Background Venous sinus stenting is an effective treatment for patients with idiopathic intracranial hypertension (IIH) and venous sinus stenosis.
Objective To determine the usefulness of venous sinus stenting in the treatment of patients with symptomatic venous sinus stenosis without a diagnosis of IIH.
Methods We performed a retrospective review of a prospective multicenter database of patients undergoing venous sinus stenting between January 2008 and February 2016. Patients with acute dural venous sinus thrombosis, arteriovenous fistula or arteriovenous malformation, or IIH were excluded. Clinical, radiological, and ophthalmological information was recorded.
Results Nine patients met the inclusion criteria and underwent venous sinus stenting for symptomatic dural venous sinus stenosis. Reasons for treatment included isolated unilateral pulsatile tinnitus (n=1), congenital hydrocephalus (n=2), unilateral pulsatile tinnitus following prior venous sinus thrombosis (n=1), acquired hydrocephalus following dural sinus thrombosis (n=2), meningitis (n=2) and tumor invasion into the dural venous sinus (n=1). Six patients underwent lumbar puncture or shunt tap, and all of these patients had elevated intracranial pressure. All stenoses were located in the transverse sinus, transverse–sigmoid junction and/or jugular bulb, and all were treated with self-expanding bare-metal stents. At follow-up, clinical symptoms had resolved in all but two patients, both of whom had congenital hydrocephalus and pre-existing shunts. There was no significant in-stent stenosis, and patients with ophthalmological follow-up demonstrated improvement of papilledema.
Conclusions Dural venous sinus stenting may be an effective treatment for patients with symptomatic venous sinus stenosis without IIH in carefully selected cases, but may not be effective in resolving the symptoms of congenital hydrocephalus.
- Intracranial Pressure
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Idiopathic intracranial hypertension (IIH) has been successfully treated with dural venous sinus stenting,1 ,2 with reports of reduction of headache symptoms, resolution of intracranial pressure (ICP) and improvement of ophthalmological findings such as papilledema and visual field deficit.3 While dural venous sinus stenosis with a pathological pressure gradient has been associated with IIH,4 it has also been observed in patients without IIH during diagnostic venography and venographic manometry.5 Here we report a cohort of select non-IIH patients with hydrocephalus or related symptoms and dural venous sinus stenosis treated with dural venous sinus stenting.
Patients and methods
This retrospective cohort study was approved by each center's institutional review board. From prospectively maintained databases of all patients undergoing dural venous sinus stenting between January 2008 and February 2016 at each institution, we identified all patients without a diagnosis of IIH because they did not fulfill the accepted diagnostic criteria (ICP ≥25 cm H2O, normal cerebrospinal fluid (CSF) contents, and no structural abnormality on neuroimaging that might cause an elevated ICP).6 Patients with acute dural venous sinus occlusion, dural arteriovenous fistulae or arteriovenous malformations, or lack of clinical follow-up were excluded. Baseline and follow-up clinical, radiological and ophthalmological information were recorded when available.
Venous sinus manometry and stenting
Cerebral venography and manometry were performed as previously described.5 Briefly, diagnostic venography and manometry were performed under local anesthesia, and multiple pressure measurements were obtained at various anatomic locations in the dural venous sinuses. A pressure gradient was defined as pathological and meriting consideration for dural venous sinus stenting if a difference in pressure of ≥8 mm Hg between two anatomically contiguous segments (eg, transverse and sigmoid sinuses) was found.2 The 8 mm Hg threshold is an arbitrarily defined value that has not been experimentally validated, but is larger than the 5–6 mm Hg pressure drop from the superior sagittal sinus to jugular bulb in normal patients.7 ,8
Patients who qualified for dural venous sinus stenting were loaded preoperatively with aspirin (325 mg) and clopidogrel (75 mg) daily according to institutional protocol. Dural venous sinus stenting was then performed as described previously.1 One or more bare-metal self-expanding stents (Zilver, Cook Inc, Bloomington, Indiana, USA; Wallstent, Boston Scientific, Marlborough, Massachusetts, USA; or Protégé, ev3, Irvine, California, USA) were deployed across the area of stenosis. Treatment of patients with dual antiplatelet medication was maintained for 3–6 months, after which aspirin monotherapy was administered indefinitely.
