Course of symptoms and median nerve conduction values in workers performing repetitive jobs at risk for carpal tunnel syndrome

Background Carpal tunnel syndrome (CTS) is a common occupational disorder associated with repetitive manual work. Little information exists about the possible relation between the variation of biomechanical hand/wrist exposure and the development of symptoms and median nerve conduction values.Aims To investigate the prevalence of CTS in a group of workers exposed to intensive use of the hands and the course of symptoms and median nerve conduction values after a period of reduced exposure to biomechanical risk factors.Methods CTS was assessed in assembly and non-assembly line workers by means of clinical examinations and nerve conduction studies (NCS). Ergonomic analysis was conducted for each assembly line work-station.Results Prevalence of CTS was significantly higher in assembly line workers compared to non-assembly line workers but there was a high prevalence of median nerve conduction abnormalities in both groups (60/102 hands and 40/110 hands, respectively). In a sizable proportion of both groups there was no relationship between symptoms and electrodiagnostic findings (45 hands and 48 hands in assembly and non-assembly line workers, respectively). When assembly line workers were re-examined after 2 years following a period of reduced work schedule, a significant proportion reported resolution of symptoms or had reverted to having normal NCS.Conclusions In our study, repetitive work was associated with a higher level of CTS and abnormal NCS. These findings appeared to be reversible following a period of less repetitive work. Overall, there was generally poor correlation between symptoms and electrodiagnostic findings.