Suppression of Voluntary Temporalis Muscle Activity by Peripheral Limb Stimulations in Healthy Volunteers, Migraineurs and Tension-Type Headache Sufferes

We studied the inhibition of voluntary temporalis muscle activity after stimulations of extracephalic cutaneous or mixed nerves in 23 healthy volunteers, 29 patients suffering from migraine without aura, 24 from episodic and 42 from chronic tension-type headache. Two successive EMG suppressions were induced bilaterally after stimulating at 40 mA the index finger or the median nerve, but not after stimulations of the sural or peroneal nerves. They differed from those obtained after labial commissure stimulation at 20 mA, i.e. the classic temporalis silent periods ES1 and ES2. Overall prevalence of index- (3%) and median nerve-induced (16%) early suppression was much lower than that of labial-induced ES1 (100%); prevalence of index-induced late suppression (index-"ES2") was 62% and that of median-"ES2" 48%, compared with 97% for labial-ES2. Latency and duration of index-/median-"ES2" were not significantly different between groups. Index-"ES2" occurred significantly more often in migraineurs (83%) than in controls (48%) suggesting that the spino-bulbar pathways involved in index-/median-"ES2" are hyperexcitable in migraine.