Brian Lacy, MD, and Greg Sayuk, MD on Chronic Abdominal Pain: Part 1

Drs Brian Lacy and Gregory Sayuk discuss the intricacies of properly diagnosing the causes of chronic abdominal pain, including irritable bowel syndrome and disorders of gut-brain interaction.

Brian Lacy, MD, is a professor of medicine and gastroenterologist at the Mayo Clinic in Jacksonville, Florida. Gregory Sayuk, MD, is an associate professor of medicine and psychiatry at the Washington University School of Medicine in St Louis, Missouri.

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TRANSCRIPT:

Brian Lacy:

Welcome to this Gastroenterology Learning Network podcast. My name is Brian Lacy. I'm a professor of medicine at the Mayo Clinic in Jacksonville, Florida. I'm absolutely delighted to be speaking today with Dr. Greg Sayuk, professor of medicine at Washington University in St. Louis, Missouri. Dr. Sayuk is an expert in the field of disorders of gut-brain interaction, disorders which were previously called functional bowel disorders. Our topic today is one frequently encountered by all gastroenterologists and internists, chronic abdominal pain. Dr. Sayuk, welcome. Chronic abdominal pain is a common reason for patients to schedule an appointment with their primary care provider and is a common reason for patients to be referred to a gastroenterologist. How common is chronic abdominal pain?

Dr. Greg Sayuk:

That's a good question. We know that chronic abdominal pain is actually very common. It happens to be one of the most common symptoms or complaints that a patient may present to their clinician, their primary care doctor with, but in particular, amongst GI practices, it probably ranks amongst the top 10 reasons for somebody to present to a gastroenterologist in consultation. And in fact, in some series they suggest that perhaps as many as one in three consultations with a gastroenterologist may relate in some way to chronic abdominal pain. So this is a very common problem that we address as gastroenterologists.

Brian Lacy:

And then to help our listeners and to really kind of frame our discussion properly, it's an important to really use a clear definition. So how is chronic abdominal pain best defined? Is it just based on the duration of symptoms or do we need to factor in the frequency or intensity or severity of symptoms into the definition as well?

Dr. Greg Sayuk:

Chronic implies that the patient has been dealing with this symptom for some time, and so typically we use a threshold of about six months as a minimum number of months that the patient has had these symptoms to define it as chronic. Now, we do typically also take into account the frequency of symptoms, that varies considerably from patient to patient. Some patients may experience symptoms as little as once a week on average, but we do have certainly patients that experience these symptoms more frequently, perhaps even daily in some cases as well. Now, with regard to the intensity and the severity, that also is quite variable. And so these are a little bit less useful in terms of defining the disorder because there's obviously a strong subjective component to the experience of intensity and severity. Severity being the degree to which these symptoms impact the individual, their quality of life, their ability to function and so forth. But collectively, I think taking into account the chronicity, the frequency of symptoms, and to a lesser degree, the intensity and severity we're able to pull together this concept of chronic abdominal pain.

Brian Lacy:

Now, abdominal pain is such a complicated process. Can you distinguish the concept of allodynia from that of hyperalgesia? And could you also comment on the role of hypervigilance in patients with chronic abdominal pain?

Dr. Greg Sayuk:

Yeah, so these are all interrelated concepts and can certainly manifest in the same individual as part of the mechanism underlying their chronic abdominal pain. So allodynia is simply put a pain experience in response to a stimulus that for a normal individual would be non-painful. So in an experimental cynic, for example, that might include the elicitation of pain with say the stroke of a feather or a light touch, something that shouldn't bother an unaffected individual. In contrast, hyperalgesia is a experience of a noxious pain response to a stimulus that is for another individual, perhaps mildly uncomfortable or perhaps barely perceived. So it's an upregulation or an enhanced experience of that stimulus for that particular individual. And we talk a lot as it relates to the disorders of gut-brain interaction, as you mentioned earlier about hypersensitivity as being a core component to the pathophysiology of those disorders. Lastly, hypervigilance is an intensified focus. It's an increase in the patient's awareness to the experience of a particular stimulus. And again, in the case of DGBI, we often see patients developing an enhanced focus and attention to things related to GI symptoms in their particular experience.

Brian Lacy:

And you mentioned DGBI disorders of gut-brain interaction, and then thinking about that and chronic abdominal pain, some experts like to think about predisposing factors for abdominal pain and precipitating factors and perpetuating factors, kind of the three Ps. Do you think this concept is helpful to healthcare providers and can you review some of these factors for our listeners?

Dr. Greg Sayuk:

Sure. So I do believe these are very important, and in fact, we conceptualize these three Ps in the context of a bio-psychosocial model of our understanding of the development of disorders like irritable bowel syndrome and chronic pain experiences. So the predisposing factors suggest characteristics or experiences that the individual may have that put them at increased risk for the consequent development of these symptoms later in life. So this may include genetic factors, for example. We know that in the case of irritable bowel syndrome, again, there are certain genetic traits, certain familial traits that convey an enhanced risk for the development of irritable bowel syndrome later in life. There may be environmental factors, early life exposures, including things such as trauma or abuse that may also be very important predisposing factors. With regard to precipitating factors, here we're talking about aspects of the patient's natural history that may have led to the onset of the chronic abdominal pain experience, and we're particularly interested here in things such as inflammatory processes that may have affected the intestinal tract at some point, infections would be a primary example there.

