Limitations on the clinical utility of the ulnar dorsal cutaneous sensory nerve action potential.
OBJECTIVE
To validate the clinical use of the ulnar dorsal cutaneous (UDCN) sensory nerve action potential (SNAP) in the topographical analysis of ulnar mononeuropathies and in the process of choosing a sensory nerve for biopsy.


METHODS
We surveyed the UDCN SNAP electrophysiological characteristics in both hands of 97 normal volunteers aged 10-84 years. The nerve was recorded from the 4th intermetacarpal space with subcutaneous needle electrodes and percutaneous stimulation was carried out at the wrist.


RESULTS
In agreement with other studies, the mean conduction velocity was 58. 6+/-6.7 m/s, but the mean and the lower normal value of the amplitude (32 and 14.7 microV) were significantly higher than previous known data. An important finding was that in 21% of our population study, the UDCN SNAP was absent on at least one side, or a significant degree of asymmetry between the left and right sides was present.


CONCLUSIONS
The UDCN SNAP is technically easy to obtain, but the high frequency of asymmetric or absent potentials detected in this study implies that caution should be taken in using this SNAP in clinical practice.
Dutra de Oliveira
A L
AL
Department of Neurology, School of Medicine of Ribeirão Preto, University of São Paulo, Paulo, Brazil.
Barreira
A A
AA
Marques
W
W
D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D002648:Child; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D005260:Female; D005542:Forearm / Q000294:innervation / Q000502:physiology; D006225:Hand / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D015203:Reproducibility of Results; D014459:Ulnar Nerve / Q000502:physiology*