RELATIVE SPARING OF EXTRAOCULAR-MUSCLES IN MYOTONIC-DYSTROPHY - AN ELECTROOCULOGRAPHIC STUDY

We studied 40 patients with myotonic dystrophy (MD) to investigate whe ther saccadic eye movement (SEM) abnormalities have a central or perip heral origin. SEMs were recorded by electrooculography and analyzed by a computer system. Six patients were followed up to 2-7 years, Slow S EMs were present in 70% of patients, while saccadic latency and accura cy were within normal ranges. Peak saccadic velocity (PSV) did not cor relate with disease duration and muscular disability, and showed a sig nificant reduction only in 1 patient during the follow-up. Muscular di sability correlated significantly with age and disease duration and wo rsened in 4 patients over time. The doll's head maneuver elicited vest ibular compensatory eye movements with high velocities. These findings suggest that the extraocular muscles are at least partially spared in MD and that supranuclear structures, most likely the burst cells in b rainstem reticular formation, may contribute to the slowing of SEMs.