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Irregular jerky tremor, myoclonus, and thalamus: a study using low-frequency stimulation
B P Bejjani1, I Arnulf, M Vidailhet
1Centre d'Investigation Clinique--Inserm U289, Fédération de Neurologíe, Paris, France.
Movement Disorders : Official Journal of the Movement Disorder Society
|September 29, 2000
Summary
Low-frequency thalamic stimulation can unexpectedly induce myoclonus and jerky tremors in Parkinson's disease (PD) and essential tremor (ET) patients. This suggests potential thalamic dysfunction beyond high-frequency stimulation benefits.
Area of Science:
- Neurology
- Neurosurgery
- Movement Disorders
Background:
- High-frequency thalamic stimulation is a known treatment for tremors in Parkinson's disease (PD) and essential tremor (ET).
- The effects of low-frequency thalamic stimulation on movement control remain largely unexplored.
- The precise origin of thalamic myoclonus is not fully understood.
Observation:
- Low-frequency (15 Hz) thalamic stimulation was applied to five drug-free patients (3 PD, 2 ET) with implanted electrodes.
- Stimulation was delivered unilaterally or bilaterally using a monopolar current.
- Clinical, electrophysiological, and video assessments were performed post-stimulation.
Findings:
- Low-frequency stimulation induced myoclonus and irregular jerky tremors in the contralateral upper limb.
- These involuntary movements were brief (<200 ms), irregular, and not synchronized with stimulation.
- The induced jerks worsened with tactile, proprioceptive, or vibratory stimuli.
Implications:
- Low-frequency stimulation in the ventral intermediate nucleus (Vim) can elicit complex movement disorders.
- This suggests that thalamic myoclonus may stem, in part, from dysfunction within the Vim and adjacent thalamic nuclei.
- Findings challenge the understanding of thalamic nuclei function in movement control and may inform future neuromodulation strategies.