Venous Hypertension as the Cause of Intracranial Hypertension in Patients With Transverse Sinus Dural Arteriovenous Fistula

We describe 2 patients with transverse sinus dural arteriovenous fistulas (DAVFs) who presented with headache and papilledema due to intracranial hypertension. It has been proposed, but never proven, that venous hypertension causes the intracranial hypertension in DAVF. The data from our patients support this hypothesis. An additional factor leading to intracranial hypertension could be stenosis of the fellow transverse sinus.

Venous Hypertension as the Cause of Intracranial Hypertension in Patients With Transverse Sinus Dural Arteriovenous Fistula Rebekah M. Ahmed, MBBS(Hons), FRACP, Bryan Khoury, MBBCh, FRANZCR, Mark Wilkinson, MBChB, FRANZCR, Geoffrey D. Parker, MBBS, FRANZCR, G. Michael Halmagyi, MD, FRACP Abstract: We describe 2 patients with transverse sinus dural arteriovenous fistulas (DAVFs) who presented with headache and papilledema due to intracranial hypertension. It has been proposed, but never proven, that venous hypertension causes the intracranial hypertension in DAVF. The data from our patients support this hypothesis. An additional factor leading to intracranial hypertension could be stenosis of the fellow transverse sinus. Journal of Neuro-Ophthalmology 2013;33:102-105 doi: 10.1097/WNO.0b013e318250575b © 2012 by North American Neuro-Ophthalmology Society Dural arteriovenous fistula (DAVF) of one transverse sinus can cause intracranial hypertension with papil-ledema but without ventriculomegaly, simulating idiopathic intracranial hypertension and leading to vision loss (1-5). Cerebral venous sinus hypertension leading to decreased cerebrospinal fluid (CSF) absorption has been proposed (3-6), although never been proven to be the mechanism. We report 2 patients with intracranial hypertension and DAVFs of one transverse sinus, in whom intracranial hypertension resolved after embolization of the DAVF. We found that in addition to the DAVF of one transverse sinus, there was a stenosis of the fellow transverse sinus. We propose that in these patients the lack of even one func-tioning transverse sinus allowed intracranial hypertension to develop (7). CASE REPORTS Case 1 A 51-year-old man presented with a 4-month history of left pulsatile tinnitus. He had an easily palpable left occipital artery, a bruit over the left mastoid, and moderately severe, bilateral papilledema. Visual acuity was 20/20 in each eye, and visual fields demonstrated enlarged blind spots without peripheral field constriction. MRA and magnetic resonance venogram (MRV) with auto-triggered elliptic centric or-dered (ATECO) sequences (8) (Fig. 1A) showed occlusion of the left transverse and sigmoid sinuses, with an associated DAVF; the occipital artery was dilated and there was subtle cortical venous reflux (Cognard grade IIB) (9). Arteriogra-phy (Fig. 1B) confirmed a DAVF of the left transverse sinus with arterial supply from a large transmastoid occipital branch of the external carotid artery, the left middle men-ingeal artery, the left internal carotid artery via the meningo-hypophyseal trunk, and from both vertebral arteries via suboccipital branches. The left superior sigmoid sinus was severely attenuated with multiple venous chan-nels, suggesting previous thrombosis. Venous sinus pressure measurements were recorded before and after embolization (Table 1). The patient underwent 2 arterial embolization procedures with Onyx. After the second, a left carotid arteriogram dem-onstrated no reflux in to cortical veins (Cognard grade IIA). Five months after embolization, the patient still had papilledema but no longer had tinnitus. Lumbar puncture showed an opening pressure of 350 mm H20 with normal CSF contents. Arteriography showed no change in the DAVF. Venography demonstrated that the left transverse sinus was occluded, and there was a swollen arachnoid gran-ulation in the right transverse sinus impairing venous flow Departments of Neurology (RMA, GMH) and Radiology (BK, MW, GDP), Royal Prince Alfred Hospital, Camperdown, Sydney, Australia. The authors report no conflict of interest. Address correspondence to Rebekah M. Ahmed, Department of Neu-rology, Royal Prince Alfred Hospital, Missenden Road, Camperdown, Sydney, NSW, Australia 2050; E-mail:[e-mail] 102 Ahmed et al: J Neuro-Ophthalmol 2013; 33: 