Importance of Sensory Latency Measurement in Early Diabetic Polyneuropathy

OBJECTIVE: To evaluate the correlation between the variables of sensory nerve conduction study of diabetic polyneuropathy patients and the factors that explain variations of multivariate data of sensory nerve conduction study. METHOD: Forty four early diabetic polyneuropathy patients and forty normal control people were included in our study. Early polyneuropathy patients were diagnosed by nerve conduction study. Their sensory nerve conduction meaurement variables were compared with normal control people in terms of correlation between amplitude and latency, and factors that were independent. RESULTS: Age controlled partial correlations between amplitude and latency suggested that early diabetic polyneuropathy patients had more association between amplitude and latency than normal control people. Cannonical correlation also reinforced the above suggestion. Factor analysis revealed degenerative factor, demyelination factor, axonopathy factors that were independent in normal control people and degenerative factors, upper extremity demyelination factor, lower extremity functional factors in the dibetic polyneuropathy patients. CONCLUSION: The latency of sensory nerve conduction study was an important variable in assessing diabetic polyneuropathy patients.

Sensitivity of Multi-electrodiagnostic Parameters in Carpal Tunnel Syndrome: Usefulness of residual latency

This prospective study following American Association of Electrodiagnostic Medicine recommended criteria in the diagnosis of Carpal Tunnel Syndrome(CTS) evaluated the sensitivity of multi-electrodiagnostic parameters and usefulness of residual latency in CTS. In 45 symptomatic hands of 26 patients with clinical diagnosis of CTS, 8 electrodiagnostic parameters-median motor distal latency, median motor residual latency, median sensory onset latency, median sensory peak latency, median to ulnar sensory onset latency difference(digit 4), median to ulnar sensory peak latency difference(digit 4), median to radial sensory onset latency difference(digit 1), median to radial sensory peak latency difference(digit 1)-were compared to the normative data obtained from the age-matched control group. In 31 CTS hands without polyneuropathy, median to ulnar sensory latency difference(digit 4), median to radial sensory latency difference(digit 1), median sensory peak latency have same sensitivity(71.0%). In 8 CTS hands with delayed proximal median motor nerve conduction velocity which were indiscernible from polyneuropathy in routine nerve conduction study, residual latency was more sensitive than median to ulnar sensory latency difference and median to radial sensory latency difference. Sensitivity difference between sensory onset latency and sensory peak latency was negligible in the electrophysiologic diagnosis of CTS. We concluded that residual latency measurement was a very useful and convenient method in the diagnosis of CTS, especially in the patients with delayed proximal median motor conduction velocity.