Hey guys, thanks for joining me today. In this episode we are going to be discussing
Ankylosing Spondylitis. Or actually more accurately, I should say we are going to be discussing
Axial Spondyloarthritis. And I say that we are going to be discussing Axial Spondyloarthritis
as opposed to Ankspond, because the terminology has changed. And we'll get to that momentarily.
But as a heads up, I want to let you know I decided to split the Axial Spondyloarthritis
topic into two parts. Part one, today, is going to discuss everything other than management.
So that means a little bit of epidemiology, a little bit of pathophys, but a big focus
on clinical presentation, workup, diagnosis, etc. And the next episode, part two of two
of Axial Spondyloarthritis, will focus exclusively on management. And lastly, before we start
the episode, I want to apologize if the sound quality is not as good as usual, I have a
bit of a head cold, but I'm confident that the information today will still provide a
comprehensive review on Axial Spa.
Welcome to Rheumatology for the Royal College, where we aim to bring you reviews that will
strengthen your knowledge going into exams and clinical encounters. We hope you'll find
it useful and enjoyable whether you're running, lifting, cooking, grocery shopping, driving,
you get the idea. I'm your host, Dr. Karim Ladak, an American-trained Canadian rheumatologist.
Before we start, my lawyer advised that I should say the information here only reflects what
I have in my personal notes and should not be used in isolation in the management of patients
nor for your boards. I'd like to thank Organon and Pfizer for supporting this podcast through
their educational grants. However, it should be noted they have absolutely no editorial
say in its production.
What do we mean when we say spondyloarthritis? Spondyloarthritis is a chronic inflammatory
disease that has a predilection for the axial skeleton. Broadly speaking, that means the
spine and the sacroiliac joints. Spondyloarthritis can also affect the peripheral skeleton. In
patients who primarily have axial disease, again broadly speaking, spine and SI joints,
we call their disease axial spondyloarthritis or axial spa. If their predominant symptoms
are in the peripheral skeleton, meaning joints in the arms and the legs, we call their disease
peripheral spa. I want to be clear, again, today we are focusing on axial spa. The classic
axial spa, axial spondyloarthritis, is ankylosing spondylitis or angspond that you've probably
heard of. Nowadays, we don't say angspond as much anymore. We instead use the term radiographic
axial spa because by definition, patients who have radiographic axial spondyloarthritis
have what we call radiographic sacroiliitis, meaning that their damage is so bad, you can
see it on just a plain simple x-ray, also known as a plain simple radiograph. But the inflammation
needs time to accrue damage to the spine and the sacroiliac joints to the point where you
can see it and therefore call it radiographic axial spondyloarthritis or ankylosing spondylitis.
What about all those patients who have earlier or milder inflammation that we can't see
on just a simple x-ray, but instead they need an MRI to visualize changes? It's very simple.
These individuals we call non-radiographic axial spondyloarthritis and they have the
potential to progress with enough chronic inflammation to the point where you can see
damage on a plain simple x-ray or radiograph. Okay, so that was a lot of terminology. Let's
quickly summarize. Spondyloarthritis means inflammation of the spine and the sacroiliac
joints broadly speaking. Patients with spondyloarthritis can primarily have axial disease, meaning spine
and SI joints, broadly speaking, or peripheral disease, meaning more predominantly affected
in their limbs. We used to say that patients had ankylosing spondylitis or angspond, but
nowadays we don't use that terminology anymore. Instead we use the term radiographic axial
spa or radiographic axial spondyloarthritis, meaning that their disease is so bad it has
been so chronic that they've accrued enough damage to be seen on a plain simple x-ray.
While on the other hand, patients who haven't had disease for as long or as severely and
therefore whose disease cannot be seen on a plain x-ray or radiograph don't have radiographic
sacroiliacitis or radiographic axial spa. Instead they need an MRI to visualize changes
and these patients we call non-radiographic axial spa, but again they can progress to
radiographic axial spa, also known previously as angspond, but at the end of the day axial
spondyloarthritis is a term that encompasses both non-radiographic axial spondyloarthritis
and radiographic axial spondyloarthritis. In truth be told, apart from the degree of
damage the distinction between non-radiographic axial spa and radiographic axial spa aka angspond
is not super important because they're part of the same disease spectrum and their burden
of disease, their comorbidities, their treatments and for the most part their response to treatments
are similar. Therefore in conclusion, axial spondyloarthritis captures both non-radiographic
and radiographic axial spa and this is the term that we should be trying to use more
in these patients rather than just angspond. Epidemiology. There are some important patient
factors to know about when it comes to axial spondyloarthritis, which again is a chronic
inflammatory disease with a predilection for involving the axial skeleton, broadly speaking
the SI joints and the spine. So what are these patient factors? Well, we more commonly see
axial spondyloarthritis in younger patients. They tend to develop the disease in their
20s. We also know that the male to female ratio for radiographic axial spa aka angspond is
about 2 to 1. So radiographic axial spa is more common in men than women. However, non-radiographic
axial spa interestingly is closer to a 1 to 1 ratio. So again, radiographic axial spa
more commonly seen in men than women but non-radiographic axial spa is equal between the sexes. In terms
of the prevalence overall about 1% of the population has axial spondyloarthritis. But
it seems like every year we're seeing more and more non-radiographic axial spa and that
might be because we're getting better at picking it up. So we're no longer just doing x-rays
or radiographs to look for radiographic sacralitis. Instead, we're realizing that many patients
have disease that's only detectable on MRI and we call those patients again non-radiographic
axial spa. And the last thing I want to say about epidemiology is that the prevalence
of axial spondyloarthritis mirrors the prevalence of a genetic association to the disease called
HLAB27. In other words, the higher the HLAB27 in a population, the higher the rate of axial
spondyloarthritis. And the lower the rate of HLAB27, the lower the rate of axial spa. So
in areas with high prevalence of HLAB27, such as northern or eastern Europe, where HLAB27
is present in 9% of the population, or in white Americans, where the prevalence of HLAB27
is 7.6%, the rate of axial spa is going to be higher versus in places such as sub-Saharan
Africa, where HLAB27 is present in less than 1% of the general population, or as one paper
from Togo put it, HLAB27 is virtually absent in most of sub-Saharan Africa. Then the rate
of axial spondyloarthritis in that population is going to be lower. So in quick summary,
axial spondyloarthritis normally starts younger in life, usually in the 20s. The male to female
ratio is 2 to 1 for radiographic axial spa, aka ink spond, but 1 to 1 for non-radiographic
axial spa. Prevalence estimates vary, but about 1% of the population has axial spondyloarthritis.
