Neurovascular Contacts in the Pathophysiology of Neuralgic Amyotrophy: An Observational Study

OBJECTIVE: Neuralgic amyotrophy (NA) is a prevalent, monophasic, multifocal immune-mediated neuropathy. A distinctive characteristic of the disease is the occurrence of nerve or fascicle constrictions and torsions (NA-associated focal nerve lesions, NAFL). The pathophysiology underlying this phenomenon remains to be fully elucidated. METHODS: This study uses an observational research design with a single center, retrospective approach. We evaluated patients who presented at the outpatient clinic of a tertiary referral hospital between January 1, 2022, and August 5, 2025, due to NA. In addition to evaluating clinical and neurophysiological data, two independent experts examined the available ultrasound images for the prevalence of NAFL and the presence of arterial vascular structures in the immediate vicinity. RESULTS: A total of 171 affected nerves from 77 patients were analyzed. The prevalence of NAFL was 31% (24/77) among all patients. In 53% of all NAFL, direct neurovascular contact could be detected. A previous mechanical trigger was identified in 71% of patients with proven NAFL but without neurovascular contact. This was the case in only 29% of patients with neurovascular contact, although this discrepancy did not attain statistical significance. INTERPRETATION: The frequency of neurovascular contacts in close proximity to NAFL suggests that these contacts play a role in its pathophysiology. Such contacts, similar to mechanical tension on the nerve, could lead to a local disruption of the blood-nerve barrier. This would explain phenomena inconsistent with the current pathophysiological model, such as the lack of preference for the dominant arm and NAFL's occurrence at certain anatomical sites.