Background: We peformed a ventral intermediate nucleus (Vim) thalamotomy in a patient with Holmes' tremor and palatal tremor. The frequencies of these movement disorders were 4 Hz and 3 Hz, respectively. Vim thalamotomy stopped the Holmes' tremor but not the palatal tremor. Our observations suggest different mechanisms for these two involuntary movements.

Methods: A 57-arm 11 months after a pontine hemorrhage. Transoral carotid ultrasonography revealed periodic motion of her posterior pharyngeal wall with a frequency of 3 Hz. Recording of neuronal activities in the thalamus revealed a 4Hz rhythmic discharge time that was associated with her tremor in the contralateral arm. A left Vim thalamotomy was performed. The resting tremor of the upper limb stopped, but the kinetic tremor recurred 6 months after the thalamotomy. No effect was observed on her palatal tremor.

Conclusions: The different effects of Vim thalamotomy on the Holmes' tremor and palatal tremor suggest different oscillation sources for these two involuntary movements.