This study included patients surgically treated in the ENT department for bilateral immobility of the vocal cords from January 1, 2008 to March 31, 2018 (10 years 3 months).

46 patients were included, with exactly half of each sex for a sex ratio of 1. The mean age of patients was 56 ± 17 years ranging between 14 and 89 years.

· Surgical technique

Partial arytenoidectomy, cordopexy, and posterior cordectomy were performed in 43 patients (93.5% of cases). Figure 2 shows the distribution of patients by type of intervention.

Table 1 shows the relationship between the positioning of the immobile vocal cords and the type of intervention.

· The operating time

18 patients (39.13%) were taken to the emergency operating room in less than six hours. The others were operated in less than 30 days, with a 1 month to 12 months delay, or after 12 months in 8 cases (17.39%), 12 cases (26.09%) and 8 cases (17.39%) respectively.

· Post-operative follow-up

Postoperative complications were reported in 18 cases (39.1%) of the study population. We registered postoperative bleeding (2 cases; 4.35%), recurrence of

glottic stenosis (2 cases; 4.35%). Both cases of bleeding from the surgical site benefited from haemostasis by adrenaline infused gauze under general anaesthesia with favourable outcomes. Revision enlargement surgery has been performed in cases of recurrence of glottic stenosis. 11 patients presented false routes that regressed after 10 readaptative sessions on average (between 6 and 20 sessions).

Male patients accounted for exactly half of our study population. Min Y.J. et al. [8] reported 59.4% of male subjects in their series. A female predominance was reported by some authors such as Omari M. in 2017 with 91.89% [9] and Sounni A. with 90% of women against 10% of men [10] . This could be explained by the predominance of thyroid pathologies in females [11] . The average age of the study population was 56 ± 17 years ranging from 14 to 89 years. Remacle et al. in 2005 in a study of a population of 69 patients, had noted a mean age of 56 years with extremes of 11 and 82 years. Amoussa-Hounkpatin K. [12] reported 57 as the average age in his series with extremes of 8 and 86. These rates are almost similar to those of Sounni A. [10] which is 51.5 ± 12.45 with extremes of 20 and 77 years and those of Omari M. [9] which is 52.46 years.

Bilateral laryngeal paralysis in the closed and paramedian position is more common. Treatments therefore most often use procedures that aim to widen the respiratory tract [13] , at the cost of a decrease in phonatory abilities. The most used surgical techniques in this series are subtotal arytenoidectomy (56.5%), followed by cordopexy or laterfixation of a vocal cord (19.6%) and posterior cordectomy (17.4%). Total arytenoidectomy is effective in terms of breathing but promotes pulmonary aspiration, and the remaining arytenoid mucosa can collable into the larynx [14] [7] . That is why we recommend respecting a posterior wall of 1 to 2 mm of the arytenoid cartilage. This cartilaginous shell prevents collapse of the arytenoid mucosa during inspiratory efforts. The risk of pulmonary aspiration is also reduced by respecting the pharyngeal side of the arytenoid. Partial endoscopic arytenoidectomy gives good respiratory results that are stable over time. For Cabanes et al. [3] , laser arytenoidectomy requires only one operating time.

Combined laterofixation or cordopexy [1] is a technique that provides glottic opening by a pexy thread that lateralizes the posterior part of the vocal cord [15] . The procedure is performed under general anesthesia. It combines a laterocervical approach and a laryngoscopic exposure in suspension. The operating time is about 30 minutes. A contralateral gesture can be carried out and an ipsilateral recovery is possible.

The posterior transverse cordectomy of Kashima [16] is called by other authors cordotomy since the vocal cord is not completely removed. It consists of an excision of the C-shaped membranous vocal cord of 5 mm by 5 mm located in front of the vocal process without stripping it. Gaillard et Haguenauer [17] , Dennis and Kashima [16] suggested a uni- or bilateral posterior cordectomy. Kashima [18] refines the gesture by performing only a transverse cordotomy but associated with an internally based triangle resection along the vocal processes. Voice quality would be better preserved. many authors favor this intervention. It should often be performed bilaterally to ensure stability of results. There is no significant difference in respiratory results (flow/volume curves) and phonatory after 6 months follow up but arytenoidectomy can allow an enlargement if the cordectomy has been insufficient. On the other hand, the subclinical pulmonary aspirations are observed in the “arytenoidectomy” group of patients. According to Rémacle [19] subtotal arytenoidectomy has two advantages: The first one is related to the arytenoidectomy itself:

· It allows reliable and durable breathing over time;

· less impact on the voice unlike cordectomy;

· and minimizes impact on swallowing unlike total arytenoidectomy.

