Dural Arteriovenous Fistula Mimicking Fulminant Idiopathic Intracranial Hypertension

Clinical Correspondence Section Editors: Robert Avery, DO Karl C. Golnik, MD Caroline Froment, MD, PhD An-Guor Wang, MD Dural Arteriovenous Fistula Mimicking Fulminant Idiopathic Intracranial Hypertension Mohini Bindal, MS, Subahari Raviskanthan, MBBS, Peter W. Mortensen, MD, Tanu Garg, MD, Yi Jonathan Zhang, MD, Andrew G. Lee, MD I diopathic intracranial hypertension or primary pseudotumor cerebri syndrome (PTCS) is a common condition, seen typically in young, overweight females. Common predisposing risk factors for secondary PTCS include obstructive sleep apnea (OSA), hypercoagulable disorders, and venous sinus thromboses. We report a dural arteriovenous fistula (DAVF) that was unmasked by cerebrospinal fluid diversion procedures performed for fulminant “primary PTCS.” A 49-year-old man was referred to the neuro ophthalmology service for evaluation of a 6-month history of painless progressive vision loss. His past medical history was significant for previously left thalamic hemorrhagic stroke, obesity (body mass index 40.35 m/kg2), severe OSA, congestive heart failure, hyperlipidemia, and hypertension. His regular medications included lisinopril, carvedilol, nifedipine, minoxidil, furosemide, hydralazine, and atorvastatin. He reported no history of smoking, drinking, or illicit drug use. On initial neuro ophthalmic evaluation, he had hand motion vision in the right eye (right eye), and 20/100 vision in the left eye (left eye). His pupils were poorly reactive with relative afferent pupillary defect in the right eye. Slit-lamp biomicroscopy showed bilateral conjunctival injection and chemosis inferiorly. Intraocular pressures (IOP) were Baylor College of Medicine (MB), Houston, Texas; Department of Ophthalmology (SR, AGL), Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas; Department of Neurology (TG), Houston Methodist Neurological Institute, Houston, Texas; Departments of Ophthalmology, Neurology, and Neurosurgery (AGL), Weill Cornell Medicine, New York, New York; Department of Ophthalmology (AGL), University of Texas Medical Branch, Galveston, Texas; University of Texas Maryland Anderson Cancer Center (AGL), Houston, Texas; Texas A and M College of Medicine (AGL), Bryan, Texas; Department of Ophthalmology (AGL), The University of Iowa Hospitals and Clinics, Iowa City, Iowa; and Department of Neurosurgery (YJZ), Houston Methodist Hospital, Houston, Texas. The authors report no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the full text and PDF versions of this article on the journal’s Web site (www. jneuro-ophthalmology.com). Address correspondence to Andrew G. Lee, MD, Department of Ophthalmology, Blanton Eye Institute Houston Methodist Hospital, 6560 Fannin Street, Ste 450, Houston, TX 77030; E-mail: aglee@ houstonmethodist.org e542 17 mm Hg in the right eye and 29 mm Hg in the left eye. Dilated fundus examination showed atrophic papilledema, Frisen Grade IV right eye and Grade III left eye. His retinal veins were dilated and tortuous. Automated perimetry showed diffuse depression in both eyes. Optical coherence tomography (OCT) of the retinal nerve fiber layer (RNFL) showed an average thickness of 157 mm in the right eye and 289 mm in the left eye. He was admitted for further workup. Initial laboratory investigations revealed a hematocrit of 57.4% (normal: 38.3%–48.6%) and hemoglobin was 18.1 g/dL (normal: 13.5–17.5 g/dL). Other laboratory investigations were unremarkable. MRI and venogram of the brain and orbits showed an empty sella turcica and evidence of previous thalamic stroke. A lumbar puncture confirmed elevated opening pressure of 48 cmH2O (normal: , 20 cmH2O) with normal cerebrospinal fluid (CSF) content. Given the presence of atrophic papilledema and severe vision loss, the patient was commenced on intravenous acetazolamide. Intravenous steroids and lumbar drain were considered as temporizing measures, but were not performed as he underwent bilateral optic nerve sheath fenestration for severe vision loss with a presumed diagnosis of fulminant PTCS the next day. Ongoing visual symptoms and the severity of his vision loss led to ventriculoperitoneal shunt insertion 1 week later. Postoperative deterioration in his mental status led to repeat workup and computerized tomography (CT) venogram of the brain now showed superior sagittal sinus thrombosis. He was commenced on therapeutic anticoagulation with dabigatran. A hypercoagulable workup showed an elevated homocysteine level of 22.6 mmol/L (normal ,11.4 mmol/L), and homozygosity for the C677T variant of the methylenetetrahydrofolate reductase mutation. He had a mild secondary polycythemia in the setting of OSA. The patient presented to the hospital 3 months later with altered mental status. Neurological examination revealed fixed eye deviation to the left, and right upper extremity weakness. Initial stroke protocol CT brain and angiogram of the head and neck were unremarkable. Repeat MRI brain/venogram did not show any new abnormalities and showed resolution of the sagittal sinus thrombosis. Continuous electroencephalogram monitoring showed diffuse slowing of the background Bindal et al: J Neuro-Ophthalmol 2022; 42: e542-e544 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence with no epileptiform changes. Over the next month while in acute rehab he had ongoing progressive encephalopathy along with aphasia, left gaze preference and right hemiparesis. He was readmitted for workup. Repeat MRI brain showed diffuse pachymeningeal thickening, and scattered leptomeningeal enhancement in the supra and infratentorial brain, most prominent in the cerebellar folia and posterior cerebral hemispheres (Fig. 1A). A new sagittal sinus flow void was seen, concerning for thrombosis. Repeat lumbar puncture showed opening pressure 