168. Understanding Vertebral Basilar Insufficiency (VBI): Symptoms, Screening, and Management

In this episode of the PT Snacks Podcast, host Kasey delves into vertebra basilar insufficiency (VBI), a condition affecting the posterior cerebral circulation. Aimed at physical therapists and PT students, the episode explains the anatomy behind VBI, its symptoms, risk factors, and how to screen for it effectively. Kasey highlights the importance of understanding VBI’s implications, potential triggers, and the role of physical therapists in identifying and managing this condition. The episode also touches on appropriate referral procedures and the limitations of traditional VBI tests. Listen in to enhance your knowledge and clinical skills regarding this critical topic.

00:00 Introduction to PT Snacks Podcast

00:15 Understanding Vertebra Basilar Insufficiency

01:33 Anatomy Review: Blood Supply to the Brain

05:17 Risk Factors for Vertebra Basilar Insufficiency

06:16 Identifying VBI in the Clinic

09:16 Diagnostic Tests and Safe Practices

11:33 Referral Guidelines and Patient Communication

13:52 Conclusion and Additional Resources

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Transcript

 📍 Hey guys. Welcome to PT Snacks podcast. This is Kasey, your host, and if you're tuning in for the very first time, what you need to know is that this podcast is meant for physical therapists and physical therapist students who are looking to grow your fundamentals in bite-size segments of time. Now, today's topic is going to be on vertebra basilar insufficiency, which while hopefully not something we see very often in the clinic, if it does come into the clinic, I hope that you see it. And if you need to brush up on what exactly to screen for, what to look for or just be exposed to it in the first place, there's no judgment here. This is what this episode is for, is really understanding what exactly is this so that we understand more of what symptoms we see, what makes sense, how to screen for it, and then what to do about it. So usually we see this in context of things gone awry when there are cervical manipulations, things like that. So we're just gonna make sure that we're all on the same page. Now, before we do that, if you've listened to this episode at least three times and you feel like it's. Been really helpful to me. If you wouldn't mind leaving a review wherever you listen to podcasts, that would mean the world to me. Uh, that really does help make the show grow. And for those of you guys who have already done so, I really do appreciate you. You've been very helpful. Thank you. But with that being said, let's dive into what exactly vertebral basilar artery vertebral bas insufficiency actually is. So when we are referring specifically to what this is, we're talking about an inadequate perfusion of the posterior. Cerebral circulation, and we will review a little bit of anatomy here in a second. But this is mainly supplied by the paired vertebral arteries that converge to form the basal artery. Another way you could define this would be where vertebral basal insufficiency or VBI, which I'll probably use throughout the episode just 'cause it's shorter. It refers specifically to a transient interruption of flow within the posterior circulation. It's not necessarily confined to a singular vascular territory. So when we're talking about posterior circulation, it does supply critical structures. The blood supply, such as our brainstem. Thalamus, hippocampus, cerebellum, occipital lobes, and medial temporal lobes. If we see a disruption in blood supply, then you'll want to go back to when you learned about the jobs of these structures, to think about what symptoms would be associated with those areas in particular, not getting the supplies that they need to. So we'll cover that here in a second, but I want you to go ahead and think about that now. Now let's review a little bit of anatomy. 'cause it's not every day we, uh, in orthopedics at least review all the blood slide supply to the brain. But in most, the vertebral arteries arise bilaterally from the subclavian arteries. Remember, artery away, oh, flows away from the heart the right common carotid or c, CA and right subclavian branch from innoforaminate artery or brachiocephalic artery. And in the left common carotid and left subclavian arise from the distal aortic arch. So I want you to picture from here, we're going up to the brain. That branch, they travel through the transverse foramina, which is a very specific and unique feature of the cervical vertebrae. These function as basically protective funnels for the vertebral arteries as they travel to the cranium. The vertebral artery can be split into four regions V one through V four, and this just is named by anatomic regions. So V one is gonna be from subclavian to transverse foramen of the C six V two is from the transverse foramen of C six to C one. V three is between sulcus and frame and