Idiopathic torsion dystonia and writing tremor within a family

A 12-year-old boy had suffered from idiopathic torsion dystonia since the age of 8 years, which had never been relieved with pharmacologic treatment. His mother had exhibited primary tremor upon writing from the age of 10 years, but had not yet developed dystonia. Surface electromyography revealed paradoxical muscular contraction of Westphal in both patients, although the main abnormal findings in the proband and his mother were continuous tonic discharges in the arms and 4–5-Hz grouped discharges in the neck, respectively. The simultaneous occurrence of dystonia and writing tremor within one family, and the presence of the paradoxical contraction in both cases suggest that a certain type of dystonia and writing tremor may be pathogenetically linked.