BACKGROUND: Routine electrophysiological parameters for diagnosing carpal tunnel syndrome do not detect median neuropathy at wrist in cases with concomitant severe peripheral neuropathy what ever its cause. Uremic patients on dialysis may have hand symptoms that may be because of peripheral neuropathy, carpal tunnel syndrome, or both.

OBJECTIVE: The authors aimed to assess the significance of the second lumbrical-interosseus (2L-INT) latency difference as a predictor of carpal tunnel syndrome in uremic patients on dialysis.

METHODS: Fifty-four consecutive cases (108 hands) of end-stage renal failure on dialysis (hemo or peritoneal) were subjected to routine electrophysiological studies for carpal tunnel syndrome. 2L-INT latency difference was measured in all cases.

RESULTS: The cases (94.3%) had abnormal electrophysiological studies. Routine tests revealed carpal tunnel syndrome in 54 hands, and all of these had prolonged 2L-INT latency difference. Peripheral neuropathy was found in another 42.9% hands, but 75.6% of these had prolonged 2L-INT latency difference, suggesting a concomitant carpal tunnel syndrome, whereas on using the routine neurophysiological studies, only 13.3% were diagnosed as carpal tunnel syndrome. Overall, the frequency of carpal tunnel syndrome in uremic patients on maintenance dialysis using standard nerve conduction parameters was 51.4%; however, the frequency increased substantially to 83.8% if 2L-INT latency difference is included in the criteria for the diagnosis.

CONCLUSIONS: Carpal tunnel syndrome is common in patients with end-stage renal failure on dialysis. 2L-INT latency difference is a sensitive test to predict median neuropathy at wrist in presence of peripheral neuropathy.