Bone wax causing a middle trunk plexopathy following vertebral artery injury: a neuroradiological pitfall

Abstract

BackgroundBone wax is a hemostatic agent widely used in surgery. Since it is neither absorbed nor metabolized, its use remains risky and a potential cause of complications. Even though its MRI radiological characteristics are distinguishable, it is generally misinterpreted as postoperative hematoma or trapped air. We report the first case in literature of brachial plexopathy due to the compressive mass effect of bone wax and the main clues that led us to establish this diagnosis prior to its surgical resection.Case presentationA 20-year-old male, victim of stabbing presented with an open wound of the right latero-cervical region with a vascular injury of the V2 segment of the right vertebral artery on CT angiography. He was first admitted for bleeding from the neck uncontrollable with external pressure. The patient underwent an emergency surgical vertebral artery ligation. Forty-eight hours later, he reported a feeling of paresthesia of right arm with right-sided weakness. Neurologic examination revealed a motor deficit of the right triceps and wrist extensor muscles and absence of the triceps reflex. A postoperative compression of the C7 cervical root or the middle trunk of brachial plexus was initially suspected. A cervical MRI demonstrated a T1- and T2-weighted images well-defined right mass located laterally to the spinal cord in the epidural space at the level of C6–C7 vertebrae with a signal-intensity void on both sequences. T2*-weighted images showed no signal attenuation. It did not enhance after contrast administration. An epidural hematoma was less probable since acute hematoma is typically hypointense on T2*-weighted images. Computed tomography helped rule out residual postoperative air trapped in the epidural space based on the density study of the mass compared to air. Finally, a residual surgical foreign material used for packing during the procedure was suspected. The massive use of bone wax was ultimately confirmed by the surgeon and surgically removed with complete immediate postoperative recovery.ConclusionsThis case highlights the importance of a nuanced critical approach of neurosurgeons and neuroradiologists when interpreting postoperative neuroimaging scans of the spine. It is crucial to always consider foreign body-related complications and to review the per-operative procedure in details.