The relationship of Myofascial
Pain, Tension-type Headache,
and
Temporalis Contraction Intensity
As the intensity of
temporalis contraction increases, without any activity from the lateral
pterygoids, the severity of temporal pain (headache) increases in the absence
of any typical TMD symptoms (graph). Myofascial pain and dysfunction of
the temporalis is described by Travell as "Temporal Headache", and can
be caused and/or perpetuated by chronic nocturnal intense temporalis
contraction (1) (L). Tension-type headache patients without
signs or symptoms of TMD (3) clench their jaws during sleep, on
average, 14 times more intensely than asymptomatic controls (2) (M).
Temporalis clenching without lateral pterygoid involvement does not cause
strain on the TMJ (slide 2).
Chronic temporalis clenching without lateral pterygoid
involvement can be considered a type of bruxism, that is, "Primary
Clenching".
Source : http://www.nti-tss.com/slide4.htm