Incidental Pediatric High-Flow Nongalenic Giant Pial Arteriovenous Fistula

A 3-year-old female presented to the emergency department with a severe headache after a fall. She was otherwise without focal neurologic deficit. Computed tomography of the head demonstrated a large hyperdense, well-circumscribed, extra-axial lesion centered along the lateral aspect of the left frontal and anterior temporal lobes with associated mass effect suggestive of vascular pathology ([Fig. 1]).Magnetic resonance imaging demonstrated an avidly enhancing lesion supplied by dilated tortuous vessels ([Fig. 2A, B]). These findings were highly suggestive of a vascular malformation. Subsequent digital subtraction angiography revealed a high-flow, nongalenic pial arteriovenous fistula (NGAVF) with dominant feeders from hypertrophic middle cerebral artery branches and venous outflow into the sphenoparietal sinus with a giant fistulous pouch ([Fig. 3A–D]). The lesion was successfully treated with coil embolization (hydrogels) of the single-hole fistulae ([Figs. 2C], [3E-L]).

Fig. 1 Computed tomography with a large hyperdense, well-circumscribed extra-axial lesion centered along the lateral aspect of the left frontal and anterior temporal lobes with associated mass effect. (A) Axial, (B) coronal.

Fig. 2 Magnetic resonance imaging pre– and post–coil embolization. (A, B) Pre–coil embolization T1 contrast-enhanced imaging with an avidly enhancing lesion (4.9 cm anteroposterior × 4.2 cm transverse × 4.7 cm craniocaudal) supplied by dilated tortuous vessels with a dominant draining tortuous vein extending to the floor of the left middle cranial fossa. (C) Post–coil embolization T1 noncontrast enhanced image demonstrating the previously enhancing giant fistulous pouch with heterogeneous signal and slightly decreased size representing evolving thrombus.

Fig. 3 (A–C) Left lateral view of the initial digital subtraction angiography with a high-flow, nongalenic pial arteriovenous fistula with dominant feeders from hypertrophic middle cerebral artery branches and venous outflow into the sphenoparietal sinus with a giant fistulous pouch. (D) Initial left anterior oblique view of the fistulous point (black arrow). (E–G) Left lateral view of initial post–coil embolization imaging demonstrating stasis of flow in the giant fistulous pouch. (H) Left anterior oblique close up view of the implanted coil material ablating the fistulous connection. (I–L) 3-month follow up imaging demonstrating a small residual arteriovenous malformation component at the medial aspect of the previous pial arteriovenous fistulous pouch with arterial supply from lenticulostriate arteries and superficial venous drainage.

NGAVFs are rare, unique vascular malformations with pial arteries feeding directly into a cortical vein without the intervening nidus of arteriovenous malformations.[1] [2] [3] The goal of treatment is occlusion of the fistulous site or the arterial feeders and proximal venous drainage as close to the fistula as able.[1] [2] [3] If left untreated, the natural history of NGAVFs are associated with poor clinical outcomes consequent to venous hypertension, infarction, or hemorrhage.[1] [2] [3]

Special Designations/Previous Presentations

None.

Disclosures

The authors declare that there are no disclosures to state.

Author Contributions

All authors have contributed substantively to the conception, design, analysis, and interpretation of the data, contributed substantively to the drafting of the manuscript and critical reason for important intellectual content, given final approval of the version to be published, and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Publication History

Received: 25 April 2020

Accepted: 14 July 2020

Article published online:
23 November 2020

• References

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