102-105 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. (pressure gradient: 25 mm Hg). Anterior sagittal sinus pres-sure was elevated at 54 mm Hg. Six months after arterial embolization, the DAVF was embolized via the right transverse sinus, with 11 hydrocoils placed in the stump of the left transverse sinus (Fig. 1C). Superior sagittal sinus and torcular pressure decreased to 29 mm Hg, and the pressure gradient across the arachnoid granulation of the right transverse sinus decreased to 5 mm Hg. The patient's papilledema resolved. The most recent venogram documented that venous sinus pressure remained stable with a superior sagittal sinus pressure of 27 mm Hg and a pressure gradient across the right transverse sinus of 7 mm Hg (Table 1). The patient remains well without headache or papilledema. Case 2 An 85-year-old woman with a long history of left pulsatile tinnitus was found to have papilledema. Her visual acuity was 20/30 in each eye, and visual fields showed enlarged blind spots but no peripheral constriction. MRV disclosed a DAVF draining into the left transverse sinus and distal occlusion of the left sigmoid sinus, with no filling of the left internal jugular vein. Arteriography (Fig. 2A) demonstrated a DAVF involving the left transverse sinus with no cortical reflux, and drainage across the torcular into the right transverse sinus and right internal jugular vein (Cognard grade IIA). Arterial supply was predominantly via the left occipital and middle meningeal branches, with lesser supply via suboccipital and posterior FIG. 1. Case 1. A, MRA with ATECO sequences (8) shows extensive, arterialized flow into a very irregular transverse/sigmoid sinus (long arrow) by a dural arteriovenous fistulous channel; left occipital artery (arrowhead); left internal carotid artery (small arrow). B, Late arterial phase from left external carotid artery injection shows extensive dural arteriovenous fistulous channels (black arrow) entering the left transverse/sigmoid sinus with rapid retrograde flow across the torcular into the right transverse/sigmoid sinus (white arrow). The distal left sigmoid sinus is markedly narrowed, with prominent flow into the left vertebral venous plexus (arrowheads). C, Onyx cast within the left transverse/sigmoid sinus and dural channels (white arrow) and coils within the proximal left transverse sinus (black arrow). TABLE 1. Venous Sinus Pressures Recorded Before and After Embolization of DAVF of Transverse Sinus Case 1 Case 2 Pre-embolization Post-embolization Pre-embolization Post-embolization 1 Month 9 Months Immediate 4 Months ASSS 53 29 27 38 21 16 MSSS 54 29 27 41 21 16 PSSS 54 29 26 42 21 15 Torcular 52 29 24 40 21 15 PTS 52 28 22 43* 21 14 Mid TS 47* 27* 22* 21 12 ATS 42 22* 15 15* 21 11 Sup. sig. sinus 22* 21 15* 19 12 9 Inf. sig. sinus 19 21 14 15 12 9 Jugular bulb 19 21 11 14 12 8 Internal jugular 18 22 9 11 11 7 Right atrium 17 17 7 9 9 6 All pressure measurements are expressed in millimeters of mercury. *Gradient across stenosis. ASSS, anterior superior sagittal sinus; ATS, anterior transverse sinus; MSSS, mid-superior sagittal sinus; PSSS, posterior superior sagittal sinus; PTS, posterior transverse sinus; sup. sig. sinus, superior sigmoid sinus; inf. sig. sinus, inferior sigmoid sinus. Ahmed et al: J Neuro-Ophthalmol 2013; 33: 102-105 103 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. meningeal branches of the vertebral arteries and meningo-hypophyseal tentorial branches. There was no drainage into the left sigmoid sinus or left jugular vein. Venography dem-onstrated a narrowing of the right transverse sinus together with rapid inflow of unopacified blood via the fistula. The narrowing was felt to be due to a combination of swelling of an arachnoid granulation and elevated intracranial pressure. Superior sagittal sinus pressure measured 41 mm Hg (Fig. 2B, 2C; Table 1), with an abrupt drop to 15 mm Hg across the narrowed segment of the right transverse sinus (Fig. 2C). The DAVF was embolized with Onyx via a transarterial approach. Superior sagittal sinus pressure decreased to 21 mm Hg, and the pressure gradient across the stenosis in the right transverse sinus resolved (Table 1). The patient developed a small intracerebral occipital hemorrhage but made a full recovery. Papilledema and pulsatile tinnitus resolved. Four months later, venography showed normal