Foramen magnum dural arteriovenous fistula presenting with epilepsy

Abstract

Intracranial dural arteriovenous fistulas (dAVFs) with perimedullary drainage represent a rare subtype of intracranial dAVF. Patients usually experience slowly progressive ascending myelopathy and/or lower brainstem signs. We present a case of foramen magnum dural arteriovenous fistula with an atypical clinical presentation. The patient initially presented with a generalised tonic-clonic seizure and no signs of myelopathy, followed one month later by rapidly progressive tetraplegia and respiratory insufficiency. The venous drainage of the fistula was directed both to the left temporal lobe and to the perimedullary veins (type III + V), causing venous congestion and oedema in these areas and explaining this unusual combination of symptoms. Rotational angiography and overlays with magnetic resonance imaging volumes were helpful in delineating the complex anatomy of the fistula. After endovascular embolisation, there was complete remission of venous congestion on imaging and significant clinical improvement. To our knowledge, this is the first report of a craniocervical junction fistula presenting with epilepsy.

Keywords: Dural arteriovenous fistula; epilepsy; myelopathy; perimedullary drainage.

Figure 1.

Pre- and post-treatment MRI. (a,b,d,e) Initial cerebral and cervical MRI. Midline cerebral sagittal T1 sequence (a) after injection of contrast, showing an abnormally dilated vein posterior to the medulla oblongata (arrow) as well as dilated and tortuous anterior and posterior spinal veins (arrow head). Cervical sagittal T2 (b) sequence showing a hyperintense central cord lesion extending from the medulla oblongata to C7, in keeping with venous oedema. Cerebral post-contrast sagittal T1 sequence (d) and axial FLAIR sequence (e) showing a dilated vein at the junction of tentorium with the superior petrosal sinus (arrow), coursing across the inferior temporal sulci (arrow head), with a surrounding area of high FLAIR signal. (c,f) Cerebral and cervical MRI 13 days after embolisation. Cervical sagittal T2 sequence (c) and cerebral axial FLAIR sequence (f) showing complete resolution of temporal lobe and cervical cord venous oedema.

Figure 2.

Angiography during embolisation. (a) Right external carotid injection, early arterial phase, showing a right sided foramen magnum dural arteriovenous fistula fed by the occipital artery (1) and the posterior trunk of the ascending pharyngeal artery (2). A microcatheter was navigated distally into the occipital artery feeder and a selective injection was performed: the lateral (b) and postero-anterior (c) projections demonstrate the venous drainage pattern. There is a single long and tortuous draining vein. It passes posterior to medulla oblongata, drains into the anterior and posterior spinal veins (3) then crosses the midline and goes up to the left tentorium through the cerebellopontine angle. There is a change of calibre and an aneurysmal dilatation (4) as it crosses at the junction between the tentorium and the superior petrosal sinus, then it courses along the inferior face of the left temporal lobe (cortical temporal vein) to drain in the left cavernous sinus. (d) Right paramedian sagittal MIP reconstruction of a rotational angiography during injection of the right external carotid. A branch of the right occipital artery (1) passes between the atlas and the occipital bone to feed the foramen magnum fistula. The fistulous point is located on the right posterior border of foramen magnum. (e) Anatomical overlay of the rotational angiography and MRI 3D FLAIR sequence using the Philips™ post-processing workstation. The trajectory of the draining vein is delineated across anatomical and parenchymal landmarks. (f) Post-embolisation right external carotid injection, lateral projection, showing complete occlusion of the fistula.