Conduction velocity through the somesthetic pathway in chronic renal failure

Uremic neuropathy: clinical features and new pathophysiological insights

Neuropathy is a common complication of end-stage kidney disease (ESKD), typically presenting as a distal symmetrical process with greater lower-limb than upper-limb involvement. The condition is of insidious onset, progressing over months. and has been estimated to be present in 60%-100% of patients on dialysis. Neuropathy generally only develops at glomerular filtration rates of less than 12 ml/min. The most frequent clinical features reflect large-fiber involvement, with paresthesias, reduction in deep tendon reflexes, impaired vibration sense, muscle wasting, and weakness. Nerve conduction studies demonstrate findings consistent with a generalized neuropathy of the axonal type. Patients may also develop autonomic features, with postural hypotension, impaired sweating, diarrhea, constipation, or impotence. The development of uremic neuropathy has been related previously to the retention of neurotoxic molecules in the middle molecular range, although this hypothesis lacked formal proof. Studies utilizing novel axonal excitability techniques have recently shed further light on the pathophysiology of this condition. Nerves of uremic patients have been shown to exist in a chronically depolarized state prior to dialysis, with subsequent improvement and normalization of resting membrane potential after dialysis. The degree of depolarization correlates with serum K(+), suggesting that chronic hyperkalemic depolarization plays an important role in the development of nerve dysfunction in ESKD. These recent findings suggest that maintenance of serum K(+) within normal limits between periods of dialysis, rather than simple avoidance of hyperkalemia, is likely to reduce the incidence and severity of uremic neuropathy.

Changes in short-latency somatosensory evoked potentials during hemodialysis in chronic renal failure

Short-latency SEPs were monitored in eight patients undergoing hemodialysis for end-stage renal disease. The peak latencies of EP,N13, and N20 were significantly delayed compared with those of the control group. Because the interpeak latency of N13 - N20 (central conduction time) was not significantly prolonged, there could be no possible subclinical involvement of the ascending sensory fibers in the brainstem. The dialysis did alter the peak latencies of EP,N20, and interpeak latencies of EP-N13 and EP-N20; these changes, however, were not highly significant. The evoked potential changes did not correlate with the routine biochemical data. Monitoring short-latency SEP may lead to early recognition of pathologic involvement of the peripheral nervous system.