Thalamotomy.

Despite astounding progress in the biochemical management of Parkinson's disease in particular and of other movement disorders, there are still patients disabled by severe tremor and not by bradykinesia in whom thalamotomy remains the treatment of choice. Though the irreducible complications of surgery must be taken into account, the problems of prolonged multiple drug therapy should not be ignored. The same rationale applies to selected patients with essential or familial tremor. For some patients with ataxic tremor caused by multiple sclerosis and other brain lesions, or with dystonia or, rarely, other movement disorders, thalamotomy may offer limited though significant relief from an otherwise intractable disability. Indications for the use of stereotactic destructive lesions in the treatment of nociceptive pain in those cases where cordotomy and intraspinal morphine infusion are unsuitable have contracted with the introduction of lower-risk alternatives such as intraventricular morphine instillation. When destructive lesions are indicated, the choice will lie between mesencephalic tractotomy, with its higher success rate but irreducible mortality and morbidity, and medial thalamotomy, which, though less risky, is also less effective. For central and deafferentation pain, the same two procedures may be considered. However, destructive lesions are seldom effective for the treatment of the most common element of these pain syndromes: steady burning or dysesthetic pain. They may be more promising, though, for the intermittent, often shooting pain and the evoked elements (hyperpathia and allodynia) of central and deafferentation pain. Even so, it is advisable first to carry out a trial of VC and PVG stimulation before considering a destructive lesion, which should be a last resort.