Venous outflow stenting for symptomatic developmental venous anomaly

Abstract

Developmental venous anomaly (DVA) is one of the commonest vascular malformations in the brain but rarely symptomatic. Various pathomechanisms such as mechanical compression, increased in-flow into DVA or outflow obstruction have been described as causative factors in symptomatic DVAs. We report a unique case of a pontomedullary DVA with venous outflow obstruction causing progressive neurological worsening in a young adult despite anticoagulation, who was treated with a novel approach of venous outlet stenting of the collector vein with favorable outcome. In carefully selected cases, this endovascular treatment can be an effective and safe alternative when other measures fail.

Introduction

Developmental venous anomaly (DVA) is one of the commonest vascular anomalies, seen in up to 10% cases in modern MRI based studies.^1,2 They are usually benign lesions, incidentally detected, and do not warrant active intervention on their own accord. The origin of DVA is understood to be an adaptive response to malformations in the venous system during embryological development due to improper regression or persistence of superficial or deep venous elements, resulting in a compensatory “anomalous” venous pathway which serves to drain the normal brain tissue of the affected region. ³ This adaptive venous outflow channel of the brain however can be vulnerable to added hemodynamic stress and can become symptomatic as a result of increased in-flow or decreased outflow, leading to venous congestion. ⁴ Mechanical compression from the DVA has also been implicated as a causative factor in trigeminal neuralgia and obstructive hydrocephalus.

We present a unique case of a symptomatic pontine DVA due to venous outflow stenosis, with progressive worsening despite anticoagulation, and a technical note on endovascular intervention for relieving the venous outflow obstruction.

Case report

A 28-year-old gentleman presented with subacute headache, progressive ataxia, right facial numbness, right lower motor neuron facial palsy and gaze paresis over 4 days. He was evaluated by neurology services and MRI showed right pontomedullary edema, and underlying DVA (See Figure 1). There was no obvious cavernoma associated with it. He was commenced on anticoagulation with unfractionated heparin. Over the next 5 days, his symptoms continued to deteriorate, with worsening ataxia and dysarthria with new onset intractable hiccups, which corroborated with the radiological expansion of edema involving dorsolateral medulla. Steroid was added as a rescue measure. A DSA was performed for evaluation of the angio-architecture of the DVA and to formulate further plans for treatment. DSA showed severe stenosis of the collector vein outflow of the DVA and excluded microshunts or micro-AVMs. DVA was draining into right superior petrosal sinus (See Figure 2). Given progressive neurological deterioration of the young patient, and radiological worsening of brainstem edema despite anticoagulation, we proposed a stenting of the collector vein stenosis in an attempt to relieve venous congestion. The exceptional nature of the intervention was explicitly explained, and thoroughly discussed with patient and patient’s family, and a written informed consent was obtained to proceed.

Figure 1.

Initial MRI and CTV showing right pontomedullary DVA with caput medusae appearance (c susceptibility weighted imaging), and collector vein draining into right superior petrosal sinus (arrow), and right pontomedullary edema on T2 FLAIR sequence.

Figure 2.

DSA: frontal projection showing venous outlet stenosis of the DVA as it enters right superior petrosal sinus (arrow), and post-stenting relief of venous outflow obstruction.

Technical note

Right transradial approach to selectively catheterize the right vertebral artery, and right common femoral vein for venous approach was selected. Primary guide catheter was taken up to right jugular bulb, and a 5F Berenstein tip Glidecath™ (Terumo Medical Corp., Tokyo, Japan) was used to facilitate selective catheterization of the right superior petrosal sinus. The Berenstein catheter tip was helpful as the sinus originated from the lateral wall of the sigmoid sinus, and it provided a better force vector for microcatheter navigation into the superior petrosal sinus. A Headway Duo™ 156 cm Microcatheter (Microvention, California, USA) was advanced over Synchro™ 14 (Stryker, Fremont, USA) microwire and later over Hybrid 007™ (Balt Extrusion, Montmorency, France) microwire to cross the stenosis. There was slight initial resistance to navigate past the stenotic point with the microcatheter, and there was a “give way” which allowed to advance the microcatheter beyond the stenotic segment of the vein. Through the microcatheter, a Neuroform Atlas™ (Stryker Neurovascular, Fremont, USA) 3 × 15 mm was deployed across the venous stenosis and placement was confirmed with a VasoCT™ (Philips Healthcare, Best, Netherlands) There was significantly improved caliber of the venous outflow (See Figures 2 and 3). Patient had been loaded on Aspirin and Ticagrelor prior to the procedure. Post-procedure, heparin was discontinued, and patient was maintained on dual antiplatelet therapy (DAPT). MRI at 48 h showed improving pontomedullary edema, and disappearance of the enhancement on post-Gadolinium imaging signifying decreased venous congestion. Patient reported improvement in ataxia and diplopia.

