Rhythmic cortical myoclonus in Niemann-Pick disease type C.
We here describe a patient with late-infantile Niemann-Pick disease type C (NPC) presenting with worsening myoclonus, seizures, cerebellar symptoms, mild mental impairment, and gaze palsy. Electroencephalographic (EEG) -polymyographic examinations showed abnormally high and diffuse background alpha-activity, enhanced by intermittent photic stimulation. The electromyographic (EMG) showed quasirhythmic myoclonic jerks during motor activation. EEG-EMG frequency analysis (better than jerk-locked back-averaging) demonstrated the cortical origin of the myoclonus. Our observations indicate that cortical myoclonus may occur as the main symptom of NPC.
Canafoglia
Laura
L
Department of Neurophysiology and Epileptology, Carlo Besta National Neurological Institute, Milan, Italy.
Bugiani
Marianna
M
Uziel
Graziella
G
Dalla Bernardina
Bernardo
B
Ciano
Claudia
C
Scaioli
Vidmer
V
Avanzini
Giuliano
G
Franceschetti
Silvana
S
Panzica
Ferruccio
F
D000293:Adolescent; D000513:Alpha Rhythm; D001611:Beta Rhythm; D002540:Cerebral Cortex / Q000503:physiopathology*; D003241:Consanguinity; D004292:Dominance, Cerebral / Q000502:physiology; D004569:Electroencephalography; D004576:Electromyography; D004831:Epilepsies, Myoclonic / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D004829:Epilepsy, Generalized / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D018482:Muscle, Skeletal / Q000294:innervation; D052556:Niemann-Pick Disease, Type C / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D010775:Photic Stimulation; D011712:Pyramidal Tracts / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted