Facial Nerve Protection And Surgical Treatment In Large Acoustic Neuroma

Objective:To explore the facial nerve functional preservation of large acoustic neuroma after microsurgical resection via suboccipital retrosigmoid approach. In large acoustic neuroma microsurgery we ceombine EMG and brainstem auditory evoked potentials (BAEP), somatosensory evoked potentials (SEP), motor evoked potentials(MEP) and so on to study their function in facial nerve protection during surgery. Meanwhile, explore the protection of petrosal vein and the management of internal auditory canal.Methods: A retrospective analysis of85consecutive cases in Department of Neurosurgery in Renmin Hospital(Wuhan University) who suffer from large acoustic neuroma between January2010and October2013. All patients were treated with microsurgery by the suboccipital retrosigmoid approach, while continuous electrophysiological monitoring provides feedback regarding the exact identity about anatomical and functional preservation of the facial and cochlear nerves. All patients were diagnosed as acoustic neuroma. Comparative analysis of the impact of a simple facial nerve function monitoring and joint monitoring of patient prognosis. The study compared the prognosis of clinical data of petrosal vein without retention group with retention group, and research the management of internal auditory canal.The preoperative and postoperative facial nerve function is judged by House-Brackmann grading standards. We evaluate facial nerve function at24hours,7days,3months,6months,9months and1year after surgery. All data are analyzed by statistical software.Results: Total resection was achieved in80cases (94.1%), subtotal resection was in5cases (4.7%), and facial nerves were anatomically reserved in82cases (96.5%). The excellent House-Brackmann classification rate (H-B I-II grade) of facial nerve function at24hours,7days,3months,6months,9months and1year after surgery were:88.2%.56.0%.41.9%.51.0%.68.6%.86.7%.85patients without intact petrosal vein in6cases, cerebellar edema (2/6), cerebellar hemorrhage (2/6);85patients with intact petrosal vein in79cases, cerebellar edema (15/79), cerebellar hemorrhage (3/79).85patients with drilling internal auditory canal in78cases (91.8%), complete tumor removal was achieved in76cases;85patients without drilling internal auditory canal in7cases (8.2%), complete tumor removal was achieved in4cases. Conclusion:1) Neurophysiological monitoring in acoustic neuroma surgery plays an important role in protection and prognosis of facial nerve function.2) Postoperative facial nerve function of large and giant acoustic changes dynamically: facial nerve function achieves the best immediately after the operation, and then deteriorates the worst from1week to3month after the surgery, improve gradually to the level of immediate postoperative6month after the surgery to more than1year. The change is a course of quick deterioration and gradual improvement.3) The effective joint monitoring of EMG+BAEP+SEP+MEP in the surgery can protect nerves brain stem function, and improve the patients quality of life.4)The texture of acoustic neuroma has correlation with the recovery of facial nerve function after surgery.5) The acoustic neuroma with hydrocephalus has no correlation with the recovery of facial nerve function after surgery.6) Protect the petrosal vein may reduce the risk of cerebellar hemorrhage.7) Drilling internal auditory canal can increase the rate of tumor total resection.