Hereditary motor–sensory neuropathy and movement disorders

To explore the relationship between hereditary motor and sensory neuropathy (HMSN) and movement disorders, we examined 7 patients with HMSN referred to our Movement Disorders Clinic and surveyed members of the Charcot-Marie-Tooth association. The following movement disorders were observed in the index patients: postural tremor in 6, rest tremor in 3, and Parkinsonism and dystonia in 2. Tremor, present in 40% of the 201 patients who responded to the survey, was first noted at a mean age of 36 years, and mostly involved the hands. Family history of tremor was more frequent in the tremor group (P < 0.005), which also had a significantly worse writing score than the nontremor group (P < 0.001). The overlap in clinical features between HMSN-associated tremor and essential tremor (ET), the high frequency of family history of tremor, and the lack of a relationship between the severity of tremor and of peripheral neuropathy suggest that the tremor in HMSN is pathogenically related to ET.