Is temporomandibular dysfunction a cranial dystonia? An electrophysiological study.
In 26 patients suffering from temporomandibular dysfunction (TMD) the silent period (ES), which consists of an early (ES1) and a late (ES2) inhibition which interrupts the voluntary electromyographic activity after an electrical stimulus, was recorded from the masseter muscles. Several different patterns were identified: in 8 patients (group I) the ES was normal; in 1 patient (group II) the ES was entirely absent; in 11 patients (group III) only the ES2 was absent and in 6 patients (group IV) ES1 and ES2 were combined. Such results can be explained by hypothesizing several functional states: normal excitability in group I, absolute (group II) or relative (group III) inexcitability and hyperexcitability in group IV. A central origin of TMD can be related either to a "dysregulation" of circuits located in the brainstem which give rise to the ES or to the centers, probably located in the basal ganglia, which control the circuits of the brainstem.
Neurological Department, Valduce Hospital, Como, Italy.
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Raudino
D000328:Adult; D004421:Dystonia / Q000150:complications* / Q000503:physiopathology; D004576:Electromyography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology*; D008875:Middle Aged; D009119:Muscle Contraction; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000209:etiology*