The thalamotomy procedure is designed to reduce tremor on the opposite side of the body (i.e. a left thalamotomy reduces tremor in the right hand). It is most commonly used for patients with Essential Tremor but also used for patients with Parkinsonian tremor, multiple sclerosis tremor or post-traumatic tremor. If you have ‘tremor dominant’ Parkinson’s Disease, then this operation may be ideal. Tremor dominant Parkinson’s disease is a subtype of PD where patients have minimal problems with bradykinesia or rigidity but major problems with tremor. This tremor is interfering with their quality of life and is not controlled by medications.
The results of placing a lesion in the thalamus, or thalamotomy, were first published by Hassler in 1954. Throughout the 1960’s different thalamic targets were lesioned until the ventral intermediate (VIM) nucleus emerged as the most effective target for tremor reduction.
Currently, the expectations following thalamotomy is that your tremor (on the opposite side of the body) will be reduced about 80%. We are aiming for the arm – since that will provide the most improvement in quality of life – but leg tremor will also be reduced. Head, jaw and body tremor will not be eliminated after a unilateral procedure since the other side of the body will not be affected. Thalamotomy does not benefit bradykinesia or rigidity. Patients with PD and symptoms of bradykinesia and rigidity that are progressing might want to consider STN-DBS instead of thalamotomy since that operation may control bradykinesia and tremor (especially if the tremor responded to medications).
The risks of thalamotomy include but are not limited to contralateral weakness, arm and foot incoordination, difficulty speaking or swallowing and cognitive decline. There is a rare (1%) chance of stroke causing death.