Introduction: The purpose of this study was to determine whether sensorimotor abnormalities are detectable in asymptomatic individuals deemed at risk of developing carpal tunnel syndrome (CTS) Methods: Seventeen individuals deemed at risk of developing CTS and 16 asymptomatic individuals deemed to be at minimal risk of developing CTS participated. Nerve conduction velocity, two-point discrimination ability, pressure acuity, Purdue Pegboard Test performance and tracking error and tracking variance on a manual tracking task performed at two different speeds were measured in all participants and compared between the groups.Results: None of the measures of nerve conduction, sensory perception, or Purdue Pegboard task performance were different between the groups. The error in the manual tracking tasks was significantly different between the groups, where the at-risk group demonstrated more error than the control group. Conclusion: These results suggest that manual tracking tasks may be useful in the identification of those individuals at risk of developing CTS before they develop any measurable sensorimotor impairment. (C) 2011 Elsevier Ltd. All rights reserved.

BACKGROUND:Studying the changes that occur in motor unit potential trains (MUPTs) may provide insight into the extent of motor unit loss and neural re-organization resulting from nerve compression injury. The purpose of this study was to determine the feasibility of using decomposition-based quantitative electromyography (DQEMG) to study the pathophysiological changes associated with compression neuropathy.METHODS:The model used to examine compression neuropathy was carpal tunnel syndrome (CTS) due to its high prevalence and ease of diagnosis. Surface and concentric needle electromyography data were acquired simultaneously from the abductor pollicis brevis muscle in six individuals with severe CTS, eight individuals with mild CTS and nine healthy control subjects. DQEMG was used to detect intramuscular MUPTs during constant-intensity contractions and to estimate parameters associated with the surface- and needle-detected motor unit potentials (SMUPs and MUPs, respectively). MUP morphology and stability, SMUP morphology and motor unit number estimates (MUNEs) were compared among the groups using Kruskal-Wallis tests.RESULTS:The severe CTS group had larger amplitude and longer duration MUPs and smaller MUNEs than the mild CTS and control groups, suggesting that the individuals with severe CTS had motor unit loss with subsequent collateral reinnervation, and that DQEMG using a constant-intensity protocol was sensitive to these changes. SMUP morphology and MUP complexity and stability did not significantly differ among the groups.CONCLUSIONS:These results provide evidence that MUP amplitude parameters and MUNEs obtained using DQEMG, may be a valuable tool to investigate pathophysiological changes in muscles affected by compressive motor neuropathy to augment information obtained from nerve conduction studies. Although there were trends in many of these measures, in this study, MUP complexity and stability and SMUP parameters were, of limited value.

Objectives: To examine the reliability of manual tracking performance and its association with impairment and disability in individuals symptomatic of an upper extremity cumulative trauma disorder (CTD). Methods: Volunteer and physician referred subjects (100 control, 140 CTD) tracked a target cursor moving quasi-randomly using a hand-held stylus interfaced with a digitizing tablet. Impairment was physician-rated and the Disability of the Arm, Shoulder and Hand questionnaire measured disability. Subsamples of 25 subjects per group were tested on three occasions. Results: Reliability of tracking performance was excellent (ICC ≥ 0.88) and sensitivity was 81%. Performance was superior in controls (p < 0.001) and deteriorated as a function of impairment level (p < 0.001). Tracking and impairment rating explained 65% of the disability score. Conclusions: Tracking performance may be an important outcome for monitoring change over time and the impact of a CTD on function in everyday activities.