A neurophysiological study of myoclonus in patients with DYT11 myoclonus-dystonia syndrome.
Mutations in the epsilon-sarcoglycan (SGCE) gene have been associated with DYT11 myoclonus-dystonia syndrome (MDS). The aim of this study was to characterize myoclonus in 9 patients with DYT11-MDS presenting with predominant myoclonus and mild dystonia by means of neurophysiological techniques. Variously severe multifocal myoclonus occurred in all of the patients, and included short (mean 89.1 +/- 13.3 milliseconds) electromyographic bursts without any electroencephalographic correlate, sometimes presenting a pseudo-rhythmic course. Massive jerks could be evoked by sudden stimuli in 5 patients, showing a "startle-like" muscle spreading and latencies consistent with a brainstem origin. Somatosensory evoked potentials and long-loop reflexes were normal, as was silent period and long-term intracortical inhibition evaluated by means of transcranial magnetic stimulation; however, short-term intracortical inhibition revealed subtle impairment, and event-related synchronization (ERS) in the beta band was delayed. Blink reflex recovery was strongly enhanced. Myoclonus in DYT11-MDS seems to be generated at subcortical level, and possibly involves basal ganglia and brainstem circuitries. Cortical impairment may depend from subcortical dysfunction, but it can also have a role in influencing the myoclonic presentation. The wide distribution of the defective SCGE in DYT11-MDS may justify the involvement of different brain areas.
Marelli
Cecilia
C
Department of Neurology (Extrapyramidal Movement Centre), IRCCS Foundation, Carlo Besta Neurological Institute, Milan, Italy.
Canafoglia
Laura
L
Zibordi
Federica
F
Ciano
Claudia
C
Visani
Elisa
E
Zorzi
Giovanna
G
Garavaglia
Barbara
B
Barzaghi
Chiara
C
Albanese
Alberto
A
Soliveri
Paola
P
Leone
Massimo
M
Panzica
Ferruccio
F
Scaioli
Vidmer
V
Pincherle
Alessandro
A
Nardocci
Nardo
N
Franceschetti
Silvana
S