magnum, and V four is the intradural segment. So at. At this point, the vertebral arteries are gonna converge at the ponto medullary junction to form the basler artery, and this is gonna be on the ventral surface of the pons and then bifurcate into posterior cerebral arteries or PCAs. So this area is gonna rise to some major branches. We have our posterior inferior cerebellar artery, or PICA. This is gonna supply the inferior cerebellum and lateral medulla. Our anterior, inferior and superior cerebellar arteries also supply our cerebellum and the brainstem. And then we already mentioned our PCAs, but this is gonna supply the occipital cortex and the inferior medial temporal lobes. Now, I said intentionally at the beginning in most people, when I was talking about the normal path. Of these arteries, but there are anatomic variations in up to one third of the population. So something to keep in mind. Now, we've reviewed our blood supply to the brain, but let's talk about who even gets this in the first place. Why is this something that people have or another way of thinking of it? Why doesn't everybody get this? So let's talk about some risk factors on why people might be more prone to develop insufficiency in these arteries. So most common risk factors would be smoking, hypertension, diabetes, mellitis. These are common risk factors in a lot of different health conditions, but it's also more common in males patients who have a family history of vascular disease. Hyperlipidemia, decrease arterial elasticity if they have progressive arteriosclerosis. So essentially. There can be several causes with this. There can be hemodynamic causes or reduced perfusion, and then embolic mechanisms of this. Now how do we identify this in the clinic because. Oftentimes in PT school, we'll learn about a whole VBI screening test. And then if you've been paying attention in discussions lately about these tests, a lot of people have doubts on whether these are actually efficient or not. Here, let's talk about just what symptoms that we are thinking of for this. And also some ways to really dive into, okay, is this VBI or is this just another condition that this person has? And then what we do about it. So in up to 5% of adults over the age of 60 years old, they can have dizziness with VBI. If they have VBI. Now here, I don't want you to think everyone who has dizziness, who's over the age of 60 probably has VBI maybe. But many causes of. Dizziness are nonvascular in origin. So what we're looking for is dizziness associated with other brainstem signs or can be reproduced with cervical extension and rotation. And if we're thinking about the transverse foramen when we are putting someone's neck in cervical extension and rotation, that can also create a basically less space for the vertebral artery to move, so therefore causing decreased perfusion. Now there are some other things that can mimic VBI. So LABYRINTHITIS is one, vestibular neuritis, benign paraxial, positional vertigo, or BPPV. Again, as I mentioned, vertigo alone can't establish a diagnosis of VBI or some other sort of transient ischemic attack on the brain. But when accompanied with brain stem signs is strongly indicative. So we're talking to our patient. How can we ask better questions? So when we're talking about dizziness and vertigo, we're asking about if there's any sudden transient episodes that are worse with head and neck movements, not just purely positional like BPPV. Okay. Other things that we're looking at. Are there any bulber or brainstem signs like dysarthria, dysphagia, ataxia, bilateral limb weakness, numbness, syncope? These are things you should be asking people anyways if they are already coming in for any sort of dizziness. Uh, what's the pattern like? Are they short-lived spells that fully resolve? Are they often clustered That could suggest a transient ischemic attack or a TIA. These are all things to consider, but a combination of dizziness plus other brainstem or visual symptoms, especially provoked with cervical movement, is the strongest historical clue for VBI and should prompt medical workup. So what do we do about it? What. If you're suspecting this, probably not gonna put your patient at in range neck movements and extension and rotation. But there are some tests that can be done. So if we're talking about imaging, the gold standard is gonna be digital subtraction, cerebral angiography. However, CTAs, MRAs, and duplex ultrasonography can be less invasive. Our traditional vertebral artery functional positional tests or fts do have. Questionable diagnostic utility, so they're not always supported as reliable safety screens before manipulation for physical therapists. Safe practice around VBI centers around understanding posterior circulation symptoms or lack thereof, um, and being able to prioritize vascular focus history over reliance of vertebral artery tests. So, you're catching signs of dizziness, things that are provoked