Intracranial dAVFs: beyond haemorrhage to the cognitive dimension

Over the past few decades, intracranial dural arteriovenous fistulas (dAVFs) have evolved beyond simply being a condition in which haemorrhagic risk was the key factor influencing management and treatment. There has also been an increasing focus, in recent times, on the cognitive effects that are experienced by dAVF patients. Here, Alejandro Tomasello (Barcelona, Spain) discusses this phenomenon in further detail, and outlines its possible implications regarding clinical research and care.

For decades, the rationale for treating dAVFs has been primarily guided by their haemorrhagic risk. Classical descriptions, such as the pioneering work of René Djindjian and J.J. Merland in the 1970s, established that certain angioarchitectural patterns—particularly those with cortical venous reflux—carried a significant risk of intracranial haemorrhage.¹ Later, the widely adopted Cognard et al and Borden et al classifications refined this risk stratification and helped clinicians select which patients require urgent intervention.^2,3 In parallel, additional treatment indications have also been recognised, particularly in relation to compressive phenomena—most notably, cranial nerve involvement in dural AVFs affecting the orbit and cavernous sinus—where endovascular therapy has emerged as the standard of care.

In recent years, however, a new indication for treatment has gained attention: cognitive impairment associated with dAVFs. While traditionally considered an incidental or minor finding in low-grade lesions, growing evidence shows that even ‘benign’ fistulas may have significant consequences for cognitive functions. The pathophysiological mechanism appears to be multifactorial, probably involving a combination of chronic venous hypertension, impaired cerebral perfusion, and possibly disturbances of glymphatic clearance. Indeed, experimental and imaging data increasingly suggest that venous hypertension disrupts glymphatic function, hindering waste clearance and promoting neurotoxic accumulation.

A recent review of the large CONDOR dataset—a multicentre, international registry including more than 1,000 dAVFs that collects clinical, imaging and treatment data—reported that patients with dAVFs and cognitive impairment frequently exhibited venous outflow obstruction, sinus stenosis, multiple arterial feeders or draining veins, and venous ectasia, thereby reinforcing the correlation with impaired venous pressure and cerebral perfusion.⁴ Subsequently, long-term follow-ups showed that patients with dAVFs frequently present with cognitive impairment, which improves after embolisation or surgery.⁵ Indeed, a prospective longitudinal study confirmed that baseline neuropsychological deficits are common and significantly improve post-treatment.⁶ These findings establish cognitive outcomes as reproducible across independent cohorts.

At Vall d’Hebron University Hospital in Barcelona, Spain, our team has been especially active in this field, serving as the leading group in the NAIF study. This work systematically evaluated patients with dAVFs, regardless of grade, through comprehensive neuropsychological testing.⁷ Strikingly, cognitive impairment was detected in more than half of the patients—even in those with small, low-risk fistulas—and proved to be reversible following endovascular treatment. Thus, these lesions are not as ‘silent’ as once believed, and cognitive dysfunction should not be regarded as an incidental observation, but as a core disease manifestation.

These findings suggest that the therapeutic paradigm must expand beyond haemorrhage prevention and symptom relief. Cognitive health should be considered a legitimate endpoint when evaluating the natural history of dAVFs and deciding upon treatment. Importantly, the benefit of fistula closure should not be confined to high-grade lesions but also extended to those kept under surveillance. This raises a new question: should all dAVFs be treated proactively to prevent or reverse cognitive decline?

The next step for our institution is to further shed light into the mechanisms driving this impairment. Thus, a novel multicentre study, conducted in collaboration with Cambridge and Oxford University Hospitals in the UK, is currently underway, employing advanced neuroimaging techniques to investigate venous congestion, brain oedema and potential glymphatic dysfunction. By combining imaging biomarkers with neurocognitive outcomes, we aim to bridge the gap between clinical observation and pathophysiology, moving toward precision medicine in dAVF management.

In conclusion, dAVFs are more than just structural vascular anomalies at risk of rupture. They are dynamic lesions capable of silently eroding cognitive reserve. The NAIF study marks a turning point—treatment should no longer be limited to preventing catastrophic bleeding but also to preserving quality of life and cognition. Understanding the physiopathology and increasing the quality of this evidence are crucial targets for the future.

References:

1. Djindjian R, Merland J J, Rey A et al. Super-selective arteriography of the external carotid artery. Importance of this new technic in neurological diagnosis and in embolization. Neurochirurgie. 1973; 165–71.
2. Cognard C, Gobin Y P, Pierot L et al. Cerebral dural arteriovenous fistulas: clinical and angiographic correlation with a revised classification of venous drainage. Radiology. 1995; 194(3): 671–80.
3. Borden J A, Wu J K, Shucart W A. A proposed classification for spinal and cranial dural arteriovenous fistulous malformations and implications for treatment. J Neurosurg. 1995; 82(2): 166–79.
4. Sanchez S, Wendt L, Hayakawa M et al. Dural arteriovenous fistulas with cognitive impairment: angiographic characteristics and treatment outcomes. Neurosurgery. 2024; 94(5): 1035–43.
5. Kumar A A, Kannath S K, Vijayaraghavan A et al. Long-term cognitive outcome in dural arteriovenous fistula after embolization therapy. J Neuropsychol. 2025; 19(3): 576–90.
6. Itsekson-Hayosh Z, Carpani F, Mosimann P J et al. Dural arteriovenous fistulas: baseline cognitive changes and changes following treatment: a prospective longitudinal study. Am J Neuroradiol. 2024; 45(12): 1878–84.
7. Gramegna L L, Ortega G, Dinia L et al. Cognitive improvement following endovascular embolization in patients with intracranial dural arteriovenous fistula: The Neuropsychology in dural ArterIal Fistula (NAIF) study. J Neurointerv Surg. 2025; 17: 87–93.

Alejandro Tomasello is an interventional neuroradiologist and head of the Neurointerventional Department at Vall d’Hebron University Hospital in Barcelona, Spain.

DISCLOSURES: The author declared no relevant disclosures.