Dural Arteriovenous Fistula Associated With a Vestibular Tumor: An Unusual Case and Review of the Literature

Abstract

Intracranial dural arteriovenous fistulae (DAVF) are rare vascular malformations. They are generally considered to be acquired lesions, often attributed to dural sinus thrombosis and intracranial venous hypertension. The authors encountered a case of DAVF associated with an octreotide-positive vestibular schwannoma. A 46-year-old female had symptoms of right ear congestion accompanied by pulsatile tinnitus and mild hearing loss. Magnetic resonance imaging (MRI) identified a lobulated mass centered at the cerebellopontine angle. Preoperatively, on cerebral angiography, there was an incidental discovery of a DAVF in the right posterior fossa. The decision was made to proceed with resection of the tumor in a staged fashion. Her latest follow-up MRI showed no evidence of recurrent tumor. This is the second reported case of DAVF associated with an intracranial schwannoma. Findings are discussed along with a thorough review of the literature. This case, combined with the data from the literature review, led us to believe that tumor-related angiogenesis might contribute to DAVF formation.

Keywords: angiogenesis; dural arteriovenous fistula; intracranial tumor; octreotide scintigraphy; somatostatin receptor; vestibular schwannoma.

Figure 1. Magnetic resonance imaging and Octreoscan

T1-weighted post-contrast MRI (magnetic resonance imaging) (A) demonstrates the avidly enhancing large right skull base mass centered at the jugular foramen, involving the right carotid space inferiorly and the right hypoglossal canal. 24-hour In-111 Pentetreotide SPECT-CT (single-photon emission computed tomography) fused images (B) demonstrates intense uptake in the mass. Initial post-operative T1-weighted post-contrast MRI (C) demonstrates expected post-surgical changes related to the skull base mass resection with no residual enhancing tumor. Follow-up MRI (D) four years later demonstrates stable post-operative changes with no residual mass. Tiny focus of enhancement beneath the tentorium likely reflected residual DAVF (dural arteriovenous fistula) (red arrow).

Figure 2. Digital subtraction angiography

Initial cerebral angiogram planned for pre-operative embolization of the suspected paraganglioma did not demonstrate significant tumor vascularity. Incidentally, a dural arteriovenous fistula was seen predominantly supplied by the right AICA (anterior inferior cerebellar artery) on right vertebral artery injection (A). The right AICA is irregular with mild fusiform dilatation (yellow arrow). Microcatheter injection in the right SCA (superior cerebellar artery) (B) demonstrates a smaller component of the fistula not well seen on the right vertebral artery injection due to rapid shunting into the AICA. Additional very small arterial feeders were identified from branches of the right MMA (middle meningeal artery). There was cortical venous drainage (blue arrow) along the right cerebellar hemisphere to the right transverse sinus (red arrow), which then drained in retrograde fashion across the torcula and into the left transverse and sigmoid sinuses. Following embolization using Onyx in the right AICA and SCA DAVF (dural arteriovenous fistula) feeders, left vertebral artery DSA (digital subtraction angiogram) injection (C) demonstrates significant reduction in arteriovenous shunting. Again, there was no appreciable vascularity in the skull base mass. Right CCA (common carotid artery) injection (D) following embolization did not reveal additional feeders to the DAVF or mass. Follow-up DSA four years after initial embolization. Right CCA injection (E) reveals recurrence of the DAVF with new prominent feeders from the right MMA (blue arrow) and occipital (red arrow) arteries. Following embolization using Onyx in the right MMA feeder, right CCA injection in the late arterial phase (F) demonstrates resolution in shunting through the right CCA. (G) Right vertebral artery injection on the most recent DSA following MMA embolization demonstrates mild residual shunting similar to prior. There has been interval resolution of the dysplastic proximal right AICA.

Figure 3. Photomicrograph

Hematoxylin and eosin stained sections showed a biphasic tumor composed of spindle-shaped cells arranged in compact interlacing fascicles with areas of denser cellularity alternating with more loosely arranged cells, consistent with a schwannoma. Tumor cells were immune-positive for S100 (not shown). Areas of collagen deposition, ancient-type changes and lymphocytic perivascular infiltrates were also present (200x magnification).