with head and neck movements, brainstem symptoms, things like that, that, that should clue you into a prompt referral for that patient. For suspected VBI issues and cervical manual therapy should be used cautiously. Now things that we can do objectively, we can do a neurological screen. You can look at cranial nerves, gaze, eye movement, speech, swallowing, coordination, strength, sensation, gait, and balance. These are all things that we can look at, especially if someone is complaining of these symptoms. We can observe her nystagmus, ataxia, dysarthria, um, especially if we're observing a symptomatic episode, if it's in clinic. I'm not saying to try and create a symptomatic episode. Now things like gentle mid-range cervical movements, if even those are reliably reproducing vertigo and a visual disturbance or other brainstem signs, then we may wanna be a little suspicious of a vascular radiology. So again, refer that's not really gonna be in our real house, but we can be very effective as physical therapists on helping those patients see the right provider. Okay. So urgent medical referral same day is what I'm talking about, is warranted if there are new or worsening vertigo and dizziness, plus visual changes, dysarthria, dysphagia, ataxia, bilateral weakness or drop attacks, particularly in an older or a high risk patient. I mentioned the risk factors before. So again, if this is happening with the patient in front of you, you're not trying to scare them, but you also don't wanna be like, oh yeah, I mean, I'm sure it'll be okay. Maybe just see it at some point. They're not gonna check it out. So being able to be like, Hey, these are some concerning symptoms. Could be totally nothing at all, but I really need you to check this out today. And if you do have a relationship with who you'd be sending them to help close the loop with them too and be like, Hey, I want you to watch out for this patient. I'm sending them your way. A more non-urgent example for a referral would be more of maybe they have recurrent unexplained vestibular visual spells in a vascular risk patient, but they're pretty stable over time. Maybe we don't need to rush right over to the er, but that is something where especially if they're coming to physical therapy for dizziness, they're gonna get more bang for the buck going to the right person. I know I've said it so many times, but I do feel like this condition can be very confusing and most of the time what we study are the positional tests in grad school. Without having an understanding of why are we asking the questions that we're asking, and what are we looking for, how can we be. Very specific and effective if we are suspicious of this. 'cause this is a big deal. And if you understand the why and still have a good understanding of your anatomy and what structures are gonna be affected by a disruption of blood flow, that's how you can feel more confident linking these symptoms together. 'cause it's often scary to. To be unsure and not want to send someone to the er without feeling confident about it. But I think it's better to be safe for your patient and make a fool of yourself than it is to protect your ego and not say anything. That's not what we're here for. All that to be said. If you have any questions, feel free to reach out at PTs Snacks podcast@gmail.com. Um, you can also reach out on Instagram, PTs Snacks podcast. I'm on threads. I'm learning how to use YouTube. So you might find me on there by the time that you listen to this, but I do want to add more of a visual component to what I'm talking about, especially with this because looking at the blood flow to the brain can be a little confusing. But all that to be said. Please reach out, especially if you have requests for future episodes. If you do wanna support the show, there is an option in the link too as well. Anything is appreciated, especially if you find that this is valuable to you. And then lastly, if you wanna take deeper dives and really any of these topics, med Bridge is actually offering listeners over a hundred dollars off their year subscription, which if you don't know who Med Bridge is, they have thousands of CCU courses that are all online. You can do them at your own convenience. There's webinars, there's specialty exam prep courses like for the SCS and OCS. And then some options even allow you and they even have a subscription level where you can put together an HEP builder for your patients. If you don't have anything like that, uh, where you can either print it off for your patients who like paper or you can give a QR code or an account to somebody who wants to watch the videos and be able to have access to those, they've got a ton of exercise on there. But you would just use the promo code, PT snacks podcast to get your discount or just check out the show notes and it's all right in there. But other than that, I hope you guys have a great rest of your day, and until next time, okay.