Restorative neurology in movement disorders.

Cell replacement for restoration of neurological functions in patients with movement disorders has been investigated for more than 15 years. Initial attempts used autologous adrenal medulla grafts implanted into the denervated striatum of patients with Parkinson's disease (PD). This approach was soon abandoned in favor of intrastriatal implantation of human embryonic mesencephalic tissue, rich in dopaminergic neurons. Available data from grafted PD patients show long-term (up to 10 years) graft survival and clinical benefits. The pattern and magnitude of symptomatic relief following transplantation, however, are incomplete and the outcome varies among patients. The need for large amounts of human embryonic tissue has to be circumvented and a better understanding of the relationship between graft placement and symptomatic recovery is necessary before this procedure can be offered to larger groups of patients. Clinical trials in Huntington's disease have so far shown inconclusive results. Neural cell replacement therapy is still an experimental procedure, but has the potential to become a future restorative treatment in PD and other movement disorders.