[Microsurgical vascular decompression for hemifacial spasm. Follow-up over one year, clinical results and prognostic factors. Study of a series of 100 cases].

BACKGROUND AND
PURPOSE: The results of a series of 100 patients operated on for hemifacial spasm (HFS), using microsurgical vascular decompression (MVD), are reported.
METHOD: MVD was performed through a retromastoid keyhole approach, under monitoring of brainstem auditory evoked potentials (BAEP) and facial EMG, and consisted in dissection of VII nerve from conflicting vessel(s), and interposition of Teflon fibers and/or screen(s).
RESULTS: The offending vessels found were: the antero-inferior cerebellar artery in 57 cases, the postero-inferior cerebellar artery in 56 cases, the vertebrobasilar artery in 22 cases. A multiple conflict was found in 32 cases (32%). The result was considered excellent if there was no residual spasm, good if only "minimal twitching" remained with relief>80%, poor for spasm relief 20 to 80%, and as a failure if relief<20%. The effect of MVD was satisfying (excellent or good) in 75 patients (75%) at discharge (10th day) and in 85 (85%) after 1 to 18 years follow-up (mean: 5 years). Amongst the latter patients, 29 (34%) experienced a delayed (up to 3(1/2) years in one) cure. Spasm recurrence was noted in 9 cases after satisfying effect on discharge. We encountered following permanent neurological complications: 1 facial palsy, 7 cases of hearing deficit (5 of them complete), and 1 case of IX-X deficit. Neither death nor ischaemic complication at brainstem or cerebellum. Most of our hearing complications occurred before using intraoperative BAEP monitoring (3 cases of cophosis among our first 7 patients vs 2 out of our last 93). Local complications were: 1 meningitis, 8 cases of CSF leakage requiring either a series of lumbar punctures or a lumbar external drain, and 3 cases of wound infection and/or delayed woundhealing requiring surgical treatment.
CONCLUSIONS: Our data are consistent with those of the literature, especially concerning high rate of long-term success and low complication rate of MVD for HFS. We do not recommend early re-operation in case of initial poor result. Again, the necessity of intraoperative BAEP monitoring to prevent hearing morbidity is highlighted.