Analysis of intention tremor.

A marked effect of stereotaxic thalamotomy on intention tremor is described and a neurophysiological interpretation is offered. Tremor-generating activity seems to start in the ventral intermediate nucleus (VIM) of the thalamus, as revealed by recording of the unitary activity through a microelectrode at the tip of the insertion needle, after diminution of facilitatory input due to pathology of the cerebellum or its efferent pathway to the cerebrum. This secondary change within the VIM and the loss of facilitatory input leads to an intention tremor as one of the cerebellar symptoms seen in various neurological diseases.