A 52-year-old African American male with a history of Diabetes Mellitus Type 2, Hypertension, and Hyperlipidemia presented to the Emergency Department with complaints of dizziness and fluctuating level of consciousness. He was on a business trip and has not been eating well and taking his insulin regularly. Vital signs on admission showed tachycardia. On exam, he had dry mucus membranes. He was alert, confused and would frequently fall asleep during conversation but easily arousable to minor stimuli. Labs were normal except for hyperglycemia (Blood sugar 320 mg/dL). No source of infection was found. He was initially suspected to have metabolic encephalopathy from dehydration and had transient improvement with fluids. The next day patient was found stuporous and only awakened by deep stimuli. Pupils were anisocoric, non-reactive and vertical gaze palsy was noted. CT scan of head without contrast did not show any bleed. Work up for cardio-embolism was negative and no arrhythmias were found. MRI brain showed bilateral midbrain and thalamic infarction suggestive of occlusion of the artery of Percheron. He was outside the window for thrombolytic therapy. Three weeks later, he continued to have varying degrees of sleep-like coma ranging from a deep state with minimal response to painful stimuli to a light somnolent state with easy arousability. He was aphasic, dysarthric with four-limb flaccid paralysis and completely dependent for all activities of daily living. He died four weeks from presentation with aspiration pneumonia and acute respiratory failure.
Artery of Percheron (AOP) occlusion is a rare cause of ischemic stroke characterized by bilateral thalamic infarcts with or without midbrain involvement. It is an uncommon anatomical variant arising as a single artery supplying both paramedian thalami. Clinical symptoms are variable including sleep-like coma (SLC), disorientation, confusion and hypersomnolence. Presentation as sleep-like coma without localizing signs can pose a diagnostic challenge and mislead physicians to look for toxic-metabolic causes delaying the diagnosis as in this case. Diffusion-weighted MRI is the imaging modality of choice for early diagnosis. Sudden onset of sleep-like coma with mild response to painful stimuli should prompt urgent imaging (MRI) to look for thalamic ischemia/infarction. Cardio-embolism is the main cause of occlusion of AOP followed by atherosclerotic small vessel disease. Treatment includes prompt intervention with thrombolytic therapy but administration is delayed due to missed or delayed diagnosis. Long term sequelae include severe extrapyramidal symptoms and neurocognitive impairment.
Diagnosis of AOP occlusion can be challenging. Hospitalists should maintain a high index of suspicion for this stroke syndrome in a patient presenting with fluctuating level of consciousness and no localizing signs. Early diagnosis and prompt intervention are crucial to prevent long term debilitating outcomes.