In 1983, approximately 40 000 patients in France and 5 760 patients in Switzerland suffered from cerebral palsy, representing more than 0.1% of their respective populations. The functional disability of these patients is particularly impressive and emphasizes the medical, social and economic importance of this problem. The term cerebral palsy is restricted to non-progressive disorders of motor function, already observed at an early age and due to cerebral lesions. These motor disorders can be of paretic, dystonic and dyskinetic nature. Their epidemiology, classification, etiology, pathology, early diagnosis and evolution are extensively reviewed by Th. Deonna. The difficulty in evaluation of treatment is the absence of a generally accepted rating scale. G. Broggi has proposed one on the basis of a large experience which could serve in the future for more objective evaluation. This monograph is devoted to the functional neurosurgical treatment of cerebral palsy. Physiotherapy and rehabilitation are part of the basic treatment of cerebral palsy, and must be continued after any neurosurgical treatment. Various conservative methods of treatment and their neurophysiological rationale are mentioned by P. Claverie. Some technical devices which improve the neurological deficits and facilitate rehabilitation are presented. Radiculotomies and neurotomies are probably the oldest neurosurgical operations for the treatment of spasticity. The neurophysiological and neuroanatomical basis of this therapeutic approach are treated in the review of the material from the neurosurgical department of Montpellier. Sixty cases were collected and the results analysed according to the type of operation (posterior radiculotomy, anterior radiculotomy, mixed) performed. Stereotactic thalamotomies and subthalamotomies are believed to be the best neurosurgical method to treat the tremor and improve other dyskinesias and hyperkinesias. The technique and a personal review of 49 cases of cerebral palsy are presented. The long-term follow-up in this study demonstrates that this type of operation markedly improves the functional disability of patients with moderate hyperkinesias, moderately improves patients severely affected, but also demonstrates that possible side effects cannot be ignored. Review of the literature indicates the difficulty in interpretation of results due to a lack of objective evaluation. Nevertheless, stereotactic thalamotomy can still be recommended when tremor and rigidity are the most prominent symptoms. Stereotactic dentatotomies in the treatment of spasticity were very popular 20 years ago, but have been largely forgotten for nearly a decade.(ABSTRACT TRUNCATED AT 400 WORDS)