Excerpt from Neurologic Complications of Organ Transplantation

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Background

Organ transplantation has developed at an incredibly rapid pace since its introduction in the 1950s, and it has become a life-saving procedure for patients with end-stage organ failure. In 2006, more than 20,000 hematopoietic stem cell transplantations and 27,000 solid organ transplantations were performed in the United States alone.

The posttransplantation clinical course is frequently complicated by dysfunction of various organ systems, and early or delayed neurologic complications may develop in 30-60% of patients.^{1, 2} Because of the constantly changing protocols of transplantation and immunosuppression, the nature of neurologic complications has changed over time. Improved survival of patients undergoing transplant also shifts the focus of neurologic complications towards long-term complications. Nevertheless, diagnosis and management of perioperative complications of organ transplantation still plays a prominent role in determining the postoperative course of allograft recipients.

Organ transplantation may also improve neurologic function in various disorders with neurologic manifestations such as Wilson disease (liver transplantation), familial amyloidosis with neuropathy (liver transplantation), and diabetic neuropathy (pancreas transplantation).

Future developments in the field of organ transplantation, including newer immunosuppressive medications and xenograft and neural tissue transplantation, will further change the spectrum of neurologic and other complications in transplant recipients.

Pathophysiology

Neurologic complications are related to the surgical procedure of transplantation, posttransplant immunosuppression, opportunistic infection, or inherent disorders that led to transplantation.

Some neurologic complications of transplant surgery are inherent to all transplant types (eg, opportunistic CNS infections, immunosuppressant neurotoxicity, anoxic encephalopathy), while others are more common with certain types of allografts.

Posttransplant immunosuppression increases the risk of opportunistic infections, particularly after 1 month posttransplantation. While greater immunosuppression increases the risk of opportunistic infections and immunosuppressant neurotoxicity, it may be needed for treatment of allograft rejection. Exposure of patients undergoing transplant to endemic pathogens may result in increased frequency of certain infections.

The variety of conditions that led to organ failure requiring transplantation may also be associated with neurologic complications, including amyloid and diabetic neuropathy. Delayed allograft function may also precipitate various complications, including impairment of consciousness with hepatic and uremic encephalopathy.

Frequency

United States

Neurologic complications affect up to 30-60% of allograft recipients.

International

Neurologic complications of organ transplantation occur internationally with a similar frequency as in the United States.

Because the spectrum of CNS infectious pathogens depends on exposure, some endemic pathogens, mucormycosis, and parasitic diseases may be more common in tropical regions.

Mortality/Morbidity

Neurologic complications in patients undergoing transplant complicate posttransplant recovery, and opportunistic CNS infections may be very difficult to treat in patients who are immunosuppressed. Opportunistic CNS infections affect 5-10% of transplant patients, with a reported mortality rate of 75-90%.

Race

No racial predilection exists.

Sex

No significant association between sex and incidence exists.

Age

Neurologic complications of transplantation may develop in patients of any age.

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