title: Postural tremor in Wilson's disease: a magnetoencephalographic study.
abstract: The following study included 5 Wilson's disease (WD) patients showing a right-sided postural forearm tremor (4-6 Hz) and addressed the question of whether the primary motor cortex (M1) is involved in tremor generation. Using a 122-channel whole-head neuromagnetometer and surface electromyogram (EMG), we investigated cerebromuscular coupling. Postural tremor was observed in a sustained 45-degree posture of the right-sided forearm. Data were analyzed using dynamic imaging of coherent sources (DICS), revealing cerebromuscular coupling between EMG and cerebral activity. Coherent sources were superimposed on individual high-resolution T1-weighted magnetic resonance images (MRI). Phase lags between EMG and cerebral areas showing strongest coherence were determined by means of a Hilbert transform of both signals. In all patients, postural tremor was associated with strong coherence between tremor EMG and activity in contralateral primary sensorimotor cortex (S1/M1) at tremor or double tremor frequency. Phase lag values between S1/M1 activity and EMG revealed efferent and afferent components in the corticomuscular coupling. Taken together, our results indicate that postural tremor in WD is mediated through a pathological oscillatory drive from the primary motor cortex.
authors.affiliation: Department of Neurology, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Südmeyer
authors.forename: Bettina
authors.initials: B
authors.lastname: Pollok
authors.forename: Harald
authors.initials: H
authors.lastname: Hefter
authors.forename: Joachim
authors.initials: J
authors.lastname: Gross
authors.forename: Lars
authors.initials: L
authors.lastname: Wojtecki
authors.forename: Markus
authors.initials: M
authors.lastname: Butz
authors.forename: Lars
authors.initials: L
authors.lastname: Timmermann
authors.forename: Alfons
authors.initials: A
authors.lastname: Schnitzler
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D004576:Electromyography; D006527:Hepatolenticular Degeneration / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D012720:Severity of Illness Index; D014202:Tremor / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*