Patients on chronic dialysis or those who suffer from chronic renal failure are prone to develop a variety of neurologic complications. Encephalopathy is most likely caused by multiple metabolic derangements, but the precise pathophysiology still remains unknown. Oxidative stress is a potential mediator of uremic encephalopathy. Reversible posterior leukoencephalopathy syndrome or posterior reversible encephalopathy syndrome are common CNS disorders in patients with uremia. It is characterized by typical radiologic findings in the posterior regions of the cerebral hemisphere and needs special attention because of its potential reversibility on prompt treatment. Dialysis itself is associated with several types of encephalopathies, including disequilibrium syndrome, subdural hematoma, and, rarely, Wernicke encephalopathy. Dialysis dementia, associated with excessive aluminum in dialysates, is now rarely encountered. The lentiform fork sign may be a reliable neuroimaging sign for an early diagnosis of uremic encephalopathy. Severe hyponatremia with renal impairment is common in COVID-19 patients and predicts increased risk of encephalopathy and in-hospital mortality. Unrecognized renal insufficiency is common among patients with acute stroke and is associated with adverse short-term outcomes. Neuropathy generally only develops at glomerular filtration rates of less than 12 milliliter/min. Carpal tunnel syndrome is more common in hemodialysis patients than in the general population. Pruritus is a common complication of end-stage renal disease, affecting about one third of dialysis patients. For patients with autonomic neuropathy, specific treatments, including sildenafil for impotence and midodrine for intradialytic hypotension, are effective. A high prevalence of sleep apnea in hemodialysis patients has been noted. In this article, the author reviews the clinical features, pathogenesis, and management of central and peripheral nervous system complications encountered in patients with renal failure.
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• Chronic renal failure causes a variety of neurologic disorders affecting the central nervous system and the peripheral nervous system.
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• These complications include diffuse encephalopathy, seizures, stroke, movement disorders, sleep alterations, polyneuropathy, mononeuropathies, and myopathy.
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• Dialysis is associated with several types of encephalopathies, including posterior reversible encephalopathy syndrome, disequilibrium syndrome, subdural hematoma, and Wernicke encephalopathy.
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• Several mechanisms involved include toxic metabolic accumulation, hyperkalemia, hypercoagulability, immunologic disturbances, and acid base disequilibrium.
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• Early diagnosis of these complications is important for their prevention and for proper management.
Historical note and terminology
Uremia occurs when renal failure results in the systemic retention of nitrogenous and other waste products. Such metabolic derangements may cause dysfunction of various tissue types including those of the central and peripheral nervous systems (52). Uremic encephalopathy is diagnosed when renal failure is responsible for alteration of mental status (15). In 1962, Kennedy and associates identified dialysis disequilibrium syndrome as a characteristic symptom complex of mental confusion, headache, and muscle twitching following rapid correction of uremia by hemodialysis in patients with chronic renal failure (26). Arieff developed an animal model of the condition by exposing acutely uremic dogs to rapid hemodialysis (03). For the first time, in 1972, Alfrey described dialysis dementia in 5 chronically dialyzed patients who developed intermittent speech abnormalities followed by a distinct encephalopathy that was later believed to be a result of aluminum toxicity to the CNS (01). In 1971, Dyck and colleagues described uremic neuropathy in detail based on their extensive nerve conduction studies in these patients. Warren and Otieno, in 1975, reported carpal tunnel syndrome in patients on intermittent hemodialysis. In 1954, the team of John Merrill, Hartwell Harrison, and David Hume, headed by Joseph Murray, ushered in the modern era of human organ transplantation.