A study on tracheoesophageal phonation based on a collapsible channel model.

Laryngeal cancer afflicts a large number of people worldwide, and some will need surgery to contain the disease. Currently, tracheoesophageal (TE) speech is a common method of voice rehabilitation for patients who have had their larynges excised. However, despite the relatively high success rate, not everyone is capable of producing the TE voice, usually due to the tonicity of the pharyngoesophageal segment (PES). The present work studies how the tonicity of the muscles of the PES affects TE phonation, focusing mainly on hypotonicity. A simplified collapsible channel model is used. Steady-state solutions are obtained and a linear stability analysis is performed. It is then shown that the steady-state solutions of the model are similar to the wide variety of possible PES configurations that are reported in the literature. The linear stability analysis results provide a simple expression for the estimation of the minimum tonicity required for self-sustained oscillations of the PES.

Parotidectomy for primary nonparotid diseases.

OBJECTIVE: To analyze the indications and results of parotid gland resections for patients with primary nonparotid diseases. STUDY DESIGN AND SETTING: Retrospective analysis of 442 consecutive parotidectomies (76 for primary nonparotid disease) in a referral head and neck surgery service, tertiary care university hospital. RESULTS: Skin cancer (mainly squamous cell and basal cell carcinomas) was the most common indication for parotidectomy. Superficial parotidectomy with preservation of the facial nerve was the most commonly performed operation (61.8%), with some form of nerve sacrifice necessary in 31.6%. Parotid gland parenchyma and/or lymph nodes were pathologically positive in 46 cases. Neck dissections were carried out in conjunction with parotidectomy in 42 patients (1 patient had had previous neck dissection), of which 16 turned out to be pN+. CONCLUSION: Parotidectomy should be considered as part of the surgical treatment of tumors whenever oncologically necessary for appropriate margins, lymph node dissection, and for proper identification and preservation of the facial nerve.