Stereotactic mesencephalic tractotomy for the relief of thalamic pain

Twenty-seven patients with pain of central origin following cerebral hemisphere or brain stem infarction underwent stereotactic mesencephalic tractotomy. Twenty-one (77.8%) were pain free or significantly improved at discharge. Twenty-four were available for later review and 1p (66.7%) reported relief up to 5 years later. The target site was revised after the first 14 patients, reducing the number obtaining long term relief (lesion I, at the level of the superior colliculus--75%; lesion II, at the level of the inferior colliculus--58.3%), but substantially decreasing the incidence of disorders of ocular function from 83.3% to 16.7%.