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New Treatments for Subdural Hematomas

A new minimally invasive approach to treating subdural hematomas, pioneered by Dr. Jared Knopman, can spare some patients the risks of open surgery. Dr Jared Knopman discusses this latest advanced treatment for subdural hematoma and talks about how the specialists at Weill Cornell Medicine can use it to help patients.
New Treatments for Subdural Hematomas
Jared Knopman, MD
Jared Knopman, MD., is a board-certified neurosurgeon and interventional neuroradiologist who specializes in cerebrovascular disorders, including aneurysms, AVM’s, brain tumors, and carotid occlusive disease. He has expertise in embolization of aneurysms and AVM’s, carotid stenting/endarterectomy, and intra-arterial chemotherapy.

Learn more about Jared Knopman, MD

Melanie Cole (Host): Welcome to Back To Health, your source for the latest in heath, wellness and medical care; Keeping you informed so you can make informed healthcare choices for yourself and your whole family. Back to Health features conversations about trending health topics, and medical breakthroughs from our team of world-renowned physicians at Weill Cornell Medicine. I am Melanie Cole and today we are discussing new treatments for subdural hematomas, and my guest is Dr. Jared Knopman. He's a board certified neurosurgeon and interventional neural radiologist who specializes in cerebral vascular disorders, and he has performed more than 400 cerebral vascular procedures per year at Weill Cornell Medicine. Dr. Knopman, please first tell us what is a subdural hematoma?

Dr. Jared Knopman, MD (Guest): Hi, Melanie. A subdural hematoma is basically a build-up of blood or a blood clot that sits outside the brain, but under the covering over the brain, which is called the dura. And what happens is that blood clot can start causing pressure on the brain itself and is neurologic symptoms deterioration.

Melanie: How do they form?

Dr. Knopman: Generally subdural hematomas form after traumas, and the trauma doesn't have to be particularly severe. Someone may hit their head, someone may take a small trip and fall. They generally form as we age, and that's because the older we are, the more our brain shrinks away from the dura, that covering over the brain. And as that potential space enlarges, it becomes at risk for bleeds or things to build up in that space.

In addition as we age, we end up taking medication for other reasons, such as aspirin which is good for us, but it can help thin our blood. And if someone has even a minor trauma and bleeds a little bit into that potential space, if their blood is thinned a little bit from something like aspirin, that bleed can become bigger.

Melanie: Then who are the subset of people that are at risk? And you mentioned people that take aspirin, so that might include people that are on blood thinners or other medications that might thin out their blood. Tell us about the risk factors.

Dr. Knopman: That's right. People on blood thinners or aspirin certainly are at risk, but really the main portion of the population at risk is the older portion of the population. As we age and our brain begins to shrink away, anybody can technically be in this risk pool. And subdural hematomas are projected to be the most common neurosurgical pathology by the year 2030, precisely because we have an aging patient population.

Melanie: Wow, so is this considered an emergent condition? What are some of the complications and what symptoms would someone experience to alert them that they need to get in to see a specialist? And who would they go see?

Dr. Knopman: So a subdural hematoma can present with a wide spectrum and range of symptoms. They can occasionally be emergent, but the vast majority of them are more of what I would call urgent, and what I mean by that is that they can build up slowly over time, and somebody may develop symptoms as mild as just headaches or not feeling right. But as they enlarge, as they continue to press on the brain, symptoms can also progress. Things like gait problems or speech problems, cognitive problems, weakness on one side of the body, even a seizure. These things may slowly develop over time.

In the rare instance when somebody has a major trauma and that subdural hematoma is fresh and acute, that can be an emergency. But the vast majority of people who present with subdural hematomas are more of the sub-acute or chronic type, those that have built up over the course of weeks to months. And that can, as I said, be progressive and insidious, but oftentimes you have the time to intervene in a safe fashion. If someone has a subdural hematoma, the first person they want to see is a neurosurgeon, someone who specializes in it, because there are lots of different forms of treatment that range from the conservative to the invasive, and now everything in between.

Melanie: Then how would you go about diagnosing it?

Dr. Knopman: So you diagnose a subdural hematoma really with brain imaging, and that can be a CAT scan or an MRI. It's a non-invasive quick test, and it tells two things. One, what is the size of the hematoma, and where is it located? And two, how old is it? When did it form? We're often able to tell in these images if it's formed within the last few days or the last few weeks or months, and then after speaking to patients you may find in their history that they recall maybe tripping or falling or hitting their head during that time period.

Melanie: So then what would you do? What comes next, Dr. Knopman? Are there non-surgical interventions that may be tried first? Medicational perhaps? What's the first line of defense?