The second is related to the laser:

· allows a precise incision with less laryngeal edema;

· good hemostasis of small vessels;

· a faster and shorter hospitalization.

Bilateral paralysis in abduction are rare and entail vital risks to the importance of pulmonary aspirations. To improve laryngeal occlusion, uni- or bilateral medialization procedures are suggested in literature. Thyroplasty consists of the placement of an inert implant through a window made in the ipsilateral thyroid cartilaginous wing by cervicotomy [20] . The advantage of this method lies in the possibility to perform it under local or loco-regional anesthesia with a real-time evaluation of the phonatory result by the surgeon and the patient. There is a prominent place for thyroplasties that can be supplemented secondarily by a fat injection in case of insufficient results. An associated medialization arytenoidopexy may also be performed [21] . Performing transiently maintained tracheostomy is recommended because of the risk of dyspnea, especially in case of arytenoid manipulation or in the presence of neuromuscular disorders [21] .

An emergency tracheostomy is performed when the cords are in adduction, followed by surgery to enlarge the glottic tract. Smith [22] , reported sudden dyspnea with respiratory distress in 50% of patients in his tracheostomy series. This tracheostomy can be avoided with a posterior cordectomy or arytenoidectomy in acute laryngeal dyspnea [23] [24] . A rescue intubation can also be performed for example during an intervention that has injured the both recurrent nerves. In our series 18 patients or 39.13% were taken to the emergency operating room among the 46 patients who were treated surgically, and 17.39% in less than a month.

In patients who received partial arytenoidectomy, 16 patients or 61.5% had no complications, 2 patients experienced postoperative bleeding and 5 experienced revision enlargement surgery. In subtotal arytenoidectomy [1] , the occurrence of posterior synechiae is possible. The results reported by Lichtenberger on cordopexy show 78% (46 patients out of 59) positive results at the first intervention (removal of the tracheostomy cannula, satisfactory breathing). Some patients required contralateral surgery (ten patients) [25] . A series of 11 patients evaluated after at least 5 years has been reported [26] : two had to be reoperated for persistent dyspnoea and one for vocal problems. This technique has the advantage of being not very traumatic. It is renewable in case of over- or under-correction. In our series, 2 of the 9 patients who received cordopexy were referred to for enlargement surgery. Four patients showed excellent results. According to Drancy [27] , the satisfactory pathway after a cordectomy was often obtained at the expense of surgical revision in more than 90% of cases for posterior partial cordotomy. These results seem to alter over time but most often without the need for long-term surgical revision. The dysphonia was often transient. We reported no complications in 5 out of 8 patients who had a posterior cordectomy.

Postoperative pulmonary aspiration in partial arytenoidectomy was absent in 17 patients and seen in 5 patients but controlled after speech therapy. Fluid aspiration is common during the first postoperative days and is rapidly compensated in subtotal arytenoidectomy [1] . Excellent results were reported by Khalifa [28] , using bilateral posterior cordectomy at the same endoscopic time. In Hariga [29] series, posterior laser cordectomy was performed in four patients with laryngeal diplegia in closed position, the result was considered satisfactory by the patients both on phonatory and respiratory levels. For Hammami B. [30] , posterior cordectomy was performed in the first stage in 4 cases. It was bilateral in two stages in 2 cases and unilateral in 2 cases. An initial arytenoїdectomy was performed for the other two patients. Only one patient retained respiratory discomfort without true dyspnea with a closed speaking cannula and decanulation was refused. A satisfactory voice was obtained for all patients. Transient false routes were noted in 2 cases.

To date, he has not reported any significant vocal or respiratory differences between arytenoidectomy and posterior cordectomy [31] . Cordectomy is easier to perform, faster and more effective in the short term. It must often be bilateral and recurrences are not rare because of fibrosis at the level of the section area. Arytenoidectomy is longer and more difficult but more stable in its results.