C3 spinal cord infarction associated with cervical ossification of the posterior longitudinal ligament presenting as a stroke mimic: illustrative case.

backgroundSpinal cord infarction is a rare cause of acute neurological deficits and may present as a stroke mimic. Cervical ossification of the posterior longitudinal ligament (OPLL) may increase ischemic vulnerability at the compressed cord level. OBSERVATIONS: A 68-year-old man presented with sudden-onset left hemiparesis and a speech disturbance without preceding trauma. Neurological examination revealed hypophonia without aphasia, facial weakness, tongue deviation, or extraocular movement abnormalities. Contrast-enhanced head and neck CT showed no intracranial hemorrhage or large-vessel occlusion, and intravenous alteplase was administered for suspected acute ischemic stroke. Brain MRI performed 48 hours after symptom onset showed no evidence of acute cerebral infarction. In contrast, cervical MRI demonstrated diffusion restriction at C3 adjacent to severe mixed-type OPLL at C2-3, consistent with spinal cord infarction. Because OPLL-related canal stenosis persisted at the infarct level, posterior decompression with C3-6 laminoplasty was performed on hospital day 8. The patient partially improved postoperatively. LESSONS: This case illustrates that cervical spinal cord infarction associated with OPLL may present as a stroke mimic. Cervical spine imaging should be considered when acute hemiparesis is accompanied by a speech disturbance but cortical or bulbar signs are absent and brain MRI findings are negative. https://thejns.org/doi/10.3171/CASE26294.