Hypersomnolence and Horizontal Gaze Palsy in Artery of Percheron Infarcts: Clinical-Radiographic Correlates (P4.367)

Objective: Report clinical and radiographic correlates in a series of Artery of Percheron (AOP) infarcts. Background: AOP supplies bilateral thalami from a solitary arterial trunk of the PCAs. Its occlusion results in bilateral paramedian thalamic infarcts with or without anterior thalamic or rostral midbrain involvement. The triad of vertical gaze palsy, memory impairment and coma is associated with infarct to the paramedian thalamus. Methods: We report four cases of AOP infarction with evidence of bilateral medial thalamic infarcts. All four patients presented with altered mental status, confusion, hypersomnolence, and coma. Two patients involved the anterior thalamus. Three of four patients had midbrain involvement and horizontal gaze palsies with at least one oculomotor nerve affected in all three. Results: Case 1: 77 year-old male with sudden onset of somnolence three days after coronary artery bypass graft (CABG). He was unresponsive to verbal or tactile stimuli. Brain MRI revealed anteromedial thalamic and right PCA infarcts. Case 2: 76 year-old male presented with confusion and mumbled incoherently. He had bilateral oculomotor nerve palsies. Head CT demonstrated infarctions in the bilateral midline thalami and rostral midbrain. Case 3: 58 year-old female was unresponsiveness one day after CABG. She had right internuclear ophthalmoplegia and left oculomotor nerve palsy. CT scan revealed infarcts of bilateral medial thalami, left paracentral midbrain and left posterior internal capsule. Case 4: 49 year-old female presented with diplopia, lightheadedness and altered mental status. She had left 3rd and 4th cranial nerve palsies. Brain MRI revealed bilateral thalamic infarcts and dilated 3rd ventricle. Conclusion: AOP infarcts can present with altered mental status due to bilateral paramedian thalamic involvement and horizontal gaze deficits with rostral midbrain ischemia. Given the broad differential for altered mental status, observation of vertical or horizontal gaze palsies may be important in making the diagnosis. Disclosure: Dr. Agarwal has nothing to disclose. Dr. Chancellor has nothing to disclose. Dr. Howard has nothing to disclose.