Preservation of Hearing and Facial Nerve with Large Vestibular Schwannomas: Experience with the Retrosigmoid Approach

Rajput MSA1, Ahmad AN2, Arain AA3, Adeel M4, Akram S5, Awan MS6, Bari ME7.

Vestibular schwannomas (VS) are the most common benign neoplasms of a cerebellopontine angle (CPA), which arise from the Schwann cells of the vestibulocochlear nerve. Eighty percent of CPA tumours are VS followed by meningioma as the second common mass lesion in this critical potential space. The primary objective of the study was to assess hearing and facial nerve status before and after the surgery via the retrosigmoid approach.

Method:

Twenty-seven patients from Aga Khan Hospital database between 2000 and 2007 were selected for the study. The variables included age, gender, presenting symptoms, size of the tumour, surgical approach, hearing levels, and facial nerve function. Hearing loss was categorized according to the Gardener-Robertson hearing classification and the House-Brackmann Scale was used for facial nerve assessment.

Results: 

Out of the 27 patients, 18 were male and nine were female. The mean age was 43 years. The most common presenting complaint in 21 patients was hearing loss and tinnitus. Headache was present in six patients, ataxia in five, and vertigo in three. Facial nerve weakness was noticed in six patients. Two patients had Grade-III paralysis, three had Grade-IV paralysis, and one had Grade-V paralysis. The audiogram confirmed the presence of sensorineural hearing loss (SNHL) in all patients. Twelve patients out of 27 had Class II hearing with the threshold between 31 and 50 decibels and a Speech Discrimination Score (SDS) of 50% to 69%. Ten patients had non-serviceable hearing and the remaining five had poor hearing. The audiogram was repeated after surgery for those 12 patients who had Class II hearing and showed that seven out of 12 patients maintained a hearing threshold within the range of Class II at the one-year follow-up (hearing preservation 58%). The facial nerve preservation rate was 56% considering House-Brackmann Grade III or less as acceptable facial nerve function.

Conclusion: 

The optimal treatment for small vestibular schwannomas is a matter of controversy; however, the choice of treatment for large vestibular schwannomas in patients without significant comorbidity is generally microsurgical excision. The surgical excision of a large VS with the retrosigmoid approach is found to be safe consistently. The hearing and facial nerve preservation in the study was comparable with the literature.