Endovascular Shunts May Be Alternative for Idiopathic Intracranial Hypertension

My mentor, Charles Matouk, MD, chief of neurovascular surgery in the Department of Neurosurgery, was the first to implant the eShunt for patients with normal pressure hydrocephalus (NPH) in North America in 2022. So, we’ve been using this technology for a few years to treat that condition.

NPH is a neurodegenerative disorder that largely impacts people of an advanced age. It is characterized by three symptoms: urinary incontinence, gait instability, and cognitive decline. That collection of symptoms with large radiography ventricles, shown on brain imaging, is suggestive of the disease and the only treatment option in that case is a cerebrospinal fluid (CSF) diversion or mechanical shunting.

The mechanical shunt is essentially a catheter that lets excess CSF flow from the brain’s ventricles to another body compartment, most commonly the abdomen. We drill a hole in the skull and place a tube into the ventricle. The ventricles in NPH patients are very large which makes it easier for shunting and why it works so well.

eShunt could be the next step in treating these patients. It is an alternative treatment option that doesn’t rely on open surgery. Instead, we place a small catheter endovascularly, so the shunt is inserted through the femoral vein in the patient’s leg. We can run this smaller catheter through the vein to the collection of CSF near the brainstem and drain it or provide a new pathway for the fluid.

The fact that it’s a minimally invasive way to help these patients is huge because we haven’t really had another treatment until now. That is what brought us to the genesis of this study. We thought, if the eShunt is effective for NPH patients, could it be equally effective for IIH patients?

The pathophysiology of IIH is totally different from NPH. IIH is highly prevalent in women and those with obesity in their late 20s to 40s. It’s characterized by elevated intracranial pressure without an identifiable cause like a tumor or a mass.

Symptoms include severe headaches and impaired vision. IIH cases have more than tripled over the last 30 years, a trend closely associated with the rising prevalence of obesity, so we know that is a primary driver.

If IIH patients are candidates for surgery, the standard of care is very similar to NPH in that it’s a CSF diversion. For our paper, we were fortunate because we have a lot of experience at Yale with IIH, which is known in the neurosurgical community to be very difficult to treat via shunting for a couple of reasons.

The main reason is these patients tend to have very small ventricles and regulating the drainage can be difficult. Unlike NPH where the ventricles are very large, the IIH patients’ ventricles are slit-like because of the elevated intracranial pressure.

The very small ventricles can lead to more complications and the traditional shunts can fail even when they're successfully placed. Also, they must be revised quite often which requires more surgeries.

Initially we weren't sure if these patients would be candidates because the pressure is so high, and the ventricles are so small that the spaces where CSF could be are also very small. There are challenges with any mechanical shunt, but it tends to be more difficult with these slit ventricles which is what makes the eShunt such a game changer.

Using the eShunt has the potential to move IIH treatment from an open surgery to a standard interventional procedure. It could take place in our interventional radiology suite, and done completely through the femoral vein. There’s no incision in the skull. There's no incision on the chest or abdomen. It's all done through a groin puncture.

Although this is only a feasibility study and efficacy and safety have yet to be established, a less invasive approach could broaden treatment options and might represent a promising alternative for this debilitating condition. That’s why we’re taking a first stab to look at that in a rigorous way.