Constrictive axillary nerve neuropathy is an idiopathic disease, which is underestimated by most of the clinicians. In most of the patients, it leads to permanent motor deficits in the shoulder area. Hourglass like constriction and torsion of the axillary nerve is evocated as the cause of symptoms, unrelated to intrinsic or extrinsic compression.
In this retrospective study, pre-, intra- and postoperative findings of 10 patients with constrictions/torsions of axillary nerve were analyzed. The patients underwent surgery in our nerve surgery center over a period of 10 years (Jan. 2014–April 2024). Surgical exploration revealed hourglass shaped constriction of the axillary nerve in all cases, without motor response in all three parts of the deltoid muscle in 7 cases, and severe involvement of the anterior and lateral deltoid muscle with sparing of posterior deltoid muscle in 3 cases. Depending on the intraoperative findings, end-to-end sutures (n = 2), nerve grafting (n = 1) and nerve transfers (n = 7) were performed.
At the follow-up, the patients were re-examined. All of them reported subjective improvement in motor deficits. Clinically and electromyographically, a reinnervation and significant increase in strength from a pre-existing strength grade of M0 to M4+ were described in the cases where nerve transfers were performed. The patient that had nerve grafting as surgical treatment recorded the least improvement (M3).
Constrictive axillary mononeuropathy must not be confused with Parsonage-Turner syndrome. The reason for the vulnerability of the axillary nerve has not been yet elucidated. This disease seems to affect more young and athletic males. Previous studies suggest that surgical exploration must be performed to exclude a compression lesion in the quadrilateral space. During surgical exploration, we have not noticed any nervous site compression, but signs of nervous inflammation were present. Considering the results, surgical treatment via neurotization with a radial nerve branch remains the best choice of treatment.
In case of constrictive axillary mononeuropathy, surgical treatment is recommended as soon as possible. However, diagnosis is often difficult and can be masked by compensatory mechanisms of the adjacent shoulder muscles. Very good results can usually be achieved with nervous transfer usually from branches of the radial nerve.