Endovascular treatment of vein of Galen dural arteriovenous fistula presenting as dementia.

Dural arteriovenous fistula (DAVF) is an important cause of neurological dysfunction that is often misdiagnosed, especially in elderly population. Galenic DAVFs are a subtype of the rare falcotentorial DAVFs with a high risk of hemorrhage and aggressive clinical course. In most cases, DAVFs present with pulsatile tinnitus, headache, or orbital symptoms such as chemosis and proptosis. We report a patient with DAVF of Vein of Galen presented with progressive dementia, treated by Onyx embolisation and had good clinical outcome.

Introduction

Dural arteriovenous fistula (DAVF) as a cause of reversible dementia is quite uncommon, more so is acquired DAVF of the vein of Galen (Galenic DAVF). The treatment of acquired Galenic DAVF is a therapeutic challenge and often requires multimodality treatment. In our case, it was possible to achieve complete cure with good clinical outcome by endovascular embolization alone.

Case Report

A 35-year-old male presented with a history of gradually progressive behavioral abnormality and anterograde memory loss since 1 year, one episode of right-sided partial seizure, and worsening of sensorium since 1 month. On examination, he was confused and irritable, with bilateral papilledema and no lateralizing signs. Neuropsychological assessment was initiated revealing severe difficulty in sustained attention and working memory. Hence, detailed neuropsychological assessment could not be conducted. His MMSE score was 15/30. Imaging study (CT) was suggestive of diffuse cerebral edema and dilation of the vein of Galen [Figure 1]. He was started on anti-epileptics and anti-edemal measures.

Figure 1

Computed tomography (CT) Brain Plain shows prominent Vein of Galen (VOG) with mild diffuse cerebral edema

Cerebral angiogram showed acquired high flow Vein of Galen DAVF [Figures 2a–b and 3] with multiple feeders from the middle meningeal artery, occipital arteries, meningohypophyseal arteries, and pial-dural supply from the branches of the posterior cerebral arteries. The fistula drained into Straight sinus. There was a reflux into the deep venous system. Right tranverse – sigmoid sinus was occluded, and there was a narrowing of the left transverse sigmoid sinus.

Figure 2

(a) External carotid artery (ECA) angiogram (early and late phase) shows Vein of Galen Dural Arteriovenous Fistula (Galenic DAVF) (b) Pre-embolization ECA angiogram in Townes View

Figure 3

Internal carotid artery (ICA) angiogram shows venous congestion without opacification of VOG and straight sinus even in late venous phase

Other investigations including thyroid function tests, vitamin B12 levels, serology for HIV and syphilis, and work up for common hypercoagulable states were negative.

The DAVF was treated over two sessions. In the first session, bilateral femoral access was obtained and 6F guiding catheters were negotiated into bilateral external carotid artery. Marathon microcatheter was negotiated over mirage wire into the right middle meningeal artery. Hyperglide 4 × 20 was negotiated into the left middle meningeal artery for regulating the arterial flow into the fistula. After confirming microcatheter position, embolization was performed using Onyx 34 and 18. Post embolization, an angiogram showed significant reduction in the flow of DAVF.

Second session was done performed after 1 month. Bilateral femoral access was obtained and 6F guiding catheter was negotiated into left external carotid artery. Marathon microcatheter was negotiated over traxcess wire into left middle meningeal artery. Using Onyx 34 (3 vials) and 18 (1 vial) embolization was done.

The procedure was uneventful, and post procedure angiogram showed complete resolution of the fistula along with anterograde flow in Vein of Galen [Figures 4a–b, 5a–c and 6].

Figure 4

(a) Post-Second session embolization ECA angiogram shows complete occlusion of fistula (b) Post-embolization ECA angiogram in Townes View

Figure 5

(a) Onyx cast after second session of embolization. The center hole in the cast is the patent VOG (b) Onyx cast post embolization lateral view (c) Onyx cast post embolization townes view

Figure 6

Post-second session of embolization ICA angiogram shows anterograde flow in VOG

The patient was extubated after the procedure and showed no worsening of symptoms. His encephalopathy gradually improved over few days. At discharge, he was conscious and coherent, and had no focal neurologic deficit.

