Ventral intermediate thalamic deep brain stimulation provides symptomatic control of Parkinson disease tremor in selected patients, according to a report.

Ventral intermediate (Vim) thalamic deep brain stimulation (DBS) provides symptomatic control of Parkinson disease tremor in selected patients, according to a report in the June issue of the Journal of Neurology, Neurosurgery & Psychiatry.

Vim DBS has previously been shown to have long-term efficacy in patients with essential tremor, the authors explain, but results in patients with parkinsonian tremor have been inconsistent.

Dr. Marwan I. Hariz from the Institute of Neurology, London, UK and colleagues investigated the long-term effect of Vim DBS on contralateral tremor at a mean of 6.6 years after surgery in 38 patients with Parkinson disease.

Tremor scores for the treated body side six years after surgery were improved when stimulation was on compared with when it was off, the authors report. Tremor scores for the non-treated side also tended to decrease over time, but the decrease was not significant.

Motor scores at six years with stimulation off were similar to those at baseline, the report indicates, but they were better when stimulation was on than when it was off.

Appendicular akinesia and rigidity showed only minor improvement on the treated body side when stimulation was on, but axial motor symptoms (speech, gait, and postural stability) deteriorated markedly at six years under both on and off stimulation conditions.

The significant improvement in functional disability one year after surgery did not persist at six years, the investigators say, despite the maintained improvement in tremor scores.

"This study confirms that patients with tremor dominant Parkinson disease who do not present with fluctuations and dyskinesias may have a relatively benign progression of the disease," the authors conclude. "Vim DBS, although having no effect on akinesia and rigidity, is a relatively lenient surgical procedure and may still have a place for long term symptomatic control of Parkinson disease tremor in selected patients."

J Neurol Neurosurg Psychiatry 2008;79:694-699