And we're seeing more and more non-radiographic axial spa, probably because we're getting
better at recognizing it. And lastly, the higher the rate of HLAB27, the higher the prevalence
of axial spa. So we see more of it in white patients, and substantially less of it in
black patients. But before we leave this topic, I want to make it very clear. It's important
to know that HLAB27 doesn't automatically confer axial spa, and by the same token, the
absence of HLAB27 does not rule out axial spa.
Pathophysiology.
In terms of the actual cellular changes in axial spa, and we're going to make this as
painless as possible. So please try to stay with me. The primary areas of pathology in
axial spa are the emphases, meaning where tendons and ligaments insert into bone, and
the subcaudal bone, the bony layer under the cartilage. Whereas synovitis is thought to
be a secondary site of inflammation because of signaling from these adjacent tissue structures.
And with all the inflammation, an important phenomenon occurs in axial spa. And that is
bony destruction and new bone formation. And in the spine, that vertebral inflammation
can eventually lead to bony growth, new bone formation and fusion with loss of spinal mobility.
Some of the important cytokines we've identified are TNF alpha, i.e. tumor necrosis factor
alpha, and the IL-2317 pathway. These pathways inappropriately induce bone destruction and
lead to inappropriate bone formation. And in part two of axial spa in the next episode,
you're going to hear that we've learned blocking TNF alpha and IL-17 has been very successful
in controlling axial spa. Unfortunately, IL-23 blockade was a flop when it came to controlling
axial spa disease. And it's thought that this could be because IL-23 is upstream of IL-17
and alternative activation pathways still have their way when IL-23 is blocked.
Okay, you cellular pathway and cytokine junkies, that's all you're getting from me today.
And I can just hear the groans from the audience right now.
All jokes aside, let's finish off pathophysiology, though, by once again reminding ourselves
that many autoimmune diseases, including axial spa, likely developed from a mix of genetic
predisposition and environmental factors. Let's start with the genetics. We're going
to reiterate what we said earlier about HLA-B27. You see, it seems that axial spa has a greater
than 90% heritability, including, but not limited to, HLA-B27, which is the strongest
genetic association. HLA-B27 can compromise correct recognition of self antigens. And as
we said earlier, we see it more commonly in patients who are of Northern and Eastern
European descent, where 9% of the population has HLA-B27. And it's much less common in
patients of sub-Saharan African descent, where the prevalence of HLA-B27 is less than 1%.
But again, the absence of HLA-B27 does not rule out axial spa, and the presence of HLA-B27
doesn't automatically confer axial spa. It does though significantly increase your risk.
So for example, if you are a Caucasian patient with a specific type of HLA-B27 called HLA-B2705,
you are about 40 times more likely to develop radiographic axial spa as someone who is negative
for that gene. Okay, now what are some of the environmental triggers that can provoke disease
in these genetically susceptible individuals? Well, for starters, smoking is a big one,
and it corresponds with the level of disease activity, including based on MRI studies of
the SI joints. Another possibility is vitamin D deficiency, because it can interfere with
normal innate and acquired immunity. And actually, if you think about it, that doesn't bode
very well for Northern Europeans who already carry a higher prevalence of HLA-B27, but
also get less sunlight. There are theories out there that another environmental trigger
is mechanical stress. Remember, the emphases are a primary site of inflammation in axial
spa. These are load bearing structures. And one study from the Oasis cohort, which is
an international cohort used to study axial spa, blue collar employment was more associated
with radiographic progression than white collar employment. But obviously, there are tons
of unaccounted biases for blue collar versus white collar employment and disease progression.
And the last environmental trigger is the microbiome. So, we see a higher prevalence of psoriasis
and inflammatory bowel disease in patients with axial spondyloarthritis. And it's postulated
that exposure to microbiologic pathogens from skin damage and psoriasis or imbalance of
the gut microbiome in IBD can precipitate an inflammatory reaction with inappropriate
recognition of self and the development of axial spondyloarthritis. In fact, several families
of gut bacteria are seen more frequently in patients who develop axial spondyloarthritis,
and these same microbe families are associated with higher fecal-cal protected levels, which
are markers of intestinal inflammation. And one Chinese study even showed that TNF inhibitor
treatment corrects gut dysbiosis and radiographic axial spondyloarthritis, restoring the microbiome
to what we see in healthy controls.
Quiz time.
All right, guys. Let's test our knowledge. Question one. In terms of terminology, axial
spondyloarthritis is a chronic inflammatory disease that has a predilection for affecting
the axial skeleton. And broadly speaking, that refers to the spine and the sacroiliac
joints. What, then, is the more appropriate term for ankylosing spondylitis?
Radiographic axial spondyloarthritis. And non-radiographic axial spondyloarthritis is
part of the same disease spectrum, but without any changes on x-ray.
Okay, question two. What is the usual age of onset of axial spondyloarthritis?
Young. Most patients have symptom onset in their 20s.
Question three. What is the male-to-female ratio for radiographic axial spondyloarthritis,
a.k.a. angspond? Two-to-one. How about for non-radiographic axial spondyloarthritis?
That's equal between the sexes at a one-to-one ratio.
And lastly, we know that the prevalence of axial spondyloarthritis in a population is
related to the prevalence of HLAB27. Which ethnic or ancestral group has the highest concentration
of HLAB27? Those of northern and eastern European ancestry,
where the rates are about 9% of the population, and that has implications on white North Americans,
in whom the prevalence of HLAB27 is about 7.6%. Considerably higher than, say, for example,
the African-American population. Clinical presentation.
Okay, bravo. That's it. You have officially survived pathophysiology. Let's talk about
clinical presentation. What are patients telling you when they come into your office?
Well, spinal and sacroiliac joint inflammation probably means back pain. And back pain is
the classic symptom of axial spondyloarthritis.
