Dynamic nature of intracranial venous sinuses in idiopathic intracranial hypertension

Abstract

There is increasing interest in venous sinus stenting in patients with idiopathic intracranial hypertension who are refractory to medical therapy. Often the transverse sinus stenoses are bilateral, however, and there is no clear evidence for whether we should stent one or both sides in these patients. Our practice is to first stent one side, and in this brief case report, we demonstrate complete resolution of the contralateral stenosis in one such patient who underwent stenting. Her symptoms also completely resolved, and so this case highlights the dynamic fluctuant nature of the transverse sinuses.

Introduction

Idiopathic intracranial hypertension is a relatively rare condition which is probably under-diagnosed. As a result of increased cerebrospinal fluid (CSF) pressures, it can lead to chronic debilitating headache, papilloedema and even vision loss. There are certain imaging features associated with idiopathic intracranial hypertension (IIH), such as stenoses of the transverse venous sinuses. Many centres are performing stenting of the transverse venous sinuses for patients who are refractory to medical therapy,¹ which is associated with symptom improvement in certain cases. Many of the patients have bilateral venous stenoses, and it remains unclear whether both sides should be stented in such cases. Our practice is to generally stent only one side and to reassess the clinical and imaging findings after some time before deciding on stenting the contralateral side. Here, we present a case highlighting why this may be sufficient in most cases.

Clinical case

A 37-year-old female presented with a clinical diagnosis of IIH refractory to medical therapy. Contrast-enhanced magnetic resonance venogram (MRV) showed severe narrowing of the transverse sinuses bilaterally (Figure 1). She presented with severe headache and papilloedema which was refractory to medical therapy. Her initial CSF opening pressure following lumbar puncture was 41 mm H₂O. Following discussion with the referring neurologist, she therefore underwent elective stenting of the dominant right transverse sinus (Figure 2). This was performed under dual-antiplatelet coverage (aspirin 81 mg and clopidogrel 75 mg once daily for three days prior to the procedure, with both continued for three months and long-term aspirin thereafter). Intra-procedural trans-stenotic pressure gradient measurement was performed under general anaesthesia, showing a drop of 25 mm Hg between the torcula (pre-stenosis) and the sigmoid sinus (post-stenosis). The stent (Wallstent 7 × 40 mm, Boston Scientific, Marlborough, Massachusetts) was deployed and did not require angioplasty before or after the procedure. The patient’s symptoms completely resolved shortly following the procedure. MRV performed six months later (Figure 3) shows right transverse sinus signal drop-out from stent artefact. A contemporaneous CTV showed that the stent was patent. Note, however, the marked interval expansion of the untreated contralateral left transverse sinus.

Figure 1.

CE MRV acquired at 1.5 T showing bilateral stenosis of the transverse sinus.

Figure 2.

Lateral intracranial venogram before (top image) and after (bottom image) stenting of the sinus stenosis. Note the significant delay in normal venous drainage secondary to the stenosis in the top image, which resolved post-stenting.

Figure 3.

CE-MRV acquired at 3 T showing signal drop out from the stent in right transverse sinus. A CT venogram confirmed that the stent was patent. Note, however, the dramatic increase in size of the contralateral transverse sinus (blue arrows).

Discussion

There is increasing interest in the intracranial venous system as it relates to conditions such as IIH.^2–4 Various groups have documented that transverse sinus stenosis can resolve after CSF withdrawal diversion procedures.^5,6 This case nicely highlights the nature of the intracranial venous sinuses, which are not fixed structures, but rather dynamic structures which can contract or expand depending on intracranial pressures. It also highlights the rationale for stenting only one sinus at a time in patients with IIH who are undergoing venous stenting. Repeat imaging and/or pressure gradient measurement a few months later can show a marked difference, as in this case.

Conclusion

The intracranial venous sinuses are dynamic structures, and while bilateral venous sinus stenoses are commonly found in patients with IIH, stenting of only one side may usually be enough to mitigate symptoms.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Supplemental material

Supplemental material for this article is available online.