Effects of tizanidine administration on exteroceptive suppression of the temporalis muscle in patients with chronic tension-type headache.

The aim of this study was to clarify the changes of inhibitory interneuronal activity in patients with chronic tension-type headache with disorder of pericranial muscle after treatment, and the pharmacological mechanisms of tizanidine--an alpha 2 adrenergic agonist. The effects of tizanidine on exteroceptive suppression (ES) of the temporalis muscle were examined in eighteen patients with chronic tension-type headache with disorder of pericranial muscles, before and two weeks after the administration of tizanidine. The left mental nerve was stimulated, under the maximal voluntary contraction of the temporalis muscles.