Study of Recurrent Laryngeal Nerve Paralysis Following Thyroidectomy

Goitre is a common thyroid disease in most part of the world. Among diferrent etiology, colloid nodule, multinodular goitre, benign thyroid cyst, papillary carcinoma, follicular carcinoma, medullary carcinoma, anaplastic carcinoma, lymphoma are most common. On the basis of histopatholoical report,among benign goitre nodular colloidal goitre was 52%, follicular adenoma was 24% and auto-immune thyroiditis was 6% and among the malignancies papillary carcinoma was 66.66%, follicular carcinoma was 22.22% and anaplastic carcinoma was 11.11%. . Thyroidectomy is widely practiced surgical procedures to treat different type of thyroid disorder and considered as a safe procedure in well Original Article Bangladesh J Otorhinolaryngol 2018; 24(2): 162-166

equipped center.There are some complications following thyroid surgery can be life threatening. 2,3 Complications such as bleeding, hypoparathyroidism and Recurrent Laryngeal Nerve Injury (RLNI) represent nearly half of all the complications of thyroid surgery. 4,15 One of the most feared complications of thyroid surgery is the recurrent laryngeal nerve(RLA) injury. 4,15 RLN injury results from severing, clamping or stretching of the nerve due to inadequate anatomical knowledge, lack of surgical skill and experience, distorted anatomy as in cancer and large multinodulargoiter. 5 Review of literature revealed that the prevalence of RLN palsy varies from centre to centre depending upon the level of experience in thyroid surgery and nature of surgery. 6 The exact incidence of recurrent laryngeal nerve injury varies widely. 7 There is some controversy in whether the identification of RLN during surgical procedure will affect the incidence of nerve damage or not. 5 Nerve identification has decreased the rate of nerve injury during thyroidectomy. 8,20 In order to improve our quality of thyroid surgery we have undertaken a study using Recurrent nerve visualization technique to determine the incidence of RLN injury in our practice.

Methods
This was a cross sectional study done in Bangabandhu sheikh Muzib Medical University (BSMMU) in the dept. of Otolaryngology during the period from July 2015 to June 2017. All adult patients irrespective of age and sex that were treated surgically by total or hemi thyroidectomy were enrolled into this study after taking informed written consent. Patient with previous thyroid surgery were excluded from this study. Thyroid gland status and pre operative diagnosis was done clinically, biochemically and histopathologically by fine needle aspiration cytology (FNAC). All surgical procedures were under taken by same surgical team in BSMMU.
Data collection done by predesigned questionnaire. All surgical procedure performed during the period of study were evaluated and post operative different variant of recurrent laryngeal nerve palsy were recorded.
Data analysis was performed by using SPSS version 21.

Discussion
There are many post-operative complications of thyroidectomy, among which RLN injury is are of the most frequent. In most of the cases, it cannot be recognized during surgery.
In our study, overall frequency of RLN injury was found to be 3.33% in 2 cases. Injury was noticed immediately after operation by developing change of voice especially in those patients who underwent total thyroidectomy for ca. thyroid. It was confirmed by Fiber optic laryngoscopy(FOL). In both cases, paralysis was temporary because those patients developed full functions of paralyzed vocal cord after having conservative treatment for six weeks.
In the study of outcomes and complication of thyroid surgery among Sudanese patient, among 1351 thyroidectomies, SaadeldinA. Idris et al. of observed incidence of rec. laryngeal nerve injury was 1.9 (26 cases) of which the incidence of transient unilateral RLN paralysis was 1.2%. Permanent RLA paralysis was 0.5%, transient bilateral RLN palsy was 0.2 %. 2 Wagner et al. have shown in their study over 1026 patient thatthe incidence of transient and permanent RLN paralysis was 5.9% and 2.4% respectively. 7 Jatzko et al shown in their study over 803 patients that incidence of transient and parmanent RLN paralysis was 3.6% and 0.5% respectively. 8 Sosa et al have shown in their study over 5860 casesthat incidence of permanent RLN paralysis was 0.8% and they did not record any transient RLN palsy. 9 Rosato et al shown their study over 14.93 in their longitudinal analysis of multi centric study that incidence of transient and permanent RLN palsy was 2.0% and 1.0% respectively. 1 Goncalves et al shown in their study over 1020 patient that incidence of transient and permanent RLN palsy was 1.4% and 0.4% respectively. 10 Mishra et al shown in their study that incidence of RLN injuries were ranging between 0.0% -13%. 11 Jamski J et al had shown in their study on recurrent laryngeal nerve injury following thyroid surgery over 2323 cases from 1994 to 1997 that post operative RLN palsy of different grade was 8.9% among which 1.7% was permanent.
Jung H et al studied over 909 cases on recurrent laryngeal nerve paralysis after thyroidectomy and they shown 92.6% benign goiter and that post operative RLN palsy was 1.7% which was permanent. 13 Hazem

Conclusion
This study proved that surgical exposure of RLN,prevent unwanted trauma to nerve and thereby reduce incidence of vocal cord paralysis. So, we advocate for routine identification and dissectionof RLN to reduce its injury to a minimum.