Comparison of high resolution ultrasonography and nerve conduction study in the diagnosis of carpal tunnel syndrome: Diagnostic value of median nerve cross-sectional area

Carpal tunnel syndrome (CTS) is a common peripheral entrapment
neuropathy. This study was performed to evaluate whether high-resolution ultrasonography
may be an alternative diagnostic method for nerve conduction study (NCS) in the diagnosis
of carpal tunnel syndrome.
Patients and Methods: 132 wrists of 82 patients and 152 wrists of controls were enrolled in
the study. The cross sectional area of the median nerve was measured at the carpal tunnel
inlet and outlet in all patients and controls. All patients had a nerve conduction study. Then
comparison between ultrasonography and NCS was performed. Combination of clinical diagnosis
and NCS was used as the gold standard.
Results: The mean cross-sectional area (CSA) of the median nerve at the tunnel inlet was
11.4±1.7 mm
2
for the patient group and 5.78 ±0.9 mm
2
for the control group (P<0.001). The
mean cross-sectional area at the tunnel outlet was 9.9±1.2 mm
2
for the patient group and
4.7±0.7 mm
2
for the control group (P<0.001). The best cut-off value of CSA at the tunnel
inlet and the outlet was 7.5 mm
2
.
Conclusion: In patients with clinical diagnosis of CTS we confirmed that the diagnostic value
of ultrasonography is similar to NCS and sonography may be used in primary evaluation of
CTS.