Coma with Vertical Gaze Palsy: Relevance of Angio-CT in Acute Percheron Artery Syndrome

Abstract

BACKGROUND: A 63-year-old woman with chronic atrial fibrillation treated with warfarin was admitted to emergency for coma and complete vertical gaze palsy. Investigations: Brain CT and MRI, echo-colour Doppler sonography of the supraaortic vessels, angio-CT of the intracranial vessels, EEG, transesophageal echocardiogram, biohumoral tests. Brain CT and MRI scans showed bilateral thalamic lesions with involvement of the right midbrain; EEG showed a diffuse alpha rhythm prevalent on the posterior regions; echo-colour Doppler sonography of the supraaortic vessels showed marked reduction of blood flow in the right vertebral artery; angio-CT scans showed occlusion of the right vertebral artery and a significant filling defect of the first part of the right posterior cerebral artery (P1) from which the artery of Percheron arises. A follow-up angio-CT showed a complete recanalization of P1. Diagnosis: Percheron artery syndrome. Treatment and Management: Aspirin, neurorehabilitation.

Fig. 1

Passive examination of the ocular movements: this manoeuvre tests the oculocephalic reflex. a-c Natural response in normal patients, referred to as doll's eye sign (the gaze deviates contralaterally in the opposite direction of where the head is turned). d, e An abnormal response is present when the eyes remain fixed on the horizontal or vertical axis during the passive movement of the head.

Fig. 2

MR imaging: axial FLAIR images show hyperintensities in the paramedian thalamic regions extending to the right mesencephalic peduncle.

Fig. 3

Angio-CT scan. a Lack of visualization of the right vertebral artery with patent basilar artery (BA = basilar artery, VA = left vertebral artery). b Focally stenotic first tract of the right posterior cerebral artery. c Persistent occlusion of the right vertebral artery with patent basilar artery after three weeks. d Stenosis resolution of first tract of the right posterior cerebral artery after three weeks.

Fig. 4

Anatomic variations of the arterial supply to the paramedian thalamic-mesencephalic region as described by Percheron [4]. a Common variation, many small perforating vessels arising from the P1 segments of both posterior cerebral arteries. b Artery of Percheron variant, arising from the P1 tract of a single posterior cerebral artery and supplying both thalami. c Arcade variant, with several small perforating branches arising from a single artery that bridges the P1 segments of both posterior cerebral arteries.