Repeat venous sinus stenting for management of recurrent sinus stenosis related treatment failure of idiopathic intracranial hypertension: A case series

Abstract

Background

Dural venous sinus stenting (VSS) has been shown to be an effective treatment for idiopathic intracranial hypertension (IIH); however over time, some patients develop treatment failure with formation of a juxta-stent stenosis and a new pressure gradient. Repeat stenting can be performed in these patients to alleviate the stenosis and relieve the elevated pressures preventing complications such as blindness. The efficacy and long-term outcomes of re-stenting is not well described in the literature.

Methods

A retrospective review of patients treated at our institution for IIH with VSS over a span of 18 years identified 18 patients who underwent re-stenting for treatment failure. Clinical features, outcomes and venographic data were collated for each patient with a follow-up period ranging from 12 months up to 9 years from their second stent.

Results

The mean time to repeat stenting was 4 years and 12 months with a range of 1 month up to 16 years and 9 months. Four patients (22.2%) were asymptomatic following second stenting and three patients had recurrent papilledema. Two of these patients (11.1%) had surgical shunting and 1 patient (5.56%) received a third stent. 13 patients (72.2%) had ongoing headaches. There were no major complications in any patient.

Conclusions

This case series demonstrates favourable outcomes for repeat VSS in patients who develop juxta-stent stenosis with a pressure gradient after initial stenting for IIH. A proportion of patients have persistent headache likely due to other mechanisms and a minority may require surgical shunting or further stenting.

Introduction

Idiopathic intracranial hypertension (IIH) is a condition of raised intracranial pressure (ICP) in the absence of intracranial mass lesions that results in symptoms including headache, visual disturbances and when untreated, can result in permanent visual loss. ¹ The precise aetiology remains a subject of ongoing research but current theories propose a cyclic interplay between venous sinus stenosis and the raised ICP itself as a cause for venous outflow impairment with resultant dysfunctional cerebrospinal fluid (CSF) reabsorption and elevated ICPs.^2,3 The use of dural venous sinus stenting (VSS) as a definitive method of treatment for this is well documented in the literature with a good safety and efficacy profile, with multiple benefits over surgical CSF diversion. ⁴ Treatment failure can occur following VSS with the development of new juxta-stent stenoses along the dural sinus with recurrence of a pressure gradient (Figure 1). The mechanisms by which this occurs are not fully elucidated but may be due to the same theory of venous stenosis and raised ICP interacting in a vicious cycle in the vicinity of or within the stent, in addition to anatomical variability in the resilience of venous calibre at different areas of the venous sinus.^5,6 Previous studies have also identified some predictors of treatment failure including female gender, higher BMI, higher initial lumbar puncture opening pressures (LP OP) and trans-stenosis gradient pressures.^6–10 There is variability in the reported rate of treatment failure in the literature that is dependent on length of follow-up, but it is approximated to be between 11 and 13%.^6,8 There is limited evidence base to guide the best approach to further treatment following restenosis in these patients and they are typically managed with either repeat stenting or CSF shunting.^7,9 In this study, we detailed the features and long-term outcomes of a case series of patients treated with repeat VSS following failure of an initial stent for treatment of IIH. To our knowledge, this study is one of the largest series of patients with an extended follow-up period in the literature.

Figure 1.

Right transverse sinus with juxta-stent stenosis before (left) and after re-stenting (right). The juxta-stent stenosis is marked by the arrows.

Methods

A retrospective review of a database of patients who underwent transverse sinus stenting for IIH was performed from the dates of January 2006 to December 2024. We then identified patients from this database who developed recurrent sinus stenosis necessitating a second stent insertion. We analysed the patient characteristics, clinical course and venographic features of this cohort of patients from their first stent to the second. Data was sourced from outpatient clinic letters, electronic medical records, electronic radiology images and procedure reports. Classification of stenoses as intrinsic or extrinsic was performed by an interventional neurologist reviewing the venograms.^11,12 Clinical follow-up in each patient following repeat stenting occurred at a minimum within 12 months with ongoing reviews extending up to 9 years at the longest to date (Mean ± SD, 3.83 ± 2.58 years). All patients received ophthalmological and neurological follow-up following stenting procedures. Persistent or recurrent symptoms, the presence of papilledema or progressive visual threat at follow-up prompted the acquisition of either CT or MR venograms in the first instance. The decision to re-stent patients was then based on a combination of their clinical features with formal catheter venogram confirmation of recurrent sinus stenosis and elevated venous sinus pressures. Patients with mild juxta-stent stenosis without visual threat or elevated sinus pressures did not proceed to repeat stenting but were monitored closely with serial CT or MR venograms.

Results

A total of 18 out of 274 patients were identified at our institution who were treated for IIH with a transverse sinus stent and required a second stent due to recurrent stenosis during the study period. The baseline patient characteristics are summarised in Table 1. There was a preponderance of female patients totalling 17 (94.4%) with a single male patient (5.56%). One patient's gender changed from male to female following the first stent. There was a wide range in the time frame to placement of the second stent extending from just 1 month up to 16 years and 9 months.

