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Titolo:
A cerebellar-like terminal and postural tremor induced in normal man by transcranial magnetic stimulation
Autore:
Topka, H; Mescheriakov, S; Boose, A; Kuntz, R; Hertrich, I; Seydel, L; Dichgans, J; Rothwell, J;
Indirizzi:
Univ Tubingen, Dept Neurol, D-72076 Tubingen, Germany Univ Tubingen Tubingen Germany D-72076 Neurol, D-72076 Tubingen, Germany Univ Tubingen, Dept Neuroradiol, D-72076 Tubingen, Germany Univ Tubingen Tubingen Germany D-72076 radiol, D-72076 Tubingen, Germany Inst Neurol, MRC, Human Movement & Balance Unit, London WC1N 3BG, England Inst Neurol London England WC1N 3BG lance Unit, London WC1N 3BG, England
Titolo Testata:
BRAIN
, volume: 122, anno: 1999,
parte:, 8
pagine: 1551 - 1562
SICI:
0006-8950(199908)122:<1551:ACTAPT>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
HUMAN MOTOR CORTEX; CORTICAL STIMULATION; BRAIN-STIMULATION; REACTION-TIME; RESPONSES; MUSCLES; HAND; MOVEMENTS; WRIST; INHIBITION;
Keywords:
intention tremor; postural tremor; cerebellar; transcranial magnetic stimulation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Topka, H Univ Tubingen, Dept Neurol, Hoppe Seyler Str 3, D-72076 Tubingen,Germany Univ Tubingen Hoppe Seyler Str 3 Tubingen Germany D-72076 ermany
Citazione:
H. Topka et al., "A cerebellar-like terminal and postural tremor induced in normal man by transcranial magnetic stimulation", BRAIN, 122, 1999, pp. 1551-1562

Abstract

Trains of repetitive transcranial magnetic stimulation (TMS) at 10-30 Hz and intensities of 90-120% motor threshold were delivered through a figure of eight coil over the motor cortex while normal subjects made either rapid,self-terminated (ballistic) wrist movements or maintained the position of their wrist at a fixed angle. Movement kinematics and EMG activity in antagonistic forearm muscles were analysed. In the ballistic task, repetitive TMS had little effect on the velocity or acceleration of the initial segment of the movement, although it induced large terminal oscillations (tremor) around the target position at frequencies between 4.4 and 7.2 Hz. The likelihood that tremor would occur increased with increasing stimulus intensitiesor frequencies. It was maximal with stimulation over the forearm area, anddecreased with stimulation over the leg area, or over parietal sites; there was no tremor during stimulation of cervical nerve roots. The frequency of the induced tremor was independent of the rate of stimulation and did notdepend on the presence of excitatory and inhibitory motor responses to thestimulus. Stimulation could also induce tremor of the same frequency in the fixed task, but only during co-contraction of forearm muscles. The amplitude of tremor was proportional to the level of co-contraction. Clinically, the tremor induced by repetitive TMS appeared very similar to cerebellar tremors. In order to confirm this we investigated two cerebellar patients, one with autosomal dominant cerebellar ataxia and the other with multiple sclerosis. Both of them had a terminal tremor of 6-7 Hz in the wrist movement task. In the holding task, the amplitude of their postural tremor increasedwith the level of co-contraction in forearm muscles. Since the frequency of repetitive TMS-induced tremor was independent of stimulus parameters, we conclude that it represents some intrinsic property of the CNS. We suggest that the tremor is caused by disruption of cortical processes involved in terminating a voluntary movement or maintaining a posture. Similarities to cerebellar patients suggest that repetitive TMS may cause tremor by interfering with adaptive cerebellar afferent inflow to motor cortex. Repetitive TMS-induced tremor, therefore, may represent a model of some forms of cerebellar tremor in man.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/10/20 alle ore 16:19:05