Patients with axial spa are going to tell you they have chronic back pain, meaning it's
been there for more than three months. It's typically insidious, started gradually, and
it occurs almost daily. Any level of the spine can be affected, but pain usually starts in
the lower spine or SI joints, causing lower back pain and pain in the buttocks. You might
have heard of inflammatory back pain, quote unquote, inflammatory back pain. And this
is a clinically defined type of back pain. There are different criteria that have been
proposed to define inflammatory back pain, but don't worry about them. They all vary
slightly depending on which one you use, but there's tons of overlap. So just remember
the general gist, which are the five following things.
Number one, pain onset less than 40 years old. Because remember, axial spond normally
starts in the 20s. Two, pain is worst in the mornings and middle of the night. It can
significantly disturb sleep because patients have to wake up and move around before they're
comfortable again. Three, the pain is relieved with exercise, not with rest. Four, the pain
is relieved with incense. And five, the pain is associated with morning stiffness lasting
at least 30 minutes and easing with activity as the day progresses. Unlike osteoarthritis,
whose stiffness is usually only present less than 30 minutes in the mornings. So inflammatory
back pain, this clinically defined entity once again is comprised of the following.
Onset less than 40 years old, worst in the mornings and middle of the night, often interrupting
sleep. It's relieved with exercise, not with rest. It improves with the NSAIDs, and it's
associated with at least 30 minutes of morning stiffness. I want to just quickly tell you
that inflammatory back pain is classic, but it's not always the rule. So please keep
it open mind when you're assessing patients. For example, one 12 year retrospective longitudinal
study found that only 30% of patients meeting criteria for inflammatory back pain were ultimately
diagnosed with axial spa. On the other hand, one third of patients with axial spa may have
symptoms more consistent with mechanical back pain than inflammatory back pain. So again,
the lesson here is that while inflammatory back pain is classic, it's not the rule.
So keep an open mind. So other than back pain, what are their symptoms might patients describe
when they're in your office with axial spondyloarthritis? Limited spinal mobility. Because with inflammation
and eventual structural damage, their spinal flexion, extension, rotation are all going
to be impaired. And true loss of spinal mobility tends to be a later manifestation. Before
we move on from the axial skeleton, I just want to say that there are other joints that
can be affected with axial disease. Those are the cost of vertebro joints, the cost of
sternal joints, and the manubrio sternal joints. And these can lead to chest and other types
of back pain. Okay, great. Before we wrap up axial one more time, because it's important,
we're going to reiterate inflammatory back pain. And that is as follows, one of five
onset less than 40, two of five worst in the middle of the night and the early mornings,
often interrupting sleep, three of five, relieved with exercise, not with rest, four of five,
improvement with NSAIDs, and five of five associated morning stiffness lasting at least
30 minutes. Okay, guys, I said earlier that patients with axial spondyloarthritis predominantly
have axial inflammation, but they can also have peripheral manifestations, which are
commonly seen in axial spa. These involve both the musculoskeletal system and extra musculoskeletal
manifestations. So when it comes to peripheral musculoskeletal manifestations, we are talking
about arthritis, enthesitis, and dactylitis. Let's start with arthritis. This occurs in
about 30% of patients with axial spa. Classically, the arthritis is asymmetric, and it tends
to involve the lower extremities more than the upper extremities. It's usually a mono
or oligoarthritis affecting two to four joints, but otherwise causes the classic pain and
swelling, as you would expect with any peripheral arthritis. Moving on, enthesitis. Now, remember
that the enthesis are sites where tendons and ligaments insert into bone. And classic
examples of this are where the Achilles tendon or the plantar fascia insert into the calcaneus.
But really, any enthesitis can occur at any enthysial site, so lateral epicondylitis,
tendisalbo, medial epicondylitis, golfer's elbow, or really any site of enthesitis. Now,
the last peripheral musculoskeletal manifestation I want to mention of axial spa is dactylitis.
Dactylitis is less common than peripheral arthritis and enthesitis, but it's still important.
It's also known as a sausage digit, where you get isolated swelling of the entire digit,
the entire toe, or the entire finger, and that's caused by a tenosynovitis, which is
inflammation of the tendons and the tendon sheath around the affected digit. As I said,
it's classic for axial spa, but it's rare, only occurring in less than 10% of patients
with axial spa. Now, there are also non-musculoskeletal manifestations of axial spa. The three most
important ones I want you to remember are uveitis, inflammatory bowel disease, and psoriasis.
Let's start with uveitis, which is inflammation of the inside of the eye. It is the most frequent
extra musculoskeletal manifestation of axial spa and occurs in about 25% of patients. It's
usually an acute anterior uveitis and associated with HLA B27 positivity. It's going to typically
be unilateral as opposed to bilateral, but can alternate from one eye to the other. Common
symptoms with this kind of uveitis are pain, redness, and phonophobia. As I said, it's
acute so it starts suddenly, but it's of limited duration and often resolves on its own. The
next non-musculoskeletal manifestation I want to mention is inflammatory bowel disease.
We see this in 5 to 10% of patients with axial spa, both Crohn's and ulcerative colitis.
The last major extra musculoskeletal manifestation of axial spa is psoriasis, again occurring
in about 10% of patients. In addition to uveitis, inflammatory bowel disease, and psoriasis,
there are some much less commonly seen extra musculoskeletal manifestations of axial spa.
These include heart disease, specifically aortic valve insufficiency, lung disease, specifically
a restrictive lung disease, classically with upper lobe or apical inflammatory changes,
nephropathy, specifically an IGA nephropathy, and low-grade fevers and weight loss. But these
are very uncommon. The more common extra musculoskeletal manifestations of axial spa are anterior
uveitis, inflammatory bowel disease, and psoriasis. Heart disease, aortic valve insufficiency,
lung disease, restrictive lung disease in the upper lungs, nephropathy, IGA nephropathy,
and low-grade fevers and weight loss are way less common. So let's quickly summarize. When
it comes to the clinical presentation of axial spa, the classic symptom is back pain. It's
chronic, meaning it's been there for at least three months, typically insidious in onset
and occurs almost daily. It can start at any level of the spine, but usually patients complain
of lower back pain or buttock pain, because in early disease, inflammation is most concentrated
in the lower spine and the SI joints. And we talk about "inflammatory back pain." This
is a clinically defined entity. There are different criteria, but there are five ingredients
I want you to remember. Number one, onset under the age of 40. Number two, pain worst
in the early mornings and middle of the night, often disturbing sleep. Number three, pain
that's relieved with exercise, not with rest. Number four, improvement in pain with NSAIDs.
