Near-nerve versus surface electrode recordings of sensory nerve conduction in patients with carpal tunnel syndrome.
OBJECTIVE
The aim of the study was to compare the relative sensitivity of sensory nerve conduction (SNC) recorded with near-nerve needle electrodes and SNC recorded with surface electrodes in demonstrating focal slowing of the median nerve in patients with symptoms of carpal tunnel syndrome (CTS).


METHODS
Eighty-two consecutive patients with clinical symptoms and signs of CTS were studied prospectively by the same clinical neurophysiologist. Orthodromic near-nerve recording from digits 1 and 3, distal motor latency, and antidromic surface recording from palm to digit 2 and wrist to digit 2 were performed in all patients. Near-nerve recording of the ulnar nerve was done in patients with abnormal median nerve conduction. Patients were compared to controls.


RESULTS
Near-nerve SNC was abnormal (slowed velocity or absent response) in 52% of the patients from digit 1 to wrist, in 51% from digit 3 to wrist, and 40% had a prolonged distal motor latency. Surface antidromic SNC was abnormal in 49% from wrist to palm, and in 43% from wrist to digit 2. Statistical analysis revealed no significant difference between the near-nerve method and the surface method. Absent sensory potentials were more common with the surface method.


CONCLUSIONS
As a routine study of CTS patients, the surface technique can be used and the near-nerve technique merely used for patients with absent surface responses.
Smith
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Department of Neurology, Odense University Hospital, Denmark.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D004566:Electrodes; D004867:Equipment Design; D005260:Female; D006225:Hand / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology*; D011446:Prospective Studies; D011930:Reaction Time; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000502:physiology; D013499:Surface Properties; D014459:Ulnar Nerve / Q000503:physiopathology