Effect of Extracorporeal Therapies on the Brain

Effect of Hemodialysis and Peritoneal Dialysis on the Brain (Chronic Setting)

End-stage renal disease (ESRD) is a major health burden worldwide and becomes increasingly common all over the world. In addition to kidney transplantation, hemodialysis (HD) and peritoneal dialysis (PD) represent two options for renal replacement therapy in patients with ESRD. Substantial cross-talk occurs between the kidney and the brain, as indicated by the frequent presentation of neurologic disorders, such as stroke, cognitive impairment, and neuropathy during the natural history of chronic kidney disease (CKD). The advent of dialysis has led to a reduction in the rate of neurologic complications associated with uremia, but a new set of complications have arisen as a consequence of the effects of dialysis on the central nervous system over the short and long term.

Hemodialysis and Peritoneal Dialysis on Stroke

Stroke is a major health concern for maintenance hemodialysis (MHD) patients, with an incidence 8 to 10 times greater in these patients than that observed in the general population. The mortality rate of stroke is approximately three times higher in patients on hemodialysis than in patients with CKD not undergoing hemodialysis. Risk factors associated with stroke that are attributable to hemodialysis include hemodynamic instability, vascular access type, and risk of thromboembolism, amyloidosis, vascular calcification, and time spent on hemodialysis. A study of 151 consecutive patients undergoing MHD patients who incurred an acute stroke found that 34% of ischemic strokes and 19% of hemorrhagic strokes occurred either during or within 30 minutes of concluding hemodialysis. Data obtained from the US Renal Data System (USRDS) also showed that the incidence of stroke increased markedly during and immediately after hemodialysis, further suggesting that hemodialysis may increase the risk of stroke. The removal of solutes and excess fluid during hemodialysis can result in low cerebral blood flow (CBF) and may predispose patients to ischemic stroke in the setting of flow-limiting vascular lesions. The association between stroke and high interdialytic weight gain is not clear, but it seems reasonable to assume that low interdialytic weight gain would be associated with greater hemodynamic stability and a lower risk of stroke.

Patients undergoing peritoneal dialysis have a higher incidence of hospitalization resulting from ischemic and hemorrhagic stroke compared with age- and sex-matched controls. However, patients undergoing peritoneal dialysis are less likely to suffer hemorrhagic stroke than those undergoing hemodialysis, possibly because of the use of anticoagulants during hemodialysis sessions. Wang et al. showed that release of glutamate into extracellular tissues during acute stroke causes neuronal death because of its excitotoxic properties. Peritoneal dialysis is effective in removing glutamate, and experimental evidence from animal models indicates that removal of glutamate by peritoneal dialysis can reduce infarct size and restore functional brain tissue.