Exteroceptive suppression of temporalis muscle activity: findings in headache.

Exteroceptive suppression of temporalis muscle activity was proposed by Schoenen and co-workers in 1987 as a tool in headache diagnosis and research. Their finding of a decreased or abolished second silent period (ES2) in chronic tension-type headache sufferers has been confirmed by several independent laboratories during the last five years. Temporalis silent periods have also been studied in various other types of headaches. Their modulation by neuropsychological factors and pharmacological agents has also been investigated as well as their retest reliability. The pathophysiological concept of muscle contraction in tension-type headache has been challenged by studies using temporalis silent periods. The exteroceptive suppression of temporalis muscle activity points unequivocally towards a central pathogenetic mechanism, although it remains unclear whether the abnormalities of temporalis ES2 represent the primary dysfunction or a secondary phenomenon in chronic tension-type headache.