[Exteroceptive suppression after mental nerve stimulation in patients with chronic headache]

In 18 normal subjects and 36 patients with chronic headache (3 cluster headache, 18 maigraine and 15 muscle contraction headache), exteroceptive suppression in the temporalis, masseter and trapezius muscles was examined. In the temporalis and masseter muscles, early and late phases (ES1 and ES2) were observed. In the present study, late response (ES2) was examined. Patients with muscle contraction headache showed an obvious decrease of exteroceptive suppression in duration and degree. Patients with common migraine showed slight reduction of exteroceptive suppression in duration and amount, when compared with normal subjects. Patients with classic migraine or cluster headache elicited almost normal exteroceptive suppression. Exteroceptive suppression in the trapezius muscle consisted of one or two suppressive phase(s). Early phase was small and unstable. In the present study, late response with latency of about 45 ms was examined. In the trapezius muscle, migraine and patients with muscle contraction headache elicited the reduction of the exteroceptive suppression in degree. There might be the failure of the inhibitory interneuron mediating the pathway of exteroceptive suppression not only in patients with muscle contraction headache, but also in patients with migraine, especially in patients with common migraine.