Screening for carpal tunnel syndrome in the workplace. An analysis of portable nerve conduction devices.
Several devices have been developed for rapid motor or sensory median nerve conduction testing. We evaluated the validity and reliability of the Neurosentinel (NS) and NervePace (NP) electroneurometer for sensory and motor testing, respectively, compared with formal electrodiagnostic studies (EDS), and examined their potential role in workplace screening for carpal tunnel syndrome (CTS). Thirty-two working subjects without CTS were examined and tested with the NS, NP, and EDS, and retested one week later. Subjects were selected who did not have CTS, other hand or nerve problems, or jobs with significant ergonomic risks, in order to decrease the likelihood of changes over time in median nerve function. Mean correlations of NP and NS with EDS latencies ranged from r = 0.069 to r = 0.85, with somewhat better correlation for NS (sensory) than NP (motor). Test-retest reliability was greatest for motor EDS (r = 0.86 to 0.91) and similar for sensory EDS, NS, and NP (r = 0.72 to 0.79); mean results were very similar. Based on the observed relationship between NS or NP and EDS results, confidence intervals were calculated to represent the range of EDS results consistent with a single NS or NP measurement. These intervals ranged from +/- 0.3 milliseconds (ms) for NS to +/- 0.6 msec for NP, with similar ranges for change over time in an individual. The magnitude of these intervals for a single test or individual implies that the NS and NP are unlikely to identify individuals with CTS or to detect changes over time that are not accompanied by symptoms or signs. The screening devices are not likely to be useful in confirming early CTS, when single latency values may be normal, and detailed EDS may be necessary to detect nerve entrapment. Compared with EDS, these devices have moderate validity and similar reliability; they are probably most useful for cross-sectional or longitudinal studies of groups, but care must be taken in using them for pre-placement or surveillance tests of individual workers. False-positive results may lead to discrimination, inappropriate referrals and interventions; false-negative tests can result in inappropriate reassurance and missed opportunities for intervention.
Pransky
G
G
Department of Family and Community Medicine, University of Massachusetts Medical School, Worcester, USA.
Long
R
R
Hammer
K
K
Schulz
L A
LA
Himmelstein
J
J
Fowke
J
J
D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology / Q000517:prevention & control*; D004568:Electrodiagnosis / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000295:instrumentation*; D008475:Median Nerve / Q000502:physiology; D008875:Middle Aged; D009431:Neural Conduction; D009784:Occupational Diseases / Q000503:physiopathology / Q000517:prevention & control*; D012680:Sensitivity and Specificity