Worker Monitoring Tests for Carpal Tunnel Syndrome: Results from an Industrial Longitudinal Study

Abstract

This paper presents the initial findings from a study using two computer-controlled functional tests for sensory and motor deficits in carpal tunnel syndrome (CTS). The gap detection sensory test quantifies dynamic tactile inspection thresholds for areas of the hand innervated by the median nerve. The rapid pinch and release psychomotor test measures the initiation and control of specific muscles innervated by the median nerve motor branch. The purpose of this ongoing study is to evaluate industrial subjects recruited from varying high risk industrial settings, such as poultry processing, automotive manufacturing, plastics manufacturing, assembly, and newspaper publishing for longitudinal changes in test outcomes. A total of 169 subjects were tested during the first year of this study. All subjects completed a symptom survey, underwent a physical examination of the upper limbs, shoulder and neck, had a nerve conduction study (NCS), and were administered the Wisconsin Test Battery. Both hands of the subjects are examined and categorized by presence of absence of physical exam findings, self-reported symptoms, and nerve conduction study (NCS) results. The data was analyzed for differences between subjects reporting positive or negative symptoms, and positive or negative physical exam and NCS findings. In summary, the psychomotor and sensory test outcomes were related to objective NCS findings but it is interesting to note that symptoms alone were not significantly associated with functional sensory or psychomotor performance. Unlike our previous studies, where CTS patients in the electromyography (EMG) clinic seeking medical assistance were tested, all subjects were from a working population. It is likely that most of the positive exam and NCS subjects in the current study involve CTS symptoms that are less severe than our previous studies using EMG clinic subjects, many whom were preparing for surgery.