Artery of Percheron infarction presenting as nuclear third nerve palsy and transient loss of consciousness: a case report

Abstract

Background: Thalamic blood supply consists of four major vascular territories. Out of them paramedian arteries supply ipsilateral paramedian thalami and occasionally rostral mid brain. Rarely both paramedian arteries arise from a common trunk that arise from P1 segment of one sided posterior cerebral artery (PCA). This is usually due to hypoplastic or absent other P1 and this common trunk is termed Artery of Percheron (AOP). Its prevalence is in the range of 7-11% among the general population and AOP infarcts account in an average of 0.4-0.5% of ischemic strokes. Clinical presentation of AOP infarction is characterized by impaired arousal and memory, language impairment and vertical gaze palsy. It also can present with cerebellar signs, hemi paresis and hemi sensory loss. We herein present a case of AOP infarction presenting as transient loss of consciousness and nuclear third nerve palsy.

Case presentation: A 51 year old previously healthy male, was brought to us, with a Glasgow coma scale (GCS) of 7/15. GCS improved to 11/15 by the next day, however he had a persisting expressive aphasia. Right sided nuclear third nerve palsy was apparent with the improvement of GCS. He did not have pyramidal or cerebellar signs. Thrombolysis was not offered as the therapeutic window was exceeded by the time of diagnosis. Diagnosis was made using magnetic resonance imaging (MRI) that was done after the initial normal non-contrast computer tomography (NCCT) brain. He was enrolled in stroke rehabilitation. Aspirin and atorvastatin was started for the secondary prevention of stroke. He achieved independency of advanced daily living by 1 month, however could not achieve full recovery to be employed as a taxi driver.

Conclusions: Because of the rarity and varied clinical presentation with altered levels of consciousness, AOP infarcts are easily overlooked as a stroke leading to delayed diagnosis. Timely diagnosis can prevent unnecessary investigations and the patient will be benefitted by early revascularization. As it is seldom reported, case reports remain a valuable source of improving awareness among physicians about this clinical entity.

Keywords: Artery of Percheron (AOP); Case report; Mid brain infarction; Nuclear third nerve palsy; Paramedian thalamic infarction; Thalamic infarction.

Fig. 1

Eye movements demonstrating right eye nuclear third nerve palsy. a Neutral position of eyes showing bilateral partial ptosis (right > left) and outward and downward deviation of the right eye due to third nerve palsy. b Attempted vertical gaze; vertical gaze palsy is apparent. c Right gaze; right eye abduction and left eye adduction is preserved. d Left gaze; right eye adduction is impaired whereas left eye abduction is preserved

Fig. 2

MRI images showing AOP territory infarction. a DWI image showing paramedian thalamic infarctions. b DWI image showing right rostral midbrain infarction (Note the assymetry in rostral mid brain involvement). c ADC image showing paramedian thalamic infarctions. d ADC image showing assymetrical right rostral midbrain infarction

Fig. 3

Neurovascular anatomical variants supplying paramedian thalamus and mid brain as was described by Percheron [10]. (Adapted from, Artery of Percheron infarction: review of literature with a case report. Radiology and oncology. 2015 Jun 1;49 (2):141–6.Written permission was obtained from the author and the journal to use as an open access figure). a Variant I - each side perforating arteries arising from each PCA. b Variant IIa - asymmetrically arising two perforating arteries from one sided PCA. c Variant IIb - bilateral thalamic perforating arteries arising from a single common trunk (AOP). d Variant III - an arc bridging P1 segments of bilateral PCA giving rise to several perforating arteries. Vessels marked by initials: AICA - anterior inferior cerebellar artery, AOP - artery of Percheron, BA - basilar artery, MP - midbrain perforators, PCA – posterior cerebral artery, SCA - superior cerebellar artery, TP - thalamic perforators