====== Intracranial pial arteriovenous fistula ======
[[Intracranial]] [[pial arteriovenous fistula]]s (AVFs) are rare [[cerebrovascular malformation]]s. Intracranial pial AVFs have single or multiple arterial connections to a single venous channel. 

Since [[1986]] they have been recognized as a distinct pathological entity from other [[intracranial cerebrovascular malformation]]s
((Lasjaunias P, Manelfe C, Chiu M. Angiographic architecture of intracranial vascular malformations and fistulas--pretherapeutic aspects. Neurosurg Rev. 1986;9:253–263.)).

===== Natural history =====

Because pial AVF has a poor natural history, the clinical suspicion of pial AVF, followed by prompt appropriate treatment is important
((Morimoto T, Yamada T, Hashimoto H, Tokunaga H, Tsunoda S, Sakaki T. Direct approach to intracranial vertebral arteriovenous fistula. Case report. Acta Neurochir (Wien) 1995;137:98–101.)).
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Pediatric pial arteriovenous shunts in the brain and spine are challenging to understand because of low incidence, variable presentation, and associations with genetic syndromes. What is known about their [[natural history]] comes from reviews of small series. To better understand the natural history and role of intervention, two cases are presented followed by a review of the literature. In the first case, an infant with a prior history of intracranial hemorrhage from a ruptured pial fistula returns for elective embolization for a second pial fistula which was found to be spontaneously thrombosed 2 weeks later. In the second case, a 5-year-old with a vertebra-vertebral fistula, identified on workup for a heart murmur and documented with diagnostic angiography, is brought for elective embolization 6 weeks later where spontaneous thrombosis is identified. In reviewing the literature on pediatric single-hole fistulae of the brain and spine, Chen et al. offer some morphologic considerations for identifying which high-flow fistulae may undergo spontaneous [[thrombosis]] to decrease the potentially unnecessary risk associated with interventions in small children
((Chen KS, Williams DD, Iacobas I, McClugage SG, Gadgil N, Kan P. Spontaneous thrombosis of high flow pediatric arteriovenous fistulae: Case series of two patients and a comprehensive literature review. Childs Nerv Syst. 2023 Dec 12. doi: 10.1007/s00381-023-06241-3. Epub ahead of print. PMID: 38085366.)).
====Epidemiology====
Intracranial pial AVFs are rare [[cerebrovascular lesion]]s, with less than 100 reported cases since 1970 to 2007
((Yamashita K, Ohe N, Yoshimura S, Iwama T. Intracranial pial arteriovenous fistula. Neurol Med Chir (Tokyo) 2007;47:550–554.)).


====Differential diagnosis====
They differ from [[brain arteriovenous malformation]]s in that they lack a true [[nidus]]. They differ from [[dural arteriovenous fistula]] in that they derive their arterial supply from [[pia]]l or [[cortical artery]] and are not located within the [[dura mater]].

====Complications====
[[De novo aneurysm]]

[[De novo dural arteriovenous fistula]]
===== Case reports =====

[[Intracranial pial arteriovenous fistula case reports]].