The impressive progress of transplantation over the last 20 years has been made possible by surgical advances, the discovery of a superb immunosuppressive agent, cyclosporine, improved postoperative care, and infectious disease surveillance. These advances, however, were not devoid of neurological complications. The risk of such complications is after surgery when the graft may deteriorate in function from vascular complications. An entirely new field of neurological complications, unique to organ transplant recipients, has emerged, but only now are some of the basic mechanisms being unravelled. Neurologists have started to play an integral part in the postoperative evaluation and management of patients after transplantation and are able now to recognize the clinical presentations. We are beginning to understand how immunosuppressive agents can cause neurotoxicity, risks of infections of the central nervous system (CNS), management of seizures, and longterm effects, including demyelinating disorders (Wijdicks, 1995, 1999). This chapter targets the major neurological disorders seen after organ transplantation.

Epidemiology

Estimation of frequency of neurological complications after transplantation is fraught with difficulties. First, most studies have reported a retrospective analysis of surgical series that are probably skewed towards the more severe neurological complications. Neurologists would only be called on when a neurological complication appears to dominate the clinical picture or could invalidate the initial success of grafting. One can also expect that, with further categorization of neurological syndromes and consequently recognition by the transplant team, neurologists will be consulted less often and only when diagnosis and management become more complex or frustrating. Prospective studies may also not capture all of postoperative events, and to be accurate, they would need a neurologist participating in rounds with the transplant team. Neurological complications in organ-transplant recipients are more common after liver and heart transplants, because these surgeries are more prone to hemodynamic instability. Neurological complications in renal transplant recipients usually appear in the years after transplantation and may be due to comorbidity associated with end-stage renal failure and a result of long-term immunosuppression.

It is useful to categorize neurological complications into major complications, such as recurrent seizures, postoperative failure to awaken, neurotoxicity associated with immunosuppressive agents, and acute neuromuscular disorders, and minor manifestations, such as tremors, transient agitation, and confusional states.