Perineural Invasion of Superior and Inferior Laryngeal Nerves in Advanced Stage Squamous Cell Carcinoma of the Larynx: A Case Series and Review

OBJECTIVE: To evaluate bilateral superior and recurrent laryngeal nerves for tumor spread in patients of advanced-stage laryngeal carcinoma undergoing surgical resection. METHODS: A prospective study was conducted including biopsy-proven cases of laryngeal squamous cell carcinoma (SCC) that were planned for total laryngectomy. Patients with metachronous or synchronous SCC were excluded from the study. All patients underwent total laryngectomy, where both superior and recurrent laryngeal nerves were harvested along with the specimen, and the proximal ends of the nerves were marked for reference. Perineural invasion (PNI) was assessed in nerves within the tumor and in bilateral extra-laryngeal nerves. RESULTS: The study included 22 patients with a mean age of 58 years. Intra-tumoral PNI was found in 7 of the 22 cases (32%). The free nerve margins of superior and recurrent laryngeal nerves, which were examined from proximal to distal orientation, showed no tumor infiltration in any of the cases. CONCLUSION: Perineural invasion of minor nerves constitutes a major pathway of spread. On the contrary, invasion of superior or recurrent laryngeal nerves does not constitute a route for tumor spread. Hence, there is no need to extend the surgical boundary for total laryngectomy to include these major nerves separately.