Venous Thoracic Outlet Syndrome Combined with Brachial Neuritis Caused by Lymphadenopathy after Vaccination for Coronavirus Disease 2019: A Case Report

Thoracic outlet syndrome (TOS) occurs due to compression of the neurovascular bundle exiting the thoracic outlet, through which the brachial plexus and subclavian vessels pass. Here, we report a case of venous TOS combined with brachial neuritis, which was caused by axillary lymphadenopathy after the first dose of the BNT162b2 vaccine against coronavirus disease 2019 (COVID-19). A 17-year-old female patient presented with left upper extremity swelling and pain after inoculation with the BNT162b2 vaccine in the left deltoid muscle. Contrast-enhanced brachial plexus magnetic resonance imaging revealed severe swelling of the left axillary and subclavian lymph nodes, which lie immediately above the subclavian vein. An electrodiagnostic study revealed left brachial plexopathy, mainly involving the lower trunk with mixed demyelinating and axonal injury. The patient received intravenous steroid pulse therapy and oral steroid therapy. A follow-up examination showed complete recovery of muscle strength and function, pain, and swelling in the left upper extremity within 3 months after vaccination against COVID-19.