From the Guidelines
The annual risk of a brain bleed with a Cognard type IV dural arteriovenous fistula (DAVF) at the petrous apex of the temporal bone is approximately 2% to 3% per year, as indicated by the available natural history studies 1.
Key Considerations
- Cognard type IV DAVFs are considered high-risk due to their cortical venous drainage and associated venous ectasias, which increase hemorrhage risk.
- The petrous apex location adds complexity due to its deep position and proximity to critical neurovascular structures.
- Immediate treatment is strongly recommended rather than observation due to the substantial bleeding risk.
Treatment Options
- The preferred treatment approaches include endovascular embolization, microsurgical disconnection, or stereotactic radiosurgery, often using a multimodal approach for complete obliteration 1.
- Each treatment option has associated risks and benefits, and the choice of treatment should be individualized based on the patient's specific condition and medical history.
Outcomes
- The outcome from hemorrhage is controversial, with mortality rates ranging from 10% to 30%, and 10% to 20% of survivors having long-term disability 1.
- The risk of recurrent intracranial hemorrhage is slightly elevated for a short period of time after the first hemorrhage, with a risk of 6% to 17.9% during the first year 1.
Recommendation
Given the high risk of hemorrhage and poor prognosis associated with Cognard type IV DAVFs, immediate treatment is strongly recommended rather than observation 1.
Important Considerations
- The patient's age, medical history, and overall health should be taken into account when making treatment decisions.
- A multidisciplinary approach, including neurosurgery, neurology, and radiology, is recommended for the management of Cognard type IV DAVFs.
- Regular follow-up and monitoring are essential to assess the effectiveness of treatment and detect any potential complications early on.
From the Research
Annual Risk of Brain Bleed with Cognard Type Four Dural Arteriovenous Fistula
- The annual risk of a brain bleed with a Cognard type four dural arteriovenous fistula is estimated to be around 7.4-7.6% for patients with symptomatic cortical venous drainage (CVD) 2.
- However, for patients with asymptomatic CVD, the annual rate of intracerebral hemorrhage is significantly lower, ranging from 1.4-1.5% 2.
- It is essential to note that these estimates are based on general data for Cognard type IV DAVFs and may not specifically apply to a fistula located at the petrous apex of the temporal bone.
- The provided studies do not offer specific annual risk rates for brain bleeds in Cognard type four DAVFs located at the petrous apex of the temporal bone 3, 4, 5, 6.
Location and Treatment of DAVFs
- DAVFs can occur in various locations, including the anterior cranial fossa 4 and the tentorial region 6.
- Treatment options for DAVFs include endovascular embolization using Onyx, which has shown promising results in achieving complete obliteration of the fistula 3, 4, 6.
- The choice of treatment depends on the location, size, and type of the DAVF, as well as the presence of symptoms and cortical venous drainage 5, 2.
Classification and Risk Stratification
- The Cognard classification is a widely used system for categorizing DAVFs based on their angiographic features, including the presence of cortical venous drainage 5.
- The addition of modifiers such as symptomatic or asymptomatic CVD can improve the accuracy of risk stratification for patients with high-grade DAVFs 2.