An Automated Electrodiagnostic Technique for Detection of Carpal Tunnel Syndrome

Christopher T. Leffler, MD, MPH
Shai N. Gozani, MD, PhD
Zung Q. Nguyen, BS
Didier Cros, MD

Published: 28 September 2000

We designed an automated electrophysiologic neurodiagnostic device (AEND) yielding a distal motor latency (DML) using automated stimulation and analysis, volume-conducted waveforms, and physiologic adjustments. AEND screening was studied in 75 symptomatic patients, who also had conventional electrodiagnostic studies, and 22 asymptomatic subjects. The AEND yielded a DML in 92% of hands with a conventional motor response. The correlation between AEND and conventional DML was .90 ( P < .001). The neurologists diagnosed 62 of 129 symptomatic hands with median neuropathy at the wrist (MNW). At 90% specificity, AEND DML had a sensitivity of 82% for MNW diagnosed by the neurologist and 87% for MNW defined by symptoms plus conventional electrophysiology. DML adjustment for age, height, and temperature was associated with an odds ratio for correct diagnostic classification of 1.80 in receiver operating characteristic curve analysis. A volume-conducted latency determined by an automated technique, designed for screening for MNW in an occupational medicine or primary care setting, is highly correlated with conventional techniques. Physiologic adjustments nearly double the odds of correct diagnostic classification.

Keywords: distal motor latency (DML), carpal tunnel syndrome (CTS), median neuropathy at the wrist (MNW), volume conduction, temperature