Abstracts

Rationale: Most patients with Unverricht-Lundborg disease or EPM1 develop during the course of the disease a locomotory disability. Our hypothesis was that negative myoclonias are the main reason for the locomotor disability and investigated their progression. Methods: In 15 patients with EPM1, all proven by mutation of the CSTB gene, ictal polygraphic video-EEG-recordings (16 channel EEG, 8 channel surface EMG) were done in freely moving or standing patients. At least two recordings were performed in 8 EPM1 patients with a mean intervall of 12.8 years between them. Criterion for the duration of the negative myoclonias was the duration of the silent periods in the EMG. In a first approach the silent periods of the 8 patients with 2 polygraphic recordings were compared at the different time points (T1, T2). In a second approach all 15 patients were cross-sectional grouped in capable of walking without aid, with aid and in need of a wheelchair. Results: All 15 patients had documented negative myoclonias in their polygraphic recordings when standing or walking. A direct confirmation for a significant extension of the duration of the silent periods over the years from 100 (SD 19.1) ms ad T1 to 128 (SD 26.6) ms at T2 was found in 7 of the 8 patients. In the second approach patients with no disturbance in walking had a mean duration of 97.3 (SD 16.5) ms, patients who were handicapped in walking had a mean duration of 106.7 (SD 16) ms, patients who were bound to a wheelchair had a mean duration of 139 (SD 23.6) ms. The increment in frequency of the negative myoclonias was not quantitativly investigated. In the wheelchair patients, the negative myoclonus was, while walking more continous and tremolous. In contrast the patients with no disturbances, negative myoclous more seldom Conclusions: We have shown, using simultaneous EEG/EMG recordings in freely moving patients, that the locomotor disability is in fact mainly due to negative myoclonus in voluntary innervated muscles. One reason for the progression of the disability is the lengthening of the duration in the measurable silent periods, as measure for the duration of the negative myoclonias