18cmH2O, with CSF protein 210 mg/dL (normal 15–45 mg/dL), glucose 72 mg/dL (normal 40–70 mg/dL). He underwent a diagnostic cerebral angiogram, which showed a Borden Type II DAVF. The DAVF was supplied by bilateral distal occipital arteries, and branches of the vertebral artery, middle meningeal arteries, and a right tentorial artery, and fed into the torcular and right transverse sinus (Fig. 1B). There was marked venous hypertension and retrograde reflux into the superior sagittal sinus and the straight sinus. He required multiple transarterial Onyx liquid embolization procedures for DAVF repair with some interval improvement in venous drainage. On his most recent follow-up his visual acuity was hand motions in the right eye and 20/70 in the left eye. The IOP were 11 mm Hg in the right eye and 14 mm Hg in the left eye. Repeat OCT showed average RNFL thickness of 149 mm in the right eye and 142 mm in the left eye. His most recent angiogram and embolization showed the DAVF now primarily draining from the occipital arteries into the torcular, and the right distal sigmoid sinus. The clinical presentation of DAVF is often dependent on the location and severity of the lesion—some patients may be asymptomatic, although common symptoms include headache and pulsatile tinnitus (1). Where there is elevated venous pressure, there may be secondary elevated intracranial pressure that can mimic primary PTCS (1). The previously reported cases of PTCS mimicked by DAVF are summarized in Supplemental Digital Content 1 (see Supplemental Table 1, http://links. lww.com/WNO/A539). This is a rare phenomenon, with only 21 cases reported in the literature previously, 13 of which were reported by Cognard in a single series (2). Of note in the cases reported in the literature, there are more male and older patients, which is not the typical phenotype for idiopathic PTCS patients. Three patients had adverse outcomes after CSF diverting procedures—2 patients had lumboperitoneal shunts inserted (leading to death and coma), and 1 patient developed an encephalopathy after lumbar puncture (2). The implications and altered management for DAVF-associated intracranial hypertension compared with idiopathic PTCS has led to some authors advocating for catheter angiogram in all cases of atypical PTCS, although this practice is not included in standard PTCS workup guidelines (2). Furthermore, all patients who had reported lumbar punctures had elevated opening pressures, making differentiation more challenging. Venous sinus thrombosis is another common cause of secondary PTCS. DAVFs may also be associated with venous thrombosis, with some literature suggesting that venous thrombosis can cause DAVFs, or that DAVF may be a risk factor for thrombosis formation (1). A retrospective review of 69 patients with DAVF showed that 39% also had venous sinus thrombosis (3). Our patient also had additional hypercoagulable risk factors including secondary polycythemia that predisposed him to thrombosis. The leptomeningeal enhancement similarly was likely a manifestation of venous congestion. Our patient presented with slowly progressive painless vision loss at presentation, but after the insertion of the VP shunt, had more rapid neurological deterioration. It is our hypothesis that his high intracranial pressure was partially tamponading the DAVF, and insertion of the VP shunt removed the tamponade, leading to progressive venous congestion, encephalopathy, and neurologic decline. The FIG. 1. A. MRI of the brain after gadolinium contrast administration showing multiple areas of leptomeningeal enhancement in the posterior hemispheres bilaterally (white arrow) most prominent in the cerebellar folia and diffuse pachymeningeal thickening (white triangle). B. Digital subtraction angiogram showing dural arteriovenous fistula from the bilateral occipital arteries draining into the sagittal sinus, torcula, and transverse sinus. Bindal et al: J Neuro-Ophthalmol 2022; 42: e542-e544 e543 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence initial findings of conjunctival injection, chemosis, and elevated intraocular pressure are atypical for primary PTCS, and suggest a secondary etiology, which was part of the reason for hospital admission and workup in our patient. On retrospective review, there were subtle findings noticeable on imaging performed in our patient 2 months after initial presentation, including venous collaterals in the scalp and cerebral convexities which slowly progressed over subsequent images to leptomeningeal enhancement (related to extensive venous collaterals). The initial imaging did not reveal any concerning findings despite the patient’s symptoms having progressed over the previous 6 months. To our knowledge this is the first case of a patient with DAVF and secondary PTCS who was managed with VP shunt insertion. Clinicians should be aware of alternate causes of PTCS such as DAVF in atypical populations, and that noninvasive imaging may not show abnormalities. e544 Patients with atypical presentations of papilledema should be evaluated for secondary causes of PTCS, including early catheter angiography if no improvement with first line treatment (medications) before more invasive methods such as ONSF and VPS. REFERENCES 1. Elhammady MS, Ambekar S, Heros RC. Epidemiology, clinical presentation, diagnostic evaluation, and prognosis of cerebral dural arteriovenous fistulas. In: Handbook of Clinical Neurology. Amsterdam: Elsevier B.V., 2017:99–105. 2. 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. 3. Tsai LK, Jeng JS, Liu HM, Wang HJ, Yip PK. Intracranial dural arteriovenous fistulas with or without cerebral sinus thrombosis: analysis of 69 patients. J Neurol Neurosurg Psychiatry. 2004;75:1639–1641. Bindal et al: J Neuro-Ophthalmol 2022; 42: e542-e544 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.