The Value of Electrodiagnostic Studies Performed before and after Microvascular Decompression

ABSTRACT

OBJECTIVE: To evaluate the usefulness of electrodiagnostic studies in hemifacial spasm patients by comparing abnormal muscle response (AMR) and irregular bursting discharge (IBD) before and after the surgery of hemifacial spasm. METHOD: Fifty nine patients who had been diagnosed with hemifacial spasm and underwent microvascular decompression (MVD) were chosen. The AMR was carried out in three different ways; 1) abnormal response of orbicularis oris when stimulating the supraorbital branch of trigeminal nerve (AMR1), 2) abnormal response of mentalis when stimulating the zygomatic branch of facial nerve (AMR2) and 3) abnormal response of orbicularis oculi when stimulating the marginal mandibular branch of facial nerve (AMR3). We identified the correlation between the loss of IBD and the AMR results per each method, the results of the electrodiagnostic studies according to the onset duration, and the point of follow up time. RESULTS: The AMR and IBD decreased or disappeared after the surgery. AMR which had a significant statistical correlation with the changes of IBD, were AMR2 and AMR3. No definite changes were seen regarding the onset duration. According to the studies done during the follow up period, there was a significant reduction in lateral spread and IBD as the length of the follow up period lengthened. CONCLUSION: Investigation of pre- and postoperative electrodiagnostic study, especially abnormal muscle response (facio- facial reflex) is very helpful in predicting the outcome of operation and the overall prognosis.