Dr. Knopman: Absolutely. A small subdural hematoma that's not causing a lot of symptoms we traditionally treat conservatively. Sometimes we will try a low dose steroid for a week or two, anti-cholesterol medications have been shown in one study to help subdural hematomas heal on their own, and really the tincture of time can help. Naturally a subdural hematoma which forms when a little draining vein in that potential space ruptures, as long as that doesn't continue to bleed or enlarge, the subdural hematoma will naturally melt away on its own. The body will resorb it.

So for a small subdural hematoma that's not causing a lot of symptoms, we'll try to give the body that benefit of the doubt and see if that subdural hematoma can get resorbed. But for larger hematomas that are causing significant symptoms, surgery or drainage of the blood either by making a small window in the bone and evacuating blood, or by putting a small burr hole in the bone and draining the blood that way, that has typically been our mainstay traditional treatments for the last fifty years for larger and more symptomatic or progressive subdural hematomas.

And obviously I'm looking forward to discussing with you our new forms of treatment that we're pioneering here at Cornell that are not nearly as invasive as what we've been doing for the last half century.

Melanie: Well you got to my next question right off the bat, Dr. Knopman. So patients with subdural hematomas previously had required major open surgery. You explained a little bit about the standard of care, so speak about what's different now and what you're doing at Weill Cornell Medicine.

Dr. Knopman: So yeah exactly, as I said the standard of care has typically entailed surgery, and any of us who operate on subdural hematomas find at the time of surgery that there's always mixed ages in the blood in many patients. That although someone may have fallen two months ago, or a month ago and they have evidence of pulled hemorrhage, there's also evidence of new hemorrhage, even if the patient didn't sustain another fall or another trauma, and that always got us a little bit curious as to why subdural hematomas have what we call mixed acuity blood products.

And in addition, at the time of surgery, the subdural hematomas are surrounded by a membrane, and that membrane is very oozy and friable, and at the time of surgery we do our best to cauterize it. But it got me thinking that a lot of these subdural hematomas, after they form, they begin to re-bleed because they've generated this oozy vascularized subdural membrane around them. And if there's a way to intervene on that membrane in a different fashion, we can change the natural history of subdural hematomas and help prevent them from having those re-bleeding episodes.

As I said before, the natural history of a subdural hematoma if it doesn't bleed again is that the body will resorb it. So our theory is that the reason why in many patients’ subdural hematomas don't get resorbed is because they begin to feed themselves. They create a vascular network through the subdural membrane that causes these spontaneous re-bleeding episodes, and that accounts for the mixed acuity blood products and the refractory nature of them, the fact that they don't go away on their own.

Melanie: So speak a little bit more about your embolization procedure, and how it might spare prolonged recovery times. What is it like for the patient?

Dr. Knopman: So in seeing that these membranes formed, and in seeing that these subdural hematomas wouldn't naturally go away on their own, we devised a procedure to minimally invasively shut down the vascular supply to the membrane. And what's nice about it is that we've been doing procedures similar to this for other pathologies in the brain for a very long time. We've never applied it to subdural hematomas. So what I started doing at Weill Cornell was going in through a small needle stick in the leg, navigating a small catheter up into the vessels that feed the dura - that membrane over the subdural hematoma - and shutting those membranes down by injecting small particles, and this procedure is called middle meningeal artery embolization.

It's nice for multiple reasons. First of all, the procedure can be done without general anesthesia, which is a very important facet when you're treating patients who are seventy, eighty, and even older. General anesthesia has associated risks- associated things such as bed rest, and sedentary post-operative courses. By doing the procedure on someone who can stay awake and is otherwise quick and painless, recovery after that procedure is much faster.

In addition, given the fact that we can go in through just a needle stick in the leg, we're able to spare the patient an open surgery or an operation. The older we get, the less our brain likes to be exposed to the natural environment. So if we can spare open surgery in a seventy or eighty-year-old patient, it goes a huge way towards post-operative recovery.

The procedure is safe and what we've now found doing it over the last year and a half, roughly 100 patients, is that it's highly effective as well. We've been able to avoid surgery in over 90% of patients who traditionally up until we began doing this procedure would have met criteria for traditional open surgical techniques.

Melanie: As these patients tend to be older, Dr. Knopman, what's the long-term outlook for them? And after the procedure, are they concerned that this could be a recurrence? Or are they always worried about certain symptoms? Speak about the recovery period.

Dr. Knopman: The recovery period is generally very quick after this. After the procedure is done, I observe the patient in the hospital for a day, and then they go home. There's basically no recovery because it's just a needle stick in the leg, so there's no post-operative pain, there's no swelling, there's no incision, there's no scar, and if there's been no anesthesia used, there's no need to metabolize that anesthesia out of the body. So the recovery is quite quick and painless.

In terms of recurrence, we're always concerned about subdural hematoma recurring. Of all the types of brain hemorrhage, subdural hematomas are the most likely to recur, and if you look across a wide spectrum population, that recurrence rate is on the order of about 10% to 15%, even with surgical treatment. What we've thus far seen in our embolization patients, although it's quite early, is that we haven't had any recurrences. And in fact, we're even applying the embolization technique to patients who need surgery because their subdural hematomas are too big, and what we've found is that by doing the embolization around the time of surgery, we've actually been able to thus far prevent recurrences as well.

