goblet cells. Gastric-type account for 20% of all endocervical adenocarcinomas in Japan [START_REF] Kojima | Gastric Morphology and Immunophenotype Predict Poor Outcome in Mucinous Adenocarcinoma of the Uterine Cervix[END_REF], and 10% in an international population [START_REF] Stolnicu | International Endocervical Adenocarcinoma Criteria and Classification (IECC): A New Pathogenetic Classification for Invasive Adenocarcinomas of the Endocervix[END_REF]. This entity is characterized by tumor glands resembling gastric and pyloric epithelium with gastric-type mucin and expression of MUC6 in 31 [START_REF] Kojima | Gastric Morphology and Immunophenotype Predict Poor Outcome in Mucinous Adenocarcinoma of the Uterine Cervix[END_REF] to 80% [START_REF] Carleton | A Detailed Immunohistochemical Analysis of a Large Series of Cervical and Vaginal Gastric-type Adenocarcinomas[END_REF] of cases.

Although gastric-type and intestinal-type endocervical adenocarcinomas are both mucinproducing adenocarcinomas and grouped under the same category in 2014 WHO classification, they differ in their pathogenesis. Indeed, the intestinal-type is related to Human Papilloma Virus (HPV) infection and is associated with adenocarcinoma in situ similar to the usual type endocervical adenocarcinoma (U-ECA), while the gastric-type is usually not related to HPV. Adenocarcinoma in situ is rarely considered as its precursor, which seems to be more often lobular endocervical gland hyperplasia [START_REF] Nucci | Lobular endocervical glandular hyperplasia, not otherwise specified: a clinicopathologic analysis of thirteen cases of a distinctive pseudoneoplastic lesion and comparison with fourteen cases of adenoma malignum[END_REF]. Since G-ECA are not associated with HPV infection, p16 is rarely expressed while p53-mutated type immunostaining is seen in 41% of cases [START_REF] Carleton | A Detailed Immunohistochemical Analysis of a Large Series of Cervical and Vaginal Gastric-type Adenocarcinomas[END_REF]. Besides, some patients with G-ECA have been reported with Peutz-Jeghers syndrome, and somatic serine-threonine kinase (STK11) gene mutation is detected in half of the sporadic cases [START_REF] Kuragaki | Mutations in the STK11 gene characterize minimal deviation adenocarcinoma of the uterine cervix[END_REF]. The underlying molecular pathways altered in the gastric-type are not very well known. Recently, a massively-parallel sequencing molecular study has been reported on 14 cases of G-ECA [START_REF] Garg | Molecular characterization of gastric-type endocervical adenocarcinoma using next-generation sequencing[END_REF], showing genetic heterogeneity in these tumors. TP53 was the most recurrently mutated gene followed by mutS homolog 6 (MSH6), cyclin-dependent kinase inhibitor 2A (CDKN2A/B), DNA polymerase epsilon (POLE), SLX4 structure-specific endonuclease subunit (SLX4), AT-rich interaction domain 1A (ARID1A), STK11, BRCA 2 DNA repair associated (BRCA2) and mutS homolog 2 (MSH2). An amplification in MDM2 proto-oncogene (MDM2) gene was reported in two cases without TP53 mutation.

To better investigate the molecular pathogenesis and the metastatic potential of mucinous endocervical adenocarcinoma, including gastric-and intestinal-type ECA, we undertook a molecular study using targeted transcriptomic profiling of a series of these tumors in comparison to usual type endocervical adenocarcinomas (U-ECA).

Methods

Patient's selection:

This is a retrospective study of all recorded cases of endocervical adenocarcinomas between January 2005 and May 2016 at Lyon University Hospital, Hospices Civils de Lyon (Hôtel Dieu, Croix Rousse and Lyon Sud). All HES (Hematoxylin, Eosin, Saffron) slides of 82 cases were reviewed independently by two pathologists (MDS and SC). Among these cases, only 18 met the criteria for mucinous adenocarcinomas (10 G-ECA and 6 I-ECA). We excluded from the study mucinous signet ring cell adenocarcinomas because of the low number (n=2). One case of intestinal-type had scarce tissue material for analysis. Six cases of usual type endocervical adenocarcinomas (U-ECA) were also retrieved from the files and used as controls. For each case, a representative formalin-fixed, paraffinembedded (FFPE) tissue block was selected for the immunohistochemical and molecular studies.

Immunohistochemistry and in situ hybridization (ISH):

The study was performed on Ventana Benchmark automated immunostainers with the following antibodies: p16 (clone E6H4, Ventana-Roche, prediluted), p53 (clone DO-7, Ventana-Roche, prediluted), MUC6 (clone CLH5, Leica, prediluted), claudin 4 (EPRR17575, Abcam, 1/500) occludin (OCLN) (clone OC-3F10, Invitrogen, 1/100) and TRKpan (clone A7H6R, 92991 S, Ozyme, Cell Signaling, 1/50). p16 staining was considered as positive if the stain was nuclear and cytoplasmic and continuous and diffuse. p53 staining was considered as mutated-type if > 80% of nuclei were stained strongly or if negative [START_REF] Köbel | Optimized p53 immunohistochemistry is an accurate predictor of TP53 mutation in ovarian carcinoma: p53 immunohistochemistry predicts TP53 mutation status[END_REF][START_REF] Köbel | Ovarian Carcinoma Histotype: Strengths and Limitations of Integrating Morphology With Immunohistochemical Predictions[END_REF]. MUC6 stain was cytoplasmic.

