gms | German Medical Science

Objectives/Interrogation: Entrapment of the median nerve at the elbow has been reported in the literature to be rare and difficult to diagnose. The compression by the lacertus fibrosus (LF) has a predominant motor clinical expression differentiating it from other syndromes. The purpose of this study was to provide the different stages of management of median nerve compression by the LF at the elbow, from diagnosis to treatment, and to underline the benefits of a procedure under WALANT surgery.

Methods: 15 patients (7 female, 8 male), with a mean age of 42.5 years (28-56), were managed for compression of the median nerve at the elbow. 16 nerves (12 on the right, 4 on the left) were released. The diagnosis was made in the presence of the clinical triad: elbow pain in 13 patients, muscle weakness in all patients (Flexor Pollicis Longus (FPL), Flexor Digitorum Profundus of the index (FDP II), Flexor Carpi Radialis (FCR)) and a positive scratch collapse test (SCT) at the elbow in 14 patients. Tinel's sign was positive in 4 patients. The electromyogram revealed compression of the median nerve at the elbow in only one case. 8 patients had concomitant CTS and underwent endoscopic decompression at the same time. Neurolysis of the median nerve at the elbow was performed under WALANT surgery (7) or axillary block (9) if an associated procedure was indicated. Muscular testing was performed intraoperatively or the day after surgery.

Results and Conclusions: Neurolysis of the median nerve consisted of a simple section of the LF by an anterior minimally invasive approach of the elbow. All patients recovered full muscle strength of the median nerve innervated muscles. Return of strength was "immediate" when surgery was performed under local anesthesia. At 3 months' follow-up, pain had totally disappeared in all patients.

Diagnosis of entrapment of the median nerve at the elbow is often misunderstood. The clinical association of elbow pain, muscle weakness and positive SCT is very suggestive of the diagnosis. The EMG-study is most often normal but remains mandatory for the diagnosis of an associated CTS. The anatomical position of the nerve fascicles of the concerned muscles innervated by the median nerve when passing under the LF (anterior for the FCR, medial for the FPL and FDPII) could explain this specific symptomatology. WALANT surgery offers the advantage of performing intraoperative muscular testing to appreciate the immediate strength recovery after median nerve release in addition to simple postoperative care and low morbidity.