And number five, associated 30 minutes of morning stiffness. I also want you to remember
that peripheral manifestations are common in axial spa. From a musculoskeletal perspective,
arthritis and enthesitis both occur in about 30% of patients. The arthritis is typically
asymmetric, prefers the lower extremities, and usually is a monoarthritis or an oligoarthritis.
Whereas enthesitis is inflammation where tendons and ligaments insert into bone, classic examples
being where the Achilles tendon inserts and where the plantar fascia inserts into the
calcaneus. And the last peripheral musculoskeletal manifestation is dactylitis, also known as
sausage digit. And finally, when it comes to extra musculoskeletal manifestations, the
most common one is anterior uveitis. But inflammatory bowel disease and psoriasis both
affect about 10% of patients with axial spa. Low grade fevers and weight loss, aortic valve
disease, restrictive lung disease and nephropathy are way less common.
All right, guys, that's a lot of information. So what I've done is that I've invited a guest
into the studio today to go through a case with me, as if he was in my office. His name
is John. Nice to meet you, John. Nice to meet you as well. Yeah, first time obviously. Never
met. Never. Okay, John, can you tell me why you're in the office today? Sure. I've been
having lower back pain for a little over three months now. Actually, I think it's been nagging
me for about at least over a year, actually, now that I think about it. And it's really
bad in the middle of the night. And they're really boring. And I'm not sleeping because of it.
Gotcha. So lower back pain, it's there on a chronic basis over three months. And it's
worst in the early mornings and middle of the night. Yeah, definitely. Got it. Do you find
that it gets better with activity or better with rest? I actually thought it was because
of my gym routine, but it hasn't been improving with rest. And it actually feels better when I
work out as opposed to just taking it easy. And apart from working out, have you noticed that
anything else makes it feel better? For example, medications? Yeah, I've been taking both Tylenol
and Advil. Tylenol isn't really seeming to work for me, but Advil helps. Okay. Do you find that
in the morning when you wake up your stiff? Definitely. I've noticed a massive decrease in
flexibility. Okay. As opposed to just being like sore and you lose a little bit after a workout,
noticing significant decreases. Okay. Moving outside of what we call the axial skeleton then,
and going more toward the limb. So your arms and your legs. Have you had any joint pain?
Yeah. Actually, my right knee has been really painful and it's been pretty swollen. And also,
my heel on my right leg as well has been really swollen as well.
Swollen. And would you say that it's painful swelling? I would just actually say more than it
hurts. Okay. And is that kind of where the Achilles tendon goes into the heel? Is that what
you mean? Yeah, another you mentioned that that makes sense. Okay. And the last thing I want to
talk to you about in your limbs is what we call a sausage digit, which basically means that the
finger or the toe is swollen disproportionately to the other digits. Yeah. Actually, my right middle
finger is really swollen right now. It's quite a bit fatter than the rest of my fingers. And a little
bit tender? Yeah. Yeah. Like a sausage. Right. All right. And outside of the musculoskeletal system,
have you ever had blurry vision or painful eyes? Yeah. Actually, another you mentioned that had
uveitis a few years ago where my left eye was really painful and I had a bit of blurry vision
and light sensitivity, but I just did some eye drops for a few weeks and it went away.
Okay. Got it. Sometimes people with inflammation of the spine can also have symptoms of their
bowels or their skin. Have you ever been diagnosed with inflammatory bowel disease or had chronic
abdominal pain, diarrhea or blood in your stool? Yeah. Actually, I have IBD currently and my family
has a series of psoriasis. Okay. Interesting. And just the last few questions here about
risk factors for inflammation of the spine. Do you have a heavy job? Yeah. I actually work in
construction. So by heavy, I think you mean manual. Manual. Yeah. Manual. And yeah. So I'm on my feet
lifting a lot of stuff. Got it. So a lot of mechanical stress on the body. Yeah. And do you smoke, John?
I do. Tisk, tisk. Tisk, tisk is correct, but this is a non-judgmental space. So it's pretty
judgmental. Only because you're not a real patient. That's rude. All right. Well, thanks for coming in.
I really appreciate it. We really appreciate it. Physical exam. So during your evaluation,
you are obviously going to examine the patient's axial skeleton for mobility and to see if you can
detect sacroiliitis. However, you should also be evaluating the patient's peripheral joints,
looking at the enthases for anthocytus, digits for dactylitis, skin for psoriasis,
abdomen for IBD, and eyes for uveitis. Because even though we call it axial spondyloarthritis,
this disease affects much more than just the axial skeleton. But for now, we're only going to discuss
five specific maneuvers which I think are important for your axial spa examination.
Let's start with two that evaluate spinal mobility. The first one is pretty easy. It's called the wall
to occipit distance. And this is to test for thoracic hyperkyphosis or excess stooping of the
thoracic spine that can happen with chronic inflammation and axial spa. The way this is done
is you have the patient stand upright with their back against the wall. You proceed to direct them
such that their heels, their buttocks, and scapulas should be up against the wall. Next,
maintaining their head in a neutral position with their chin being straight. See if they can touch
the back of the head against the wall. And if you're not sure whether their head is straight or not,
we classically say that the lower orbital margin and the acoustic meadus should be in the same
horizontal plane. Then you check to ensure there's no space between the back of their head and the
wall. And if there is, then you measure it out with a measuring tape. But a normal wall to occipit
distance is 0 centimeters. Anything more than 0 centimeters can suggest hyperkyphosis of the
thoracic spine, aka excess stooping of the thoracic spine that can happen with chronic inflammation
from axial spa and reduced spinal mobility. The next test we're going to do for spinal
mobility is called the Schober's test. Now there are different variations of the Schober's test.
There's the original Schober's test, the modified Schober's test, the modified Modified Schober's
test, the Wolfson Modified Schober's test, and all of them will determine whether there's a decrease
in forward flexion of the spine. I think probably the most commonly taught one nowadays is the
Modified Schober's test, and that's the one that I personally use, so let me describe it to you.
First, you have the patients stand with their feet shoulder-width apart. Find the posterior
superior iliac spines, which are at the level of the dimples of venus. Draw a line between them.