An immunostaining score was performed for CLDN4 and OCLN by multiplying the percentage of the stained cells by the intensity of staining [START_REF] Kojima | Gastric Morphology and Immunophenotype Predict Poor Outcome in Mucinous Adenocarcinoma of the Uterine Cervix[END_REF][START_REF] Kurman | WHO classification of tumours of female reproductive organs[END_REF][START_REF] Stolnicu | International Endocervical Adenocarcinoma Criteria and Classification (IECC): A New Pathogenetic Classification for Invasive Adenocarcinomas of the Endocervix[END_REF].

We performed ISH to detect HPV DNA using a biotinylated DNA probe set (Kit ISH Iview Blue Plus, Ventana-Roche) according to the manufacturer's protocols. Nuclear dot signals were considered positive. 2.3. NanoString analysis: RNAs were extracted from FFPE tumors. Depending on the size of each lesion between two and six 5-µm slides were used. Slides were first dewaxed with two baths of D-Limonene (2min) and a bath of Absolut Ethanol (2min). RNA extraction was then performed using High Pure FFPET RNA Isolation Kit (Roche, Switzerland, #06483852001).

Depending on concentrations, hybridization with Human PanCancer Progression probes (Nanostring Technologies, USA, #XT-CSO-PROG1-12) was performed using 88 ng to 175ng RNA, according to manufacturer instructions. This panel targets 770 mRNA involved in cancer progression, invasion and metastases plus 30 housekeeping genes for normalization.

After 19 hours of incubation at 65°C, samples were processed on a Nanostring nCounter FLEX platform. Raw counts for individual digital molecular barcodes were normalized on six positive internal controls and thirty housekeeping genes using nSolver 4.0 analysis software (Nanostring Technologies, USA). The background was estimated from blank wells and six negative internal controls and removed from raw counts. 2.4. Statistical Analysis: Expression of the 770 genes was compared between gastric-, intestinal-and usual-type ECA. For each gene, a fold change ratio and FDR-adjusted p-value were computed. To visualize the differences observed between our two populations, we used R Studio software (v1.1.463) and generated heatmaps, Principal Component Analysis (PCA) and correlogram. Heatmaps were built using heatmap.3 from gplots 3.0.0 R package.

PCA and biplot were obtained using factomineR 1.41 and factoextra 1.0.5 R packages, respectively. Keeping two components for PCA explained 70.3% of the total variance (55.6% for PC1 and 14.7% for PC2). Correlogram resulted from a Pearson test with an alpha=0.05 and was realized using corrplot 0.84 R package. Network analysis was performed using STRING database (https://string-db.org/). Finally, Welch two-sample test used to compare the level of expression of OCLN and CLDN4 was performed using the t-test function on R.

Results

Clinical presentation, histopathology and immunostainings

The immunohistochemical study was performed on 22 ECA, organized into three groups of G-ECA, I-ECA and U-ECA.

Ten cases showed the characteristic morphology of gastric-type adenocarcinomas [START_REF] Pirog | Gastric-type Adenocarcinoma of the Cervix: Tumor With Wide Range of Histologic Appearances[END_REF]. Eight tumors were composed of glands of various sizes, occasionally presenting intraluminal papillae, lined by very large cells with distinct cell borders and clear or pale cytoplasm, sometimes with foamy or densely eosinophilic cytoplasms (Figure 1A). Two cases showed the morphology of minimal deviation adenocarcinoma, which is a very well-differentiated variant of G-ECA, with large and cystic glands infiltrating the cervical stroma. The nuclei were very bland in the well-differentiated variant while they showed atypia with prominent nucleoli in the six classic G-ECA. On immunohistochemical study, all but four cases of classic G-ECA were positively stained with MUC6. These four MUC6 negative cases were excluded from the study. Only cases with no doubt on the gastric-type differentiation were included in the molecular analyses (n = 6). All the 6 cases of G-ECA were P16 and HPV negative. One case showed a mutated p53 immune profile. In this group, patients' age ranged from 32 to 51, with a mean of 42.3 years. The FIGO stage at diagnosis was IB in 4 and IIA in 2 cases.

Five cases showed the characteristic morphology of I-ECA. They were composed of tumor glands entirely lined by mucin-producing goblet cells (Figure 1B). In three cases, a colloid pattern was seen with pools of mucin dissecting the cervical stroma, associated with intestinal-type malignant glands. All cases of I-ECA were p16 and HPV positive and showed a wild-type immune profile for p53. Three cases stained for MUC6. In this group, patients' age ranged from 29 to 70, with a mean of 43 years. The FIGO stage at diagnosis was IB in 4 and IA2 in one case.

Six cases of U-ECA showed a well-differentiated proliferation of glands lined by stratified columnar cells with no or very little endocervical type mucin, showing many mitoses and apoptotic bodies (Figure 1C). All these cases were p16 and HPV positive, MUC6 negative and showed a wild-type immune profile for p53. In this group, patients' age ranged from 34 to 62, with a mean of 44.5 years. The FIGO stage at diagnosis was IB in 5 cases and IA2 in the last case.

Differentially-expressed genes between mucinous and usual-type ECA

First, we compared mucinous (G-ECA plus I-ECA groups) versus usual type adenocarcinomas (U-ECA) to identify candidate genes capable of discriminating these two entities.

