Multidisciplinary Management of Cerebrospinal Fluid Leaks and Idiopathic Intracranial Hypertension (Podcast)

Cerebrospinal fluid (CSF) leaks can be underrecognized and present in a variety of ways, but their occurrence can cause debilitating symptoms and increase the risk of severe infections, such as meningitis. For this reason, it’s important to maintain a high index of suspicion, using advanced diagnostic tools and imaging, and collaborating across specialties to provide comprehensive care. A recent episode of Head & Neck Innovations podcast focuses on the evaluation and management of cerebrospinal fluid leaks, particularly those involving the lateral and anterior skull base.

The episode features insights from Edward Doyle, MD, an otolaryngologist and neurotologist specializing in skull-based surgery, and Varun Kshettry, MD, a neurosurgeon specializing in minimally invasive skull base surgery. Both describe how CSF leak management often requires collaboration among neurotologists, rhinologists, neurosurgeons, neuroradiologists, ophthalmologists, neurointerventional specialists and other team members.

“With spinal fluid leaks, if they occur into the sinus cavity, I work with rhinologists, and if they occur into the middle ear, I work with neurotologists, like Dr. Doyle,” says Dr. Kshettry. “I would mention that actually the vast majority of these patients initially present to our colleagues in otolaryngology because of ear or sinus symptoms, and it's actually quite uncommon that their primary presentation would be a neurologic symptom and present to the neurosurgeon.”

CSF leak causes and presentation

CSF leaks typically fall into three categories: traumatic, often occurring after a fall or motor vehicle accident; iatrogenic, following previous sinus, ear or skull surgery; and spontaneous, which is often associated with the thinning of the skull base. Dr. Doyle says that his patients often present after developing progressively worse hearing loss.

“It seems like they have fluid behind the ear, and from a primary care perspective, that's where the problem kind of stops,” he explains. “If they get sent to another otolaryngologist, normally what happens is a tube is placed at some point, and they think that the tube is infected or they've been treated for recurrent infections of the tube that was placed. So, if we see them and it seems consistent with a brain fluid leak, where it's just clear drainage from the ear, oftentimes the patient will say their pillow is wet at night.”

However, in rare cases, patients may present with meningitis or seizures if brain tissue has herniated through a skull base defect.

“Iatrogenic and traumatic presentations tend to be a little more obvious, but the spontaneous patient population that mimics eustachian tube dysfunction or allergic rhinitis, these can be more difficult to diagnose,” says Dr. Kshettry. “But when the index of suspicion is there, we want some sort of confirmatory test, and the main test that we will get is a beta-2 transferrin, which is highly sensitive and highly specific for cerebral spinal fluid. In cases where there's a high index of suspicion, we may often repeat that a second or even a third time. We also want to get high-resolution imaging of the skull base to get great views at those thin areas of bone.”

In addition to covering CSF presentation and diagnostic strategies, the episode also discusses:

• Surgical repair strategies
• Cleveland Clinic’s approach to pressure assessment and risk stratification
• Emerging role of GLP-1 receptor agonists
• Prevention and vaccination
• The value of multidisciplinary, collaborative surgical approaches
• Advancements in imaging and diagnostic testing
• Idiopathic intracranial hypertension as an underlying cause of spontaneous CSF leaks

Click the podcast player above to listen to the episode now, or read on for a short, edited excerpt. Check out more Head and Neck Innovations episodes at https://my.clevelandclinic.org/podcasts/head-and-neck-innovations or wherever you get your podcasts.

Excerpt

Paul C. Bryson, MD, MBA (podcast host): As you look ahead, it seems like this is a pretty dynamic space. There are some traditional things that you described, but clearly imaging has gotten better. What other sort of innovations do you foresee or are you experiencing now with how you are managing CSF leaks? It sounds like maybe in the idiopathic intracranial hypertension space, you're pretty familiar with all of that, but maybe in that particular category?

Dr. Doyle: I think the multidisciplinary nature of this problem has become much more prevalent, or that we know more about it and how to use various members of our team. I think consultation with our dietitians, as far as weight loss as a management option for idiopathic intracranial hypertension, can be a really impactful part of this. With the advent of new medications for the treatment of obesity, I think that has had an impact and will continue to have an impact on this problem going forward. But I think that the most important part is working together as a team for treatment from an idiopathic perspective,

Dr. Kshettry: I can discuss a little bit about IH. So just for those who might not be familiar, this is increased intracranial pressure and increased spinal fluid pressure. The other term often used is pseudotumor cerebri because historically it might mimic somebody who has increased intracranial pressure from a tumor, but there's not actually a tumor. It's a spinal fluid issue. There's an extremely strong association with severe obesity, and that's why in the U.S. we've seen an increase in the prevalence of IH. The mechanism, simply put, is thought to be that obesity will increase venous pressure, and in particular, the jugular veins draining blood from the brain are transmitted intracranially to the venous sinuses. and the normal CSF reabsorption into the sinuses occurs through arachnoid granulations into the venous sinuses. So, when there's resistance for that CSF to get reabsorbed, the CSF doesn't, and that causes an increase in pressure in the brain.

Unfortunately, that increased ICP further compresses the venous sinuses. So venous sinus stenosis is seen in about 95% of people with IIH, and it's more of a functional stenosis that occurs. This then has negative feedback where the increase of that venous stenosis causes an even worse increase in venous pressure and even less CSF absorption. So, it becomes a negative cycle that leads to this increased pressure…

As Dr. Doyle was saying, a lot of the focus is to try to diagnose whether this patient has IH that probably caused this leak. So, at Cleveland Clinic, we developed and have been using this algorithm for the last eight to 10 years, where we actually measure the spinal fluid pressure at the time of surgery. We devised a three-risk profile from low-, intermediate- and high-risk based on what the intraoperative pressure was. We feel that when people are above 30 centimeters of water, they fall into this high-risk category, and if we don't address the IH, they're very likely to leak again from the same area. Or we sometimes see a few years later, they spring a leak in a totally new area. Now, some patients, because they're leaking, we worry that this is a falsely normal pressure. So, part of the algorithm is often a recheck of the pressure in about six weeks to see whether the pressure has gone up now that the leak has been sealed.

We use that to diagnose and figure out how we're going to treat, whether a patient has IH as Dr. Doyle was mentioning, and this is where we work with our dietitians and bariatric specialists and metabolic health specialists to look at weight loss. There are a couple of medications that can have some very minor effects to decrease spinal fluid production, like topiramate. Coming back to the venous stenosis side of the equation, we can actually treat patients with an invasive procedure to stent the venous sinuses open, and that's shown to significantly help the intracranial pressure in patients with IIH. And then we always have options that we've used for many years that's CSF diversion, such as a ventriculoperitoneal shunt that can be very effective to decrease pressure. However, shunts are basically plumbing systems, and like any plumbing system, the tubing can clog. So sometimes those can result in the need for multiple procedures over one's lifetime.

Lastly, I would mention there is interesting new research happening within the space on GLP-1 receptor agonists. So GLP-1 receptor agonists, of course, we know that they can be very effective for weight loss, and even just 10% can have a dramatic effect to reduce intracranial pressure. However, new research from the last couple of years shows that some of these medicines have had a direct, immediate effect at reducing intracranial pressure. So, the choroid plexus of the brain, which makes spinal fluid, has been shown to have GLP-1 receptors, and when activated, it actually causes it to reduce the production of spinal fluid. And there were a couple of studies in the last couple of years that showed that even within six hours of administering a single dose of a GLP-1 and at 24 hours, intracranial pressure can reduce by five to six points, and that pressure reduction is sustained even at three months, whether or not the patient has any weight loss.