Sonography Useful in Diagnosing Carpal Tunnel Syndrome

July 8, 2004

By Will Boggs, MD

NEW YORK (Reuters Health) Jul 05 - Sonography is comparable to

electrodiagnostic study in diagnosing carpal tunnel syndrome (CTS),

according to a report in

the July issue of Radiology....

For right hands, the combination of a median nerve cross-sectional area of

0.09 square centimeters or more proximal to the tunnel inlet and 0.12 square

centimeters at the tunnel outlet accurately predicted CTS, the authors

report,

with 94% sensitivity, 65% specificity, 12% false-positives, and 19%

false-negatives.

A different cutoff for the left hand, 0.10 square centimeters proximal to

the

tunnel inlet, predicted CTS with 83% sensitivity, 73% specificity, 15%

false-positives, and 31% false-negatives, the results indicate.

Raising the tunnel inlet cutoff for the right hand to 0.10 square

centimeters

decreased the sensitivity and false-positives, but increased the specificity

and false-negatives, the researchers note. Lowering the cutoff for the left

hand to 0.09 square centimeters had opposite effects.

" Sonography measures a different parameter (structural pathologic

abnormalities of nerve swelling) from that (physiological malfunctions of

the median

nerve) measured at an electrodiagnostic study, " the investigators explain.

" It

would be interesting to follow the group of patients with sonographically

determined false-positive cases of CTS longitudinally to see if they

eventually

develop abnormalities that are compatible with CTS at an electrodiagnostic

study. "

" For confirmation of CTS, sonography maybe used as the initial test instead

of nerve conduction studies for those without diabetes, " Dr. Wong concluded.

" I think our results need to be replicated elsewhere initially, " Dr. Wong

added. " Also, we are currently conducting studies to refine the technique of

sonography used in the diagnosis of CTS. "

Radiology 2004;232:93-99.

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