So we believe that we're affecting the natural history of subdural hematomas on multiple fronts. In certain patients, we're able to avoid surgery altogether, and in other ones, those patients whose subdural hematomas are too large and their symptoms are too severe and they need the benefits of immediate surgery, we're utilizing the procedure as sort of a belt and suspenders adjunct to help prevent recurrences, and we're seeing efficacy in both these arms.

Melanie: Dr. Knopman, as you are a pioneer in this procedure, tell us a little bit about the learning curve. And you're teaching other neurosurgeons how to do this procedure. Speak about the learning curve for it.

Dr. Knopman: What I like about the procedure is that it's very safe. I specialize in doing minimally invasive procedures for generally pathologies such as brain aneurysms, and AVMs, and oftentimes those procedures carry inherently higher risks. What's nice about this procedure is that we're operating on the blood vessels that aren't actually in the brain itself, but outside the brain. So I think after adequate training, this procedure can really be picked up by lots of interventionalists because I think the learning curve is actually less than for some other more complex procedures we do.

The most important thing about the procedure is doing it safely, because we are doing these procedures on older people, and older people tend to have more plaque in their blood vessels, sometimes more tortuous access in their blood vessels, so being experienced in interventional neuroradiology is obviously a pre-requisite. But overall what I tell patients is that I can assure them their safety. Given that this is new, given that we're still studying the efficacy of this, and although we're highly encouraged by what we're seeing right now, we wouldn't ever say that the standard of care for subdural hematoma treatment is ready to be changed at this point after only 100 patients. But what we can say is that the procedure is safe. With a well-trained eye and with someone with good experience working on even more complex pathologies, this can be passed on and replicated across the country.

Since I've started the procedure, I've had about eight other institutions throughout the country reach out and ask how it's done, and what our protocols are, and we're sharing that now across the country so that other physicians can bring it to their regions as well.

Melanie: What about lifestyle for the patient after this procedure? Do they go through physical therapy? Do you want them to be involved in lifestyle changes? Speak about some of the other modalities that might be used post-procedure.

Dr. Knopman: Certainly physical therapy is an important part in anyone who has a neurologic pathology. A subdural hematoma, if it begins to cause neurologic deficits, may require that that patient then have some physical therapy to help speed up the improvement. The procedure itself, as I alluded to before, interrupts that vicious cycle of bleeding and re-bleeding, and at that moment the brain begins to re-expand as the blood is resorbed, but that resorption doesn't occur overnight. It can take a couple weeks for the blood to be resorbed. Once we've interrupted that cycle, the body then does naturally what it wants to do. But during that time period, physical therapy and certain lifestyle modifications can help speed up the recovery.

What's nice about subdural hematomas is that they don't tend to cause rapid neurologic decline. The decline is progressive and it's insidious, but it's not generally rapid. So patients have the kind of time needed to let the blood resorb on its own over time after the embolization, and physical therapy during that time period will certainly help keep them on their feet, limber, active, and preventing deconditioning while they're healing.

Melanie: This is a fascinating topic, Dr. Knopman, and what you've pioneered is absolutely tremendous. Wrap it up for us, what you would like listeners to take away from this, with your best information about subdural hematoma, the technique of embolization that you have pioneered, what you would like them to know.

Dr. Knopman: I think that subdural hematoma is and will only be an ever larger phenomenon in healthcare, and an extremely big both economic and health-related impact given the aging population. This is a particularly fragile and brittle population to treat, and subdural hematomas, which we've been treating the same way for fifty years, is inherently wrought with risks; risks of recurrence, risk of open surgery, and risk of an inherently fragile patient population.

I think what we're seeing with this new procedure is what I hope to be a real sea change in how we treat this, and I anticipate the standard of care will change. I'm extremely excited by what we're seeing. I think that we're helping patients avoid surgery at the outset, we're helping those who've had surgery and recurrent hematomas get treated again with a minimally invasive procedure, and we're adding this onto patients who need surgery to help prevent recurrences. And I think that this has the potential to fundamentally change the way we treat one of our most common and devastating neurosurgical pathologies.

Melanie: Thank you so much, Dr. Knopman, for joining us today, for sharing your expertise, and explaining so very clearly for the listeners about your procedure, explaining subdural hematoma, and so that we can all understand what's going on in the brain. It's absolutely fascinating. Thank you again for being with us. This concludes today’s episode of Back To Heath. We’d like to thank our listeners and invite our audience to download, subscribe, rate and review Back To Health on Apple Podcast, Spotify, and Google Play Music. For more health tips go to and search podcasts. Parents – don’t forget to check out Kids Health Cast!