All right, we're going to get started now and finish up the morning. So, our next speaker is Susanna Skokalik. She is a nurse practitioner at Emory. She practices in mostly cerebrovascular, but just took on a new role and will be chief of advanced practice providers for the neurology and neurosurgery division at Emory. And so, her talk today is on cerebrovascular zebras. Good morning. I'm Susanna, and I'm very happy to be here with you guys. We're going to talk about cerebrovascular zebras, and so, I don't have any disclosures. So, when I was asked to speak about cerebrovascular zebras, I actually wasn't exactly certain. I know, we all know aneurysms and AVMs, but I went to my trusty and very reliable source and looked up what a zebra was in sort of the medical field, and the Urban Dictionary actually says that a zebra is an obscure illness, a disease, or a condition affecting a comparatively small number of people, but with symptoms somewhat similar to one or more different and more common illnesses. So, and I think that if you sort of look across a lot of different types of providers in neurosurgery, you probably get some different answers about what actually a zebra is, and depending on if you're in a center where you do a lot of cerebrovascular cases, that can kind of vary even within the group. So, I sort of pulled some of the folks that I work with, some of the surgeons and APPs that I work with, and this is a short list of what I came up with. We're going to talk about cavernous carotid fistulas, even though they're not technically carotid, because they're fistulas that are seen in practice, but not necessarily frequently, especially if you're not seeing a large population of vascular patients. I wanted to talk about bowhunter syndrome, because these are patients that typically are referred from spine surgeons or other neurosurgical practices, orthopedic practices, where a lot of times you're working your patient up, and the symptoms that they're describing of cervical disease just aren't all adding up, and so that's how we end up with a lot of these patients, working them up for bowhunters. And then finally, we'll get to spinal dural arteriovenous fistulas. So, I'm going to start with a case study. So, we'll start with a 46-year-old female. She presented to the ophthalmology clinic with complaints of double vision and some visual distortion. She first noticed binocular horizontal diplopia two months prior, and she described the diplopia in primary position that worsened on right gaze. She had resorted to wearing an occlusive patch to try to help control the symptoms, and three months prior, she noted the presence of a large blood vessel above her right eye, and she also reported a whooshing sound in her right ear for two to three months. Her past medical history was significant for a bike accident that had occurred four months prior. She sustained a small zygomatico-malar complex fracture, and she was seen in the ophthalmology clinic three weeks later, but she had no diplopia, no gaze restriction, and she had a normal eye exam. So, she was just going to follow up in a couple of months. The rest of her history, you know, she had a negative past surgical history, no family history significant to this, and then her only medications were Claritin. So, on physical findings, she had an abduction deficit in the right eye. She had full extracular movements on the left. Her pupils were both six millimeters, and she had no relative afferent pupillary defect. Pupillary pressure in the right eye was slightly elevated compared to the left eye. Her visual fields were full in both eyes, and then on the external exam, she had venous engorgement in the right upper and right lower lilids, and she had an orbital brui that was present over the right eye with a mild right eye proptosis. She had some conjunctival injection, but otherwise, her exam was pretty normal. And then her fundoscopic exam was also normal. So, this is what she looked like on exam, and the pictures on the left side show a right lateral gaze that the right eye has an abduction palsy. She's got some chemosis of the right eye kind of in the medial aspect, and then she's got some engorgement and some enlargement of the right upper lid, and it's hard to tell in these pictures, but she does have some mild proptosis as well. So, what is the diagnosis? This is a cavernous carotid fistula. And so, what are these fistulas? So, they're commonly, these fistulas are mistaken for other things like conjunctivitis, blepharitis, and basically, it's an abnormal connection between the venous cavernous sinus and the internal carotid artery or its branches, and it creates a short circuit of arterial blood into the venous cavernous sinus. It can be spontaneous, but typically, these are seen after head trauma, and the time to presentation can vary from one day to as late as two years. So, what do these look like? So, the picture on the left, figure A, shows the normal orbit, and then you can see above the eye, so above the eye, you'll see these dilated, the dilated superior ophthalmic vein, and then draining into the cavernous sinus, you can see the internal carotid artery and the external carotid artery. And I guess when I was starting practice, I always had a hard time sort of envisioning what the cavernous sinus was. I felt like it was like this elusive space that people talked about, and