Carpal Tunnel Configuration Measured by Ultrasonography as a Risk Factor of Carpal Tunnel Syndrome in Motor Part Manufacturing Workers / 대한산업의학회지

ABSTRACT

OBJECTIVES: This study was conducted to evaluate individual susceptibility to carpal tunnel syndrome (CTS) by ultrasonographic measurement of the carpal tunnel configuration in workers doing repetitive work. METHODS: The study subjects consisted of 24 male and 11 female workers in a soundproof material manufacturing company in Gyeongju. We conducted a self-reported questionnaire survey, a physical examination and an electrodiagnostic study (EDS) in April 2000. After the examination, jobs were rearranged for workers with CTS. A follow up physical examination, EDS, and measurement of the carpal tunnel by ultrasonography was done six months later. RESULTS: Of those studied, prevalence of CTS was 63.6/100 persons among women and 29.2/100 persons among men. Mean depth and width of wrist was shorter in those with CTS compareal to the controls (p<0.05). The risk of CTS was higher in workers whose carpal tunnel ratio (displacement/width) was 0.17 or higher (OR 7.13, 95 % confidence interval 1.18-43.1), and in workers whose carpal tunnel area was less than 300 mm2 (OR 8.00, 95 % confidence interval 1.18-68.5). Carpal tunnel depth and depth/width ratio had a positive correlation with motor latency of the median nerve and median-ulnar sensory latency difference (p<0.05), whereas the carpal tunnel width, displacement/depth ratio, and area (width X displacement) had a negative correlation with median nerve latencies after adjusting for gender. Workers who showed an improvement in the clinical stage of CTS after job rearrangement had a significantly lower carpal tunnel displacement/width ratio and displacement/depth ratio. They also had smaller upper carpal tunnel area ( width X displacement) and larger upper carpal tunnel area [(depth-displacement) X width] than the controls (p< 0.05 ). CONCLUSIONS: Ultrasonographic measurement of the carpal tunnel is a good predictor of susceptibility and prognosis of CTS in workers doing repetivive work.