From this original line, use a measuring tape and mark a spot that's 10 centimeters up,
then mark a spot that's 5 centimeters down from the original line. So again, posterior superior
iliac spines, draw a line between them, there again at the level of the dimples of venus,
mark a spot that's 10 centimeters up, and another spot that's 5 centimeters down,
and you should have a total distance of 15 centimeters. Okay, now if you ever forget,
are you supposed to go up 10 centimeters and down 5 or down 10 and up 5? If you try to go down 10,
you will quickly realize that you get uncomfortably low right into or very near their gluteal cleft,
and so one more time, it's up 10 down 5 for a total distance of 15 centimeters.
Now when you've marked your upper and your lower points, you're going to ask the patient to keep
their knees straight and bend down as far as they can to try to touch their toes. The total
length should increase by at least 5 centimeters, meaning when you re-measure the distance between
the upper and the lower point as the patient is flexed forward, they should have a total distance
of at least 20 centimeters, and if they don't, then they have impaired spinal mobility.
Okay, that's spinal mobility maneuvers. Let's discuss three sacroiliac joint provocative
maneuvers. The first one is known as the Faber, which is spelled F-A-B-E-R and stands for flexion,
abduction, external rotation. So you lay the patient on their back, then you flex the hip,
abduct the hip, and externally rotate the leg. F-A-B-E-R, Faber, flex, abduct, and externally
rotate the leg. Then rest the ankle on or just above the opposite knee, and what you should have
created is a figure of four shape with the legs. Now you stabilize the opposite pelvis by placing
one of your hands on the patient's opposite anterior superior iliac spine, their aces,
and apply light to moderate pressure downward on the ipsilateral knee, the one that you're testing,
until you get to pain or the end of their range of motion. If they have pain in their SI joint region,
it's a positive Faber test, which can indicate SI joint disease, such as sacroiliitis. Something
you should know is that patients will frequently report pain in their anterior leg, lateral hip,
et cetera. That is not sacroiliac disease. That can suggest iliopsoas strain or hip osteoarthritis
or hip impingement and other things you're not really interested in when evaluating for axial
spa. The second test you can do for SI joint disease is called the pelvic compression test.
This one's very simple. You lay the patient on their side and you push down on the pelvis.
Pain in the SI joints is a positive test. Now the last test for sacroiliac disease is called
the Gaines-Linds test. You lay the patient on the examination table once again on their back.
You scooch them right up to the side and let their leg drop over the side of the examination table.
Then you bring their opposite knee up to their chest, and if they get pain in the SI joint
on the side that's dropped, that's a positive test. So in summary, when you're examining your
patients, do some provocative maneuvers to look at spinal mobility and SI joint disease. Spinal
mobility testing can include the wall to ox foot distance or the modified shober's test or any
other variation of the shober's test, and SI joint provocation maneuvers include the Faber,
the pelvic compression, or the Gaines-Linds maneuver. Quiz time. Question one. When it comes
to clinical presentation, can you describe the features of inflammatory back pain?
Okay, here we go. Onset under the age of 40. Pain that's present in the morning and at night time.
Improvement with exercise. No improvement with rest.
Significant improvement with NSAIDs and associated morning stiffness for more than 30 minutes.
Again, those are onset less than the age of 40. Pain that's present first thing in the morning
and at night time and can disturb sleep. Improvement with exercise. No improvement with rest.
Morning stiffness exceeding 30 minutes and a significant improvement with NSAIDs.
Now, if you remember from earlier, I said there are different criteria and I don't think you need
to memorize a specific set. However, if you are listening to this in advance of a rheumatology
board exam, the exam may ask you to outline five criteria that ASAS, ASAS, ASAS defines as inflammatory
back pain. This is essentially what we talked about. Age with onset less than 40. Pain that's
present at night time. Improvement with exercise. No improvement with rest. And one additional
feature is that they say the pain is gradual or insidious in onset. The ASAS criteria, again,
only if you are writing a rheumatology fellowship exam, do not include improvement with NSAIDs
or associated morning stiffness as part of their criteria. Okay, that's enough about inflammatory
back pain. Let's move on to question two. Please name nine extra axial features of axial spondyloarthritis.
So nine features of the disease that occur outside of the axial skeleton.
Give you a few seconds to think about this nine features outside of the axial skeleton.
Let's organize our thoughts. Start with the peripheral musculoskeletal system.
So number one, inflammatory arthritis. This is usually a mono or oligoarthritis affecting
one to four joints, usually asymmetric, most commonly affecting joints in the legs.
Feature number two, anthocytus. This is inflammation where the ligaments and tendons insert into bone.
The most common ones in axial spa being where the Achilles tendon and the plantar fascia
insert into bone. The third extra axial feature, dactylitis. This is also known as a sausage digit,
and it's caused when you have tinocynovitis of an entire digit. So an affected toe or an affected
finger looks quite chubby compared to the others. Now let's move on to the non-musculoskeletal
manifestations. We'll start with uveitis, which is the most common extraarticular manifestation of
axial spa and will usually manifest with an acute anterior uveitis. The fifth manifestation, psoriasis,
sixth inflammatory bowel disease, and then manifestations seven, eight, and nine are quite
rare. They're more bonus point territory, but these would be fibrosis or restrictive lung disease
of the upper lungs, aortic valve disease like aortic insufficiency, and finally,
IgA nephropathy. So again, when you're thinking about extra axial features of axial spondyloarthritis,
you would think of peripheral arthritis, anthocytus, dactylitis, and then the non-musculoskeletal stuff
like uveitis, psoriasis, IBD, and potentially the rare manifestations including upper lung fibrosis,
aortic valvular insufficiency, and IgA nephropathy. But again, these last three are very rare.
And the final question, when you are examining a patient with axial spa, there are special maneuvers
you can do. Can you name two spinal mobility tests and their normal reference ranges?
And can you also name three sacroiliac joint provocation maneuvers to test for sacroiliitis?
Why don't we start with the two spinal mobility maneuvers and their reference ranges?
Number one, the wall to occiput distance, and that should be zero centimeters.
And number two, the modified chauvers test with an increase of at least five centimeters.
Moving on to the three sacroiliac joint provocation maneuvers. The first one is the Faber
Fluxion Abduction External Rotation Test. The second is the Pelvic Compression Test.
