Hand tremor in patients with spasmodic torticollis.

The occurrence of hand tremors in patients with spasmodic torticollis (ST) was investigated in 55 patients by clinical and quantitative measurements. Ten patients had first-order or second-order relatives affected with postural tremor. Although 40% of the patients had a medical history and clinical findings for mild postural and action tremor of the hands, only four had moderate tremor amplitudes. One patient had a severe tremor, including resting tremor, and two had mild voice tremor. A positive correlation was found between hand and head tremor. Patients with hand tremor were younger at the onset of ST than were those without. The mean amplitudes of postural tremor were only slightly higher than for the controls and much smaller than those found in classic essential tremor. The tremor caused only mild disabilities. The tremor frequencies were indistinguishable from physiologic tremor. Further analysis of the tremor records showed evidence for physiologic tremor mechanisms only. We conclude that slightly enhanced postural hand tremors are common in ST but have a low amplitude and are only rarely clinically relevant for ST patients. Although the present data support the notion of an enhanced risk of postural tremor in families of patients affected with ST, none of the criteria allowed the separation of the hand tremor of ST from other postural/action tremors and especially from enhanced physiologic tremor. Thus, the present data do not support the classification of hand tremor in ST as either "dystonic" or essential tremor.