Clinical diagnosis and wide-awake surgical treatment of proximal median nerve entrapment at the elbow: a prospective study.

BACKGROUND

Proximal median nerve entrapment (PMNE, or pronator syndrome) at the elbow has traditionally been considered an elusive and rare diagnosis, as it is seldom detectable using electrophysiological techniques. In this paper, the clinical manifestations, physical diagnosis, surgical technique, and results of surgical treatment of PMNE are presented, with accompanying instructional video.

PATIENTS/METHODS: During 2011, 44 patients with PMNE were surgically released and followed prospectively, 22 women/22 men, mean age 48.8 (range 25-66). The patients were equally distributed between right/left hands (23/21) and the dominant hand was treated in 56 % of cases. The diagnosis was based on: (1) weakness in median innervated muscles distal to the lacertus fibrosus; (2) pain upon pressure over the median nerve at the level of the lacertus fibrosus; and (3) positive scratch collapse test. A minimally invasive surgical treatment using only local anesthesia with lidocaine-epinephrine and no tourniquet was used, and direct perioperative return of strength in median innervated muscles was seen in all subjects.

RESULTS

The average preoperative quick DASH was 35.4 (range 6.8-77.2); work DASH, 44.3 (6.25-100); and activity DASH, 61.6 (12.5-100). There were 71.1 % patients who completed the 6-month follow-up, and the average postoperative quick DASH was 12.7 (range 0-43.1), which is a statistically significant reduction (p < 0.0001; Student's paired t test). Similarly, the work and activity DASH was significantly reduced (p < 0.001) to 12.5 (0-75) and 6.25 (0-50), respectively.

CONCLUSIONS

PMNE at the level of the lacertus fibrosus should be called lacertus tunnel syndrome to distinguish it from other levels of median nerve entrapment. It is a clinical diagnosis based on three distinct clinical findings: weakness, pain over point of compression, and positive scratch collapse test. Surgical release in local anesthesia allows for a safe, ambulatory, and cost-efficient procedure with low morbidity.