Differentially-expressed genes were ranked on False Discovery Rate (FDR)-adjusted p-values. Setting up the FDR cut-off at 0.2, we retained nine candidate genes: neurotrophic receptor tyrosine kinase 1 (NTRK1), KiSS-1 metastasis suppressor (KISS1), somatostatin receptor 2 (SSTR2), occludin (OCLN), sphingosine-1-phosphate receptor 1 (S1PR1), TAL bHLH transcription factor 1 (TAL1), thromboxane A2 receptor (TBXA2R), thrombospondin 4 (THBS4) and vav guanine nucleotide exchange factor 3 (VAV3). Most of the genes were less expressed in the usual type compared to mucinous endocervical carcinomas except for OCLN and VAV3 with fold changes of +2.6 and +5.7, respectively (Supplementary Table 1).

Hierarchical clustering heatmap confirmed the robustness of this nine-genes signature to discriminate the mucinous from U-ECA (Figure 2A). The distance matrix representation (Figure 2B) objectifies that U-ECA cases form a homogeneous group wide-different from mucinous ECA. As expected, it also emphasizes that mucinous carcinoma is a more heterogeneous entity at the molecular level.

One of the most discriminant gene between mucinous (G-ECA plus I-ECA groups) and U-ECA was OCLN. This gene encodes a membrane protein localized in tight junctions. The level of expression of this gene (Nanostring counts) was statistically decreased in mucinous ECA when compared to the U-ECA (p=0.001 at 95% CI). We confirmed the loss of OCLN at the protein level by immunohistochemistry (p=0.005 at 95% CI). Importantly, levels of CLDN4, another essential protein of the tight junction, were also significantly decreased in both gastric and intestinal types (p-value=0.036 at a risk α=5%) (Figure 3). These results point out to tight junctions' disruptions as a potential mechanism explaining the aggressive phenotype of these rare tumors.

Comparison of genes expression between gastric-type and intestinal-type ECA

To further explore the phenotypic heterogeneity of mucinous ECA, we compared genes expression profiles between G-ECA and I-ECA. Using the same filtering strategy, we identified 11 differentially-expressed genes (Supplementary Table 2) able to segregate these two mucinous subtypes. Heatmap of these genes demonstrated a clear clustering of I-ECA and G-ECA (Figure 4A). Compared to the intestinal type, the gastric type ECA presented with high levels of PPFIA binding protein 2 (PPFIBP2), DENN domain-containing 5A (DENND5A), asporin (ASPN), GATA binding protein 4 (GATA4), vascular endothelial growth factor B (VEGFB) and zinc finger FYVE-type containing 16 (ZFYVE16). On the other hand, the intestinal-type endocervical carcinomas presented high expression of heat shock protein 90 beta family member 1 (HSP90B1), AKT serine/threonine kinase 1 (AKT1), ribosomal protein S6 kinase B2 (RPS6KB2), eukaryotic translation initiation factor 2 alpha kinase 3 (EIF2AK3) and PTTG1 regulator of sister chromatid separation (PTTG1) (Figure 4A). Using the STRING database to test functional protein association networks, we identified a strong implication of the AKT pathway in differentiating gastric from intestinal types with six out of the eleven differentially-expressed genes included in this pathway: HSP90B1, AKT1, RPS6KB2 and EIF2AK3 high in I-ECA versus GATA4 and VEGFB high in G-ECA (Figure 4B). Altogether, these results emphasized that gastric-and intestinal-type ECA activate distinct signaling pathways.

Comparison of HPV-related and gastric-type endocervical adenocarcinomas

When comparing gastric-type with HPV related endocervical adenocarcinomas (intestinal and usual types), two discriminant genes were identified: RB transcriptional corepressor like 1 (RBL1) (FDR=0.02) and CDKN2A (FDR=0.09). We then built up a composite a geneexpression signature capable of classifying these three entities. We associated the nine genes of the first signature segregating mucinous from U-ECA to the two most discriminant genes of the I-ECA versus G-ECA signature. We obtained an 11-gene signature based on the expression of EIF2AK3 (high in I-ECA), PPFIBP2 (high in G-ECA compared to I-ECA), NTRK1, KISS1, SSTR2, TAL1, S1PR1, TBXA2R, THBS4 (low in U-ECA) and OCLN and VAV3 (high in U-ECA). This composite signature was able to cluster the three subtypes (Figure 5A) efficiently.

Next, we performed a PCA using two dimensions (Figure 5B). The first dimension which explains 55.6% of the total variance, opposes all U-ECA samples plus I3 with high levels of expression of VAV3, OCLN and PPFIBP2 to mucinous ECA with high levels of expression of the others genes (most contributory: SSTR2, NTRK1, S1PR1, KISS1 and TAL1). Higher expression of neurotrophic receptor tyrosine kinase 1 (NTRK1) transcript was observed in both intestinal-and gastric-type endocervical adenocarcinomas. The second dimension explained 14.7% of the total variance. It allowed distinguishing the intestinal type with high expression of TBXA2R and EIF2AK3 from the gastric type of carcinomas of the cervix. The most contributory genes overexpressed in G-ECA were PPFIBP2 and TAL1.

The matrix correlogram (Figure 6) confirmed the positive correlation between VAV3 and OCLN (high in the usual type, r²= 0.84) and the negative correlation of these two genes with all the others. In mucinous endocervical adenocarcinomas, the two pairs of overexpressed genes most positively correlated were: NTRK1/SSTR2 and TAL1/SSTR2 (r²=0.83 and 0.81 respectively).

Discussion

Here we describe a gene-expression signature composed of 11 genes which allows the distinction between the three most frequent type of ECA, usual type, gastric-type and intestinal-type (Figure 5). Given the small size of this cohort due to the rarity of these tumors, this set of genes needs to be further validated in an independent cohort.

