Uremic encephalopathies: clinical, biochemical, and experimental features

Patients with renal failure may manifest a variety of neurologic disorders. Patients with chronic renal failure who have not yet received dialytic therapy may develop a symptom complex progressing from mild sensorial clouding to delirium and coma, with tremor, asterixis, multifocal myoclonus, and seizures. After the institution of adequate maintenance dialysis therapy, patients may continue to be afflicted with more subtle nervous dysfunction, including impaired mentation, generalized weakness, and peripheral neuropathy. These central nervous system disorders are referred to as uremic encephalopathy. The dialytic treatment of end-stage renal disease has itself been associated with the emergence of two distinct, new disorders of the central nervous system; dialysis dysequilibrium and dialysis dementia. The dialysis disequilibrium syndrome consists of headache, nausea, muscle cramps, obtundation, and seizures, and is a consequence of the initiation of dialysis therapy in some patients. Dialysis dementia is a progressive, generally fatal encephalopathy which affects patients on chronic hemodialysis. There are at least three different forms of dialysis encephalopathy: sporadic, epidemic; and that associated with renal disease in children. In addition to the foregoing neurologic diseases which are specifically related to uremia and/or dialysis, a number of other neurologic disorders occur with increased frequency in patients with end-stage renal disease on chronic hemodialysis. These include subdural hematoma, electrolyte disorders, vitamin deficiencies, drug intoxication, hypertensive encephalopathy, and acute trace element intoxication. Renal transplantation is associated with a variety of central nervous system infections, reticulum cell sarcoma, and central pontine myelinosis. The present manuscript will review the clinical, structural, and biochemical components of those neurologic disorders which are peculiar to the uremic state and its treatment with dialysis.