Abstract Number ‐ 228: Two Cases of Vertebrobasilar Dolichoectasia +/‐ Obstructive Hydrocephalus
Authors: Choudhury Omar , Jumah Ammar , Nour Hassan Aboul 
Published: April 2023

Introduction
Dolichoectasia; “dolichos'' and “ectasia” respectively meaning elongation and distention of blood vessels is a process by which arteries undergo deterioration of the tunica intima or tunica media, resulting in smooth muscle atrophy.1 It can be atherosclerotic, non‐atherosclerotic, and dissection‐related. Prolonged hypertension resulting in breakdown and remodeling of collagen‐elastin meshwork produces the atherosclerotic subtype, though hyperlipidemia also plays a role. The incidence is approximately 3%, higher in males.2 Vessels commonly affected by dolichoectasia are in the vertebrobasilar system but the internal carotid arteries are also at risk. Vertebrobasilar dolichoectasia (VBDE) is radiographically defined by basilar artery diameter > 4.5 mm, though it is sometimes overlooked due to healthy variations in basilar tortuosity and diameter. Smoker’s criteria includes artery diameter, laterality, and bifurcation height.3 Neurovascular compression often occurs, but high‐risk complications of VBDE such as hemorrhagic or ischemic stroke, TIA, brainstem compression, hydrocephalus, or subarachnoid hemorrhage are also possible.4 We present two cases of ventriculomegaly in the setting of VBDE.

Methods
Case Report

Results
Case #1: A 40 year‐old man with history of hypertension, gout, anal fissures, and bicuspid aortic valve presented to the hospital for intermittent visual obscuration for 2 weeks. He described it as a “Polaroid picture: starting dark and slowly developing” featuring positional exacerbation with Valsalva, leaning forward, and laying flat. Examination revealed bilateral papilledema, right eye ptosis, and right 6th nerve palsy. CT head showed hydrocephalus. CTA and CTV were negative. MRI brain with contrast showed dilated lateral ventricles (left > right) and anterior third ventricle lacking significant transependymal CSF flow. The distal basilar was tortuous extending towards the mid‐portion of the third ventricle (Figure 1). A precipitating factor was thought to be an epidural for anal fissure surgery 2 months prior. Initially treated with acetazolamide, the patient later underwent endoscopic third ventriculostomy (ETV). One‐year follow‐up showed significant improvement of papilledema with minimal residual visual field deficits. Case #2: A 71 year‐old man with history of atrial fibrillation presented to the Neurology clinic for memory loss. It started with misplacing belongings, complicated by an episode of getting lost while driving to a familiar location. Examination showed 1/5 word recall at 5 minutes and mild impairment of serial sevens and abstract thinking. MRI brain revealed dilatation of the lateral and third ventricles out of proportion to the sulci and fourth ventricle, dolichoectatic basilar artery up to 8 mm with superior displacement of nearby structures and effacement of the anterior third ventricle. Repeat MRI with CSF flow one month later showed unchanged ventricular dilatation favored secondary to volume loss without evidence of an obstructive process.

Conclusions
These cases characterize the rare phenomenon of VBDE and highlights the importance of acquiring MRI with CSF flow when it presents with hydrocephalus.