Nevertheless, this study points out to relevant biological functions that might explain the differential metastatic potential of these three entities and provide new therapeutic opportunities.

The mucinous adenocarcinoma of the cervix comprises two different subtypes of carcinomas with distinct biology and behavior. Indeed, G-ECA is a non-HPV-related carcinoma with important differences in tumor behavior and patient survival. Patients with G-ECA have a significantly worse clinical outcome, even when matched for stage and G-ECA more frequently metastasize to distant sites, including viscera and peritoneum when compared to usual-type adenocarcinoma [START_REF] Karamurzin | Gastrictype Endocervical Adenocarcinoma: An Aggressive Tumor With Unusual Metastatic Patterns and Poor Prognosis[END_REF]. However, I-ECA lumped together with the G-ECA under the same category by 2014 WHO classification, have a histogenesis and clinical behavior closer to usual-type ECA than G-ECA. Indeed, I-ECA is HPV-related and has the same prognosis as the usual-type adenocarcinoma when matched for the stage. A new international classification of endocervical adenocarcinoma recommends to classify uterine cervical carcinomas in two categories of HPV-associated (usual or mucinous, essentially intestinal) and HPV unassociated (gastric, clear cell, endometrioid, mesonephric) carcinomas [START_REF] Stolnicu | International Endocervical Adenocarcinoma Criteria and Classification (IECC): A New Pathogenetic Classification for Invasive Adenocarcinomas of the Endocervix[END_REF]. Indeed, when comparing HPV-dependent ECA (I-ECA and U-ECA) with non-HPV-related ECA (G-ECA) in our series, two discriminant genes were identified, RBL1 and CDKN2A. These two cell cycle regulators have already been found to be more expressed in HPV-positive oropharyngeal squamous cell carcinomas compared to the HPV-negative forms [START_REF] Martinez | Identification of differentially expressed genes in HPV-positive and HPV-negative oropharyngeal squamous cell carcinomas[END_REF].

However, our study also shows that intestinal-type ECA has a distinct molecular signature that differs from U-ECA.

We report a significant increase of expression of NTRK1 transcript in both intestinal and gastric types ECA when compared to the usual type (Figures 2 &5, Supplementary Table 1).

NTRK1 is a receptor for the nerve growth factor and is overexpressed in lung [START_REF] Vaishnavi | Oncogenic and drug-sensitive NTRK1 rearrangements in lung cancer[END_REF], thyroid [START_REF] Greco | Rearrangements of NTRK1 gene in papillary thyroid carcinoma[END_REF] and many other cancers, mainly by gene fusion mechanisms. However, we were not able to detect any NTRK1 fusion in our samples nor to objectify its overexpression at the protein level using a panTRK antibody. This discrepancy between RNA and protein might be explained by a lack of sensitivity of the immunohistochemical staining due to: 1/ a weak level of basal expression in U-ECA (RNA counts 22,26 ± 2,84 compared to 370,62 ± 96,53 for OCLN) and 2/ a fold-change of 1.85 between the 2 groups (but highly significant with an FDR-adjusted p-value of 0.04). Additional studies are needed on a more significant number of mucinous ECA to confirm this finding.

Intestinal-and gastric-type ECA are sharing common transcriptomic patterns that allow to distinguish them from the usual-type ECA (Figure 2). Among them, the loss of occludin and claudin 4 (Figure 3) that lead to tight junctions disruptions may explain the difference in their metastatic potential. Loss of OCLN in breast cancer has been associated with modification of the membrane permeability and metastatic disease [START_REF] Martin | Loss of occludin leads to the progression of human breast cancer[END_REF]. Reduced expression of OCLN by hypermethylation of its promoter also decrease sensitivity to apoptotic cell death [START_REF] Osanai | Epigenetic Silencing of Occludin Promotes Tumorigenic and Metastatic Properties of Cancer Cells via Modulations of Unique Sets of Apoptosis-Associated Genes[END_REF].

Other genes involved in cell adhesion and metastatic dissemination pathways were also altered. THBS4, another protein involved in cell-cell adhesion and the remodeling of the extracellular matrix, was overexpressed in mucinous compared to usual-type ECA.

