Data from: Carpal tunnel syndrome sssessment with ultrasonography: value of inlet-to-outlet median nerve area ratio in patients versus healthy volunteers

Objective: To evaluate the diagnostic value of the Inlet-to-outlet median
nerve area ratio (IOR) in patients with clinically and
electrophysiologically confirmed carpal tunnel syndrome (CTS). Methods:
Forty-six wrists in 46 consecutive patients with clinical and
electrodiagnostic evidence of CTS and forty-four wrists in 44 healthy
volunteers were examined with ultrasonography. The cross-sectional area
(CSA) of the median nerve was measured at the carpal tunnel inlet (the
level of scaphoid-pisiform) and outlet (the level of the hook of the
hamate), and the IOR was calculated for each wrist. Ultrasonography and
electrodiagnostic tests were performed under blinded conditions.
Electrodiagnostic testing combined with clinical symptoms were considered
to be the gold standard test. Receiver operating characteristic (ROC)
curves were used to evaluate the diagnostic value between the inlet CSA
and IOR. Results: The study population included 16 men and 30 women (mean
age, 45.3 years; range, 18–83 years). The control population included 18
men and 26 women (mean age, 50.4 years; range, 18–79 years). The mean
inlet CSA was 8.7 mm2 in healthy controls and 14.6mm2 in CTS group
(P<0.001). The mean IOR in healthy volunteers (1.0) was smaller
than that in patients (1.6, P<0.001). Receiver operating
characteristic analysis revealed a diagnostic advantage to using the IOR
rather than the inlet CSA (P<0.01). An IOR cutoff value of ≥ 1.3
would yield 93% specificity and 91% sensitivity in the diagnosis of CTS.
Conclusion: The IOR of median nerve area promises to be an effective means
in the diagnosis of CTS. A large-scale, randomized controlled trial is
required to determine how and when this parameter will be used.