Brain targets in surgery for Parkinson's disease. Results of a survey of neurosurgeons.

Sixteen neurosurgeons were requested to define their preferred surgical target for treatment of parkinsonism. The scattergram thus obtained showed a great variability among surgeons. Although there was a concentration of targets in the ventrolateral (VL) nucleus of the thalamus, there was a separation by as much as 6 to 7 mm between targets. One surgeon placed the lesion in the subthalamic white matter below the VL nucleus, and two placed it outside the thalamus in the pallidothalamic pathways in Forel's field. It is assumed that successful surgery interrupts the pallidothalamocortical pathways that transmit tremor and rigidity impulses, regardless of which part of the pathways is severed.