I just didn't really quite get it. But basically, the cavernous sinus, it's one of the dural venous sinuses, and it's a network of veins that sits in a cavity. It's about one by two centimeters in size in an adult, and it's surrounded by bone, the temporal and the sphenoid bones. And then through it run several of the cranial nerves, including cranial nerves three, four, the V1 and V2 aspects of cranial nerve five, and then the sixth cranial nerve as well. They kind of all pass through this space. There are different classifications of fistulas, and we're going to talk about them. So, type A, we use the baro classification of CC fistulas to talk about them. So, type A is where the internal carotid artery abnormally connects directly with the cavernous sinus. And these are typically what we call direct fistulas, and they're usually traumatic. Type B through C are the dural fistulas. And in type B, you'll have the dural branches of the internal carotid artery directly connecting with the cavernous sinus. Type C is the external carotid artery connecting directly with the cavernous sinus. And then type D has both the internal and external carotid arteries connecting directly with the cavernous sinus. So, the etiology and classification of fistulas, they're classified by etiology, whether they're traumatic or spontaneous. They're also classified by the velocity of blood flow. So, they can be high or low flow lesions. And they're also classified by anatomy. So, these can be direct, as we talked about in type A, or dural or indirect. And they can involve the internal and or the external carotid artery. So, with the first type that we'll talk about is type A, is the direct CC fistulas. These are most common after head trauma. And these traumas can be things like car accidents, falls, fights. These are probably the most common settings where these occur. And these can be penetrating or non-penetrating injuries. And they can also be associated with basal or skull fractures as well. These account for 70 to 90% of all the fistulas. And they have high rates of arterial blood flow. Most commonly, these are caused by a single traumatic tear in the arterial wall. And this can be from trauma or surgical manipulation. It can be an aneurysmal rupture. Or it can be spontaneous. And probably one of the more profound cases that I saw of this was a patient that I had seen. I had just been a nurse practitioner for not very long. And I went, I was told to go discharge a patient who presented and was transferred from an outside hospital with a giant cavernous aneurysm. And she was completely asymptomatic from this. So, we were going to just have her follow up in clinic. This was before the age of flow diversion and some of the endovascular treatment options that we have. So, I went to go and see her. And I had seen her a few hours earlier. She had a completely normal neurological exam. And I went back to go over her discharge with her. And I went to see her. And she said, you know, I have, I feel like I have a Phantom of the Opera mask on my face. And I said, well, you know, that's new. And so, we started talking. And I examined her. And it turned out she had a very subtle six nerve palsy also. And I called my attending and said, you know, she was completely normal. I was going to send her home. But what do you think? And sure enough, she had actually had an aneurysmal rupture of this giant cavernous aneurysm while she was in the hospital a few hours after I'd seen her. And so, she ended up going for endovascular treatment and had the fistula treated endovascularly. So, these things can happen. That was obviously a very kind of unusual and rare situation, but also very scary and one that I'll never forget. Because over the course of the time that I saw her and the time that we took her for intervention, her eye actually became rather large and proctotic. And it was quite obvious that something new and different had happened. So, direct CC fistulas, if they're left untreated, can cause ocular complications, proptosis, conjunctival chemosis. And visual loss are common with these, or can be common. Central retinal artery occlusions and secondary glaucoma are probably the most, the more severe complications, ocular complications that we can see with these. And then several studies have reported some very severe epistaxis with these fistulas, life-threatening intracerebral hemorrhages, and also subarachnoid hemorrhage, although that's much less common. Next, B through D of the fistula classifications, these are typically low, these fistulas have low rates of arterial blood flow. They are generally congenital. And they can occur spontaneously or they can be associated with other disease processes like atherosclerosis or systemic hypertension, collagen vascular diseases, pregnancy. They can occur during or after childbirth. And these typically affect middle-aged and elderly women, although they can occur at any age, including in infancy. With these fistulas, visual loss is much less common. And these can, the visual loss can be due to secondary ischemic optic neuropathy, central retinal vein occlusions, and uncontrolled glaucoma. Sorry. So, these patients often present as a very extreme picture of some of the findings, but patients can present with a mildly red eye or a very engorged and proctotic eye. They can have diplopia. They can have a brewy. And