There is no recurrence of symptoms on subsequent follow up at 3 months, 6 months, and 12 months, and he can independently perform activities of daily living. A repeat Mini Mental status examination showed a score of 30 at 3 months. His Neuropsychological assessment revealed adequate attention, working memory, planning, response inhibition, and set shifting ability. His performance on verbal and visual learning and memory was also found to be in the adequate range. There was no evidence of finger agnosia, color agnosia, constructional apraxia, agraphia, acalculia, and left-right disorientation. Follow up control angiogram at 1 year showed persistent obliteration of the fistula [Figure 7].

Figure 7

ECA angiogram (after 1 year) shows persistent occlusion of fistula

Discussion

DAVFs are acquired lesions from the cerebral arterial vasculature to dural sinuses.[1] They represent 10–15% of cerebrovascular malformations, and most commonly develop in the region of the transverse and sigmoid sinuses.[2] It is postulated that the lesions occur due to increased pressure within the dural sinuses, most commonly caused by sinus thrombosis.[2345] Symptoms generally do not develop unless there is increased venous sinus pressure from an increased volume via the DAVF or from sinus obstruction.[4] Variable degree of venous hypertension results in sequelae ranging from mild reversible symptoms to fatal intracranial hemorrhage.[1456] The common presenting symptoms of DAVFs range in severity from simple pulsatile tinnitus and focal neurological deficits to acute intracranial hemorrhage. Rarely, patients with DAVF present with progressive dementia due to venous hypertensive encephalopathy; this cognitive impairment has the potential for complete resolution following treatment of the fistula. Cases of cognitive decline with more insidious onset, as in our case, have been reported.[14567] Dural AVFs may also mimic well-known cognitive disorders such as Parkinson's disease[1] and normal-pressure hydrocephalus.[5] We should perform cerebral angiogram if CT or MRI is showing abnormal tortuous blood vessels or dilated veins.

Galenic DAVFs are a subtype of the relatively rare, falcotentorial DAVFs[8] and have a high risk of hemorrhage.[9]

Endovascular approaches are generally recommended as the initial treatment in most DAVFs.[5] Depending on the anatomy, a transarterial, transvenous, combined transarterial/transvenous, or transorbital approach can be used to cure a DAVF.[10111213] Multiple embolization agents can be used; however, liquid embolization agents and coils are primarily used.[14] These techniques have been shown to eliminate the symptoms as well as offer an anatomic cure,[5] as in our case. If the patient continues to experience symptoms, a combined endovascular and neurosurgical approach is recommended to obliterate any remaining fistula.[15]

The present patient has the Galenic DAVF with main feeders being the middle meningeal artery and occipital artery. Subsequent embolization with Onyx completely obliterated the fistula, with very good preservation of the vein of Galen, as shown in the post treatment Onyx cast pictures. The preservation of vein of Galen is not possible if we perform transvenous coiling. The post procedure ICA angiogram showed a good anterograde flow in the deep venous system. No recurrence of symptoms has occurred after 6 months and 1 year of follow up. Detailed Neuropsychological evaluation was also suggestive of complete recovery of cognitive deficits.

Treatment of Galenic DAVFs is more challenging and endovascular approach cannot obliterate it completely. Hence, it may require microsurgical or radiosurgical fistula interruption.[1617]

Steven De Vleeschouwer et al.[16] reported a case of Galenic DAVF in which a session of embolization of the falcotentorial feeding vessels followed by additional surgical transsection of the remaining tentorial arterial feeders failed to exclude the Galenic DAVF.

Shin M et al. described two cases of DAVF draining into the vein of Galen which were successfully treated by gamma knife radiosurgery.[17]

John B. Weigele et al.[18] described a case of Galenic DAVF, in which the clinical and imaging findings were suggestive of brainstem glioma, successful endovascular treatment led to clinical recovery in the patient.

Our case indicates acquired Galenic DAVF as an uncommon cause of reversible dementia and shows that it can be completely cured by careful endovascular embolization alone, with preservation of the lumen of vein of Galen and anterograde flow in the deep venous system.