The Value of Brainstem Auditory Evoked Potentials on Diagnosis of Hemifacial Spasm

Abstract

Hemifacial spasm (HFS), is an involuntary, repetitive movement disorder of the muscles innervated by facial nerve. The importance of Magnetic Resonance lmaging (MRI) and Magnetic Resonance Angiography (MRA) are widely accepted as diagnostic procedures.However different ratios of the specificity have been reported. Also there is little information about value of brainstem evoked potentials (BAEP). Therefore we evaluated MRI, MRA and BAEP of 18 patients with HFS, without .any other neurological disease. In 11 of 18 patients (%61,1) vessel abnormalities were detected by MRI and MRA. The vessel causing compression was basilar artery in 6 patients, vertebral artery in 3, anteriorinferior cerebellar artery in I, posterior inferior cerebellar artery in I patient. When we compared BAEPs of the patients with the control group, consisting 16 healthy volunteers, statistically significant prolongation of I-V interpeak latency (IPL) was observed. When we divided the patients into 2 groups, symptomatic and idiopathic groups, there wasn't any significant difference between them in the evaluation of BAEPs. This might be theresult of the the minimalisation of the subgroups when divided into two. Consequently, we think that MRI and MRA are very important for imaging of brainstem structures and vessels in HFS and such an easy and cheap examination of brainstem with BAEP can help the diagnosis.