Heart-Shaped Bilateral Medullary Pyramidal Infarction as a Pathognomonic Finding of Anterior Spinal Artery Occlusion

Background: Unilateral anterior spinal artery (ASA) occlusion resulting in bilateral medullary pyramidal (BMP) infarction is a rare and devastating stroke subtype. We present two cases highlighting the diagnostic and clinical challenges of BMP infarction. Methods: Case reports and literature review. Results: A 57-year-old man rapidly had severe vomiting and diarrhea 2 h after a meal. Examination revealed bulbar weakness and areflexic tetraplegia. Respiratory failure developed, requiring intubation and mechanical ventilation. Brain magnetic resonance imaging (MRI) showed a heart-shaped region of diffusion abnormality, characteristic of BMP infarction. Cerebral angiography showed an occluded left vertebral artery with unilateral left-sided origin of ASA. The patient required tracheostomy and percutaneous gastrostomy tube and was discharged to rehabilitation, with little improvement of his tetraplegia at 3-month follow-up. A 43-year-old woman presented to the emergency department with acute onset of lower-extremity paresthesia and history of upper respiratory infection 2 weeks prior. Initial examination findings included bulbar weakness, dysphagia, hyporeflexia, and generalized weakness. After admission, she had severe respiratory distress and required intubation. Lumbar puncture was evaluated for Guillain–Barré syndrome, but cerebrospinal fluid protein concentration was normal. Changes on diffusion-weighted MRI of the brain showed the characteristic heart-shaped BMP infarction, indicating occlusion of a unilateral ASA. She required tracheostomy and percutaneous gastrostomy tube placement, with no paralysis resolution. Conclusion: Acute BMP infarction may present with flaccid tetraplegia mimicking neuromuscular disorders. When the infarction is recognized early, intravenous thrombolysis can be considered to reduce morbidity of this rare stroke subtype.