And the third is the Gaines-Lens Test. Workup. Okay, when it comes to workup,
we always start with labs, right? But in axial spa, there aren't any helpful biomarkers or
antibodies. It's not like you have a rheumatoid factor or a CCP or an ANA. Really, the diagnosis
of axial spa is going to be based on clinical evaluation and imaging. But there are two lab
tests that you can draw. The first is an HLAB 27, as we previously discussed. It's present in about
70 to 90% of patients with axial spa. Though remember, it's not specific. And its absence also
does not rule out axial spondyloarthritis. But its presence or absence will increase or decrease
your pre-test probability for true axial spondyloarthritis. The other lab test you can order
is inflammatory markers. I'm talking about ESR and CRP. However, the caveat with axial spa is that
up to 60% of patients will have normal inflammatory markers despite active inflammatory disease.
I'm going to say that a different way. Many patients, if not most patients with axial spa,
even when their disease is active, will have completely normal ESR and CRP, which makes
inflammatory markers way less helpful in the diagnosis and ongoing management of patients
with axial spa. Now, this brings us to the heart and soul of the workup of axial spa. And that is
imaging. Imaging is crucial for the diagnosis of axial spa. And we are going to discuss
three different modalities. The first is the humble x-ray, i.e. radiographs. The second is the MRI.
And the third is CT scans. Let's begin with the humble x-ray or radiograph. You see they are
recommended as the first imaging method because they're relatively cheap. You can get them pretty
much anywhere. And if they show changes of axial spa, no further workup is required for the diagnosis.
You can do x-rays of either the SI joints or the spine. Let's start with SI joint imaging.
The structural damage you can see on SI joint x-rays includes sclerosis,
erosions, joints-based narrowing, or what we call pseudo widening, and ankylosis, i.e. full-on fusion.
And from a practical perspective, when you're looking for these changes, the erosions, the
sclerosis, the narrowing, or the pseudo widening, or the fusion, you can order one of two different
views. You can either order an AP pelvis x-ray or a dedicated SI joint x-ray, also known as the
Ferguson view. Now, if you are looking at a lot of x-rays of the SI joints, you may see that MSK
radiologists grade SI joint changes from zero to four. And they do this according to something
called the modified New York classification criteria for radiographic sacroiliitis, meaning
classification criteria to decide whether or not the patient has enough sclerosis or erosions
or joint-based changes or ankylosis to say that they have sacroiliitis based on x-ray. From a
practical perspective, I don't think you need to memorize the modified New York classification
criteria. However, if you are writing a rheumatology fellowship exam, it may come up. And so very
quickly, I will tell you that the grading goes from zero to four. Zero is completely normal, four
is full-blown ankylosis or fusion. To elaborate just a smidge more, grade zero is normal. Grade
one is suspicious changes. Grade two is minimal changes, such as a small erosion or isolated
sclerosis. Grade three is unequivocal abnormalities, and grade four is ankylosis. And according to the
modified New York criteria, graded zero to four, we usually say there is radiographic sacroiliitis
if there are bilateral grade two changes or at least unilateral grade three changes.
Again though, from a practical perspective, I'm not sure you need to know the modified
New York criteria unless you are writing a rheumatology fellowship board exam.
So in conclusion, the SI joint x-rays, the radiographs of the SI joints can show erosions,
sclerosis, joint-based narrowing or pseudo widening or ankylosis.
All right, so that's the SI joints. How about the spine? Well in the spine we can see some pretty
classic changes. We can see syndesmophytes, we can see calcification or ossification of the
vertebral discs, we can see squaring or shiny corners of the vertebral bodies, and in their
totality we can see something called a bamboo spine. Let's elaborate on each of these starting with
syndesmophytes. So syndesmophytes are a classic change we can see on x-rays of the spine in
patients with axial spa. Syndesmophytes are not osteophytes, osteophytes are something we see in
osteoarthritis, syndesmophytes are something we see in axial spa. A syndesmophite is a new vertical
bony growth between the corners of adjacent vertebral bodies along the intervertebral spinal
ligaments. So picture the vertebral bodies in the spinal column. They're connected by intervertebral
ligaments and with axial spa the inflammation can cause ossification whereby these ligaments go from
being nice and loose to being bony and hard. And syndesmophytes cause a very real problem because
as they grow they cause irreversible reduction in spinal mobility and eventually cause fusion
of the vertebral column. So once again syndesmophytes are a classic finding in radiographic axial spa
aka ankylosing spondylitis. Another change we can see of the intervertebral soft tissue structures
is calcification or ossification of the intervertebral discs specifically their outer lining
called the annulus fibrosis. Additionally the inflammation can affect the bony vertebrae themselves
so you can get sharpening of the corners of the vertebral bodies also known as squaring
while in addition to squaring another inflammatory change in the corners of the vertebrae is a
reactive sclerosis known as shiny corners. So in summary if you get a spinal x-ray of a patient
who has axial spa you may see syndesmophytes that link vertebral bodies. You may see that the discs
themselves are ossified. You may see squaring of the vertebrae you may see shiny corners of the
vertebrae and if you see all of these changes on an x-ray in their totality it kind of looks
like the undulating wall of a bamboo shaft a radiographic appearance that we call bamboo spine.
Now I don't think I'm poetic enough to nicely illustrate in your minds that syndesmophytes
ossification of the intervertebral discs squaring of the vertebrae and shiny corners can
lead to something that looks like bamboo spine so I encourage you to google it please don't do so
while you're driving but take a look. So the humble radiograph is a great study to do first
because it's low cost and it's super easily accessible however it usually takes several
years of symptoms to see damage on radiographs. MRI is much more sensitive and can see changes
consistent with spondyloarthritis way earlier. In particular the big sign we're looking for with
MRI is bone marrow edema because that suggests active inflammation. You can get other changes too
in addition to bone marrow edema these include fatty deposition as well as the other structural
things we talked about earlier with x-rays including erosions and ankylosis. So if you have
normal or equivocal x-rays and you still suspect axial spa the next step is MRI. Now from a practical
perspective you need to decide what you're ordering when asking for an MRI in axial spa.