these are patients where you want to dust off your stethoscope if you haven't used it in a while. Many of us that work in neurosurgery don't often pull out our stethoscopes, but this is the case where you want to take it out and actually auscultate for a brewy. These patients also may complain of decreased vision, a bulging eye, and facial pain. Other problems that can be seen are proptosis. They can have eyelid edema. They can have ocular pulsations. And these can be visible, and I think once you've seen a patient with a fistula, like a symptomatic fistula, you probably will never forget it because it's quite obvious and profound. Patients can have pulsating exophthalmos. They can have what we talked about, ocular brewies. And actually, you can put the – when you're examining your patient, you can actually put the stethoscope over the eye, and you can hear the brewy. You can hear the whooshing sound, or you can put it in the temporal area as well and hear it as well. It's usually pretty obvious. You can get conjunctival arterialization and chemosis, exposure keratopathy, the dilation of retinal veins can occur. You can get optic disc swelling and intraretinal hemorrhages. And oftentimes, all the time, we will refer these patients for neuro-ophthalmology evaluation to really look at the eye and look for some of the other findings, central retinal vein occlusions, to check for intraocular pressures, and then to look for neovascular angle-closure glaucomas. So these – fistulas can look like other things. They can look like a thyroid ophthalmopathy. And kind of the distinguishing feature with this is with a thyroid ophthalmopathy, these findings are typically symmetric and bilateral, whereas with the CC fistula, these are unilateral lesions. But it can also look like conjunctivitis. It can look like blepharitis. It can look like allergies and kind of the – like just kind of an allergic environmental reaction. Or it can look like somebody, you know, had an irritant to the eye. So sometimes it's not as obvious until the symptoms actually become more progressive. How do we diagnose these fistulas? So a CT scan of the orbits and the head is kind of our first start. Ophthalmology will do orbital echography to help confirm the diagnosis. And this sort of helps look at the enlargement of some of the extraocular muscles. It also looks at – it can show dilation of the superior ophthalmic veins and enlargement of the cavernous sinus. But we also use MRI and MRA to help diagnose these lesions. And then cerebral angiography, that's sort of the definitive diagnostic test to look at diagnosing these lesions. This is preoperative CT imaging of the orbits. And you can see the image on the left shows – it's an axial image that shows a prominent proptosis. And you can see sort of about a 3 millimeter difference between the right and left eye. And then in the second image on the right, you'll have – you can see actually the congestion. It's sort of marked with the arrows on the right. Congestion of the extraocular muscles due to venous stasis in the left orbit. So you can see enlargement there. This is an MRI. Looking at the arrow pointing to enlargement of the superior ophthalmic vein right here. And then in this other image, you can actually see the fistula on the right. And then this is a left internal carotid artery injection angiogram. And it shows the direct CC fistula with drainage into the sigmoid sinus, which is this arrow right here. You can see drainage of the fistula from the superior ophthalmic vein and the inferior ophthalmic vein sort of draining into the fistula sac. So, these lesions can sometimes be managed medically, and typically we engage, as I've said, the neuro-ophthalmologists or general ophthalmology. In our institution, it's always neuro-op, though, and they help us sort of manage some of these things, but you can treat the exposure keratopathy. And these can be treated with things like ocular lubricants, ocular lubricating drops, taping of the eyelid at night, especially if the lids don't close or if they only close partially. And then in kind of more severe cases where the lids don't come together at all, we'll engage them to do a tarsor hephae to actually suture the eyelids closed so that the eye remains lubricated. Glaucoma can be, may require treatment with, if the patient has increased intraocular pressures, and we can use oculus suppressants and hyperosmotic agents to do that. And then there are a whole group of sort of different procedures that our neuro-ophthalmologists can perform, the laser peripheral iridectomy to eliminate the contribution of the pupillary block. You can use cycloplegic agents, laser iridoplasty, and then pan-retinal photocoagulation in patients with glaucoma to try to reduce the risk of any vitreal hemorrhages or retinal detachments. So, the optimal treatment of the direct cavernous carotid fissile is actually closing the abnormal connection between the artery and the vein and trying to preserve the patency of the internal carotid artery. And then different techniques that we can use to do that include surgical repair of the portion of the intercavernous internal carotid artery, or embolizing the connection endovascularly or actually using balloon occlusion to close that connection. You can see in this picture, the cavernous sinus here and the internal carotid artery running through it. And then