Abstract
Background
We searched -in transverse ultrasound view- the value of the difference (Delta) between -proximal to the tunnel- CSA (a) and -in the tunnel's inlet- CSA (b) for separating normal from abnormal median nerves.
Methods
51 patients –suspicious for CTS- underwent Phalen and Tinnel tests. After that, we used a high frequency ultrasound to measure CSAa, CSAb and Delta CSA in both hands. 33 of our 51 patients did not experience any clinical symptoms at the contralateral hand, so that we could perform a comparative study of normal and pathological median nerves (on the same patients). Then, all of them completed a Q-DASH questionnaire and a visual analogue scale (VAS 100/100) and they carried through with a nerve conduction study (NCS).
Results
We found that a CSAb more than 0,010 and a Delta CSA > 0,003 are both very sensitive findings for CTS, but only DeltaCSA has good specificity. Comparing to NCS the Delta CSA>0,003 had no statistical difference in sensitivity, specificity, true negative and true positive results. Furthermore, patients with Delta CSA>0,009 were suffering from heavy CTS according to NCS, Q-DASH and VAS. On the other way, a Delta CSA between 0,003 and 0,006 suggests a mild or moderate CTS.
Conclusion
Delta CSA could be the golden standard for the detection of CTS in patients that feel uncomfortable to undergo NCS. We propose a grading scale that distinguish mild or moderate syndromes (where we could try a conservative treatment) from heavy syndromes and help as on decision-making.