Nine patients met the inclusion criteria. Seven of the nine patients were female and the median age was 23 years (range 15–65). Patient diagnoses are shown in table 1 and included congenital hydrocephalus (as related to craniosynostosis in one case and cerebral palsy in another, n=2), acquired hydrocephalus (such as previously resolved dural venous sinus thrombosis, a veno-occlusive neoplasm, or meningitis, n=5), and unilateral pulsatile tinnitus without additional symptoms (one of whom had a history of resolved dural venous sinus thrombosis, n=2). Two of nine patients (22.2%) had existing ventriculo- or lumboperitoneal shunts for congenital hydrocephalus at the time of stent placement. Both of these patients had been shunted shortly after birth and both had intermittent symptoms of chronically elevated ICP for several months before referral for cerebral venography and manometry. Shunts were not immediately revised in either patient owing to the chronic nature of their shunt failures and patient and family preference towards a non-shunt treatment for chronic hydrocephalus symptoms. Six of nine patients (66.7%) had ICP measurements by lumbar puncture, a shunt tap, or ICP monitoring within 30 days of venography, and all of these patients had elevated ICP (mean 44 cm H2O; range 29–80), including both patients with pre-existing shunts. All but one patient (No 1) also had had recent non-invasive cross-sectional cerebrovascular imaging (CT angiography, CT venography, MR angiography, or MR venography), all of which demonstrated venous sinus stenosis (figure 1A, B). All patients had significant venous sinus stenosis and an elevated pressure gradient across the stenosis (mean 27.1 mm Hg; range 10–65). There were no complications of the dural venous sinus stenting procedures.
Follow-up data are shown in table 2. The median clinical follow-up was 8 months (range 1–44). One patient with congenital hydrocephalus, papilledema, and a pre-existing ventriculoperitoneal shunt with distal catheter fracture for 4 months before venous sinus stenting had symptoms of intermittent shunt obstruction 1 week after stenting, requiring distal shunt revision despite ICP measurements that improved from 29 cm H2O before stenting to 6 cm H2O after stenting. Patient symptoms improved immediately after distal shunt revision. A second patient with congenital hydrocephalus and a pre-existing lumboperitoneal shunt also required shunt revision during follow-up owing to persistent ICP elevation after the patient's headaches failed to improve. After placement of a ventriculoperitoneal shunt, the patient's headaches also resolved.
The remaining seven patients reported subjective improvement of presenting symptoms (including headache and/or pulsatile tinnitus) on clinical follow-up. Radiological follow-up was available for eight patients with a median radiological follow-up of 4.75 months (range 1–40) and consisted of either CT venography, MR venography or cerebral angiography (figure 1C). There were no cases of in-stent stenosis or thrombosis, though two patients were found to have mild, non-flow-limiting stenosis either proximal or distal to the stent. Ophthalmological follow-up was obtained in three patients successfully treated with venous sinus stenting with a median follow-up of 3 months (range 1–8). All three patients had preoperative papilledema, and all showed marked improvement or resolution of papilledema at follow-up.
This is the first report of a retrospective cohort of non-IIH patients treated with dural venous sinus stenting for hydrocephalus or related symptomatology. We have previously reported an 11.8% incidence of a pathological pressure gradient across a dural venous sinus stenosis in patients without IIH,5 but the outcome of subsequent dural venous sinus stenting in such patients is not well-characterized.
Recent meta-analyses of surgical treatments of IIH found that dural venous sinus stenting is associated with a low rate of complications (1.5–6.8%) and revision (10.3%).3 ,9 ,10 A low rate of in-stent stenosis has also been reported in long-term follow-up.11 There is a high revision rate (46% in a recent large study)12 and infection rate (up to 15%)13 after CSF shunt procedures, with substantial attendant clinical and economic impacts.13 ,14 In patients with IIH, there are significant cost savings with venous sinus stenting compared with CSF shunting, given the high rate of revision surgery.15 Thus, when indicated by a venous pressure gradient, dural venous sinus stenting may be an attractive alternative in both patients with and without IIH with symptoms of venous sinus stenosis.
