Stuck with a drowsy patient, evoke the Percheron

Background: Strokes caused by normal variants of the cerebral circulation can be difficult to diagnose, hence a high index of suspicion is needed. This case series discusses the clinical and radiological aspects of one such stroke caused by occlusion of the artery of Percheron (AOP). Materials and Methods: Computerized discharge summaries, outpatient records and imaging from picture archiving and communication system (PACS, GE), of patients with AOP infarction over a period of 12-years (2002-2014) were identified and their clinical and radiological features analyzed. Results: Of 3589 strokes (both ischemic and hemorrhagic), 17 (0.47%) were due to AOP infarction. Their mean age was 50 years (range: 31-72 years). Disorders of consciousness (94%) were the most common presenting symptoms followed by gaze (53%) and memory impairment (24%). At follow-up, 2/17 (12%) patients developed extrapyramidal features. All patients had bilateral paramedian thalamic infarcts on magnetic resonance imaging (MRI). Associated anterior thalamic (5/17; 30%) and mid brain (10/17; 59%) infarcts were also seen. CT scan done in 11/17 patients prior to the MRI picked up only 6/11 (55%) of these infarcts. The most common etiological factors detected using the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria were cardio embolic (8/17; 47%) followed by small vessel occlusion (7/17; 41%). Mortality occurred in 2/17 (12%) patients. At 6 months, a modified Rankin score of 2 or less was seen in 8/17 (47%) patients. Conclusions: Artery of Percheron infarcts should be considered in the differential diagnosis of patients presenting with sudden alterations in consciousness. MRI should be the investigation of choice. An embolic etiology should be actively looked for.