Carpal tunnel syndrome: clinical and epidemiological studies in 668 cases

Between January/1989 and June/1996, 1059 carpal tunnel syndrome hands (CTS) from 668 patients were studied. None had been previously operated and all bad bilateral conduction studies: peripheral neuropathy was excluded. The patients were selected with sensory median/radial difference (MRD)greater than or equal to 1.0 ms that strongly supports electrodiagnosis of CTS (standard deviation >6) after stimulation on wrist and recording on thumb. Normal MRD were obtained in 125 hands with upper limit of normality = 0,43 ms (mean + 2 SD). The age ranged from 17 to 83 years (mean 47.5) and 91.3% were female: the complaints were bilateral in 72% and nocturnal/awakening in 85.3%. Pain, numbness and paraesthesia occurred in 64.4%; pain as the only symptom was rare but proximal extension was Frequent (39.4%). All ringers were symptomatic in 42.5%, followed by middle, middle-ring, thumb-index-middle and then index-middle-ring ones. There was no correlation with traumatic past history on wrist. The duration CTS symptoms ranged from 1 to > 120 months. Diabetes mellitus was present in 4.4% even after peripheral neuropathy exclusion.