Importantly THBS4 gene was reported to facilitate invasion and dissemination of tumor cells in gastric [START_REF] Förster | THBS4, a novel stromal molecule of diffuse-type gastric adenocarcinomas, identified by transcriptome-wide expression profiling[END_REF], colorectal [START_REF] Greco | Thrombospondin-4 is a putative tumour-suppressor gene in colorectal cancer that exhibits age-related methylation[END_REF], prostate [START_REF] Dakhova | Global Gene Expression Analysis of Reactive Stroma in Prostate Cancer[END_REF] and breast cancer [START_REF] Reed | Thrombospondin-4 expression is activated during the stromal response to invasive breast cancer[END_REF]. We also observed an increase of S1PR1 gene expression in mucinous carcinomas (I-ECA and G-ECA). S1PR1 has been identified as a target to inhibit signal transducer and activator of transcription 3 (STAT3) signaling in DLBCL [START_REF] Liu | S1PR1 is an effective target to block STAT3 signaling in activated B cell-like diffuse large B-cell lymphoma[END_REF]. After secretion of S1P by tumor cells, the S1P-S1PR1 complex promotes resistance to apoptosis, cell proliferation and migration and increased resistance to treatment [START_REF] Ogretmen | Sphingolipid metabolism in cancer signalling and therapy[END_REF]. This receptor is also implicated in the tumor neovascularization [START_REF] Chae | Requirement for sphingosine 1-phosphate receptor-1 in tumor angiogenesis demonstrated by in vivo RNA interference[END_REF]. High levels of S1PR1 are therefore associated with a more aggressive disease with a higher risk of metastases. TBXA2R gene encodes a G proteincoupled receptor. The oncogenic role of this receptor has been well described. TBXA2R gene was reported to increase tumor cell migration in prostate cancer [START_REF] Nie | Thromboxane A2 Receptors in Prostate Carcinoma: Expression and Its Role in Regulating Cell Motility via Small GTPase Rho[END_REF], to reduce diseasefree survival in breast cancer [START_REF] Watkins | Expression of thromboxane synthase, TBXAS1 and the thromboxane A2 receptor, TBXA2R, in human breast cancer[END_REF] and to increase cell proliferation in lung cancer [START_REF] Li | Activation of thromboxane A2 receptors induces orphan nuclear receptor Nurr1 expression and stimulates cell proliferation in human lung cancer cells[END_REF]. Here we describe a significantly higher TBXA2R gene expression in intestinal-and gastric-type compared to usual-type ECA. KISS1 gene is another interesting player in cancer. It encodes a ligand of a G protein-coupled receptor called GPR54. KISS1 has been initially described as a tumor suppressor and anti-metastatic gene in numerous cancers such as melanoma [START_REF] Lee | KiSS-1, a Novel Human Malignant Melanoma Metastasis-Suppressor Gene[END_REF], bladder [START_REF] Sanchez-Carbayo | Tumor Suppressor Role of KiSS-1 in Bladder Cancer[END_REF], breast [START_REF] Lee | Suppression of Metastasis in Human Breast Carcinoma MDA-MB-435 Cells after Transfection with the Metastasis Suppressor Gene, <em>KiSS-1</em>[END_REF] and lung cancers [START_REF] Zheng | Expression of KISS1 and MMP-9 in non-small cell lung cancer and their relations to metastasis and survival[END_REF]. Surprisingly, we observed higher levels of KISS1 in mucinous carcinomas as compared to U-ECA. Similar results were reported in breast [START_REF] Martin | KiSS-1 Expression in Human Breast Cancer[END_REF] and thyroid [START_REF] Savvidis | The role of KISS1/KISS1R system in tumor growth and invasion of differentiated thyroid cancer[END_REF] cancers with significantly higher expression of KISS1 in patients with aggressive tumors and dissemination potential. Thus, KISS1 seems to play a dual role in cancer development. There was also a significant difference in the expression of TAL1, VAV3 and SSTR2 in U-ECA and mucinous intestinal and gastric type carcinomas. VAV3 is underexpressed in mucinous carcinomas whereas TAL1 and SSTR2 are overexpressed in these tumors when compared to usual type U-ECA. However, the biological significance of these three genes has to be further explored.

Altogether, these findings show that at the molecular level, I-ECA differs from U-ECA and shares molecular similarities with G-ECA. Indeed, loss of OCLN and VAV3 and increased expression of TAL1, SSTR2, THBS4, S1PR1, TBXA2R and KISS1 are molecular characteristics of mucinous carcinomas, of intestinal and gastric type and may explain in part their metastatic potential.

If intestinal and gastric types share some common signaling pathways, they are also distinguishable based on the expression of two genes: EIF2AK3 and PPFIBP2. EIF2AK3 is increased in I-ECA compared to G-ECA and U-ECA. This gene encodes a kinase localized at the endoplasmic reticulum. This enzyme phosphorylates the alpha subunit of EIF2 in the unfolded protein response pathway, leading to inhibition of the translation. Also known as PERK, this protein has been involved in normal intestinal epithelial stem cell differentiation under homeostatic conditions [START_REF] Heijmans | ER Stress Causes Rapid Loss of Intestinal Epithelial Stemness through Activation of the Unfolded Protein Response[END_REF]. Levels of PPFIBP2 are twice lower in I-ECA than in G-ECA (Figure 5). Also known as liprin-β2, this gene encodes a protein member of the LAR family involved in axon guidance and neuronal synapse development [START_REF] Serra-Pagès | Liprins, a Family of LAR Transmembrane Protein-tyrosine Phosphatase-interacting Proteins[END_REF]. Recently high levels of expression have been negatively associated with breast tumor cell motility and invasion by inhibiting the degradation of the extracellular matrix [START_REF] Chiaretti | Effects of the scaffold proteins liprin-α1, β1 and β2 on invasion by breast cancer cells[END_REF].

In conclusion, we identified a distinct molecular profile for the three most frequent categories of ECA, distinguishing U-ECA from G-ECA and I-ECA. Although, both U-ECA and I-ECA are HPV-related, they have a different molecular pattern justifying their diagnosis as separate entities.

Declaration of competing interest: None

Financial support :

 support Lyon University Hospital (Hospices Civils de Lyon) Author contributions: Damien Vasseur: Formal analysis, Data curation, Writing original draft; Jonathan Lopez: Conceptualization, Data curation, Methodology, Project administration, Supervision, Validation, Writing review & editing; Sabrina Croce: Data curation, Formal analysis, Resources, Writing review & editing; Garance Tondeur: Formal analysis, Writing original draft; Lucie Bonin: Resources; Françoise Descotes: Data curation, Supervision, Writing review and editing; François Golfier: Resources, Writing review and editing; Mojgan Devouassoux-Shisheboran: Conceptualization, Data curation, Formal analysis, Resources, Writing review & editing, Funding.

