Neuroendovascular Intervention: Evolving at the Intersection of Neurosurgery and Neuro-Ophthalmology

Our goal was to evaluate the safety and efficacy of stenting of venous sinus stenosis (VSS) in patients with medically-refractory, medically-intolerant or fulminant idiopathic intracranial hypertension (IIH) in a prospective, observational study. Thirteen patients with IIH who were refractory or intolerant to medical therapy or who presented with fulminant visual field (VF) loss underwent stenting of VSS at the transverse-sinus sigmoid sinus junction, using a Precise Pro carotid stent system (Cordis). Inclusion criteria included papilledema-related VF loss with mean deviation (MD) worse than or equal to -6.00 dB, elevated opening pressure (OP) on lumbar puncture (LP), VSS (either bilateral or unilateral in a dominant sinus), and an elevated (≥8 mm Hg) trans-stenotic gradient (TSG). The main outcome measures were pre- to post-stent change in symptoms related to intracranial hypertension, MD (in dB) on automated (Humphrey) VFs, grade of papilledema (1-5), retinal nerve fiber layer (RNFL) thickness as measured by spectral domain optical coherence tomography (SD-OCT), TSG (mm Hg), and OP on LP (cm H20). Improvement or resolution of headaches occurred in 84.7% of patients, pulse-synchronous tinnitus in 100%, diplopia in 100%, and transient visual obscuration in 100%. Out of 26 eyes, 21 showed an improvement in MD, with an average improvement of +5.40 dB. Of 24 eyes with initial papilledema, 20 showed an improvement in Frisen grade, (mean change in grade of 1.90). Of 23 eyes undergoing SD-OCT, 21 (91.3%) demonstrated a reduction in RNFL thickness, with a poststent mean thickness of 90.48 μm. Mean change in OP was -20 cm H2O (reduction in mean from 42 to 22 cm H20) with all subjects demonstrating a reduction, although a second stenting procedure was necessary in one patient. Complications of the stenting procedure included one small, self-limited retroperitoneal hemorrhage, transient head or pelvic pain, and one allergic reaction to contrast. No serious adverse events occurred. Stenting of VSS is safe and results in reduction of intracranial pressure in patients with IIH. This is associated with improvement in papilledema, RNFL thickness, VF parameters, and symptoms associated with intracranial hypertension.

Editorial Neuroendovascular Intervention: Evolving at the Intersection of Neurosurgery and Neuro-Ophthalmology Jason M. Davies, MD, PhD, L. Nelson Hopkins, MD N euroendovascular interventions have evolved tremendously over the course of the past several decades. First as a diagnostic aid, neuroendovascular techniques and technology have developed to allow access to and interventions for pathologies throughout the neuroaxis. The modern interventionist is expected to be facile in treating intracranial aneurysms, carotid stenosis, carotid trauma, fistulas and arteriovenous malformations of the brain and spine, and ischemic stroke. As indications expand and complexity increases, it is critical for neurospecialists to work together, being aware of each other's potential treatments as well as pitfalls. The current issue of the Journal of Neuro-Ophthalmology includes 2 reports of neuro-ophthalmic disorders related to neurointerventional procedures that highlight the intersection of our fields. Treatment of Complex Intracranial Aneurysms La Pira et al (1) describe the case of a woman with an anterior cerebral artery aneurysm who underwent endovascular intervention with a combination of endosaccular coiling and endoluminal flow diversion. Treatment was complicated by delayed transient visual decline that on imaging evaluation was found to correlate with optic tract edema and likely compression by the thrombosing aneurysm. This was managed with high-dose steroid therapy with near-complete return of vision and occlusion of the aneurysm. This report highlights 2 areas of evolving understanding, namely, the biology of aneurysm thrombosis and how our device choices modulate those processes. Flow diverters, such as the Pipeline device (Medtronic, Minneapolis, MN) used in this patient, embody a new treatment paradigm known as endoluminal reconstruction. These devices are essentially stents constructed with a much more densely woven braid, the effects of which are 2-fold: 1) the high metal coverage conferred by the weave tends to redirect the flow along the lumen of the vessel and away from the aneurysmal sac; and 2) the stent acts as a structural scaffold for endothelial ingrowth whereby the lumen of the vessel is renovated over the course of months, healing over the aneurysmal outpouching. For some aneurysms, flowdiverting stents are insufficient to remodel flow dynamics within the aneurysm, so some neurointerventionists advocate the use of adjunctive endosaccular coils to further disrupt flow and expedite thrombosis (2). Although questions remain relating to the fluid dynamics of flow diversion, those processes are relatively well-understood by comparison with the biological cascades these devices put in motion. Case reports and series detail poorly understood sequelae of treatment ranging from significant headaches to catastrophic failure with fatal rupture. Phenomenologically, aneurysms located near the skull base are often noted to swell as the aneurysm goes through its "death throes," which can stretch the dura and induce pain. The finding of optic tract edema by La Pira et al (1) is entirely consistent with such swelling and represents another potential complication of the procedure. As we