Movement-related cortical potentials in myotonic dystrophy

To investigate a possible deficit of the voluntary movement mechanism within the central nervous system (CNS) in patients with myotonic dystrophy (MyD).

Movement-related cortical potentials preceding voluntary extension of the right middle and index fingers were studied in 9 patients with MyD and compared with those in 11 age-matched healthy subjects and 9 age-matched patients with other neuromuscular disorders (NMDs).

The amplitudes of Bereitschaftspotential was smaller in MyD patients than in age-matched controls and age-matched patients with other NMDs although there was no statistically significant difference. The amplitude of negative slope was significantly smaller in MyD patients than in age-matched controls and age-matched patients with other NMDs. Clinical findings such as age, disease duration, degree of motor impairment and cognitive function had no effect on the individual electrophysiological parameters.

The present results suggest that subclinical abnormalities exist in CNS function associated with motor preparation and execution, which is independent of muscle weakness.