Figure 1 :

 1 Figure 1: Hematoxylin and Eosin (H&E) Staining of the three groups of endocervical

Figure 2 :

 2 Figure 2: Gene-expression signature to distinguish usual-type from mucinous carcinomas. A.

Figure 3 :

 3 Figure 3: Immunohistochemical study of occludin (A and C) and claudin 4 (B and D) in

Figure 4 :

 4 Figure 4: Molecular differences between gastric and intestinal types. A. Heatmap based on

Figure 5 :

 5 Figure 5: Composite gene expression signature to classify usual-, intestinal-and gastric-type

Figure 6 :

 6 Figure 6: Correlation matrix. Orange's dots are for strong positive correlation, whereas light

Acknowledgments

also points out to disruption of tight junctions as a potential mechanism of metastatic dissemination of these rare tumors.


Louis Marin

Sacha Nahon-Esteve

Elsa Toumi

Arnaud Martel
email: martel.a@chu-nice.fr

De

MD Martel Arnaud

Keywords: Etude anatomique, voie d'abord rétro-caronculaire, dacryocystorhinostomie, décompression orbitaire, fixation périostée du globe oculaire Anatomical study, retro-caruncular approach, dacryocystorhinostomy, orbital decompression, eyeball periosteal fixation Bases anatomiques Etude anatomique, voie d'abord rétro-caronculaire, dacryocystorhinostomie, décompression orbitaire, fixation périostée du globe oculaire Anatomical study, retro-caruncular approach, dacryocystorhinostomy, orbital decompression, eyeball periosteal fixation

Bases anatomiques de la voie rétro-caronculaire et ses applications cliniques en oculoplastique : étude sur cadavre.

RESUME :

Objectif : décrire les rapports anatomiques de la voie d'abord rétro-caronculaire ainsi que des ses applications cliniques en oculo-plastique à partir d'une étude conduite au laboratoire d'anatomie.

INTRODUCTION :

La voie d'abord rétro-caronculaire est une voie mini-invasive décrite pour la première fois par Shorr et al. en 2000 pour permettre l'abord chirurgical de la partie médiale et postéro-médiale de l'orbite. [START_REF] Shorr | Transcaruncular approach to the medial orbit and orbital apex[END_REF] Elle est régulièrement utilisée par nos collègues maxillo-faciaux dans le cadre des reconstructions des fractures de la paroi médiale de l'orbite. [START_REF] Choi | Medial orbital wall fractures and the transcaruncular approach[END_REF] La voie d'abord retro caronculaire est beaucoup moins utilisée par les oculoplasticiens. [START_REF] Adenis | Retrocaruncular approach to the medial orbit for dacryocystorhinostomy[END_REF] Son principal avantage est sa rançon cicatricielle nulle comparativement à une voie d'abord cutanée externe traditionnelle, telle que réalisée dans la dacryocystorhinostomie (DCR). [START_REF] Heichel | Diagnostics and treatment of lacrimal duct diseases : A structured patient-centred care concept[END_REF] La difficulté principale repose sur l'étroitesse du champ visuel per opératoire et sa courbe d'apprentissage. [START_REF] Kaynak | Transconjunctival dacryocystorhinostomy: Long term results[END_REF] L'objectif de notre étude était de décrire les rapports anatomiques de la voie d'abord rétro-caronculaire ainsi que des ses applications cliniques en oculo-plastique à partir d'une étude conduite au laboratoire d'anatomie.

PATIENTS ET METHODES :

8 orbites provenant de 4 cadavres frais ont été disséquées au laboratoire d'anatomie de la faculté de médecine de Nice entre Octobre 2018 et janvier 2019.

RESULTATS : 1) DESCRIPTION DE LA VOIE D'ABORD ET PRINCIPAUX RAPPORTS

ANATOMIQUES

Les paupières étaient rétractées médialement par des fils de traction. Une injection sous conjonctivale de sérum physiologique permettait une hydro dissection de l'espace situé entre la caroncule et le repli semi lunaire (Figure 1A). Une incision de 15mm était réalisée entre le repli semi lunaire et la caroncule à la lame de 15. La dissection était réalisée avec des ciseaux de Stevens en direction de la crête lacrymale postérieure (avec 30° d'inclinaison postérieure) (Figure 1B). Une lame malléable était introduite afin de refouler la graisse orbitaire. Une incision périostée était réalisée à la lame de 15 (Figure 1C). Le périoste était ensuite récliné postérieurement à l'aide d'un décolleur (Figure 1D) avec précaution afin de ne pas léser la lame papyracée ethmoïdale. Le muscle de Horner était identifié (Figure 1E) puis chargé par un écarteur de Desmarres afin de le protéger. Une incision cutanée (incision de Lynch) permettait d'évaluer les rapports anatomiques entre l'incision rétro-caronculaire et la crête lacrymale antérieure. La crête lacrymale antérieure était située en moyenne à 0,6 +/-0,2 cm en avant de l'incision rétro caronculaire (Figure 1F).

• Rapports anatomiques postérieurs :

La dissection était maintenue dans un plan sous périosté et prolongée dans un plan postérieur. Le premier rapport anatomique rencontré était le foramen ethmoïdal antérieur (Figure 2A) localisé en moyenne à 2,2 +/-0,3 cm en arrière de l'incision retro-caronculaire (Figure 2B). Le second rapport anatomique rencontré était le foramen ethmoïdal postérieur situé à environ 1 +/-0,2 cm en arrière du foramen ethmoïdal antérieur (Figure 2C). Le foramen optique était palpé en moyenne 0,5cm en arrière du foramen ethmoïdal postérieur (Figure 2D). Le septum orbitaire était incisé et la graisse orbitaire réséquée. Le muscle droit médial était ensuite chargé (Figure 2E) afin de délimiter l'espace intra et extra conique.