Table 1.

Patient characteristics, symptoms and venous pressures.

Characteristic	Value (N = 18)
Age (years)
Median (interquartile range)	28 (25–36.5)
Range	15–48
Gender (%)
Female	17 (94.4)
Male	1 (5.56)
Time to second stent
Mean	4 years & 12 months
Median	3 years & 2 months
Range	1 month – 16 years & 9 months

A comparison of the measured venous sinus pressures and symptoms present prior to both the first and second stenting is summarised in Table 2. The superior sagittal sinus (SSS) pressures prior to the first stenting were overall elevated with a mean of 34.9 mmHg with a range of 7–94 mmHg (normal range is reported to be about 16–18 mmHg ³ ). At second stenting, the mean SSS pressures were elevated to a similar level with a mean of 32.0 mmHg ranging from 18 to 91mmHg. Prior to the first stent, most patients had intrinsic stenoses (61.1%); however, at recurrence all had extrinsic stenoses with two patients (11.1%) that also had associated intrinsic stenosis. All recurrent stenoses were located adjacent to the original stent.

Table 2.

Comparison of venous pressures and symptoms prior to 1^st and 2^nd stenting.

Characteristic	1st stent (N = 18)	2nd stent (N = 18)
Superior sagittal sinus pressure (mmHg)
Mean	34.9	32.0
Range	7–94	18–91
Trans-stenotic gradient (mmHg)
Mean	18.9	15.4
Range	6–60	8–74
Type of stenosis (%)
Extrinsic	7 (38.9)	18(100)
Intrinsic	11 (61.1)	2 (11.1)
Symptoms prior to stent (%)
Headache	16 (88.9)	16 (88.9)
Papilledema	15 (83.3)	4 (22.2)
Tinnitus	1 (5.56)	8 (50.0)

The most prevalent symptom prior to both first and second stenting was recurrent headache with 16 patients (88.9%) reporting this in both instances. At the second stenting, there were only two patients (11.1%) who did not develop recurrent headache, one patient represented with only pulsatile tinnitus and the other patient represented with both recurrent papilledema and pulsatile tinnitus.

The patient outcomes following the second stent are summarised in Table 3. One patient had insufficient follow-up clinical documentation available although they did not require any CSF diversion procedures at latest follow-up. Amongst the remaining patients, there was a recurrence of headaches associated with visual threat and papilledema in three patients, two of these patients were managed with a ventriculoperitoneal shunt and the other patient had a third stent inserted due to evidence of further juxta-stent stenosis. None of the remaining patients developed recurrence of visual threat following the placement of a second stent. Four patients (22.2%) had resolution of their symptoms and were asymptomatic at latest follow-up. There was pulsatile tinnitus remaining in one patient (5.56%). This patient also had persistent headache with an elevated LP opening pressure of 31cmH2O without papilledema and is currently under consideration for shunt insertion at latest follow-up. There were no procedural complications in any of the patients.

Table 3.

Clinical features at latest follow-up post second stenting (follow-up period 12 months - 9 years, mean ± SD, 3.83 ± 2.58 years).

Clinical features at follow-up	Value (N = 18)
No re-intervention required	15 (83.3%)
Re-intervention required (papilledema)	3 (16.7%)
VP shunt inserted	2 (11.1%)
Third stent inserted	1 (5.56%)
Headache	13 (72.2%)
Tinnitus	1 (5.56%)
Asymptomatic	4 (22.2)
Insufficient data	1

VP: ventriculoperitoneal.

Discussion

This case series reported on the outcomes and clinical features following re-stenting as a treatment for recurrent sinus stenosis in patients already treated with a transverse sinus stent for IIH. Most patients were able to avoid debilitating vision loss due to high ICPs with only a small proportion of patients requiring further intervention. Whilst headaches persisted in the majority patients despite treatment with a second stent, there were a group of patients who were treated of all symptoms without the need for further intervention.

To our knowledge, this case series includes the longest follow-up periods and one of the largest series of patients followed for re-stenting in the treatment of IIH. The use of transverse sinus stenting in the treatment of IIH is a well-described intervention with a favourable safety profile and the ability to reduce ICPs, improve papilledema and alleviate symptoms such as headaches and tinnitus. ¹³ Overall, the reported rates of treatment success following initial placement of a sinus stent are high and there are variable rates of treatment failure reported in the literature with ongoing discussion surrounding the parameters that are predictive of this.^6,9,10,13 Treatment failure is generally defined as a combination of clinical features, in particular, recurrent symptoms such as high-pressure headaches and objective features including the presence of papilledema, high CSF pressures or radiological evidence of recurrent venous sinus stenosis. The rate of treatment failure requiring retreatment ranges in the literature from 6% up to 26%.^9,14 Previous studies have identified higher LP opening pressures (LP OP) and trans-stenotic gradients prior to initial stenting as features that may be predictive of treatment failure.^6,8,9 The findings of our study resonate with this as there were overall high SSS and trans-stenotic gradient pressures in the patients prior to the first stent insertion. Although LP OP was not collated in this study (due to incomplete data availability), prior studies have shown evidence of correlation between LP OP and pressures within the torcula.^3,6

