A 22 year old male with acute seizures and hemiparesis Teaching NeuroImages Neurology Resident and Fellow Section © 2015 American Academy of Neurology

Vignette A 22 year old previously fit male presents with acute seizures, a left hemiparesis and a Glasgow-Coma-Scale of 7 on admission. There was no known history of drug abuse, trauma or infection. CT on admission (Figure 1) shows a right frontal parenchymal hematoma with intraventricular extension and subarachnoid haemorrhage. Bilateral established anterior cerebral artery infarcts were also evident. CT-angiography (Figure 1) and intracranial Digital-Subtraction- Angiography (Figure 2) demonstrate the abnormal vessel. Hermes et al. © 2015 American Academy of Neurology

Imaging Hermes et al. Figure 1: CT and CTA head CT and CTA head at presentation. Axial CT head (a) showing right frontal haematoma extending into the ventricles, anterior interhemispheric subarachnoid haemorrhage and bilateral anterior cerebral artery infarcts. Sagittal CTA (b) and 3D reconstruction (c) revealing an aneurysm of the right callosomarginal artery (arrows). Figure 2: Cerebral Angiogram (DSA) Cerebral angiogram lateral view (a) and oblique view (b) confirming the diagnosis of an intracranial dissecting fusiform aneurysm at a non-branching point of the right callosomarginal artery. Note the focal stenoses proximally and distally (‘pearl-and-string’ sign) (arrows). Hermes et al. © 2015 American Academy of Neurology

Intracranial Arterial Dissection CT-Angiography and Digital-Subtraction-Angiography show a dissecting aneurysm of the right callosomarginal artery at a non-branching site with the characteristic ‘pearl-and-string sign’. Other indicators of intracranial artery dissection are an intramural haematoma or an intimal flap1. Although rare, intracranial arterial dissection is under- recognised1 probably due to a lack of awareness of this entity. Patients present most commonly with subarachnoid haemorrhage and/ or cerebral ischaemia1. Our case presented with subarachnoid haemorrhage and bilateral anterior cerebral artery infarcts which were likely the result of both vasospasm and mass effect from the parenchymal haematoma. Reference: 1 Debette S, Compter A, Labeyrie MA, et al. Epidemiology, pathophysiology, diagnosis, and management of intracranial artery dissection. Lancet Neurol. 2015 Jun;14(6):640-654 Hermes et al. © 2015 American Academy of Neurology