-Case Reports-

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

Pei-Ya Chen¹, Yu-Hsiu Juan^2,3 and Shinn-Kuang Lin^1,3

¹Stroke Center and Department of Neurology, Taipei Tzu Chi Hospital
²Department of Radiology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taiwan
³School of Medicine, Tzu Chi University, Hualien, Taiwan

Intracranial dural arteriovenous fistula (DAVF) with perimedullary venous drainage may cause brainstem swelling and represent a diagnostic challenge.
A 66-year-old man presented to the emergency room with recurrent vertigo, minimal truncal ataxia with a wide-based gait, and a slightly impaired tandem gait. Brain magnetic resonance imaging (MRI) revealed a hyperintense lesion in the left pontomedullary area on T2-weighted images (T2WIs) with partial gadolinium enhancement, but without increased signals on diffusion-weighted images. Abnormal serpentine flow void vessels surrounding the medulla and upper cervical spinal cord were initially overlooked but discovered later. An angiogram revealed DAVF with feeders from the right occipital artery and the meningeal branch of the right distal vertebral artery with drainage into the anterior medullary venous system and the perimedullary veins. The patient underwent a successful transarterial endovascular embolization and improved gradually. A brain MRI at 3-month follow-up revealed a residual hyperintense signal on the T2WIs in the left lower medulla. Six cases of patients exhibiting DAVF with isolated unilateral brainstem swelling from the literature were reviewed.
Isolated unilateral brainstem swelling due to intracranial DAVF with perimedullary venous drainage is extremely rare and might mimic a tumor on MRI. Abnormal serpentine flow void vessels on the surface of the brainstem or spinal cord are crucial diagnostic clues.

J Nippon Med Sch 2019; 86: 48-54

Keywords
brainstem swelling, dural arteriovenous fistula, perimedullary venous drainage, venous congestion

Correspondence to
Shinn-Kuang Lin, MD, Department of Neurology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, No. 289 Jian Guo Road, 231, Xindian district, New Taipei City 23142, Taiwan
stuartlin0428@gmail.com, sk2022@tzuchi.com.tw

Received, May 15, 2018
Accepted, September 21, 2018