Experience With Proximal Median Nerve Entrapment by the Lacertus Fibrosus

Abstract

Background: Unconscious bias of the clinician favors the diagnosis of carpal tunnel syndrome (CTS) in patients with median paresthesia. We hypothesized that more patients in this cohort would be diagnosed with proximal median nerve entrapment (PMNE) by strengthening our cognitive awareness of this alternative diagnosis. We also hypothesized that patients with PMNE may be successfully treated with surgical release of the lacertus fibrosus (LF). Methods: In this retrospective study, cases of median nerve decompression at the carpal tunnel and in the proximal forearm for the 2-year periods before and after adopting strategies to mitigate cognitive bias for CTS were enumerated. Patients diagnosed with PMNE and treated by LF release under local anesthesia were evaluated to determine surgical outcome at minimum 2-year follow-up. Primary outcome measures were changes in preoperative median paresthesia and proximal median-innervated muscle strength. Results: There was a statistically significant increase in PMNE cases identified after our heightened surveillance was initiated (z = 3.433, P