Spasmodic torticollis may be defined as hyperkinesis of the musculature of the neck, of all the large and small, superficial and deep muscles that make up its complex motor system. According to Meige1 and Barré,2 the smaller, deep muscles of the neck (the anterior and posterior groups) contract first; the larger muscles, the trapezius and the sternocleidomastoid, act later, accentuating and completing the movements of the former. Thus the muscular contractions of the neck do not occur simultaneously, but successively. Grossly, they usually show in the large muscles—sternocleidomastoid, splenius and trapezius—but they may predominate in the smaller muscles and result in brisk rotatory movements of the neck. The movements are often unilateral; they may be symmetrical, when, for instance, both trapezii or both sternocleidomastoids are involved. They may manifest many other varieties, depending on the predominance of the groups of muscles affected.
Thévenard3 considered spasmodic torticollis a
HASSIN GB, SCHAUB CF, VORIS HC. SPASMODIC TORTICOLLIS. Arch NeurPsych. 1931;26(5):1043–1052. doi:10.1001/archneurpsyc.1931.02230110141008
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