normal measures of median nerve motor and sensory latency in carpal tunnel syndrome

background : despite the high incidence and prevalence of cts, there is no exclusive data about normal values increment of motor and sensory distal latencies of median nerve at wrist according to age. this research was done in electrodiagnosis lab of physical medicine & rehabilitation ward in nemazi hospital in shiraz between 1374-1379. material and methods : this study was performed on 1200 cases that had no history of paresthesia and numbness in both hands and no history of diabetes mellitus, systemic disease, and electrodiagnosis evidence of no cervical radiculopathy or peripheral neuropathy. tinel’s and phallen’s tests were also negative in all cases. normal values, increment of motor and sensory distal latencies of both hands median nerves were studied and analyzed in ten age groups from 10-80 years. results : in this study, the mean normal value for distal motor latency of median nerve was 3.3 ms (2.50-4.20ms). increment of this value is mild (about 0.1ms per decade after 5th decade of life) and could be calculated with the following formula: dml (8cm)= (3.30+ ) ± 0.0025age. the mean normal value for distal sensory latency of median nerve was 3.2ms (2.7-3.70ms). increment of his value is mild (about 0.1ms per decade after the 5th decade of life) that could be calculated with the following formula: dsl (14cm) =(3.20 + ) ± 0.0025age. conclusions : it seems that age has significant influence on distal motor and sensory latencies at wrist. we recommend electrodiagnostic evaluations to be performed according to the age