Injection of the thalamus through a cranial bur hole is performed for rigidity and tremor,1-3 spasticity,4 intractable pain,5,6 dystonia musculorum deformans,7 or hemiballismus.8 Some of the more precise stereotaxic methods take several hours. With the cannula and balloon technique, there is a mortality rate of 2.4%, and an additional complication rate (usually hemiplegia) of 3%.2 Furthermore, only about one out of three Parkinsonians are accepted for the procedure.9
We had had previous experience with radiologically planned and controlled percutaneous placement of a needle through the foramen ovale into the region of the Gasserian ganglion and subsequent injection of procaine, followed by alcohol.10,11 We report here a similar approach to making lesions in the thalamus, thalamolysis, primarily to relieve contralateral rigidity and tremor of Parkinsonism.
The target (a mathematical point) in the ventrolateral nucleus of the thalamus is determined by measurement from the