Interestingly, within this case series, there was still a wide range of pressures and there were outliers with particularly low pressures. The lowest SSS pressure prior to initial stenting measured at 7mmHg in one patient and the lowest trans-stenotic gradient pressure measured at 6mmHg in another patient (Table 2). Despite these low pressures, there was venographic evidence of significant stenosis in both patients which, in the context of their symptoms, prompted stent insertion. This suggests that even mildly elevated initial pressures and gradients can still result in treatment failure over time. The occurrence of juxta-stent stenosis in these patients despite lower initial CSF pressures could be explained by the proposed dynamic nature of the interaction between venous sinus calibre and ICP. ¹⁰ Localised intracranial venous hypertension caused by intravascular defects that lead to an overall smaller venous sinus or in-stent calibre could lead to the development of juxta-stent stenosis in the absence of overall generalised venous sinus hypertension. Fargen discusses another theory of differential susceptibility to stenosis across the venous sinuses, with the torcula and sigmoid sinus thought to be regions that are less commonly associated with stenosis and are resistant to extrinsic compression. ⁵ This would suggest that there can be variable susceptibility to the development of juxta-stent stenosis depending on the original stent location and its vicinity to these areas along the venous sinuses. For a given individual, a specific combination of these factors probably leads to the development of juxta-stent stenosis thus giving rise to a potentially wide variability in pre-stenting CSF pressures and trans-stenotic gradients as seen in this study.

Our study also demonstrates the possibility of extended lengths of time between the initial stent and the development of treatment failure necessitating further intervention. In the literature, there are variable follow-up durations reported with reports of a range of about 10–18 months^6,9 and a metanalysis by Nicholson et al. reporting a median of 18 months. ¹⁵ At our institution, long-term indefinite follow-up is performed in each patient where possible which allowed for the identification of initial treatment failure at 16 years and 9 months (table 1) in one patient. This outlier patient had represented with recurrent severe headaches and tinnitus without visual disturbance with angiographic evidence of juxta-stent stenosis and a significant pressure gradient. The absence of visual symptoms at this delayed recurrence highlights the importance of indefinite follow-up of IIH patients treated with stents to enable rapid identification and intervention in these patients prior to the development of any optic nerve damage. Another patient in this series had a recurrence at 13 years and was also described in a case reported by Winters et al. ¹⁶

Table 3 summarises the symptoms and outcomes across the clinical features present at treatment failure prior to second stent insertion. Overall, following the second stent insertion a clear majority of patients (83.3%) did not require any further intervention at latest follow-up. Although there is insufficient clinical follow-up data for one patient, four patients (22.2%) reported complete resolution of all symptoms at most recent follow-up and there was a reduction in headache to 72.2% of patients with only three patients with recurrent papilledema requiring either shunting or a third stent and one patient with persistent high pressures currently under consideration for shunting. Headache can persist in patients with IIH despite treatment of sinus stenoses, and it has been hypothesised that this may be due to allodynia from dysfunctional pain modulation in sensitised meningeal nociceptors resulting from chronic bouts of IIH headaches. ¹⁷ There are also often other headache syndromes identified in these patients such as chronic migraine that may persist concurrently despite normalisation of sinus pressures.^18,19 Persistent headache is thus notoriously difficult to treat in these patients. Despite this, the cohort of patients in this study demonstrates that repeat VSS can be an effective intervention for treating recurrent papilledema and avoiding irreversible blindness. Patients with IIH are commonly co-morbid and avoiding permanent optic nerve damage without resorting to surgical CSF diversion or optic nerve sheath fenestration is highly beneficial, particularly as this comes with its own host of complications.^20,21 Whilst there is no consensus on the optimal treatment for patients that represent with recurrent stenosis post-stenting for IIH, this case series demonstrates an overall majority of favourable long-term outcomes in performing repeat stenting with no major complications encountered. Furthermore, some patients may achieve cure of their disease without any recurring symptoms.

To our knowledge, the current study is one of the largest case series of patients followed for re-stenting after an initial stent for treatment of IIH. Despite this, the results of this study are limited by the small number of patients. Furthermore, there is incomplete follow-up data in one patient although at latest follow-up it was known that this patient did not require any surgical CSF diversion. The data on stent type and size was also not available in this study and the way this may have impacted outcomes could not be assessed. Further studies are needed with larger cohorts of patients to confirm the efficacy and safety of re-stenting in IIH and to elucidate the mechanisms behind recurrent stenosis. This could lend insights into optimal technique both at the initial stent insertion and with re-stenting to avoid recurrent stenosis.

Conclusion

This case series of post-stent IIH patients treated with a repeat sinus stent for recurrent symptoms and juxta-stent stenosis demonstrates favourable long-term clinical outcomes and safety of this approach for managing these patients in an area with limited evidence base to guide treatment.