Temporal arteritis

-[Voiceover] Temporal arteritis is a large vessel vasculitis that affects the superficial temporal arteries and it can also affect the ophthalmic arteries which I'll touch on a little bit later but the superficial temporal arteries give this vasculitis its name. Also note that there's another name that this goes by and it's called giant cell arteritis. Giant cell arteritis refers to what you see under a microscope and we'll also take a look at that in a little while as well. First, I really want to focus on the general symptoms that you see in the body. To understand these general symptoms, let's take a look at a blood vessel and what I'm going to do is draw two sides of a blood vessel and imagine this is a cross section. This right here that I'm shading in is the wall of the blood vessel. Remember, blood vessels are like pipes and blood travels through these pipes. To really give you some dimension, let's kind of make this look a little 3D. You can see, we're just taking a slice right down the middle of it and like in other vasculitis, you have antibodies that attach onto the blood vessel wall. These antibodies recruit white blood cells over and these white blood cells come in and cause damage. Now, this is all in the stake. These antibodies are accidentally targeting the blood vessel wall and causing damage by recruiting white blood cells. They're acting as a signal marker for these white blood cells. The release of all these damaging components and other immune peptides, immune proteins can go downstream down the blood vessel. They can travel throughout this body and you may actually see symptoms like fevers, chills, night sweats, fatigue, myalgias which are muscle aches, so generally feeling crummy. This is really caused by the immune system releasing all of these molecules to fight off what it thinks is an infection. Now with damage to this blood vessel wall, we have release of components in the blood vessel wall and these components are also targeted by the antibodies. Antibodies bind together and surround these components and they form a large group of molecules which are referred to as immune complexes. These immune complexes will also travel downstream. Interestingly these immune complexes will travel and get stuck in joints. They have a certain affinity for joints, knees, elbows, shoulders, really any other joint that you might see. In fact, 50% of patients have these arthralgias, this joint pain. Now very notably about temporal arteritis is it seems to affect women primarily who are older than 60 years old or around 60 years old. These older women may come in with fatigue, chills, night sweats, along with joint pain. With joint pain you might think it's just arthritis that she's having along with maybe an illness like a viral illness. This can be a misdiagnosis of an older lady. There are many different types of arthritis including osteoarthritis or you may have heard of rheumatoid arthritis and these are other causes of joint pain. Temporal arteritis on the other hand isn't primarily affecting joints. It's affecting joints as a secondary cause of these immune complexes. Along with these general symptoms that we see of fever, night sweats, fatigue and along with this joint pain, we can also see some local symptoms that affect the temporal artery as well as the ophthalmic artery. Let's go ahead and take a look below. Now, here we have the common carotid artery, goes up and actually splits into your internal carotid artery and external carotid artery. I'll go ahead and label this right here. This is the external carotid artery. Now, you'll notice that the superficial temporal artery is actually continuation of the external carotid artery. We'll see there's a lot of other branches but when this continues along further is just the continuation of the external carotid. Here's the temporal, in fact the superficial temporal. Patients can come in with headache because they feel pain all along the superficial temporal artery and they think it's just head pain. Notice also the pathway along this artery crosses behind the mandible, this is the angle of the mandible right here, so it crosses behind it. When a patient chews, it can press against the artery and cause pain. You would imagine touching it could cause even more pain. We have headache, we have jaw pain, we have general symptoms like fatigue, fever and we have arthritis as well. Now the other artery that I want to focus on is the ophthalmic artery. Notice over here we're talking about the external carotid and it bifurcates into the internal and the external carotid arteries. Over here on the skeleton, imagine having peeled away the skull just to look inside. You kind of take a cross section right down the middle of the head. Over here, this is the external carotid artery which we've cut off. Here's the common carotid artery which I've highlighted and up here is the internal carotid artery. With the internal carotid artery, we've got many other branches that come off of it but we're just going to focus on this one branch, the first branch of the internal carotid. This branch is the ophthalmic artery and it supplies the eyes. If you have damage to this artery, blood flow decreases through here and therefore you can have a lot of symptoms with your eyes related to blurred vision, double vision, even blindness potentially. Now lastly I want to point out that you have eye symptoms as well as a headache. Can you think of any other disease that has eye symptoms, vision changes along with a headache? Migraines. Migraines are actually a big misdiagnosis. Migraines of course the patient has headache but also the patient may experience a vision aura. They may see something, lights may flash in their eyes, they may get blurry vision. How do you differentiate between the two? Remember, temporal arteritis is a little old lady that is also having this pain. Patients coming from migraine is a lot earlier and so if you're seeing new ones that have headache and new ones that have vision changes in an elderly lady, then you should be thinking temporal arteritis. If you see these clinical symptoms, there's one value that you should really be looking for and that's ESR, erythrocyte sedimentation rate. An ESR is performed by taking a very long tube and taking the patient's blood. After it sits for a long time, it's going to go from being full red to being a layer of blood on the bottom and a layer of plasma. Plasma is white blood cells, proteins, everything else that's in your blood that's not red blood cells. Over an hour, you take a look at the blood. Now, an acute inflammation, these red blood cells will travel very far down and leave a layer of plasma on the top. This tube you measure how far the red blood cells travel down. Red blood cells are actually negatively charged on their cell surface. This is from proteins, other things that they have on their surface. Here's a bunch of negative charges. In a normal healthy individual, red blood cells are going to repel each other however in a patient with acute inflammation they're going to get positively charged proteins that are secreted by the body to combat pathogens. These are released during inflammation and so these interfere with the cell surface of red blood cells and which you end up seeing is red blood cells start to stack together. Therefore they can stack more easily in this tube and they sediment further. In temporal arteritis, the damage you get to the blood vessels is very splotchy and all over the place, very segmental damage. In order to diagnose temporal arteritis, you need to take a biopsy which is a cut of the blood vessel that you look at under a microscope. Now because there's a segmental damage, if you take a small biopsy, you may actually miss the disease and not see it under a microscope. For temporal arteritis, you must take a large biopsy of the temporal artery just to make sure that you catch the segmental damage. It's important to know that a negative biopsy does not necessarily mean that you can rule out temporal arteritis because if you take too small of a biopsy, you may be missing the segmental damage. Now, under a microscope, you'll see something called granulomatous inflammation with giant cells and fibrosis. Let's take a cross section here, take a look at it. Under the microscope, you see white blood cells forming a tight circle or sphere around something that it thinks is bad. This formation is called a granuloma and what's interesting is the white blood cells involved can get so tight that they combine together to form giant cells. How can we treat temporal arteritis? We do so with steroids. Steroids inhibit the immune system by preventing the formation of immune peptides that attract more immune cells to an area of local inflammation. Decrease attraction of the immune system to the blood vessels causes less damage.