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There is substantial recent interest in the pages of JNIS regarding cerebral venous disease. Considered a neglected area in neurointervention for many years, there has been an uptick particularly in the study of venous sinus stenosis and idiopathic intracranial hypertension (IIH; previously known as pseudotumor cerebri). A recent editorial1 described the first meeting of the SNIS Cerebral Venous and Cerebrospinal Fluid (CSF) Disorders Committee, including a motivation to ‘provide thought leadership for the SNIS on the science, regulatory, device innovation, and clinical trials related to these disease processes’. The formation of this committee is welcome, and needed, to provide assistance to neurointerventionalists treating cerebral venous disorders.
Stenting for IIH is perhaps the most common cerebral venous treatment currently performed by neurointerventionalists.2 This procedure originally grew from observations of venous sinus stenosis in patients with IIH, followed by early reports of balloon angioplasty providing temporary symptomatic relief.3 The advent of improved catheter and stent technology provided the opportunity for stenting to become a viable alternative to typical cerebrospinal fluid (CSF) diversion surgery for IIH treatment. In conjunction, a reappraisal of the pathophysiological relationship between CSF absorption and venous drainage4 has transformed IIH from an ‘orphan disease’ to a cerebrovascular disorder for many affected patients.
There is now a reasonable body of work demonstrating the safety and efficacy of stenting for IIH. A recent meta-analysis of 20 studies comprising 474 patients across 18 centers showed excellent efficacy with a low complication rate, with data heterogeneity suggesting moderate bias.5 Because of the rarity of this disease, subsequent small or medium-sized single- and multi-center series have focused in particular on the reduction of intracranial pressure,6 the beneficial effect on ophthalmological outcomes, the application of upper extremity vascular access,7 and the prevention of stent-adjacent stenosis.8 Complication rates are reportedly low,9 as are retreatment rates,10 although publication bias may lead to underestimations and real-world rates are likely to be slightly higher.11
It is important to consider the pros and cons of currently acceptable treatments for symptomatic IIH when evaluating the safety and efficacy of a newer therapeutic option such as stenting. Unfortunately, the quality of published data in support of such treatments remains troublingly low. Medical treatments such as acetazolamide, which was studied in a prospective randomized trial, and less commonly topiramate, are only marginally effective and only in patients with mild vision loss, and have side effect profiles that are difficult for many patients to tolerate.12 Optic nerve sheath fenestration can lead to temporary vision improvement, but nearly half of patients will have persistent vision loss at long-term follow-up, and it does not relieve other IIH-associated symptoms (such as headache or tinnitus).13 14 CSF shunt surgery, which has been the mainstay for surgical IIH treatment for many years, similarly lacks high-quality prospective data, with the most recent meta-analysis of 15 studies comprising 372 patients and a moderate risk of bias.15 CSF shunting was found to have a higher complication rate in patients with IIH than in other shunt populations, and a retreatment rate of up to 42%. The rate of improvement in papilledema and visual symptoms was similar to venous sinus stenting. Finally, significant weight loss, while effective in some series, is often not practical, possible or effective in most patients without gastric bypass surgery,16 17 which is rarely available and associated with its own potential complications.
As with any new technology or treatment paradigm, there is a potential for stenting in IIH to be overused, which may lead to unnecessary surgery (at best) or patient harm (at worst).9 While there are currently no official guidelines for this technique, recommendations have been proposed.18 Chief among them are objective criteria for indications and patient selection. This author posits that, while the symptoms of IIH are often multifactorial, IIH is at its core an ophthalmological disease, so selection of any patient for surgical intervention should be multidisciplinary in nature, incorporating input from ophthalmology, neurosurgery, neurointervention, and headache specialists. This decision should be based in most cases on the quantitative degree of vision loss, such as optical coherence tomography measurements or, more commonly, visual field perimetry testing19 rather than subjective or unreliable criteria. Headaches in the absence of vision loss should rarely, if ever, be an indication for surgical intervention of any kind, given their considerable multifactorial nature in patients with IIH.20 Patients with symptoms too mild to consider shunt insertion (such as pulsatile tinnitus) should not be referred for stenting, and stent insertion should be performed only when objective physiological criteria are met, including elevated dural venous sinus pressures and a pressure gradient across the stenotic segment. Because many patients without IIH will have sinus abnormalities on cross-sectional imaging,21 and the presence and degree of stenosis is not predictive of pressure gradients, retrograde venous manometry remains the best method for determining stent eligibility.22 23 The ideal pressure gradient to select patients with IIH for stenting has not been established. Recent studies suggest that patients with gradients lower than the traditional (and empirically defined) 8 mm Hg may still benefit from stenting,24 although the precision of the pressure measurements being obtained must be considered when defining a lower threshold.25
In summary, the treatment of IIH remains imperfect, and there is much about this disease that is not well understood. Rigorous prospective randomized trials comparing treatment strategies have been proposed and should be encouraged, similar to any new neurosurgical intervention. However, the body of evidence suggests that stenting for IIH in appropriately selected patients should be considered a first-line treatment option.
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Twitter @DrMichaelLevitt
Funding The author has not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests Unrestricted educational grants from Medtronic and Stryker; consulting agreement with Medtronic, Aeaean Advisers and Metis Innovative; equity interest in Proprio, Cerebrotech, Apertur, Stereotaxis, Fluid Biomed, and Hyperion Surgical; editorial board of Journal of NeuroInterventional Surgery and Frontiers in Surgery.
Provenance and peer review Not commissioned; externally peer reviewed.