Neurological disorders in liver transplant candidates: Pathophysiology and clinical assessment

Compromised liver function, as a consequence of acute liver insufficiency or severe chronic liver disease may be associated with various neurological syndromes, which involve both central and peripheral nervous system. Acute and severe hyperammoniemia inducing cellular metabolic alterations, prolonged state of "neuroinflammation", activation of brain microglia, accumulation of manganese and ammonia, and systemic inflammation are the main causative factors of brain damage in liver failure. The most widely recognized neurological complications of serious hepatocellular failure include hepatic encephalopathy, diffuse cerebral edema, Wilson disease, hepatic myelopathy, acquired hepatocerebral degeneration, cirrhosis-related Parkinsonism and osmotic demyelination syndrome. Neurological disorders affecting liver transplant candidates while in the waiting list may not only significantly influence preoperative morbidity and even mortality, but also represent important predictive factors for post-transplant neurological manifestations. Careful pre-transplant neurological evaluation is essential to define severity and distribution of the neurological impairment, to identify the abnormalities still responsive to current treatment, and to potentially predict the inherent post-operative prognosis. The preferred specific indices of neurological pre-transplant assessment may vary among centers, however, even with the aid of the current biochemical, neurophysiological, neuropsychological and neuroimaging diagnostic tools, the correct diagnosis and differential diagnosis of various syndromes may be difficult. In this article the relevant pathophysiological and clinical aspects of the most frequent brain and peripheral nervous system diseases affecting liver transplant candidates with acute or advanced chronic liver failure are briefly reported. The practical diagnostic findings useful for the preoperative assessment and treatment, as well as the expected neurological evolution after liver transplantation are also evaluated.