Figure 3.

Reconstruction of rotational angiogram showing venous outflow stenosis of the DVA as it enters superior petrosal sinus (single arrow), and restoration of venous outflow after stenting (double arrows).

At 8 weeks post-procedure, the MRI showed progressive improvement in edema and absence of contrast enhancement (See Figure 4). He was significantly better with almost complete resolution of ataxia and facial numbness and paresis, only mild gaze paresis without diplopia and impaired tandem gait. At the last clinical follow up at 5 months post-treatment, patient had made further neurological recovery, with only mild residual left sided dysmetria and tandem gait impairment. All previous cranial nerve deficits had completely resolved.

Figure 4.

Evolution of pontomedullary edema (A–C), contrast enhancement representing venous congestion (D–F), and susceptibility weighted imaging (SWI; G–I). The panels on left (A, D, G) are from the initial imaging at presentation, middle (B, E, H) from repeat imaging due to clinical deterioration despite anticoagulation and pre-stenting, showing worsening of edema, contrast enhancement and petechial hemorrhage on SWI, and right (C, F, I) are from 8 weeks post-stenting showing progressive improvement in imaging characteristics.

Discussion

Symptomatic DVAs are very rare and management of a symptomatic DVA depends on the mechanism of symptoms. ⁴ The rarity of the condition means the scientific information regarding treatment is limited to short case series. The important caveat is preservation of the DVA to allow venous drainage of the normal brain, regardless of what modality of treatment is chosen.^3–5

Venous outflow obstruction is an important cause of symptomatic DVA due to local venous congestion. Outflow restriction can occur due to stenosis or thrombosis of the collector vein or further downstream stenosis in the path leading to the dural venous sinus or an associated arteriovenous shunting into the downstream pathways which competitively impede normal venous outflow from the DVA. ⁴

Historically, symptomatic DVAs have been treated conservatively, with anticoagulation, antiepileptic medications or surgery depending on the presentation. In cases of micro-AVM associated with DVA, radiosurgery, ⁶ targeted embolization ⁴ or microsurgical resection ⁷ of the AVM while preserving the venous radicles have been reported. Occlusion, intentional or inadvertent, of the venous drainage pathways have almost always resulted in severe brain swelling or venous infarction or hemorrhage.^5,7–10

The natural history of symptomatic DVAs, especially with regard to venous outflow obstruction is incompletely understood because of the rarity of the condition. One publication cited 31 cases from literature suggesting good clinical recovery in up to 73% cases with anticoagulation or serial observation alone. ⁹ The reports demonstrating good clinical recovery with anticoagulation all showed early clinical improvement after starting anticoagulation.^8,9 Although reassuring, the clinical course of a patient, the initial trend after initiating anticoagulation, and the etiopathogenesis of the venous obstruction—thrombosis or stenosis—are important determinants in recommending a treatment. In our case, failed anticoagulation, pontine swelling and worsening patient made us consider an individualized strategy for him.

Stent-reconstruction of the venous outlet stenosis is an intuitive strategy to relieve the venous congestion which results in symptomatic edema. We chose an open cell stent with high radial force design to effectively improve venous outflow. Although we did not come across a previous description of this technique and indication in the literature, a sophisticated understanding of the pathomechanism of why a DVA becomes symptomatic was crucial in devising an effective treatment plan. Improvement in patient’s neurological condition and MRI appearances corroborated well with the original theory and execution of the plan.

This treatment can have potential complications such as venous injury due to perforation of thin-walled veins, which may result in worsening of congestive venopathy, hemorrhage and neurological deterioration. Transvenous access can be challenging due to difficult navigation angles and tortuosity, and 3D rotational angiograms obtained in venous phase are critical to understanding the navigation roadmaps. It is imperative that such a treatment be undertaken at highly specialized centers with skilled operators. Long term results of this intervention are yet to be known.

Conclusion

Venous outlet obstruction is an important cause of the rarely symptomatic DVA, and endovascular transvenous stenting of the stenosis can be an effective and feasible alternative strategy when medical measures fail.