Intracranial pial arteriovenous fistula – surgical challenges and a review of a rare differential diagnosis

Background: Intracranial pial Arteriovenous Fistulas (AVF) are rare vascular (about 150 cases have been described) lesions that are composed of one or more arterial connections to a single venous channel without an intervening network of vessels. Because of the direct arteriovenous shunting, the attendant high blood flow usually predisposes to hemorrhage. Its vascular supply comes from cortical and pial vessels which are not located in the dura leaflets. They can be acquired traumatically, iatrogenic or can be congenital lesions. Due to its unfavorable natural course, the conservatory management is associated with a mortality rate up to 63%.

Methods: Systematic review of the literature were performed through Pubmed database considering all articles published in English language. Also a rare and illustrative case is described.

Results/Case Report: A 50-year-old female patient presented to emergency department with a sudden and explosive onset of a holocranial headache and left hemiparesia. She received analgesic medications and a proper investigation was performed initially through brain CT that disclosure a right frontal hemorrhage. More exams were required to elucidate her diagnosis. A brain MRI and angiography were performed and had shown a right frontal pial arteriovenous fistula. Vascular microsurgery was proposed and the fistula was completed excluded through clipping. The patency of the vessels were evaluated by the visualization of a normal flow after intravenous sodium fluorescein administration. Electrophysiological monitoring was performed as well as she was awake during fistula manipulation and clipping. The patient evolved without no further neurological sequelae.

Conclusions: Because of its high mortality index, despite being rare lesions, pial AVF must be considered as a differential diagnosis. Intraoperative resources such as the sodium fluorescein and intraoperative monitoring should be used to increase the therapeutic success preventing neurological complications and further surgeries.