in the kind of enlarged photograph over here, the actual connection between the cavernous sinus and the internal carotid artery. So, the goal is to kind of eliminate that abnormal connection. Dural carotid fissionalis may close spontaneously. For those lesions that continue to cause progressive or unacceptable symptoms, standard coil embolization or endovascular balloon occlusion is generally what we perform. I've actually not seen any open surgical treatment for this, at least not in my practice. Most of it is endovascular. And so, this is the follow-up angiogram after transarterial embolization which shows complete occlusion of the cavernous carotid fistula. So, the prognosis for these lesions, the direct CC fistula is when they're treated, they rarely recantilize. With the dural fistulas, it's important to have close follow-up and most of the time that involves follow-up with ophthalmology to check ocular pulse amplitudes. And typically, most of these patients are healthy at six months. Patients, when they're treated, they actually report improvement of ocular bruise, the ocular pulsations and the thrill almost immediately. These patients wake up and they say that horrible sound is gone. I feel so much better. And then the other sort of ophthalmological findings sort of take a bit longer to improve. Sometimes they improve right away, but most of the time, things like the engorgement of the eyelid, chemosis, some of these dilated vessels, the disk swelling and the elevated intraocular pressures can improve over a period of weeks and months. And then the direct CC fistula is like the visual loss, the ophthalmoparesis and the proptosis may or may not return to baseline. But if they do, they usually return to baseline over a period of weeks and months. So, that sort of covers CC fistulas. And so, we're going to kind of shift and talk a little bit about Bowhunter's syndrome. So, what is Bowhunter's syndrome? Have you all heard of Bowhunter's? Anybody in the audience? Everybody? No? Okay. All right. Good. So, it is a zebra maybe. So, Bowhunter's is actually a rotational vertebral artery occlusion syndrome. And it's a rare form of vertebral basilar insufficiency. It's secondary to dynamic compression of the vertebral artery. And it's usually the dominant vertebral artery. The vertebral basilar insufficiency typically is induced by voluntary rotational head movements causing intermittent vertebral artery compression. And it typically happens most commonly at the atlantoaxial level. Although the term stroke is used throughout the literature to refer to the condition, Bowhunter's typically encompasses sort of a wide array of hemodynamic insufficiency, anywhere from TIA type of problems to actual stroke. So, it's an extremely rare syndrome. It's mostly limited to case reports. And the first description was actually made by neurosurgeon Sorensen in 1978. He had a patient with a right hemiparesis and sensory deficits that were discovered during archery practice when he rotated and turned his head. And in this patient, this patient was treated conservatively. But as the name implies, the patient was an archer. And he would become symptomatic. And the symptoms can occur on head rotation or extension. It has a lot of different predisposing etiologies. But most often, this is due to an osteophyte or some atlantoaxial hypermobility. Patients will present with symptoms of vertebrobasilar insufficiency. Symptoms like dizziness, nystagmus. They can have nausea and vomiting, vertigo, syncope, diplopia. They can have sensory motor disturbance, a Horner's, and dysphagia. And probably another kind of profound patient that I saw that I'll never forget was a patient that I'd seen 15 years ago in clinic came in with a cervical choleron. And he basically lived with this choleron all the time. And he said, if I turn my head, I will pass out. And I guess one of our medical assistants didn't believe him. So, she made him take his choleron off and sat him on the exam table. And literally before he got to the exam table, he had collapsed on the floor. And, you know, they called a code. And it was an unforgettable kind of experience. But literally, he would come to when his head was in primary position. And then he would pass out if he turned his head. And so, again, kind of an unforgettable thing. So, the classic presentation with bowhunters is rotational vertigo with horizontal nystagmus towards the compressed artery. The symptoms typically are transient, but not always. And the direction of the head rotation does not reliably predict the side of the vessel compression. So, you can see these patients actually can develop ischemic symptoms. And sometimes these are irreversible. They can have medullary and cerebellar infarcts. That's also described in the literature. So, this is just a drawing of the vertebral artery on the left. And the different segments are five segments that make up the vertebral artery. As it comes off of the subclavian, it's broken into kind of five different segments. And you have sort of the angiographic equivalent in the picture on the right. Typically, the vertebral artery comes off of the subclavian. It traverses the cervical spine until it sort of comes together to meet its counterpart vertebral artery on the other side, joins together, and joins to form the basilar artery up above. So, some of the mechanics with bowhunters. So, this