Median-to-ulnar sensory nerve action potential amplitude ratio as an electrodiagnostic adjunct for carpal tunnel syndrome.
OBJECTIVE
(1) To obtain normative data for the median-to-ulnar sensory nerve action potential (SNAP) amplitude ratio (MUSAR) and (2) to discuss the adjunctive use of MUSAR in electrodiagnosis of carpal tunnel syndrome.


METHODS
Analysis of previously collected normative data.


METHODS
Veterans Administration electromyography laboratory.


METHODS
Forty-six apparently healthy male volunteers without neurologic complaints.


METHODS
Antidromic median and ulnar SNAPs were recorded and the respective MUSAR ratios were calculated. Descriptive statistical analysis was completed, with the assumption that SNAP values are not Gaussian in distribution.


RESULTS
The normal MUSAR ranged from .74 (5th percentile) to 2.5 (95th percentile).


CONCLUSIONS
The MUSAR, being an intrapersonal ratio, may decrease the false positives and false negatives that would otherwise arise when using absolute values of SNAP amplitudes. Hence, it may increase the diagnostic specificity for carpal tunnel syndrome. Further studies are needed to confirm the clinical and presurgical application of the MUSAR value.
Nesathurai
S
S
Department of Rehabilitation Medicine, Boston Medical Center, MA 02118-2393, USA.
Gwardjan
A
A
Kamath
A N
AN
D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D004576:Electromyography / Q000379:methods*; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D011930:Reaction Time; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014459:Ulnar Nerve / Q000503:physiopathology*