Sonographic short-term follow-up after surgical decompression of the median nerve at the carpal tunnel: a single-center prospective observational study

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>Carpal tunnel syndrome causes increased cross-sectional area (CSA) of the median nerve, which can be assessed by high-definition ultrasonography. It is unclear today, however, whether high-definition ultrasonography may play a role in the postoperative period. This prospective study aimed to determine the natural history of the morphology of the median nerve at the carpal tunnel after surgical decompression assessed by high-definition ultrasonography.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Between October and December 2014, patients with suspected carpal tunnel syndrome who were referred to the authors’ center for peripheral neurosurgery were prospectively enrolled and underwent pre- and postoperative (3 months) high-definition ultrasonography, electrophysiology, and clinical testing.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>Eighty-one patients were enrolled in the study, and 100% were clinically better at the 3-month follow-up. The mean CSA decreased from 14.7 ± 4.9 mm<jats:sup>2</jats:sup> to 12.4 ± 3.4 mm<jats:sup>2</jats:sup> (mean ± SD, p &lt; 0.0001). The mean distal motor latency decreased from 6.6 ± 2.4 msec to 4.8 ± 1.0 msec (mean ± SD, p &lt; 0.0001). Ninety-eight percent of patients who were available for electrodiagnostic follow-up showed an improvement of the distal motor latency; only 80% had a reduction in the CSA.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>The authors present the second-largest series of patients with sonographic follow-up after surgical decompression of the carpal tunnel reported in the literature so far. This study, which showed a decrease in size of the median nerve after surgical decompression, suggests that the preoperative increase in median nerve CSA at the carpal tunnel may be due to compression and that enlargement of the median nerve is (partially) reversible.</jats:p></jats:sec>

Ultrasound (US) Changes in the Median Nerve Cross‐Sectional Area After Microinvasive US‐Guided Carpal Tunnel Release

“…Comparing these results with previously published studies examining the postoperative proximal median nerve CSA after CTR is challenging because of methodological differences with respect to patient populations, US equipment, measurement techniques, operator experience, and follow‐up periods. Nonetheless, the quantitative reductions in the CSA observed in this investigation are similar to those reported previously for open CTR, endoscopic CTR, and the single published case report of US‐guided CTR …”

“…Postoperative median nerve CSA reductions appear to be similar among patients treated with open and endoscopic CTR, and in both cases, the reduction in the median nerve CSA has been interpreted to represent a reduction in intraneural edema as a result of successful TCL transection . Despite the improvement in median nerve CSA after open and endoscopic CTR, the CSA does not necessarily return to normal even at long‐term follow‐up in clinically improved patients . The precise reason for these observations is unknown but may be reflective of permanent structural changes within the median nerve (eg, fibrosis).…”

“…Multiple studies have used US to document changes in the proximal median nerve CSA within the proximal carpal tunnel region after open or endoscopic CTR. Despite potentially significant methodological differences, most of these studies reported reductions in the proximal median nerve CSA during follow‐up periods of 1 to 12 months after CTR . Postoperative median nerve CSA reductions appear to be similar among patients treated with open and endoscopic CTR, and in both cases, the reduction in the median nerve CSA has been interpreted to represent a reduction in intraneural edema as a result of successful TCL transection .…”

“…Despite potentially significant methodological differences, most of these studies reported reductions in the proximal median nerve CSA during follow‐up periods of 1 to 12 months after CTR . Postoperative median nerve CSA reductions appear to be similar among patients treated with open and endoscopic CTR, and in both cases, the reduction in the median nerve CSA has been interpreted to represent a reduction in intraneural edema as a result of successful TCL transection . Despite the improvement in median nerve CSA after open and endoscopic CTR, the CSA does not necessarily return to normal even at long‐term follow‐up in clinically improved patients .…”

Ultasonographic indicators of carpal tunnel syndrome demonstrate reversibility following carpal tunnel release

“…These advantages make ultrasonography a useful tool for making comparisons before and after surgery. Previous reports indicated that the enlarged median nerve CSA seen in CTS can shrink after surgery [12][13][14][15], and this is consistent with the present findings. About the displacement of median nerve induced by finger movement, Yoshii reported no significant changes after carpal tunnel release [16].…”