venous sinus pressures (Table 1) and narrowing of the right trans-verse sinus had improved (Fig. 2D). DISCUSSION It has been proposed that intracranial hypertension in the setting of a transverse sinus DAVF is the result of a decreased FIG. 2. Case 2. A, Arteriogram demonstrates left transverse sinus dural arteriovenous fistula. B, Venogram shows high venous pressure throughout the venous sinuses before embolization and narrowing of the right transverse sinus (arrows). C, Manometry of the venous sinuses reveals a pressure gradient of 28 mm Hg (arrow) across stenosis of the right transverse sinus. D, Four months after embolization, venogram shows normal venous pressures throughout the sinuses and less narrowing of the right transverse sinus. ASSS, anterior superior sagittal sinus; ATS, anterior transverse sinus; MSSS, mid-superior sagittal sinus; PSSS, posterior superior sagittal sinus; PTS, posterior transverse sinus; RA, right atrium; RIJV, right inferior jugular vein; R. Inf. Sig., right inferior sigmoid sinus; R. Sup. Sig., right superior sigmoid sinus. 104 Ahmed et al: J Neuro-Ophthalmol 2013; 33: 102-105 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. CSF absorption secondary to venous hypertension (3,4,10). Our 2 cases support this concept. In our first patient, after embolization, venous pressure remained mildly elevated due to the ongoing arterial supply to the DAVF and narrowing of the right transverse sinus. Yet, treatment was sufficient to resolve the patient's tinnitus and papilledema. In our second patient, embolization not only terminated flow in the DAVF but also lessened stenosis in the contralateral transverse sinus. Again, the patient's symptoms resolved as did the papilledema and the venous hypertension. It has been shown that the lack of even one functioning transverse sinus may lead to venous hypertension and intracranial hypertension (7,11). We propose that this also might be true in transverse sinus DAVFs causing intracra-nial hypertension, given the findings in our 2 patients. Adding to the increase in venous pressures was the flow of arterialized blood into the transverse sinuses, leading to further venous hypertension and intracranial hypertension through decreased CSF absorption at the arachnoid villi. By embolizing the DAVFs, the venous hypertension improved, as did the intracranial hypertension and papilledema. We propose that if a patient has a DAVF of one trans-verse sinus and the other transverse sinus is functioning, significant venous hypertension and subsequent intracranial hypertension will not develop. Cognard et al (3) in their review of DAVFs leading to intracranial hypertension reported that only 4 of 13 patients had normal venous sinuses. However, the authors did not look for stenosis of the contralateral sinus nor obtain pressure gradient meas-urements. It was reported that all patients had abnormal cerebral venous flow. DAVFs with reflux into cortical veins (Cognard type IIB) pose great risk for hemorrhage and focal neurological damage (5). We believe that a DAVF with anterograde flow (Cognard type I) and reflux into the affected sinus (Cognard type IIA) are also not "benign" and may cause venous hypertension with papilledema and potential vision loss. Patients having arteriography for investigation of DAVFs should be considered for venography and manometry. In patients where venous hypertension is identified, especially in the setting of only one functioning transverse sinus, a full ophthalmic evaluation should be performed, including visual acuity, visual fields, and funduscopy. Embolization should be considered if there is any indication of risk of visual loss. ACKNOWLEDGMENT Dr Steve Reddel referred the second patient. REFERENCES 1. Johnston I, Hawke S, Halmagyi GM, Teo C. The pseudotumor syndrome. Disorders of cerebrospinal fluid circulation causing intracranial hypertension without ventriculomegaly. Arch Neurol. 1991;48:740-747. 2. Cockerell OC, Lai HM, Ross-Russell RW. Pseudotumour cerebri associated with arteriovenous malformations. Postgrad Med J. 1993;69:637-640. 3. Cognard C, Casasco A, Toevi M, Houdart E, Chiras J, Merland JJ. Dural arteriovenous fistulas as a cause of intracranial hypertension due to impairment of cranial venous outflow. J Neurol Neurosurg Psychiatry. 1998;65:308-316. 4. 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