Optimal recording electrode placement in the lumbrical-interossei comparison study.
The lumbrical-interossei comparison study is commonly employed in the electrodiagnosis of carpal tunnel syndrome. Placement of the recording electrodes relies on anatomic landmarks as the muscles being recorded cannot be seen or palpated. To determine the optimal active electrode location, 15 controls and 5 patients were studied using a grid of 12 electrodes placed over the lateral palm. Amplitudes, rise-times, and latencies of the responses at each location were measured. The lowest control latency difference was located in the lateral mid-proximal palm (mean 0 ms, upper range of 0.5 ms). This location also had the highest lumbrical amplitude and rise-time. More distal in the palm, the mean latency difference increased to 0.5 ms with an upper range of 0.9 ms. When performing the lumbrical-interossei comparison study, it is essential to place the active recording electrode in the optimal location. Failure to do so will result in an increased number of false-positive studies.
Al-Shekhlee
Amer
A
Department of Neurology, University Hospitals of Cleveland, Case Western Reserve University, Ohio 44106-5040, USA. amer.alshekhlee@uhhs.com
Fernandes Filho
Jose A
JA
Sukul
Devraj
D
Preston
David C
DC
D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D004553:Electric Conductivity; D004566:Electrodes; D004568:Electrodiagnosis / Q000295:instrumentation / Q000379:methods*; D005189:False Positive Reactions; D006225:Hand / Q000033:anatomy & histology* / Q000294:innervation*; D006801:Humans; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000293:injuries / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology; D015203:Reproducibility of Results; D014459:Ulnar Nerve / Q000503:physiopathology