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Irregular jerky tremor, myoclonus, and thalamus: A study using low‐frequency stimulation
Author(s) -
Bejjani Boulos Paul,
Arnulf Isabelle,
Vidailhet Marie,
Pidoux Bernard,
Damier Philippe,
Papadopoulos Savvas,
Bonnet AnneMarie,
Cornu Philippe,
Dormont Didier,
Agid Yves
Publication year - 2000
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/1531-8257(200009)15:5<919::aid-mds1024>3.0.co;2-0
Subject(s) - thalamus , myoclonus , stimulation , essential tremor , thalamic stimulator , deep brain stimulation , proprioception , neuroscience , movement disorders , medicine , electrophysiology , psychology , intention tremor , parkinson's disease , ataxia , disease
High‐frequency thalamic stimulation alleviates tremor in Parkinson's disease (PD) and essential tremor (ET). The origin of thalamic myoclonus is unexplained and the effects of low‐frequency thalamic stimulation on movement control are still unknown. We studied the effects of stimulation at a low frequency of 15 Hz in five drug‐free patients (3 PD, 2 ET) 6 months after thalamic implantation of quadripolar electrodes (unilateral in four patients, bilateral in one patient). Clinical, electrophysiological, and videotaped assessment, using a monopolar 15 Hz frequency (3 V, 90 μs) stimulation current applied simultaneously through two adjacent contacts of the electrode, was performed. We observed myoclonus and irregular jerky tremor in the upper limb contralateral to the site of stimulation. The jerks lasted less than 200 ms, were irregular and not synchronous with stimulation, were superimposed on rest or postural tremor, and increased in response to tactile, proprioceptive, or vibratory stimuli. The fact that this complex movement disorder can be induced by low‐frequency stimulation in the ventral intermediate nucleus (Vim) of the thalamus suggests that it results, at least partly, from dysfunction of the Vim and possibly adjacent nuclei of the thalamus.