Effects of Divalproex sodium for Visual Cortex Excitability in Migraine: A Study Using Transcranial Magnetic Stimulation

J Korean Neurol Assoc > Volume 22(5); 2004 > Article

Journal of the Korean Neurological Association 2004;22(5): 499-503.

경두개 자기자극을 이용한 편두통 환자의 시각피질 흥분성에 대한 divalproex sodium의 효과

강병욱, 김은희 이호원 김정일* 정두교 서정규 박성파

경북대학교 의과대학 신경과학교실, 굿모닝병원 신경과*

Effects of Divalproex sodium for Visual Cortex Excitability in Migraine: A Study Using Transcranial Magnetic Stimulation

Byung-Wook Kang

Department of Neurology, Kyungpook National University School of Medicine, Daegu; Department of Neurology, Good Morning Hospital*, Daegu, Korea

Abstract

Background: The pathophysiology of migraine has not been fully understood. One of the hypotheses is cortical hyperexcitability. Transcranial magnetic stimulation (TMS) is a noninvasive electrophysiologic tool for the investigation of cortical excitability. Divalproex sodium may prevent migraine attacks by increasing the GABA-ergic tone. We examined the phosphene generation using TMS in migraine patients in order to investigate the cortical excitability and its response by valproate prophylaxis.
Methods: We applied TMS to 27 migraineurs and 27 control subjects. TMS was performed by a Magstim Rapid Stimulator connected to a 70 mm figure-of-eight coil to examine the phosphene threshold between migraineurs and controls on primary (V1) and bilateral secondary (V5) visual cortices. Twelve migraine patients completed a one month administration of divalproex sodium 500 mg/day. We compared the phosphene threshold between pre- and post-treatment with devalproex sodium in these patients.
Results: The prevalence of the phosphene generation was significantly higher in migraineurs compared with controls in V1 and V5. The phosphene average thresholds were significantly lower in migraineurs compared with controls in V1 and V5. The phosphene average thresholds in the same areas were significantly higher in post-treatment compared with pre-treatment in migraineurs.
Conclusions: The differences of the phosphene threshold in the visual cortex between migraineurs and controls comply with the theory of cortical hyperexcitability for the pathophysiology of migraine. Valproate might play a significant role in the prophylaxis of migraine by decreasing cortical hyperexcitability.Key Words: Migraine, TMS, Visual cortex, Phosphene threshold, Cortical excitability, Divalproex sodium