The relationship between dural venous sinus stenosis and hydrocephalus has not been fully elucidated. It is hypothesized that areas of dural venous sinus incompetence become narrowed from external compression in response to elevated ICP, and a pressure gradient across the stenosis produces venous hypertension, in turn reducing cerebrospinal fluid resorption and further elevating ICP.16–18 This hypothesis is supported by evidence of elevated dural venous sinus pressures in patients with hydrocephalus and venous sinus stenosis, as well as the near-immediate resolution of elevated ICP after dural venous sinus stent placement.19 ,20 Conversely, reduction in ICP can alleviate some cases of venous sinus stenosis,21 ,22 though others have not found such a relationship.23
Our understanding of the pathophysiological relationship between dural venous sinus stenosis and hydrocephalus remains incomplete as such stenosis is also found in 31–39% of patients without IIH,24 ,25 including 15.9% of those with headache and normal ICP.26 Despite incomplete understanding of the relationship between dural venous sinus stenosis and hydrocephalus, the final common pathway of elevated venous sinus pressures and increased ICP does not appear to be limited to patients with IIH, though correcting venous outflow obstruction may not be enough to effectively treat patients with congenital hydrocephalus.
A related pathophysiological mechanism has been reported in two patients with IIH-like symptoms due to styloid process compression of the extracranial jugular vein, which was responsive to surgical decompression;27 in a patient with Chiari malformation, spinal cord syrinx and IIH, in which venous sinus stenting resolved the IIH symptoms and also improved the syrinx and tonsillar herniation;28 and in a patient with bilateral abducens palsies from IIH, which resolved after stenting.29 In addition, resolution of preoperative papilledema after venous sinus stenting has been reported in the IIH population,30 but not in patients without IIH. Although ophthalmological follow-up is limited to only three patients, all three had complete or near-complete resolution of preoperative papilledema.
These preliminary results suggest that patients with acquired hydrocephalus, especially those with abnormalities in the dural venous sinus system on neuroimaging, could be considered for diagnostic venography and venographic manometry to evaluate the possibility of stent placement. After stenting, appropriate candidates may have alleviation of a constellation of symptoms related to elevated dural venous sinus pressure, including headache and also vision loss and other associated sequelae of raised ICP.
Venous sinus stenting failed to improve symptoms in both patients with congenital hydrocephalus in our cohort despite a preoperative pathological pressure gradient. Both patients had pressure gradients and stenosis similar to those of the other patients in this study and in IIH cohorts. In one patient (No 6) with post-stent ICP measurements, the ICP had improved from 29 cm H2O to 6 cm H2O. However, headache symptoms in both patients resolved only after shunt revision. The relationship between hydrocephalus and venous sinus stenosis in these patients may differ from that in the other patients in our cohort, and also from patients with IIH. A previous study of MRI-based quantification of venous sinus blood flow in patients with and without IIH found higher total blood flow in patients with IIH and, conversely, reduced superior sagittal sinus flow in those patients without IIH.31 This suggests that differential patterns of venous drainage may make venous sinus stenting less successful in congenital hydrocephalus, though our small sample size prevents definitive comparison.
This study has several limitations. It is a retrospective study without a control group, and includes only a small cohort of patients with heterogeneous non-IIH pathology. Thus its results may not be generalizable to other non-IIH populations with venous sinus stenosis, including (as we report) patients with congenital hydrocephalus. In addition, the cut-off point for a ‘pathological’ pressure gradient across a dural venous sinus stenosis was arbitrarily defined as ≥8 mm Hg, though this has not been prospectively or experimentally validated. However, previous studies have demonstrated efficacy when using this threshold,2 and it exceeds the physiologically normal 5–6 mm Hg pressure drop between the superior sagittal sinus and jugular bulb.7 ,8 Despite these limitations, our results suggest that further investigation into the application of dural venous sinus stenting for carefully selected non-IIH patients is warranted.
Dural venous sinus stenting is safe and effective in a small retrospective cohort of carefully selected non-IIH patients with a pathological pressure gradient associated with dural venous sinus stenosis, except in patients with congenital hydrocephalus.
Contributors All authors made significant contributions to the conception, design, implementation, data collection and analysis, and drafting of the manuscript.
Competing interests None declared.
Ethics approval Ethics approval was received from each center's institutional review board.
Provenance and peer review Not commissioned; externally peer reviewed.
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