Case Report
Infratentorial Pial Arteriovenous Fistula in the Elderly Ryuichi Kanai, MD, PhD,* Jun Shinoda, MD, PhD,* and Seiya Akatsuka, MD, PhD†
Background: Intracranial pial arteriovenous fistulas (pAVFs) are rare vascular lesions, which may present with, but are distinct from arteriovenous malformation and dural arteriovenous fistula. They most often manifest during infancy or early childhood, but rarely in adulthood. Methods: We report an exceptionally rare case of infratentorial pAVF in a 73-year-old man, who presented with progressive gait disturbance due to cerebellar edema resulting from arteriovenous shunts. Results: The patient was successfully treated by endovascular flow reduction followed by surgical extirpation of the fistula. The diagnosis was confirmed by pathological findings. Conclusions: Pial arteriovenous fistula is rare, but can occur in the elderly. Combination of endovascular flow reduction and surgical disconnection yielded an excellent clinical outcome. Key Words: Pial arteriovenous fistula—infratentorial arteriovenous fistula—elderly patients—suboccipital transtentorial approach—coil embolization. Ó 2015 by National Stroke Association
Intracranial pial arteriovenous fistulas (pAVFs) are rare, accounting for only 1.6%-4.7% of all intracranial arteriovenous malformations.1,2 Most pAVFs manifest in children, but rarely in the elderly.3
Case Report A 73-year-old man was admitted to our hospital because of progressive gait disturbance of 3-month duration. He had no history of coagulopathy, head trauma, or congenital diseases such as hereditary hemorrhagic telangiectasia. Head computed tomography disclosed diffuse hypodense areas in the right cerebellum, where abnormally dilated vessels were delineated by contrast admin-
From the *Department of Neurosurgery; and †Department of Pathology, Eiju General Hospital, Higashi-Ueno, Taito-ku, Tokyo, Japan. Received April 21, 2015; revision received June 22, 2015; accepted July 9, 2015. Address correspondence to Ryuichi Kanai, MD, PhD, Department of Neurosurgery, Eiju General Hospital, 2-23-16 Higashi-Ueno, Taito-ku, Tokyo 110-8645, Japan. E-mail:
[email protected]. 1052-3057/$ - see front matter Ó 2015 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2015.07.003
istration (Fig 1, A). On magnetic resonance imaging, multiple low-intensity dots were noted on T2* images, suggesting edema with hemorrhages. Angiography revealed an infratentorial arteriovenous shunt beneath the straight sinus, which was fed by branches from left superior cerebellar artery, and refluxed to superficial cerebellar veins (Fig 1, B). We performed endovascular flow reduction, and surgical obliteration of the fistula. After the main feeding branch of left superior cerebellar artery was embolized with coils (Fig 1, C,D), the lesion was surgically extirpated via left occipital transtentorial approach. The fistula located on the superior aspect of vermis was meticulously inspected and excised so as not to compromise normal blood flow. Pathological examinations confirmed the diagnosis (Fig 1, E). The patient regained normal daily living and has been followed for 3 years.
Discussion To our knowledge, this is the only case of an elderly man presenting with a symptomatic infratentorial pAVF. The preferred treatment of pAVF is interruption of feeding vessels as close to the fistula as possible, while leaving the venous drainage intact.1,4 Endovascular
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Figure 1. Radiological and pathological findings in Case 1. (A) Contrast-enhanced CT on admission. Note dilated tortuous vessels in the right cerebellum. (B) Right vertebral angiogram (late arterial phase). Left: A-P view. Right: lateral view. Note early filling of venous structure on the midline of cerebellum (arrowheads) and dilated superficial veins on the right cerebeller hemisphere (arrows). (C) Superselective angiogram of the main feeder from left SCA, before coil occlusion. Left: A-P view. Right: lateral view. Arrows indicate the shunting point. (D) Right vertebral angiogram after coil occlusion of the main feeder. The AV shunt is still patent. (E) Left and middle: histopathological examination with Elastica van Gieson staining shows that the arterial structure, typified by the presence of internal and external elastic laminas (arrows), is lost in venous side (V) of the specimen. Scale bars left: 500 mm, middle: 200 mm. Right: histopathological examination with Masson’s trichrome staining shows smooth muscle layer in arterial walls, but it is absent in venous side (V) of the specimen. Scale bar 200 mm. Abbreviations: A-P, anteroposterior; AV, arteriovenous; CT, computed tomography; SCA, superior cerebellar artery.
occlusion can provide less invasive treatment,3,5 but high tortuosity and small caliber of affected vessels sometimes limit its feasibility. On the other hand, open surgery may provide more complete therapy, when the fistulas are superficially located.6 In our case, the pAVF was symptomatic, accompanied by previous parenchymal hemorrhages. We chose surgery after endovascular flow reduction, which resulted in an excellent outcome. It is cardinal to preserve normal venous drainage, which is often obscured by engorgement with high-flow AV fistulas. pAVFs are frequently associated with genetic disorders such as Rendu–Osler–Weber syndrome.7 However, they can be acquired, manifesting after venous thrombosis, trauma, or iatrogenic events.8-10 Complicatedly, there
have been reports of pAVF associated with arteriovenous malformation or dural AVF, which may make the accurate diagnosis more difficult. Nevertheless, it is important to differentiate between dural and pAVF and recognize their precise angioarchitecture, because the therapeutic goal of these vascular diseases can be different.3
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PIAL AVF IN THE ELDERLY 3. Wang YC, Wong HF, Yeh YS. Intracranial pial arteriovenous fistulas with single-vein drainage. Report of three cases and review of the literature. J Neurosurg 2004; 100:201-205. 4. Hoh BL, Putman CM, Budzik RF, et al. Surgical and endovascular flow disconnection of intracranial pial singlechannel arteriovenous fistulae. Neurosurgery 2001; 49:1351-1363. discussion 63-4. 5. Lv X, Li Y, Jiang C, et al. Endovascular treatment of brain arteriovenous fistulas. AJNR Am J Neuroradiol 2009; 30:851-856. 6. Yang WH, Lu MS, Cheng YK, et al. Pial arteriovenous fistula: a review of literature. Br J Neurosurg 2011; 25:580-585.
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