By Andrew G. Lee, MD
This “Point Counter-Point” article published in December in the Journal of Neuro-Ophthalmology describes theories regarding idiopathic intracranial hypertension (IIH) and transverse sinus stenosis (TSS) and presents arguments in support and opposition to cerebral venous stenting for IIH. While it remains unclear if TSS is the cause or effect of IIH, the possibility of an alternative to the current surgical interventions of a cerebrospinal fluid (CSF) shunting procedure or an optic nerve sheath fenestration (ONSF) is certainly tantalizing, given their well-known complications. A clinical trial for venous sinus stenting that is ongoing may provide more insight into this new treatment.
Authors Rebekah Ahmed, MBBS, and G. Michael Halmagyi, MD, FRACP, present the case in support of stenting for TSS in patients with IIH. They note that when maximum medical treatment (e.g., weight loss, acetazolamide, furosemide and topiramate) fails in IIH patients, invasive treatments, such as ONSF or CSF shunting, are often recommended. However, they say that although these can be effective initially, they can also have significant complication and failure rates. They propose stenting a transverse sinus in IIH patients unresponsive to maximal medical therapy, who have stenosis of a dominant transverse sinus or stenosis of both transverse sinuses, as a viable and effective alternative to CSF shunting procedures.
They say that by stenting just one transverse sinus and providing a normally functioning sinus, venous pressures are lowered and papilledema resolves in IIH. In a study they conducted, although 13 percent of patients required a repeat stent, they say this is a significantly lower rate than the current failure rate of CSF shunting.
They suggest a dynamic positive feedback cycle involving high intracranial pressure (ICP) causing stenosis/collapse of the transverse sinus, which causes venous hypertension and in turn decreased CSF absorption and increased ICP. By preventing TSS with stenting, the cycle is blocked, regardless of whether TSS or an initial increase in ICP started the process. The authors suggest high-resolution MR venogram or CT venogram followed by cerebral venography with manometry if TSS is suspected, and propose stenting as a reasonable intervention.
In a counterargument, Deborah I. Friedman, MD, MPH, agrees that there is evidence to suggest an association between TSS and IIH but disagrees that stenting of TSS is currently a reasonable treatment for most IHH patients. She is concerned primarily about the lack of randomized controlled clinical studies to support stenting’s efficacy and the risk of the procedure’s potentially life-threatening complications, such as the intracranial bleeding, to treat a nonfatal disease.
In contrast, even though she finds the current surgical options of ONSF and CSF shunting suboptimal, she argues that they do not expose patients to the same risks, particularly in the case ONSF, whose main complications are vision loss and diplopia. She says that in the setting of continued vision loss after maximal medical therapy and accepted surgical intervention (ONSF and/or shunt), stenting could be considered only after there is proof from larger clinical studies that TSS resolves after lowering CSF and if an interventional radiologist with experience in venous sinus angiography and stenting is available with neurosurgical backup.