is a lateral view of motion at the atlantoaxial joint. In figure A on the left, you can see that the joint is in neutral position. And the vertebral artery here is nice and wide open. The picture in B, the next picture, is actually with 10 degrees of rotation. And you can see that the artery starts to sort of become stretched. And then in figure C, this actually shows the artery with 20 degrees of rotation. And so, the vertebral artery progressively narrows with rotation. The most common kind of inciting factor is cervical spondylosis, although there have been other causes such as like surgical fixation, chiropractic manipulation, and rheumatoid sublux also. And then also, other causes are things like fiber spans or thickened atlantoaxial membranes that can also contribute to the condition. So, a detailed history and a physical exam is critical. It's essential to identifying and excluding alternative diagnoses that may lead to posterior circulation ischemia. So, some of the mimics for bowhunters are things like vertebral artery dissection, vasculitis, reversible cerebral vasoconstriction syndrome, mitochondrial encephalopathies can look like this, lactic acidosis, and then stroke-like episodes, as well as subclavian, steel, or cardiac, or paradoxical embolisms. So, you need a very high clinical suspicion to diagnose bowhunters. It's often delayed because you want to really rule out the more common causes of vertebral basilar insufficiency, things like atherosclerosis, or an emboli, or another like type of arterial dissection. If it's left untreated, the condition can lead to incapacitating strokes, ischemic symptoms, and posterior circulation infarcts. Once you suspect that the patient may have something like this, and a lot of times these patients are patients that are, as I said, they're sort of referred from either the community or other spine surgeons who have a patient that has all of the symptoms of, it could be, you know, spondylosis, or other kind of cervical findings, but then they have other symptoms that also don't kind of fit the picture. And so, they get referred to us to sort of look at other underlying causes, and this is when you sort of want to think of bowhunters as a possibility. Your diagnosis from here would move to noninvasive imaging, things like an MRI, or an MRA, and a CTA can be helpful in diagnosing. And you can also use ultrasound, although in some of the studies that I was looking at, it seemed like at least half of those determined to have bowhunters didn't have any dynamic occlusion on the ultrasound, even though this was the most commonly used preoperative imaging. If your suspicion is high, you can order a dynamic CTA or an MRA. And really, the gold standard of diagnosis is a dynamic angiogram. It illustrates the vertebral artery compression on head movement. And occasionally with these patients, the area of compression actually can be in more than one location. Why is it so rare? So, it's not the compression of the vertebral artery is necessarily rare, but most patients, because most patients actually get collateral flow from their contralateral vert. But for the compression to be symptomatic, the contralateral vert has to have something wrong with it. It has to be impaired in some way. And so, it can be impaired by a congenital absence, a hypoplastic vert. You can have previous injury there affecting the vert, a mechanical obstruction, or atherosclerotic disease. In the study by Lu, this was a series several years ago, and it looked at the different causes of vertebral artery compression. By far, the most likely cause was osteophytes. And then following that were fiber spans and herniated discs as a cause. Muscle hypertrophy and instability were also reported as causes of the compression. Location, location, location. It's very, very important because the location of the compression actually dictates the cause and the treatment. The classical definitions really focus on compression at the level of C1 and C2. And the occlusion usually occurs by stretching of the vertebral artery when the head is turned to the contralateral side. So, that's usually at C1 and C2. Or it can occur when the compression is, when the head is turned to the ipsilateral side. And typically, that involves below C2. So, bow hunters at C1, C2, so as I said, it's the vertebral artery contralateral to the direction of the head turn is occluded. So, if you're turning your head to the left, the right vertebral artery becomes occluded. And this is, again, due to the subluxation of the C1, C2 joint causing stretching of the artery between the foramen transverse area. And this picture here just sort of shows the vertebral artery kind of in a neutral position. And then with head turn, you can actually see the artery stretched. So, there was a neurosurgical review that was published several years ago that looked at the sort of treatment algorithm of bow hunters. And we've sort of talked about like the diagnostic portion of that and sort of working that up with non-invasive imaging and then with a dynamic angiogram. If you find that you have compression of the vertebral artery with instability, the algorithm sort of moves towards decompression, either anterior or posteriorly. If the compression is associated with instability, then we move towards a cervical fusion. And then if the compression is associated with a proximal