You see x-rays are easy they're fast they're cheap and so you can get x-rays of the entire
spine and the SI joints. MRI takes a long time it's much more expensive and can be a kind of
claustrophobic experience for your patient. The fact of the matter is that most patients are
going to have changes in their SI joints. It is seldom that you see a patient who has changes
isolated to the spine without changes in the SI joints but it is not uncommon to see a patient
with isolated changes in the SI joints and minimal to no changes in their spine and so you are usually
ordering an MRI of the SI joints for diagnosis of axial spa. By contrast you are almost never
ordering an isolated spinal MRI for the diagnosis of axial spa and even the value of adding a spinal
MRI to an SI joint MRI in the diagnosis of axial spa is unclear. Many experts will try to add an MRI
of the entire spine to an MRI of the SI joints so that they can pick up those very few patients who
have only spinal changes and so that they can assess the degree of damage elsewhere in the axial
skeleton. My personal approach is that if the patient and or the health care system has the
resources for a total axial MRI then I do add spinal MRI to the SI joint MRI but you are not
wrong if you skip spinal MRI you are not wrong if you always include it. We made a big jump
from the humble x-ray all the way up to the MRI and that begs the question what about the CT skin?
How about meeting somewhere in the middle? Well there might actually be a role for CT after all.
You see while we feel that MRI is excellent at looking for active inflammation very simply
speaking bone marrow edema the CT scan is probably better at looking for structural changes so while
CT cannot assess for bone marrow edema i.e cannot look for active inflammation it can cut thin imaging
slices and give higher spatial resolution of the cortical bone compared with MRI and so increasingly
we're seeing more use of the CT scan in the diagnosis of axial spa so if MRI is not available
or if MRI is inconclusive then you may consider CT scan to look for structural lesions in the SI
joints that suggest sacroiliitis. Quiz time. Okay question one there are different lab tests you
can order in axial spa below arthritis HLA B27 inflammatory markers and less commonly bone
specific ALP or even IGA though these last two are not commonly ordered starting with HLA B27
true or false all patients with axial spa have a positive HLA B27
false it's present in up to 90% of patients with axial spa but many patients will have
the disease without HLA B27 and just as importantly most people who have HLA B27 do not have axial spa
question two true or false inflammatory markers like ESR and CRP are good measures of disease
activity in axial spa false they are very frequently normal even with active disease
okay let's move on to imaging so question three when you want to look at the sacroiliac joints
you'll order x-rays to start these can be x-rays dedicated to the SI joints like the
Ferguson view or ap pelvis views both can show you abnormalities please list four changes you can see
on x-rays which suggest sacroiliitis
okay one erosions two sclerosis three narrowing or pseudo widening of the joint space
four ankylosis or fusion again erosions sclerosis narrowing or widening of the joint space
and ankylosis question four can you list four abnormalities you can see on spinal
radiographs so x-rays of the spine in axial spa
okay one shiny corners of the vertebral bodies two squaring of the vertebral bodies
three syndesmophytes these are the bony growths of the intervertebral spinal ligaments that can
reduce spinal mobility four ossification of the annulus fibrosis and five bamboo spine
so again shiny corners of the vertebral bodies squaring of the vertebral bodies
syndesmophytes ossification of the annulus fibrosis or the intervertebral disc
and finally the classic bamboo spine and the final question which is less for clinical practice
more for a rheumatology fellowship exam is please describe the new york criteria for radiographic
sacroiliitis i'll give you a quick hint the new york criteria for radiographic sacroiliitis
is to grade changes of the sacroiliac joints on x-ray to evaluate for the presence of inflammatory
disease and it's graded from zero to four okay grade zero is normal grade one is suspicious changes
grade two is definite but minimal changes so something like a small erosion or sclerosis
without changes in the actual joint space grade three is unequivocal abnormalities
and grade four is full-blown ankylosis so again zero normal one suspicious two definite but
minimal changes like a small isolated erosion three unequivocal changes and four ankylosis
to be considered radiographic sacroiliitis the scoring criteria requires at least
bilateral grade two or at least unilateral grade three meaning bilateral definite but minimal
changes or unilateral grade three unequivocal abnormalities classification in rheumatology
we have very few diagnostic criteria more commonly we talk about the classification
criteria the difference being that classification criteria are meant to identify a homogeneous
population to include in a study in other words therefore research purposes and not for clinical
purposes now axial spa has some diagnostic algorithms like the asas adapted berlin algorithm
but it's not commonly used so instead let's focus on the classification criteria previously we used
to use the 1984 modified new york criteria for ang spond radiographic sacroiliitis was an essential
part of those criteria but the modified new york criteria were based on the presence of radiographic
abnormalities and as time went on we realized that young individuals with chronic inflammatory back
pain needed years of symptoms on average before radiographic damage was seen and so in 2009
the asas axial spa criteria were created these criteria are applicable to patients with chronic
back pain meaning present for at least three months an onset that began prior to age 45
the beauty with these criteria is that they include both non radiographic axial spa and
radiographic axial spa patients allowing classification of patients at earlier stages
in their disease so they can also be included in research studies and this was a big advancement
including non radiographic axial spa early patients along with radiographic axial spa patients
within the axial spa classification criteria so how do these 2009 asas classification criteria work
well as we said earlier patients to be included have to have chronic back pain
meaning present for at least three months and the onset had to start before the age of 45
and there are two ways to be classified within this criteria the first pathway is radiologic
and the second pathway is clinical in the radiologic group patients must have evidence of
sacroiliitis either on radiograph or on MRI and then they need to have at least one typical spa
feature this includes most of what we talked about earlier msk symptoms like inflammatory back pain
peripheral arthritis dactylitis or anthocytus non musculoskeletal manifestations like uveitis
psoriasis Crohn's or ulcerative colitis good response to NSAIDs a family history of spa
or the presence of an HLA B-27 or elevated CRP on the other hand there's a clinical arm for
classification as well whereby patients must have the presence of an HLA B-27 and not one
but two associated spondyloarthritis features so again 2009 asas classification criteria include
both non radiographic and radiographic axial spa you can be classified if you have at least
three months of back pain making it chronic and the pain started at less than 45 years of age
and there are two arms for classification the first is radiologic so you have sacroiliitis on
imaging either MRI or x-ray and one associated feature of spondyloarthritis the second arm
is clinical so you have HLA B-27 positivity and at least two spa features again these are not for
diagnosis they're for classification they're for research purposes to give you a sense of why I say
that let me tell you about one study which found that these criteria have only an 83 percent sensitivity
