Wiesler ER,Chloros GD,Cartwright MS,Smith BP,Rushing J,Walker FO.
The Journal of Hand Surgery. 2006;31-A(5):726-732.
Traditionally the diagnosis of carpal tunnel syndrome (CTS) is made with a history, examination and supported with nerve conduction studies (NCS). The authors used ultrasound (USS) to try and correlate the size of the median nerve with NCS findings to test the validity of USS diagnosis for CTS.
44 wrists with CTS and 86 asymptomatic control wrists were ultrasounded with a 12/5 MHz linear array transducer and the cross-sectional area of the median nerve was measured at the distal wrist crease. All wrists also underwent NCS.
The average axial cross-sectional area at the wrist was 9mm2 (range 5-14 mm2) in the control group and 14 mm2 (range 5-32 mm2) in the CTS group. This difference in size was statistically significant (p<0.001). Higher values of cross-sectional areas were associated with abnormal NCS results (p=0.013, Pearson Correlation Coefficient). Sensitivity (91%) and specificity (84%) tests suggested that USS was a good diagnostic tool and adjunct to NCS.
The authors suggest that the ease of use, non-invasive nature and shorter time, with reduced costs makes USS an attractive modality.
This certainly would be a useful adjunct in the diagnosis of CTS as NCS are not always conclusive for patients who have CTS. It may prove to be a useful alternative diagnostic tool for an already burdened neurophysiology department. It could also allow the clinican to administer safe therapeutic injections thus avoiding any potential for median nerve injury.