The neurological complications of cardiac transplantation.

Review of the neurological complications encountered in 83 patients who received cardiac homografts over a seven-year period leads to the following conclusions: (1) Neurological disorders are common in transplant recipients, occurring in over 50 per cent of patients. (2) Infection was the single most frequent cause of the neurological dysfunction, being responsible for one-third of all CNS complications. (3) The infective organisms were typically those considered to be usually of low pathogenicity: fungi, viruses, protozoa and an uncommon bacterial strain. (4) Other clinical neurological syndromes were related to vascular lesions, often apparently from cerebral ischaemia or infarction occurring during the surgical procedure, metabolic encephalopathies, cerebral microglioma, acute psychotic episodes and back pain from vertebral compression fractures. (5) The infectious complications and probably the development of neoplasms de novo, are related to immunosuppressive therapy which impairs virtually all host defence mechanisms and alters the nature of the host's response to infective agents or other foreign antigens. (6) Because neurological symptoms and signs were usually those of behavioural changes or deterioration in intellectual performance, the neurological examination was often of little value in diagnosing the nature or even the anatomical site of the neuropathological process. (7) The possibility of an infectious origin of the neurological manifestations must be aggressively pursued even in the absence of fever and a significantly abnormal spinal fluid examination. The diagnostic error made most frequently was to ascribe neurological symptoms erroneously to metabolic disturbances or to "intensive care unit psychosis" when they were in fact due to unrecognized CNS infection. (8) Maintenance of mean cardiopulmonary bypass pressures above 70 mmHg, particularly in patients with known arteriosclerosis, may reduce operative morbidity. (9) Though increased diagnostic accuracy is possible with routine use of a variety of radiological and laboratory techniques, two further requirements probably must be met before a significant reduction in the frequency of neurological complications will occur: the advent of greater immunospecificity in suppressing rejection of the grafted organ while preserving defences against infection; and a more effective armamentarium of antiviral and antifungal drugs.