for axial spa and an 84 specificity compared to diagnosis by a rheumatologist instead diagnosis
requires you to recognize the pattern we use a lot of the same features from the classification
criteria but the classification criteria are a dichotomous yes or no yay or nay for inclusion
in a study whereas when it comes to diagnosis you need more flexibility with our diseases
whether the patient has inflammatory back pain the onset the family history the labs the imaging
the non-musculoskeletal manifestations they all have to be taken into account
and may not fit perfectly in the classification criteria box differential diagnosis the most
common differential diagnosis for axial spondyloarthritis unsurprisingly is degenerative
or mechanical back pain fine the reason I'm talking to you about differential diagnosis though
is not because of the clinical differential diagnosis but the radiologic differential
diagnosis specifically I want to bring up two conditions with you the first is osteitis condensans
iliai and the second is dish again osteitis condensans iliai osteitis condensans iliai oci and dish
let's start with osteitis condensans iliai this is a condition that's typically an
incidental radiographic finding because it's usually asymptomatic and is picked up incidentally
on imaging that's done for an unrelated complaint so again usually osteitis condensans iliai is
asymptomatic however can present with non-specific lower back pain as well that is not inflammatory
in character what you see on x-rays is sclerosis at the sacroiliac joint but only of the iliac bone
not the sacrum so again oci is just sclerosis of the iliac bone and it's in the name itself
osteitis condensans iliai this is a condition that's more common in women particularly women who are
perigestational or postpartum because the hormone changes and the increased mechanical stress from
carrying a baby lead to sclerosis of the iliac bone we also see this in patients who've had recent
weight gain this is not sacroiliitis because it spares the joint space and it is not progressive
you won't see erosions you shouldn't see effusions but you might intermittently see some
subconjural bone marrow edema and most of these patients will do very well because typically
it's an asymptomatic condition okay so that's osteitis condensans iliai the second condition
is dish d ish also known as diffuse idiopathic skeletal hypostosis diffuse idiopathic skeletal
hypostosis whereby you develop ossification of spinal ligaments which kind of sounds like the
syndesma fights of axial spa doesn't it and to make it even more confusing for you the rheumatology
gods said that both dish and radiographic axial spa i.e. enclosing spondylitis are seen more
frequently in men than women so how do we differentiate well there are some good markers
you see dish is a non-inflammatory condition whereas axial spa obviously is inflammatory
and the inflammatory markers and the clinical symptoms that go along with inflammatory disease
will obviously be absent in dish the second thing is age part of the pathophysiology of dish
is felt to be an age-related phenomenon so patients who have dish are usually men over the age of 50
older men whereas patients with axial spa typically have symptom onset under the age of 40
next dish spares the si joints whereas you've heard multiple times now that axial spa loves
affecting the si joints and lastly dish will involve the anterior longitudinal ligament of
the spine whereas radiographic axial spa spares the anterior longitudinal ligament so again
dish sounds like it could be very closely related to axial spa new ossification of the spinal
ligaments in men however it is a distinct condition it is non-inflammatory unlike
inflammatory axial spondyl arthritis it happens in men over the age of 50 whereas axial spa occurs
in patients under 40 dish involves the anterior longitudinal ligament whereas axial spa spares
the anterior longitudinal ligament and dish should not affect the si joints whereas axial spa
obviously will involve the si joints some extra stuff there is just one quick thing
I want to elaborate on in one minute or less and that is bone marrow edema on MRI now previously
we used to think that bone marrow edema on MRI automatically meant inflammation so if you saw
bone marrow edema around the sacroiliac joint we used to assume that this was axial spondyloarthritis
however nowadays we are understanding that this is not the case you can see bone marrow edema
in non-inflammatory conditions for example runners can get bone marrow edema postpartum
or peripartum women can get bone marrow edema patients with non-specific mechanical back pain
can get a little bit of bone marrow edema patients with osteitis condensans ilii might even have a
small amount of bone marrow edema and there are other conditions as well so the takeaway
is that the presence of bone marrow edema around the sacroiliac joint doesn't automatically mean
axial spondyloarthritis now on the other hand we also have a better understanding nowadays
that the absence of bone marrow edema doesn't necessarily rule out axial spondyloarthritis
the way we used to think it did there is a small group of patients usually female
who can have axial spondyloarthritis but negative MRI imaging it's an area we're starting to
understand more about but just keep an open mind when you're seeing patients who have a
convincing story even if their imaging is negative quiz time okay guys really well done
so far just a few more questions before we wrap up question one in terms of classification
the ASAS classification criteria are used to identify patients for research studies
they are not diagnostic criteria but it can still be helpful to prompt you through your
patient evaluation so as best as you can question one is please describe the ASAS classification
criteria and i'll give you some hints to jog your memory the prerequisites to be included for
the ASAS classification criteria are chronic pain for at least three months and age of onset less
than 45 the other hint i will give you is that there are two pathways to qualify for classification
the first ASAS pathway is radiologic and the second ASAS pathway is clinical
so i'll give you a few more seconds and then you can tell me the radiologic pathway and the clinical
pathway all right let's start with the radiologic pathway so in the radiologic pathway under the
ASAS classification criteria patients are classified as axial spa if they have radiologic
sacroiliitis identified by either x-ray or MRI plus at least one typical feature of spondyloarthritis
on the other hand the clinical pathway requires the presence of HLA b27 plus at least
two typical features of spa okay so that's more for the rheumatology fellowship board exams
but let's be a little bit more practical with question two can you name two differential
diagnoses for axial spa based on imaging one osteitis condensens ilii and two dish and finally
question three can you compare and contrast at least three features between radiographic axial spa
aka ang spond and dish
all right you could say any three of the following five things
number one both radiographic axial spa and dish are more common in men than women
number two radiographic axial spa is an inflammatory disease dish is a non-inflammatory
disease number three radiographic axial spa typically occurs under the age of 40 to 45
whereas dish is a disease of men who are a little bit older above the age of 50
number four radiographic axial spa spares the anterior longitudinal ligament whereas dish
involves the anterior longitudinal ligament and lastly number five radiographic axial spa
will cause sacroiliac disease whereas dish does not affect the sacroiliac joints
and that's it for today guys great job of making it through this topic you deserve a well earned
break if you enjoyed today's session please subscribe i would also tremendously appreciate
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future episodes content accuracy or sound issues my email is room for the rc that's r-h-e-u-m-f-o-r-t-h-e
[email protected] have a great one
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