Rest tremor in idiopathic adult-onset dystonia.

BACKGROUND: Tremor in dystonia has been described as a postural or kinetic abnormality. In recent series, however, patients with idiopathic adult-onset dystonia also displayed rest tremor.

METHODS: The frequency and distribution of rest tremor were studied in a cohort of 173 consecutive Italian patients affected by various forms of idiopathic adult-onset dystonia attending our movement disorder clinic over 8 months.

RESULTS: Examination revealed tremor in 59/173 patients (34%): 12 patients had head tremor, 34 patients had arm tremor, whilst 13 patients presented tremor in both sites. Head tremor was postural in all patients, whereas arm tremor was postural/kinetic in 28 patients, only at rest in one and both postural/kinetic and at rest in 18 patients. Patients with tremor were more likely to have segmental/multifocal dystonia. Patients who had rest tremor (either alone or associated with action tremor) had a higher age at dystonia onset and a greater frequency of dystonic arm involvement than patients with action tremor alone or without tremor.

CONCLUSIONS: Both action and rest tremor are part of the tremor spectrum of adult-onset dystonia and are more frequently encountered in segmental/multifocal dystonia. The higher age at dystonia onset and the greater frequency of arm dystonia in patients with rest tremor may have pathophysiological implications and may account, at least in part, for the previous lack of identification of rest tremor as one possible type of tremor present in dystonia.