Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 2, 2011, pp. 285-288

Neurology India, Vol. 59, No. 2, March-April, 2011, pp. 285-288

Case Report

Subacute involvement of the medulla oblongata and occipital neuralgia revealing an intracranial dural arteriovenous fistula of the craniocervical junction

Johann Peltier¹, Marc Baroncini², Laurent Thines², Arnaud Lacour³, Xavier Leclerc⁴, Jean-Paul Lejeune²

¹ Department of Neurosurgery, University of Amiens, Amiens, France
² Department of Neurosurgery, Hospital Roger Salengro, Lille, France
³ Department of Neurology, Hospital Roger Salengro, Lille, France
⁴ Department of Neuroradiology, Hospital Roger Salengro, Lille, France

Correspondence Address: Johann Peltier, Service de Neurochirurgie, Centre Hospitalier Universitaire d'Amiens,Place Victor Pauchet, 80054 AMIENS cedex 1, France, peltier.johann@chu-amiens.fr

Date of Submission: 23-Dec-2010
Date of Decision: 09-Jan-2011
Date of Acceptance: 09-Jan-2011

Code Number: ni11076

PMID: 21483135

DOI: 10.4103/0028-3886.79153

Abstract

Keywords: Dural arteriovenous fistula, medulla oblongata, myelopathy, spinal angiography

Introduction

Dural arteriovenous fistulas (AVF) are the malformations with the nidus in dura mater. Intracranial dural AVFs account for 12%-15% of all cerebral vascular malformations. ^[1],[2] Dural AVFs in the posterior fossa are very rare and mostly drain into the lateral sinus. ^[3] Pulsatile tinnitus is the most common presenting feature of intracranial dural AVFs and rarely subarachnoid hemorrhage. ^[1],[2],[3] This article reports a patient with cervicomedullary dural AVF and reviews the literature.

Case Report

A 58-year-old woman presented for the first time with transient weakness of the left lower limb and occipital neuralgia of 5 min duration. Computer tomography (CT) scan of brain was normal. Two months later, she presented with progressive quadriparesis. Neurologic examination showed marked weakness of all the 4 lower limbs, hyperactive stretch reflexes, ankle clonus, bilateral extensor plantar response, decreased perception of light touch and pinprick below C6 level, diminished rectal sphincter tone and urinary retention. During the hospital course she developed sudden onset of breathing difficulty, hiccups, swallowing difficulty, weakness of soft palate, loss of gag reflex, dysphonia, and paralysis of left trapezius muscle. Blood biochemistry and cerebrospinal fluid studies, and immunoglobulin G electrophoresis were normal. Magnetic resonance imaging (MRI) of brain showed a hyperintense signal in the lower brainstem and upper cervical spinal cord. She was given intravenous dexamethasone. Further review of MRI also revealed a serpentine vascular signal coursing medially on the posterior aspect of the high cervical spinal cord [Figure - 1] and [Figure - 2]. Four-vessel cerebral angiography and spinal angiography revealed a dural AVF with feeder from posterior meningeal branch of the left vertebral artery arising near its dural crossing. The fistula drained intradurally via the left C1 radiculomedullary vein [Figure - 3].

Embolization was considered as the initial procedure. Catheterization of the feeding artery distally enough to allow embolization with Onyx was not technically feasible. A suboccipital craniotomy was then undertaken with clipping and section of the venous stem of the left C1 radicular vein. In the immediate postoperative period the arm strength and sensory disturbance improved. Postoperative course was uneventful. A follow-up angiography done 10 days later showed complete obliteration of dural AVF. MRI performed 2 weeks after surgery showed marked reduction in the hyperintense signals on T2-weighted sequences in the medulla oblongata. At 6 months follow-up she had mild spasticity in the lower limbs causing disability.

Discussion

In most of the cases, dural AVF represents an acquired abnormal communication between arterial and venous channels embedded in the dura. As the intradural spinal venous system is valveless and the venous perimedullary coronal plexus is in direct continuity with the veins of the posterior fossa, a venous congestive myelopathy is facilitated by the transmission of a high venous pressure to the spinal cord tissue. ^{[1],[2],[4],[5],[6],[7],[8]} A thrombosis of a transverse sinus can be the cause of an aberrant venous drainage of the fistula into the spinal perimedullary veins. ^[9] Dural AVF produce dilated, tortuous, and elongated veins on the cord surface by shunting blood under high pressure from the dural AVF into the normal venous system of the spinal cord. ^[9] This can occur after a shunt at any level in the neural axis. ^[10] Stagnation of blood flow and chronic hypoxemia can result in the ischemia of both the spinal cord and brainstem. The occipital neuralgia in our patient is probably due to the ectatic vessels coursing both over the posterior roots of the C1 nerve and the spinal branch of the accessory nerve. This has been documented during microsurgery [Figure - 4].

Dural AVFs commonly occur in the thoracolumbar region and the presenting features include myelopathy, subarachnoid hemorrhage, radiculopathy, and cranial nerve palsies and brainstem syndromes in patients with cervicomedullary dural AVFs. Most often these patients present with subacute or chronic symptoms. The duration of symptoms before the diagnosis of dural AVF is superior to 6 months in 89% of cases. Rarely they can present acutely. ^[1],[2],[4] Spinal MRI shows intrinsic hyperintense cord signals on T2-weighted sequences and the draining veins as a flow void signals. The diagnostic imaging modality to establish the diagnosis is spinal angiography. ^[1],[3] EC-TRICKS, a multiphase single-station contrast-enhanced 3D MRA acquisition technique to visualize dynamic processes, such as passage of blood with contrast agent through the vascular system, can help in establishing the diagnosis. This technique eliminates the need of a timed automatic triggering of scan along with the flow of contrast. The primary purpose of EC-TRICKS application is to obtain high temporal resolution for angiographic examinations. ^[11] The feeding arteries in AVFs located at the craniocervical junction are the petrosal branch of the middle meningeal artery, the meningeal branch of the ascending pharyngeal artery, meningeal branch of the occipital artery, meningeal branch of the posterior inferior cerebellar artery, meningeal branch of the meningohypophyseal trunk (from the internal carotid artery) or more rarely meningeal branches of the intracranial segment of the vertebral artery. The draining is usually into the anterior pontomesencephalic vein or the left transverse sinus or very rarely into a radicular vein as seen in our patient via the anterior and posterior medullary vein forming the coronal venous plexus. About 40%-50% of dural AVF have varices on the draining vein. ^[1],[3] The Cognard classification proposes 5 patterns of venous drainage: Type I-the main sinus, with antegrade flow ^[12] ; Type II-main sinus with reflux into the sinus (IIa), cortical veins (IIb), or both (IIa + b); Type III-direct cortical venous drainage without venous ectasia; Type IV-direct cortical venous drainage with venous ectasia; and Type V-with spinal venous drainage. ^[12] Treatment of the dural AVF can be either surgery or embolization. Simple interruption of the main draining dural veins to the spinal cord can be sufficient to achieve a cure of the dural AVF. ^[1] Transarterial and transvenous embolization have the advantage of predictive obliteration at the site of dural AVF. ^[2],[3],[13] The clinical characteristics, treatment, and outcome of 9 patients with brainstem involvement reported in the literature are reviewed in [Table - 1].

References

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