Unilateral contrast-enhancing pontomedullary lesion due to an intracranial dural arteriovenous fistula with perimedullary spinal venous drainage: the exception that proves the rule

Abstract

Dural arteriovenous fistulas (DAVFs) are abnormal communications between dural arteries and dural venous sinuses, meningeal veins, or cortical veins. They account for 10%-15% of intracranial arteriovenous malformations.12,33 Grading of DAVF is based on the venous drainage pattern according to the classification schemes of Borden et al. and Cognard et al. 4,8 Venous cortical or perimedullary drainage and dilation are the hallmarks of high-grade DAVF and strongly correlate with increased risk of intracranial hemorrhage and nonhemorrhagic neurological deficit. The exact etiology of DAVFs is unknown. They are predominantly idiopathic, though they may also be congenital lesions or found in association with dural venous sinus thrombosis, trauma, previous craniotomy, and tumors. While spinal DAVF is an established cause of vascular myelopathy, intracranial DAVFs with perimedullary spinal venous drainage (Cognard Type V) are rare disorders and often represent a diagnostic and therapeutic challenge. They have been mainly described in case reports or small series that reported a typical clinical and radiological presentation of progressive myelopathy, central cord edema, and engorged perimedullary veins.Here, we report a case of an intracranial DAVF with exclusive perimedullary spinal venous drainage that presented initially with a very unusual MRI appearance suggestive of a right lateral brainstem neoplasm. After delayed diagnosis, the DAVF was completely occluded by transarterial embolization and the patient's symptoms gradually improved.abbreviatioNs DAVF = dural arteriovenous fistula; DSA = digital subtraction angiography; MRA = MR angiography. A large spectrum of possible diagnoses must be taken into consideration when a contrast-enhancing lesion of the pontomedullary region is found on MRI. Among these diagnoses are neoplastic, inflammatory, and infectious, as well as vascular pathologies. The authors report a rare case of an intracranial dural arteriovenous fistula (DAVF) with perimedullary spinal venous drainage (Cognard Type V) that initially presented as a unilateral contrast-enhancing pontomedullary lesion mimicking a brainstem neoplasm in a 76-year-old man. Following occlusion of the DAVF by transarterial embolization that resulted in clinical and radiological improvement, the fistula recurred 10 months later and was finally cured by a combined endovascular and surgical approach that resulted in complete occlusion. Clinical symptoms and MRI findings gradually improved following this treatment. A literature review on the MRI findings of Cognard Type V DAVF was performed. Centrally located medullary or pontomedullary edema represents the typical imaging finding, while unilateral edema as seen in the authors' patient is exceptionally rare. The hallmark imaging finding suggestive of DAVF consisting of perimedullary engorged vessels may not always be present or may only be very subtly visible. Therefore, the authors suggest performing contrast-enhanced MR angiography or even digital subtraction angiography in the ...

Cognard Type V intracranial dural arteriovenous fistula presenting in a pediatric patient with rapid, progressive myelopathy

“…5 The presentation and symptoms are often mistaken for other diagnoses, such as spinal stenosis, infarct, tumor, Guillain-Barré syndrome, or multiple sclerosis, although improved access to MRI and angiography have allowed for better detection and management. Roelz et al 9 recently reviewed MRI findings in 58 patients who presented with a Type V dAVF. Seventy-three percent of patients had central medullary edema on MRI, and 76% had T2 flow voids typical of engorged perimedullary veins.…”

Dural Arteriovenous Fistulas: A Characteristic Pattern of Edema and Enhancement of the Medulla on MRI

“…4 With contrast-enhanced imaging, the detection rate of atypical perimedullary vessels increases to 76% but is often subtle. 5 Use of MRA increases the detection rate to 85%. 5 Four of our 5 patients (80%) retrospectively demonstrated atypical perimedullary vessels or flow voids on initial MR imaging, subtle in some instances.…”

“…Ultimately, improper management and, in some reported instances, biopsy for a suspected neoplasm may occur. 5 We report a series of 5 patients who presented at 2 nearby academic institutions from 2012 to 2016 with DAVFs demonstrating medullary edema and enhancement at initial imaging. Most interesting, the unique pattern of edema was nearly identical in all 5 cases and, retrospectively, has been anecdotally mentioned previously.…”

“…Most interesting, the unique pattern of edema was nearly identical in all 5 cases and, retrospectively, has been anecdotally mentioned previously. [5][6][7] All 5 patients underwent CT and MR imaging examinations, and 2 patients underwent MR spectroscopy/perfusion because there was concern for a neoplasm. All patients eventually underwent conventional angiography.…”

An Isolated Unilateral Pontomedullary Lesion Due to An Intracranial Dural Arteriovenous Fistula Mimicking A Brain Tumor - Case and Review

“…The laboratory studies revealed a slightly elevated fast- A carotid and transcranial duplex sonographic study 8,13 . Including the patients mentioned here, only 6 patients with an isolated unilateral brainstem lesion due to DAVF have been reported in studies in the English language literature 6,8,13,14,16 . A summary of these 6 cases is presented in Table 1.…”