Blink Reflex Alterations in Chronic Renal Failure

Objective: The purpose of this study was to investigate the effects of hemodialysis and peritoneal dialysis on the peripheral and central nervous system in patients with uremia associated with chronic renal failure. Method: In this study, 35 hemodialysis and 35 peritoneal dialysis patients were compared with 70 healthy controls by working in blink reflex after assessment of peripheral neuropathy by neurological examination and performing EMG. Results: Ipsilateral R2 (R2i) and contralateral R2 (R2c) response latencies were found to be significantly prolonged in patients with chronic renal failure compared to those of controls. Also, latencies of R2 responses in hemodialysis patients, in whom polyneuropathy was detected, were significantly longer than those of the peritoneal dialysis patients, while latencies of R1 responses were unaffected. Conclusion: For extraaxial lesions, R2 is less sensitive than R1, but in intraaxial lesions abnormality of R2 is as frequent as short latency responses, the R2 being more complex and spreads to the caudal medulla. Hence, in chronic renal failure patients sparing of the R1 and prolongation of the R2 indicates a subclinical intraaxial involvement. There was no significant difference in R1, R2i and R2c values between peritonal dialysis patients with polyneuropathy and controls. R1 values in hemodialysis patients with polyneuropathy were found to be within normal range while R2i and R2c values were significantly prolonged when compared to controls; suggesting that intraaxial subclinical involvement is more frequently seen in hemodialysis patients. (Archives of Neuropsychiatry 2012; 49: 102-107)