• Rapports anatomiques supérieurs :

Le principal rapport anatomique rencontré en supérieur était la poulie du muscle oblique supérieur (Figure 3 et vidéo N°1).

• Rapports anatomiques antérieurs :

Les rapports anatomiques étaient évalués à l'aide d'une incision cutanée antérieure (incision de Lynch). La voie d'abord rétro-caronculaire permettait un accès postérieur au muscle de Duverney-Horner. La dissection sous périostée était poursuivie en antérieur et permettait le décollement de la loge lacrymale (Figure 4) jusqu'à la crête lacrymale antérieure située en moyenne à 0,6 +/-0,2 cm de la projection orbitaire de l'incision rétro-caronculaire (Vidéo N°2).

• Rapports anatomiques inférieurs :

La dissection était poursuivie par voie sous périostée en inférieur. Le premier rapport anatomique rencontré était le canal lacrymo-nasal (Figure 4). Quelques millimètres en dehors, l'insertion du muscle oblique inférieur était identifiée. (Vidéo n°3)

• Rapports anatomiques en fonction de l'abord pré-ou rétro-caronculaire :

La projection orbitaire de la voie rétro-caronculaire se situe en arrière du sac lacrymal (figure 5A). La projection orbitaire de la voie pré-caronculaire se situe en regard de la portion haute du sac lacrymal. Il existe, à ce niveau, un risque de plaie iatrogène sacculaire (Figure 5B granulomes conjonctivaux (7,4% pour Kaynak contre 5% pour Ganguly) , symblépharon (3% pour les 2 séries) et des érosions cornéennes. Les difficultés opératoires sont liées à l'étroitesse du champ opératoire avec notamment un prolapsus de graisse orbitaire voire une lacération de la voie lacrymale. L'issue de la graisse orbitaire dans le champ opératoire peut induire un hématome rétro-septal ou un échec chirurgical par incarcération de la graisse dans le site de rhinostomie. Une plaie du muscle oblique inférieur est rare mais cause de diplopie irréversible [START_REF] Kaynak | Transconjunctival dacryocystorhinostomy: Long term results[END_REF]. Une conversion ou une reprise est possible par voie externe cutanée.

2) Réparation des fractures de la paroi médiale de l'orbite:

La chirurgie d'une fracture de la paroi médiale de l'orbite permet de prévenir et/ou traiter la diplopie binoculaire et l'énophtalmie. Shen et al ont retrouvé dans leur série une diminution de 88% des énophtalmies préopératoires supérieure à 2 mm et une réduction des limitations oculomotrices de 73%. [START_REF] Shen | Retrocaruncular approach for the repair of medial orbital wall fractures: an anatomical and clinical study[END_REF] L'incision peut être étendue jusqu'au fornix inférieur permettant l'accès à la paroi inféro-médiale de l'orbite lors de fractures multiples de l'orbite. Les fractures de la paroi médiale associées aux fractures de la paroi inférieure représentent 7 à 12% des fractures de l'orbite. [START_REF] Pedemonte | Reconstruction of medial orbital wall using a retrocaruncular approach[END_REF] La revue de la littérature de Choi et al. rapporte un taux de complications de 2.6% pour 228 réparations de fractures médiales de la paroi de l'orbite par voie rétro-caronculaire.

  Patients et méthode : 8 orbites provenant de 4 cadavres frais ont été disséquées au laboratoire d'anatomie de la faculté de médecine de Nice entre Octobre 2018 et Janvier 2019. Résultats : les principaux rapports anatomiques rencontrés sont le muscle de Duverney Horner et le sac lacrymal en avant, les artères ethmoïdales antérieures, postérieures et l'ethmoïde en arrière, la poulie du muscle oblique supérieur vers le haut, le canal lacrymo-nasal et le tendon d'insertion du muscle oblique inférieur vers le bas. La voie d'abord rétro-caronculaire permet d'aborder l'orbite postérieurement au sac lacrymal et au muscle de Duverney Horner permettant une meilleure protection de ces derniers. La voie d'abord rétro-caronculaire permet la réalisation de plusieurs procédures oculoplastiques : la dacryocystorhinostomie, la réparation des fractures orbitaires médiales, la décompression de la paroi médiale de l'orbite, la biopsie de tumeurs extraconiques médiales et la pexie périostée du globe oculaire en cas de paralysie complète du III. Conclusion : La voie d'abord rétro-caronculaire est une voie fiable permettant de s'affranchir d'une cicatrice cutanée. Elle permet un abord large de la portion médiale de l'orbite même si le champ opératoire est plus réduit que celui obtenu en cas d'abord cutané. Elle nécessite une connaissance anatomique précise et une courbe d'apprentissage accrue.

Figure 6 +

 6 Figure 6 + Vidéo N°5

Figure 7 C 9 E 1 )

 791 Figure 7

[ 7 ]

 7 L'abord cutané de Lynch permet une exposition chirurgicale large de la portion antéro-supérieure de la paroi médiale, sans toutefois offrir un accès correct à la portion postéro-médiale, zone stratégique dans la prévention de l'enophtalmie post-traumatique.[8] Parmi les autres techniques (voie palpébrale supéro-médiale, inférieure sous ciliaire ou transconjonctivale), seule la voie d'abord coronale expose la totalité de la paroi médiale, mais son indication est limitée en traumatologie orbitaire isolée.[9] L'abord rétro-caronculaire permet une visualisation directe de la paroi médiale jusqu'à l'apex orbitaire. Elle permet une réduction satisfaisante du foyer de fracture et l'insertion d'un implant orbitaire [10].

