Brachial plexus compression by venous aneurysms. Case illustration.

Abstract

Two patients were referred to our institution for evaluation of right brachial plexus lesions. One, a 34-year-old man, complained of pain in his supraclavicular region that radiated down his arm and worsened with repetitive activity. This patient noted grip weakness and paresthesias in his right forearm and radial two digits. The other, a 44-year-old woman, presented with shoulder pain without other symptoms. Neither patient had a history of penetrating trauma and both had normal neurological and orthopedic examinations. A T 2 -weighted magnetic resonance (MR) imaging study obtained in the first patient revealed a 13-mm lesion in the right brachial plexus region superior to the subclavian artery (Fig. 1). The T 1 -weighted MR studies obtained in the second patient with and without gadolinium enhancement demonstrated a 2 3 1.5‐cm mass overlying the right brachial plexus (Fig. 2). Surgical exploration in the first patient revealed a large vein lying over the proximal plexus that was ligated and resected. On exploration of the second patient’s plexus, a large, ballottable, black mass was encountered medial to the lateral cord that appeared to drain into the subclavian vein. An intraoperative venogram was obtained (Fig. 3). Electrocautery was used to shrink the venous anomaly away from the plexus. True venous aneurysms are anomalies, with relatively few cases reported in the literature. 2‐4 They often present as isolated asymptomatic masses, but pain may occur with venous distension following increased activity. 1,5 Preoperative MR imaging may not allow differentiation of venous aneurysms from nerve sheath tumors. Both lesions may exhibit enhancement with gadolinium injection, and the characteristic flow voids seen in arterial structures are absent on MR images of venous aneurysms. Features that support a venous anomaly include continuity with a major vein and small linear flow voids related to phase shifts from the motion of blood along the field gradient. The diagnosis may be confirmed by phase-contrast or time-of-flight MR imaging sequences.