Pial arteriovenous fistula fed by an angular branch of the left middle cerebral artery with associated aneurysm and subdural hematoma: illustrative case.

BACKGROUND

Pial arteriovenous fistulas (pAVFs) are rare vascular abnormalities in the subpial space, characterized by high-flow connections between pial arteries and draining veins, without an intervening nidus. This case report describes a left parietal pAVF feeding from the angular branch (M4) of the left middle cerebral artery, which presented as an acute subdural hematoma (SDH).

OBSERVATIONS: The authors present the case of a 68-year-old neurologically intact male with 1-week history of progressive holocranial headache. Initial noncontrast CT imaging of the head revealed a left-sided SDH. Subsequent CTA confirmed the SDH with a spot sign in the posterior part of the SDH. Digital subtraction angiography identified a left parietal pAVF with an associated saccular aneurysm. The patient underwent successful microsurgical ligation and hematoma evacuation, with no residual fistula or vascular abnormality on follow-up angiography.

LESSONS: This case highlights the importance of a lower threshold for advanced imaging in acute SDH with no known predisposing factors. It also focuses on the complexity of managing pAVFs with associated aneurysms, along with the importance of individualized treatment strategies integrating advanced imaging and microsurgical techniques. https://thejns.org/doi/10.3171/CASE25605.