contralateral stenosis, what the role of potentially endovascular treatment and stenting would have with that. And that's, we'll talk about that in a minute. And then in patients where the bow hunters or the compression is inoperable using medical management and medical adjuncts like anticoagulation therapy for treatment. Surgical intervention through the C1 and C2, using a C1, C2 fusion has been used. But it's restrictive, right? So, we permanently restrict neck movements and in order to try to prevent the vertebral artery from becoming compressed. So, obviously, it has a serious disadvantage of limiting range of motion. But it also lowers the risk of re-stenosis. And it removes the life-threatening risks of potential posterior circulation in farcs. So, with the compression without instability, surgical procedures like a decompression and using different approaches like posterior cervical approach or minimally invasive approaches to try to remove the causative either disc or the causative underlying reason. And this is just a picture showing a patient prepped for surgery in a left lateral decubitus position with exposure. We have a posterior cervical incision with exposure at C1 and C2. And you can actually expose the VIRT and see a bone spur, and then removing the bone spur at the time of surgery and taking the pressure off of the vertebral artery right here. So the treatment is almost, so subaxial bow hunters, which is below C2. The treatment is almost universally anteriorly done, and the surgeon will spend a significant amount of time to adequately decompress the VIRT from bone and fiber spans. And you can confirm the decompression with an intraoperative angiogram. Conservative treatment, the avoidance of sort of neck rotation using immobilization with cervical collars can be used. And some authors, you know, in some of the studies that I read, have reported successful remission of symptoms using these techniques. But it's obviously, you know, limiting and can affect a patient's quality of life. Medical adjuncts like antiplatelet therapy, antihypertensive medications, and or anticoagulation can also be used. And though conservative treatment does carry a risk of continued progressive symptoms that can interfere with quality of life or worse the development of, again, posterior circulation strokes. So finally, I know we're kind of rapid fire going through these. But so finally, the spinal dural arteriovenous fistulas are the last sort of cerebrovascular zebra I want to touch on. And these are abnormal connections between an artery and a vein located near the dura. These are also high pressure, high flow arterial blood flowing into low pressure, low flow veins. And these interfere with the normal spinal cord circulation producing symptoms. These fistulas are not directly on or within the spinal cord. But they nevertheless cause dysfunction by interfering with the normal spinal cord drainage of blood. And these can produce severe and sometimes irreversible problems. So as I said, these lesions, the shunting of these lesions is located on the dura. It's not in the cord or on the cord. It's at the level of the intervertebral foramen and the nerve root. And this shunt gives rise to a draining vein which follows the dura at the nerve root level. It subsequently reaches the perimedullar venous system. And then it causes symptoms of spinal venous hypertension. These fistulas are the most frequent vascular malformations of the spine. And they account for about 70% of all spinal vascular malformations. They can be solitary. Most of them are solitary lesions. And most of them are found in the thoracolumbar region. And about 80, more than 80% of them are located between T6 and L2. The etiology of these is unclear. These are typically acquired lesions. They can occur spontaneously. They affect people in the, mostly in the fifth and seventh decade of life. And they can affect men seven times more likely than women. They have an insidious onset. They do not hemorrhage. And the average time from the onset of symptoms to a diagnosis is somewhere between two and a half years. So oftentimes by the time we see these patients, they have had a progressive decline in their function. Many times they've already had lumbar or thoracic decompressions and fusions. And they continue to have progressively worsening symptoms. So they get referred to our center for additional workup. So the way that fistulas cause trouble is by preventing normal spinal cord blood circulation. And in this picture, you can see the spinal cord in the back. You can see the arteries supplying the fistula here. And then the veins right here. So the arteries go directly into a venous system. They create these kind of large swollen veins on top of the spinal cord. And then over time, these veins sort of dilate. And you can actually get these thrombus outlet veins. So actually drainage of the blood outside of the, out of the spinal cord becomes sort of backed up. Patients can develop venous hypertension. And then they begin to develop progressive neurological symptoms because the spinal cord isn't being perfused. And then over time, that situation continues to get worse. And patients eventually develop myelopathy. They can end up paraplegic. And they develop ongoing symptoms, or they can develop ongoing symptoms of sexual dysfunction and bowel or bladder dysfunction as well. So