Abstract 285: Intraventricular And Subarachnoid Hemorrhage Secondary To Arteriovenous Malformation, A Diagnostic Neurologic Manifestation Of Osler‐Weber‐Rendu Disease
Authors: Ahmed Hamza M. , Amos Jessica V. , Gatchoff Philion L. , Garcia‐Ramiu Jonathan L. , Ortiz‐Garcia Jorge G. 
Published: March 2024

Introduction
Osler‐Weber‐Rendu disease, also known as hereditary hemorrhagic telangiectasia (HTT), is a developmental vascular disease characterized by multiple arteriovenous malformations (AVMs) due to genetic defects in endothelial angiogenesis pathways. HHT is a clinical diagnosis based on the fulfillment of the Curacao Diagnostic Criteria, including involvement of internal organs with AVMs, significant recurrent nosebleeds, telangiectasias, and family history of HHT. HHT has a prevalence of 1.5 to 2 people/10,000, although this is considered a falsely low representation due to missed diagnosis and variable penetrance. Autosomal dominantly inherited heterozygous mutations disrupt the TGF‐beta‐mediated pathways causing aberrant blood vessel development with fragility and AVM formation. There are two forms of HHT: (HHT1) has a higher incidence in women and typically involves pulmonary and cerebral arteriovenous malformations (AVM). Mutations in the endoglin gene are thought to be responsible for HTT1 and comprise approximately 61% of the cases. HTT2 is associated with a higher rate of liver AVMs, involves a mutation in Activin A Receptor‐Like Type 1 (ACVRL1), and is responsible for approximately 37% of cases. Other genetic mutations include SMAD4 and GDF2, which are transmitter and binding proteins and occur about 2% of the time.

Methods
Case report and review of literature

Results
Case:A 52‐year‐old woman with a large frontoparietal arteriovenous malformation originally found at the age of 17, with a history of frequent epistaxis, mucocutaneous telangiectasias and two children with epistaxis and telangiectasias. Her diagnosis of HHT was made at her third hjospitalization due to a non‐traumatic subarachnoid hemorrhage. A Chest CT angiography and a CT angiography of the intra and extracranial vasculature demonstrated an extensive right holohemispheric cerebral AVM, an unruptured 8‐mm basilar artery aneurysm, and multiple enlarged pulmonary arteries with narrow inlet and outlets concerning for pulmonary AVMs. A subsequent digital subtraction angiogram (DSA) of the brain confirmed the extensive holohemispheric AVM, unruptured basilar artery aneurism with subarachnoid hemorrhage originating from the AVM. On examination she had multiple lingual, and hard/soft palate telangiectasias and an extensive anterior pedal telangiectasia. Given the heavy cerebral AVM burden with multiple cerebral artery feeders, the AVM angiosclerosis and basilar artery aneurysm embolization were deferred. The patient proceeded under medical management alone with a plan for personal and familial genetic testing.

Conclusion
HHT is a rare cause of cerebral AVMs at high risk of spontaneous bleeding. Managing these AVMs can be a challenge, given the extent and location of these. However, diagnosis of HHT can inform prognosis and guide medical management due to improved prognosis for HHT‐related AVMs and aneurysms compared to non‐HHT AVMs.