[ 2 ] 3 ) 4 ) 5 ) 6 )

 23456 Les complications de la voie rétro-caronculaire dans cette indication sont mineures et le plus souvent transitoires (granulomes conjonctivaux, symblépharon, érosions cornéennes) [13]. Une désinsertion du muscle oblique inférieur lors de la pose d'implant puis sa réinsertion peut conduire à une diplopie post-opératoire [14]. Fixation périostée dans les paralysies du III: Le traitement chirurgical des paralysies du III complètes est complexe. Dans un premier temps, la déviation incomittante doit être prise en charge. Lorsque la transposition musculaire n'est pas possible dans la chirurgie d'une paralysie oculomotrice, la fixation du globe à l'orbite couplée à l'affaiblissement du muscle antagoniste permet le réalignement de l'axe visuel en position primaire [15]. La pexie du globe au périoste orbitaire interne par voie rétro-caronculaire a été réalisée par plusieurs équipes avec d'excellents résultats anatomiques et fonctionnels. Saxena et al. ont récemment publié une série de 14 yeux opérés par fixation périostée par voie rétro-caronculaire via des sutures de polyester 5-0. La déviation horizontale moyenne a été corrigée de 90° (+/-4,8) à 10° (+/-8,3) en post-opératoire avec un suivi moyen de 8,9 mois (range, 6-21 mois). Un alignement était satisfaisant dans 13 des 14 yeux (92,8%).[16] D'autres matériaux de fixation périostée ont été utilisés dans la littérature. Dans la série de Villaseñor et al., 11 yeux sur 15 (73,3%) étaient alignés grâce à l'utilisation du tendon du muscle oblique supérieur par voie rétro-caronculaire avec un suivi moyen de 19 mois (range, 8-41 mois).[17] Goldberg et al. constataient une réduction de la déviation strabique de 49,5° à 9° sur une série de 5 patients au terme d'un suivi moyen de 15 mois grâce à l'utilisation d'un lambeau périosté levé par voie rétro-caronculaire.[18] Décompression orbitaire : La voie rétro-caronculaire permet la réalisation d'une décompression de la paroi médiale très postérieure. Etendue en inférieure via une voie transconjonctivale, l'effondrement de la paroi médiale du plancher de l'orbite peut y être associée avec une réduction de l'exophtalmie de 3 à 6 mm en moyenne selon les séries [19]. Une lipectomie peut être associée dans le même temps opératoire, même si la loge inféro-externe est généralement préférée. Décompression du canal optique dans les neuropathies optiques compressives : La prise en charge de la neuropathie optique post traumatique est débattue. En cas d'esquille osseuse, une décompression du canal optique peut être réalisée. La décompression endoscopique endonasale est la plus fréquemment réalisée mais nécessite un équipement et des opérateurs rompus à ce type d'intervention en urgence.[20] La voie d'abord rétro-caronculaire permet un accès satisfaisant au canal optique, après coagulation des artères ethmoïdales antérieures et postérieures.[21] L'exposition est, au mieux, réalisée à l'aide d'un endoscope endonasal.[22] Le maniement des instruments est délicat compte tenu de l'étroitesse de l'espace entre le globe oculaire et la paroi médiale de l'orbite. Une étude étude préliminaire conduite par Méningaud et al. a démontré la faisabilité de la voie d'abord rétro-caronculaire assistée par endoscopie.[23] Biopsie de tumeurs extra-coniques médiales : La voie rétro-caronculaire permet également la biopsie des tumeurs orbitaires extra coniques internes. Le traitement des mucocèles frontales est au mieux réalisé par voie endoscopique endonasale. [24][25] CONCLUSION : Depuis sa première description en 2000 par Shorr et al. [1], la voie d'abord rétrocaronculaire s'est imposée comme un abord fiable et esthétiquement supérieur aux voies d'abord cutanées dans la prise en charge des pathologies intéressant la paroi médiale de l'orbite. L'abord rétro-caronculaire peut facilement être étendu en inférieur par voie transconjonctivale permettant un jour chirurgical satisfaisant dans la prise en charge de la traumatologie orbitaire et des décompressions orbitaires. Sa principale limitation réside dans sa faible exposition nécessitant une bonne connaissance anatomique et une courbe d'apprentissage accrue. REMERCIEMENTS : Benjamin Maes, Technicien en anatomie, Faculté de médecine de Nice Sophia Antipolis, France.

Figure 1 :Figure 2 :Figure 3 :Figure 4 :

 1234 Figure 1 : Rapports anatomiques de la voie rétro-caronculaire

Figure 5 :

 5 Figure 5 : Rapports anatomiques en fonction du caractère pré ou rétro-

Figure 6 :

 6 Figure 6 : DCR par voie retro-caronculaire

Figure 7 :

 7 Figure 7 : Traitement chirurgical d'une fracture de la paroi médiale de l'orbite

Figure 8 :

 8 Figure 8 : Décompression orbitaire médiale par voie rétro-caronculaire

Figure 9 :Figure 10 :

 910 Figure 9 : Décompression du canal optique par voie rétro-caronculaire