Clinical Diagnosis and Wide-Awake Surgical Treatment of Proximal Median Nerve Entrapment at the Elbow: A Prospective Study

Abstract

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.

The wide-awake approach to ulnar nerve entrapment: results of an integrated one-stop wide-awake surgical pathway

“…Distal entrapment in the ulnar tunnel is less well described, but in our experience it is not uncommon, and decompression is the standard surgical procedure 26 . As per the recent paper by Hagert on wide awake treatment of (occult) proximal median nerve entrapment 27 : it is our experience that distal ulnar nerve entrapment may similarly be overlooked and is not usually detected on nerve conduction studies. Moreover, in the present series all the three cases of ulnar tunnel syndrome had a false negative nerve conduction study result for ulnar tunnel entrapment; and this has confounded the diagnosis of their clinically obvious ulnar tunnel syndromes.…”

The Scratch Collapse Test Supported the Diagnosis and Showed Successful Treatment of Tarsal Tunnel Syndrome

“…We have since this first patient experienced similar positive scratch collapse test in two additional patients. The patho-physiology is similar to the carpal tunnel syndrome and similar nerve entrapment on the arm [6]. Brown et al found that the scratch collapse test was a seemingly reliable physical examination technique for localizing the point of maximal nerve compression in patients with cubital tunnel syndrome [7].…”

Nerves of the Upper Extremity

“…In the cubital fossa, the median nerve may be entrapped by a thickened lacertus fibrosus (Hagert 2013) or accessory tendons of the biceps brachii (Spinner et al 1991).…”