Endoscope-Assisted Cerebellopontine Angle Surgery

Objective To report experiences with use of otoendoscopy in cerebellopontine angle(CPA) surgeries.Methods Twenty five cases of CPA surgeries performed between November 2002 and December 2008 in which microscope enabled otoendoscopy was used were reviewed.The 25 cases included 19 cases of acoustic neuroma,3 cases of CPA facial nerve tumors,1 case of trigeminal neurinoma,a case of glossopharyngeal neuralgia and 1 case of hemifacial spasm.Endoscopy was used in all cases together with monitoring of brainstem auditory responses and facial electromyography.Postoperative hearing and facial nerve function were evaluated and compared to pre-operative levels.Results Endoscopy provided improved visualization of local anatomy,revealed hidden lesions and reduced unnecessary anatomical distortions.Total resection was achieved in 18 of the 19 acoustic neuroma cases,Facial nerve anatomical integrity was preserved in all 19 cases.One week postoperative House-Brackmann grading was I in 3 cases,Ⅱ in 10 cases and Ⅲ in 6 cases.Facial nerve function continued to improve in some cases at 3 months.Total tumor resection was achieved in all 3 patients with facial neurinoma.The facial nerve was sacrificed in 2 of the 3 cases with primary faciohypoglossal nerve anastomosis.Facial nerve function was Grade Ⅱ and Grade III one year after surgery,respectively.In the case with anatomically preserved facial nerve,postoperative facial nerve function was initially Grade Ⅲ and improved to Ⅱ at 3 months.The tumor was completely resected in the trigeminal neurinoma patient with a Grade Ⅲ postoperative facial nerve function which improved Grade II three months later.Seventeen of the 19 patients with acoustic neuroma retained hearing postoperatively,of these 12 maintained preoperative levels of hearing.Preoperative hearing capacity was preserved in 2 of the 3 patients with facial nerve tumors,but lost in patients with other tumor types.Glossopharyngeal neurotomy(n=1) and microvascular decompression(n=1) resulted in satisfactory symptom relief and no recurrence at 5-and 3-year follow up,respectively.Conclusions Otoendos aope-aided technique greatly helps surgical management of CPA and internal auditory canal lesions and other disorders.This minimally invasive technique overcomes many shortcomings inherent to the traditional retrosigmoid approach.