better understand Departments of Neurosurgery (JMD, LNH), Biomedical Informatics (JMD), and Radiology (LNH), Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York; Department of Neurosurgery (JMD, LNH), Gates Vascular Institute at Kaleida Health, Buffalo, New York; and Jacobs Institute (JMD, LNH), Buffalo, New York. L. N. Hopkins: grant/research support-Toshiba; consultant-Abbott, Boston Scientific, Cordis, Medtronic; financial interests-Boston Scientific, Claret Medical Inc, Augmenix, Endomation, Silk Road, Ostial Corporation, The Stroke Project, Apama, StimSox, Photolitec, ValenTx, Ellipse, Axtria, NextPlain, Ocular; board/trustee/officer position-Claret Medical, Inc; honoraria-Complete Conference Management, Covidien, Memorial Healthcare System. The remaining author reports no conflicts of interest. Address correspondence to Jason M. Davies, MD, PhD, University at Buffalo Neurosurgery, 100 High Street, Suite B4, Buffalo, NY 14203; E-mail: [e-mail] Davies and Hopkins: J Neuro-Ophthalmol 2017; 37: 111-112 111 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Editorial potential determinants of such symptoms and how to modulate the biological response, we may be able to better prevent and treat such sequelae. Treatment of Idiopathic Intracranial Hypertension Dinkin and Patsalides (3) present a prospective study of 13 patients with idiopathic intracranial hypertension (IIH) in whom venous sinus stenosis and visual field changes were documented. The authors first measured pressure gradients across the venous system and subsequently performed transvenous stenting of the gradient-confirmed stenosis. They demonstrated significant visual improvements across the cohort after reduction of the pressure gradient caused by the outflow obstruction in the sinus. This series is one of several recent reports that advance the hypothesis that pressure gradients across the venous sinuses are a significant contributor to intracranial hypertension. This understanding of etiology creates a mechanical problem that is amenable to endovascular intervention. Although investigators continue to probe patient selection issues and the limits of the technique, this is a promising avenue that provides an alternative to cerebrospinal diversion, a set of surgical techniques that are prone to mechanical failure and infection. Ongoing Innovations in Neuroendovascular Intervention Neuroendovascular intervention will continue to grow through refinement in devices for current indications. For instance, there remains a significant need for devices that allow for treatment of aneurysms that occur at vessel bifurcations. These remain among the most difficult to treat with current technology, and as a result, are often treated either through a direct surgical approach or with increased risk and difficulty by adapting current endovascular devices. As the science underpinning aneurysm rupture and repair continues to develop, new treatment paradigms and clever engineering will certainly allow for safe and effective treatment of an even larger proportion of lesions. Neuroendovascular intervention will also grow through expansion of new indications, treating disorders that were not previously considered amenable to endovascular intervention. 112 Until recently, IIH was included in this category. There is emerging research suggesting that subdural hematomas may likewise be amenable to endovascular therapies. Furthermore, site-directed intra-arterial delivery of chemotherapy may permit more effective treatment of certain varieties of brain tumors. One of the more recent additions to the neurointerventionist's armamentarium is solid evidence that stroke thrombectomy improves outcomes. Stroke intervention remains in its infancy and will continue to evolve as physicians and engineers work to refine access and thrombectomy devices, imaging modalities, and neuroprotectants. Laboratory investigation further extends the promise of neurorestoration, rebuilding crucial function by implanting or infusing stem cells into damaged regions of the brain. Neurorestoration, potentially in the form of catheter-based delivery of stem cells, holds promise for myriad other conditions, from neurodegenerative disorders to traumatic brain injury to movement disorders. Although the science remains to be proven, the potential is vast. CONCLUSIONS Neuroendovascular therapies have revolutionized treatment options across the neuroaxis. As these therapies proliferate and expand the scope of practice, there will be increasing need for collaboration and interaction with our fellow neurospecialists. Ideas intermix as fields collide, adding richness of understanding, new concepts and ways of thinking, and hopefully fruitful collaborations that will allow us to more effectively treat a broader spectrum of disease. REFERENCES 1. La Pira B, Brinjikji W, Hunt C, Chen JJ, Lanzino G. Reversible edema-like changes along the optic tract following Pipelineassisted coiling of a large anterior communicating artery aneurysm. J Neuroophthalmol. 2017;37:154-158. 2. Lin N, Brouillard AM, Krishna C, Krishna C, Mokin M, Natarajan SK, Sonig A, Snyder KV, Levy EI, Siddiqui AH. Use of coils in conjunction with the Pipeline embolization device for treatment of intracranial aneurysms. Neurosurgery. 2015;76:142-149. 3. Dinkin MJ, Patsalides A. Venous sinus stenting in idiopathic intracranial hypertension: results of a prospective trial. J Neuroophthalmol. 2017;37:113-121. Davies and Hopkins: J Neuro-Ophthalmol 2017; 37: 111-112 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.