the time between when the fistula forms and when a patient develops symptoms is pretty variable. Patients can be initially asymptomatic. And they can have kind of initial symptoms of venous congestion. So they can kind of have wobbly legs or have some gait disturbance, maybe some off and on problems getting up the stairs. But later they develop, as the spinal cord edema develops, they can develop additional symptoms including lower extremity weakness. And this can be, usually it's an ascending symptomology. They can get back and leg pain. And it doesn't have to be just one limb. It can be both limbs and diffuse. They can also develop bowel and bladder problems, sexual dysfunction, and then sensory changes as well. So it's typical for this disease to go un- or misdiagnosed for a long time. And you should have a high level of suspicion if your patient isn't getting better after a decompression or a fusion. Education of providers and early recognition provide the best chance for optimizing recovery after treatment. As delaying the treatment significantly decreases the chance of a good outcome. So again, maintaining a high index of clinical suspicion when you're talking with your patients and being careful not to label them as MS or myelitis of unknown etiology until you've really ruled out all potential causes. You want to know the limitations of noninvasive imaging. And you want to know the noninvasive imaging findings. The longer the diagnosis is delayed, the less the chance that the patient will recover post-treatment. So our imaging workup, typically the diagnosis rests on MR imaging, is guided by MR angiography, and is confirmed by diagnostic angiography. And angiography is the gold standard for looking at these lesions. And we use MRA with time-of-flight and time-resolved sequences to help guide the diagnosis and to help localize the shunting location. So the images that I have up here on the left, image A, it's a T2-weighted MRI. And you can see, well, it's kind of hard to see, but you can see the white here is the centromedullary edema. And then you get these sort of dilated vessels back here. You can see it a little bit better in this second image. You can see the sort of edema pattern in here. And then these sort of flow voids down below. The gold standard, as I said, for diagnosis is spinal angiography. And you want to start in the high lumbar and low thoracic areas. You want to look for delay of spinal cord venous phase off of the anterior spinal artery injection. And you want to continue all the way down. You want to image all the way down until all the anatomy has been covered. And as I said, MRA angiography with time-of-flight and time-resolved sequences allows localization of the shunting area. And then allows for a targeted angiogram. Sometimes these can be hard to find on angiography alone. So we use MR as an adjunct to the diagnostic workup. And again, you can see in this first image these sort of the perimedullary edema here along the cord and some of the flow voids here. And then in the third picture on the right is a spinal angiogram. And you can see the shunting zone is sort of demarcated by this asterisk here. And then you can see sort of the injected segmental artery that's supplied by the radiculo-meningeal artery, which is the main supply to the shunt up here. And then there's sort of additional ascending from a lower segmental artery with a small arrow that's filled via the longitudinal collaterals down here. So with the spinal angiogram, you want to make sure, as I said, to image all the way down. So you're looking at the bilateral verts, the thyrocervicals, the costocervicals, the intercostals, the lumbars, and the internal iliacs. And you want to make sure to include a long sequence for anterior spinal artery looking for a delayed venous phase. So indications for treatment. So all diagnosed patients should be treated. Palliation has no role for these fistulas. And you want to embolize with the goal of cure. So we use, most of these treatments are endovascular. And we'll use a permanent agent that's directed into the nidus of the fistula to kind of remove that abnormal connection between the artery and the vein. So, and then also, it's important that the embolic agent is also not just placed in the fistula, but also in the first one to two centimeters of the proximal vein to actually definitively treat these lesions. And if embolization fails, if you're only able to get to the proximal arterial side, then that patient should go to surgery for definitive and permanent treatment. Some of the agents that we use, the permanent embolic agents, we used to use NBCA, which is basically a liquid embolic, like a glue. And nowadays, we mostly use Onyx. So there should only be one goal for these lesions. As I said, cure of the lesion with a permanent embolic agent. And as I said, this can be achieved with Onyx or kind of in the old days, we use NBCA. But we sometimes use NBCA. Treatment should be as early as possible after diagnosis. Treatment should be definitive, either endovascular or surgical. And we shouldn't use particles, as a particle embolization. So you may, in the old days, they did use particles. And your patient may temporarily improve. Their symptoms may temporarily improve. But they'll come back because they'll begin to form collateral circulation. So unless you use kind of a permanent agent, you