Blink Reflex in Patients with Hemifacial Spasm Before and After
 Botulinum Toxin Treatment

J Korean Neurol Assoc > Volume 16(6); 1998 > Article

Journal of the Korean Neurological Association 1998;16(6): 859-865.

편측 안면경련 환자에서 보툴리눔 독소 주사 전후의 순목반사 검사

김병준, 이원용, 김민기*

성균관 대학교 의과대학 삼성서울병원 신경과, 지방공사 강남병원 신경과*

Blink Reflex in Patients with Hemifacial Spasm Before and After Botulinum Toxin Treatment

B.Joon Kim, M.D., Won Yong Lee, M.D., Min Ky Kim M.D.*

Department of Neurology, Samsung Medical Center, Sung Kyun Kwan University, Kangnam General Hospital Public Corporation*

Abstract

Background: Previous blink reflex studies using paired stimulation demonstrated the increased excitability of brainstem interneurons in hemifacial spasm (HFS). We compared the changes in blink reflex before and after botulinum toxin treatment and investigated whether the treatment influenced brainstem interneuronal hyperexcitability.
Methods: In 14 patients with HFS, we performed blink reflex test in 100, 200, and 300ms intervals of paired stimuli before and one month after botulinum toxin injection. We measured the amplitudes of ipsilateral R1 and bilateral R2 responses evoked by conditioning and test stimuli. We compared the amplitude ratio of test to conditioning stimuli in each R1 or R2 response between studies at pre- and post-botulinum toxin treatment.
Results: In preBotox blink reflex studies, ipsilaterla R2 (iR2) responses by test simuli (TS) were detected in 10, 13, and 13 out of 14 patients in affected side, while 3, 9, and 12 in unaffected side at each interval. Differences of amplitude recovery of iR2 responses by TS between two sides were significant (p=0.036, 0.030, 0.007 at each interval), which suggest brainstem interneuronal hyperexcitability at least in affected side. Differences of R1 or contralateral R2 (cR2) responses were not significant. At 100 and 200ms intervals, the recovery indices of iR2 were 22.6% and 40.8% at preBotox, and 12.1% and 24.3% at postBotox studies respectively, which meant reduction of amplitudes were greater significantly at postBotox period (p<0.05). Reductions of R1 and cR2 amplitudes before and after botulinum toxin treatment were not significantly different.
Conclusions: We conclude that brainstem interneuronal hyperexcitability shown by paired stimulation in HFS is reduced by successful botulinum toxin treatment. These results may suggest that botulinum toxin might have a central action. Key words: hemifacial spasm, botulinum toxin, blink reflex