Magnetic resonance imaging after endoscopic carpal tunnel release.

ABSTRACT

PURPOSE: To determine with magnetic resonance imaging (MRI) the morphologic changes in the carpal tunnel and median nerve 3 months after endoscopic carpal tunnel release (ECTR). METHODS: We enrolled patients who had complete resolution of numbness and pain by 6 weeks after ECTR. Patients who met these inclusion criteria received an MRI at 3 months after surgery. Images were analyzed to determine whether median nerve morphology changes and discrete gap or separation of the flexor retinaculum could be appreciated on MRI. RESULTS: There were 17 patients screened and 15 met the inclusion criteria. Three-month MRI in all patients demonstrated changes in the flexor retinaculum over the median nerve. In all 15 patients, a distinct gap or separation in the fibers of the flexor retinaculum overlying the median nerve could not be appreciated. Median nerve width-to-height ratios at the level of the pisiform and at the hook of the hamate were 2.4 and 2.1, respectively. Median nerve cross-sectional area was 14.1 at the pisiform and 13.3 at the hook of the hamate. CONCLUSIONS: MRI of patients 3 months after successful ECTR does not demonstrate a discrete gap or separation in the flexor retinaculum overlying the median nerve but may be useful for evaluating median nerve morphology. TYPE OF STUDY/LEVEL OF EVIDENCE Diagnostic II.