Síndrome do túnel do carpo: aspectos clínico-epidemiológicos e de condução nervosa em 668 casos

Abstract

Carpal tunnel syndrome: clinical, epidemiological and nerve conduction studies in 668 cases Between January/89 and June/96, 1,059 carpal tunnel syndrome hands (CTS) from 668 patients were studied. None had been previously operated and all had bilateral conduction studies; peripheral neuropathy was excluded. The patients were selected with sensory median/radial difference (MRD) ³ 1.0 ms that strongly supports electrodiagnosis of CTS (standard deviation > 6) after simultaneous stimulation on wrist and recording on thumb. 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 fingers were symptomatic in 42.5%, followed by middle, middle-ring, thumbindex- 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 without precise correlation with the severity of conduction abnormalities on median nerve. MRD ³ 1.0 ms correlates in 95% with median distal motor latency > 4.25 ms (80 mm distance) and with median distal sensory latency to index finger ³ 3.01 ms, middle finger ³ 3.14 ms and ring finger ³ 3.26 ms, all of them 140 mm distance, antidromic and onset-measured. The results have brought new values for the limit of normality in our EMG laboratory since MRD ³ 1.0 ms is very sensitive for CTS diagnosis.