Beware the Wandering Needle: Inadvertent Intramedullary Injection During an Attempted Cervical Medial Branch Block.

A 27-year-old man developed sudden neck pain, severe quadriparesis, and right shoulder allodynia during an outpatient cervical medial branch block procedure. Cervical spine imaging revealed evidence of an interlaminar needle trajectory with abnormal signal in the right hemicord at the level of C4, consistent with intramedullary injection and contusion. Following a 48-hour stay in the intensive care unit, during which hemodynamic vasopressor support was administered to optimize spinal cord perfusion, the patient exhibited almost complete neurologic recovery with resolution of the neuropathic pain. He was eventually discharged home and underwent outpatient physical therapy for a mild residual right hemiparesis.