case report

Schwannoma of the Left Recurrent Laryngeal Nerve, Review of the Literature and Proposed Technique to Avoid the Nerve Injury

Goran Merma1,2*, Buta Marko1,2, Kozomara Zoran1,2, Medic Miljijic Natasa3, Markovic Ivan1,2

1Surgical Oncology Clinic, Institute for oncology and radiology of Serbia, Belgrade, Serbia

2School of Medicine, University of Belgrade, Belgrade, Serbia

3Department of Pathology, Institute for oncology and radiology of Serbia, Belgrade, Serbia

*Corresponding author: Goran Merma, School of Medicine, University of Belgrade, Surgical Oncology Clinic, Institute for oncology and radiology of Serbia, Belgrade, Serbia

Citation: Goran M, Buta M, Kozomara Z, Medic Miljijic N, Markovic I (2023) Schwannoma of the Left Recurrent Laryngeal

Received Date: 07 February 2023

Accepted Date: 07 February 2023

Published Date: 07 February 2023

Nerve, Review of the Literature and Proposed Technique to Avoid the Nerve Injury. Ann Case Report. 8: 1161. DOI:https://doi.org/10.29011/25747754.101161

Abstract

Schwannomas are very rare, benign tumours origin from nerve sheath cells, with low possibility of malignant alteration. They can arise from cranial, spinal and peripheral nerves. Recurrent laryngeal nerve (RLN) schwannomas are extremely rare, and we found only eleven cases that have been described so far. It is a big differential diagnostic problem, and usually presented clinically as a thyroid tumour. We present 26-year-old woman with compressive symptoms that were present for six months. Clinically and by ultrasound a tumour in the left thyroid lobe was detected. Preoperatively, patient did not have voice changes or hoarseness, indirect laryngoscopy was normal and tracheal displacement to the right side recorded by X-ray. Patient had normal thyroid function, with normal levels of tumour markers and antibodies. The decision for surgery was made multidisciplinary. Intraoperatively, the left thyroid lobe presented with a cystic tumour in the lateral part of the lobe, about 4 cm in diameter, witch extending posteriorly and compressing surround structures but without infiltration. During the mobilization of the lobe together with tumour, which was considered as part of the lobe, the left RLN was accidentally cut. Nerve reconstruction was done immediately using anastomosis with the longest branch of the ipsilateral ansa cervicalis. Histopathological findings showed a schwannoma. In conclusion, in order to preserve the nerve, tumour should be mobilized, so it will clearly indicate its origin from RLN, by tightening the nerve ends. Nerve-sparing sub capsular resection should be performed with using intraoperative neuromonitoring probe, if available. When RLN is resected, end-to-end anastomosis should be made, or anastomosis with ansa cervical is, depending on the size of the nerve defect.

Keywords: Nerve Anastomosis; Recurrent Laryngeal Nerve; Schwannoma

Introduction

Schwannomas (synonym: neurilemomas) are benign neoplasms originating from Schwann, nerve sheath cells, and with a possibility of malignant alteration. They can arise from cranial, spinal and peripheral nerves. Generally, they are very rare tumours. Over than 40% of cases occur in the head and neck region [1]. Recurrent laryngeal nerve (RLN) schwannomas are extremely rare, and we found only eleven cases that have been described so far [2-12]. It is a big differential diagnostic problem. Most commonly, they are presented clinically as a thyroid, parathyroid or oesophageal tumour, enlarged lymph node or lymphoma. We report a young women patient in whom RLN schwannoma simulated thyroid tumour.

Case Presentation

We present 26-year-old woman with dyspnoea, dry cough and difficulty swallowing for six months. Clinically a tumour in the left lobe of the thyroid gland about 4 cm in diameter was detected. Ultrasonically tumour was heterogenic and hypo echogenic with intranodal vascularization, cystic degeneration and in some places, it was trabecular, 33 mm of the longest diameter (Figure 1). Considering to tumour size and clinical presentation, surgery was indicated, and the decision for surgery was made multidisciplinary. As a standard, within the preoperative examination, tracheal displacement to the right side was recorded by X-ray, while the finding of indirect laryngoscopy was normal. The patient did not have voice changes or hoarseness preoperatively. Chest X-ray and abdominal ultrasonography was normal. Thyroid function was normal and the patient was norm metabolic. Levels of antibodies (thyroid peroxidase and thyroglobulin antibodies) were normal, as well as tumour markers (thyroglobulin and calcitonin). Intraoperatively, left lobe was polynodal with dominant cystic node in the lateral part of thyroid lobe about 4 cm in diameter, extending posteriorly and compressing esophagus and trachea but without infiltration. During the preparation and mobilization of the lobe together with tumour, which was considered as part of the lobe, the left RLN was accidentally cut. Nerve was positioned partially over the cystic tumour and partially through the sulcus between the tumour and the left lobe. With the neuromonitor probe we checked the transacted left RLN as well as left vague nerve, and confirmed the complete lesion of the left RLN. The tumour together with left thyroid lobe was removed and sent for histopathological analysis. In the same act, the reconstruction of the left RLN was done, using anastomosis with the longest branch of the ipsilateral ansa cervicalis with single vascular suture 6.0. The histopathological findings showed a schwannoma with a low proliferative index (Ki67 was 2%) (Figure 2), and with areas of old haemorrhage (Figure 3). Immunohistochemically tumour showed activity on Vimentin and S100 protein (Figure 4). In the immediate postoperative course, the patient had hoarseness with difficulty swallowing liquids thus suggesting injury of RLN and outer branch of upper laryngeal nerve (neuropraxia), while respiratory function was normal. A control indirect laryngoscopy examination confirmed immobility of the left vocal cord. After being discharged from the hospital, the patient began phoniatric rehabilitation. Four years after surgery she had a normal voice without difficulty swallowing and without dyspnea, although the left vocal cord was still in medial position.

 

Figure 1: Preoperative ultrasound of thyroid gland.

 

Figure 2: Haematoxylin-eosin stain; original magnification x 20; low proliferative index.