Patients with movement disorders usually have disabling features not affected by surgery; for example, paraplegia in patients suffering from spasticity and ataxia in patients with cerebellar tremor. Relieving one aspect of the problem does not correct the patient's overall disability.

Similar problems affect assessment of surgery for movement disorders; a spastic paraplegic's life expectancy is not altered by successful baclofen infusion. One possible exception, the question as to whether ‘successful’ thalamotomy alters the course of Parkinson's disease will be discussed. The quantitative assessment of change in movement disorders is a major problem in clinical research. The plethora of protocols for assessing patients with Parkinson's disease for example, attests to difficulties with this process. Hemifacial spasm, though regularly successfully treated by microvascular decompression is relatively infrequent in North America compared with the Far East, and therefore in the author's practice, so that it will not be discussed. This condition can also be treated with botulinum toxin injection, with favourable results, but direct comparison of medical and surgical therapy is lacking.

Surgery for movement disorders

Although a variety of surgical operations have been proposed for the treatment of movement disorders, those in common use today are all stereotactic except for microvascular decompression in hemifacial spasm, botulinus toxin injections and procedures for spasmodic torticollis. This author has no experience with these last modalities other than the use of multiple rhizotomies in spasmodic torticollis in which little recent information has accumulated. The bulk of published data in stereotactic surgery relates to Parkinson's disease, information concerning essential and cerebellar tremor and dystonia being so sparse as to make a survey of ‘outcomes’ difficult.