Objective: To investigate the value of the endoscopy in the operation of microvascular decompression (MVD) for the hemifacial spasm by approach of postauricular suboccipital to the cerebellopontine angle (CPA) with posterior auricular small incision.
Method: Two hundred and eighty-six cases of hemifacial spasm had received the operation of MVD with endoscopy by approach of postauricular suboccipital to the CPA.
Result: Responsible blood vessels were found in 285 cases (99.7 percent), including 264 cases of anterior inferior cerebellar artery, 21 cases of basilar artery. The root entry zone of the facial nerve were completely decompressed with Teflon. There is no responsible blood vessels but adhesion in 1 cases (0.3 percent). After surgery, hemifacial spasm immediately disappeared. House-Brackmann(1985) grading system was used to evaluated the recovery of facial nerve function. After 1 week of operation 196 cases' facial nerve function are stage 1/6, 62 cases' are stage 2/6, 23 cases' are stage 3/6, 4 cases' are stage 4/6, 1 cases' is stage 5/6. And after Six months of operation, 274 cases' are stage 1/6, 10 cases' are stage 2/6, 2 cases' are stage 3/6. After 1 month of operation there is no significant change of hearing in 238,there are 35 cases of hearing loss less than 20 dB, 10 cases of hearing loss more than 20 dB, but less than 50 dB,3 cases of hearing loss more than 50 dB. Ear-nose cerebrospinal fluid leakage occurred in 2 cases are cured. During 1 year to 4 years following-up, only 3 (1.0 percent) preliminary suffered relapse,among which 1 case was cured by the secondary operation. The long term cure rate was 99.3 percent without occurrence of serious complications such as death.
Conclusion: The microneurosurgery of MVD for the treatment of hemifacial spasm is an ideally functional and etiotropic operation. It is useful not only to discover the responsible blood vessels which are regarded as those pressing the root entry zone of facial nerve,but also to protect the function of the brain tissue and nerves as well. It is a safe, minimally invasive and efficient operation. To avoid the complications, enough knowledge of the craniotopography and skilled technique of endoscopic operation are primary.