will not have a definitive, at least endovascular cure. Outcomes are typically good when the disease is treated early or when it's diagnosed early. And poor if you wait too long. And as I said, a lot of times, these patients are already very, very compromised by the time we see them. They may be wheelchair bound. They may be paraplegic already. But oftentimes, they have some weakness, some bowel and bladder dysfunction. And these symptoms actually can be reversed. And what I normally tell our patients is, you know, the goal of treatment is to halt symptom progression. It's not going to necessarily change the damage that's already been done. But there's a good chance that halting the symptom progression can lead to improved neurological symptoms. But mostly, it's to stabilize the symptoms and to prevent further deterioration. The risks and complications, so less than 1% to 2%. And some of the other complications can include spinal venous thrombosis. And obviously, the major risk is just delaying surgery. So again, the treatment outcomes are to halt symptom progression. And the degree of clinical recovery depends on how long the disease went undiagnosed. So the longer the duration, the less chance for recovery. And a return to normal is unusual. But I always try to be as hopeful and optimistic with our patients because they really need that. Many of these patients have really been given the runaround for a long time. And so just kind of instilling hope, getting them involved in aggressive postoperative physical and occupational therapy and getting them in a rehab program is really, really helpful. And just keeping an optimistic attitude. I think that makes a big difference in their motivation and their outlook. So just to summarize, spinal fistulas are an insidious disease that can cause significant core damage and clinical impairment over time. The challenge for optimum management is making an accurate and early diagnosis to maximize the chances of recovery. And Bowhunter's disease, you know, definitely mimics other disease processes and requires early recognition, especially of vertebral basilar insufficiency. It's important to rule out other causes of vertebral basilar insufficiency with Bowhunter's. And then for all of the cerebrovascular zebras, including the cavernous carotid fistulas and Bowhunter's, early recognition of symptoms, a timely diagnosis and treatment in order to halt symptom progression and improve the likelihood of reversal of symptoms is really, really important. Thank you. Thanks for listening. Thanks. Any questions for the speaker? In terms of spinal fistulas, have you seen any patients do surprisingly well, you know, ones that do surgery or were not candidates for surgery, like they live without symptoms for many years? Well, are you saying like an asymptomatic patient or? Usually, I mean, these patients, we are recommending treatment. If they're coming to us, they're not leaving without treatment. And unless there's some, you know, either some mechanism by which we can't treat them, either they have other comorbidities or something else going on that really precludes intervention, these patients typically don't do well. They will continue to progress. And it's not necessarily a linear progression. So they can have sort of remissions and exacerbations. But I mean, they typically over time, if they're not treated, they continue to progress and worsen. I actually, when you said Bowhunter's, I wasn't familiar with it. However, I remember many years ago, we had a young kid, maybe 14, 15 years old, who always felt that he had pressure in his neck and was constantly cracking his neck. And came in with symptoms of stroke. And so that must have been what it was. But he was kind of, and what we said to him was, well, don't crack your neck. Yeah, don't do that. But he was admitted with symptoms of stroke. And neurosurgery was consulted. And it was like, well, just don't crack your neck. So that must have been what it was. You said it's, it was rare. Rarely talked about, so. I have a question about CCF. So with some of the newer endovascular treatments, like photoversion, and you think about that being potentially a nice treatment to cover, or partially cover the carotid and prevent flow back into that. Is there any role for flow diversion with CCF? I haven't seen that. I haven't either. But I just wondered, has anyone else seen flow diversion being used? Yeah. Okay. Wouldn't be enough to treat it adequately. Right. Yeah. That's right. Yeah. And if you've seen a CCF, oh my gosh, the eye findings that she showed you, you don't miss it. It's not like subtle, where you go, I don't know. I mean, it's pretty obvious. It's pretty obvious. But, you know, sometimes you'll see these patients, and they don't, they don't look like that. They can look like that. But they start looking like, you know, you got something in your eye, or maybe a little proptosis. But it's usually not that significant. The whooshing. Yes. And that, and that, it's incredible how quickly that goes away right after they wake up, and they're like, oh my God, it's gone. I feel so much better. So, thank you guys. Thank you so much. Thank you.

cerebrovascular zebras

cavernous carotid fistulas

Bowhunter's syndrome

spinal dural arteriovenous fistulas

diagnosis

treatment options

MRI and angiography

surgical repair

vertebral artery occlusion syndrome