And as you know, in recent years, there's been an intense focus on changes to the gut microbiota and the role that this may play as a precipitating factor in the development of chronic abdominal pain. Then lastly, these perpetuating factors may be experiences or events or traits that the individual possesses that propagate the experience of these symptoms over time. And this can include, again, a variety of things such as cognitive factors, the patient's attention, again, as we discussed earlier, life stressors, mood disorders and so forth that may allow for the continued experience of this pain over time for the individual.

Brian Lacy:

Thank you very much, Greg. So I know you've got a long laundry list in your head and this long differential diagnosis, but when you see patients in your clinic, what are some of the most common causes of chronic abdominal pain?

Dr. Greg Sayuk:

So we've already mentioned one of them, which is irritable bowel syndrome, and this is one of the prototypical conditions disorders that we associate with chronic abdominal pain. It's again, one of the more common diagnoses that we see in our clinic. This implies an irritable bowel syndrome and experience of chronic abdominal pain and association with bowel symptoms, so changes in the individual stool frequency, stool form, perhaps worsening or improvement of the pain in association with defecation. Functional dyspepsia happens to be another common disorder. This is more of a upper GI or foregut focus disorder. Does often cohabitate with irritable bowel syndrome. So you often see patients that have both symptoms in the upper GI tract and the lower GI tract in the same patient. A couple of other things that we consider. There is a disorder that is focused on more of the pain experience in the absence of the bowel symptoms, and this is a central mediated abdominal pain syndrome or CAPS for short, probably a little bit less common than irritable bowel syndrome or functional dyspepsia.

And one other diagnosis that I always think about, Brian, is the diagnosis of narcotic bowel syndrome because this is a very common thing that we encounter, particularly in patients that are on chronic opiate medications for the management of pain in other areas, and these individuals can actually develop a paradoxical hyperalgesia as a consequence of that opioid use. And so this becomes a very important focus for individuals that are on maintenance opiates for perhaps chronic musculoskeletal pain. Those are three or four of the common things that we think about and see with patients presenting with chronic abdominal pain.

Brian Lacy:

Thank you. Great teaching point about narcotic bowel syndrome. So everybody's pretty rushed in clinic, they're trying to be efficient, and when we think about somebody with chronic abdominal pain and the GI clinic, are there key questions we should be asking? I mean, should we just focus on abdominal bowel habits or should we explore psychological distress or do we start thinking about uncommon causes and ask about exposures to heavy metals?

Dr. Greg Sayuk:

All of these things I think are important in the proper context. I think it's important to recognize that common things are common, and as we've discussed earlier, disorders of gut-brain interaction, irritable bowel syndrome is a very likely diagnosis just at the outset because of its prevalence in the population. One important thing that I think we need to at the forefront consider is whether the patient has any red flag features or alarm symptoms that we need to focus on, which would then direct our diagnostic evaluation towards a more aggressive evaluation early on. And so here, of course, we're talking about things such as blood in the stool, anemia, weight loss, onset of the symptoms over the age of 50. Some would regard nocturnal symptoms as a red flag feature. These are things that we need to focus on our history early and direct therapy accordingly.

Psychological factors, again, can be very important for two reasons. Number one, they often associate with disorders of gut-brain interaction. So we know that upwards of 30 to 40% of patients with irritable bowel syndrome, for example, may have an overlapping mood disorder, anxiety, major depression, and this enhances our ability to confidently make a diagnosis in such a disorder when these other psychological factors are present. Secondly, those same factors also are important to the symptom experience of the individual. So we know, again, that patients with overlapping mood disorders have more severe symptoms, also tend to be more treatment refractory than patients who do not have overlapping anxiety and depression, for example.

Then lastly, as you mentioned, uncommon causes. I don't focus on that initially, but I do think it's important that we don't entirely forget about these less common causes of chronic abdominal pain. It's easy to become focused on these DGBI because they are so common, but if you don't take the time to at least consider in your mind other diagnoses that may be rarer, things like acute hepatic porphyria, systemic mastocytosis, mesenteric ischemia, some of these disorders that may not be very common but can certainly be important to diagnose in the sense that they take the patient's treatment in an entirely different direction, at least require consideration at some point along the course of that patient's journey, particularly if we're initiating treatment, we're trying different approaches that aren't really yielding the results that we were hoping for in terms of symptom improvement.

Brian Lacy:

Greg, that's wonderful, and you kind of beat me to the punch and thank you for kind of going through some of those warning signs or red flags in terms of anemia or bleeding and significant weight loss or family history of a GI malignancy. And so thinking about it that way, are there any specific tests that should be always performed to start an evaluation of a patient with chronic abdominal pain without those warnings?

Dr. Greg Sayuk:

Right. In the absence of those warning signs, really a fairly limited workup is what we recommend in terms of the evaluation of chronic abdominal pain, at least initially. And so the things that I do typically do, I will check the patient for celiac disease using serologic markers, a tissue transglutaminase antibody, for example, an association with a quantitative IGA level. I will do some form of an inflammatory marker, typically a C-reactive protein or perhaps a fecal calprotectin to raise a potential for an increased concern relating to inflammatory bowel disease. Basic chemistries, of course, so a complete metabolic panel, I'll usually do a complete blood count, check a TSH. But collectively, this is a fairly limited workup. We're not talking about a million dollar workup here. Most of the tests that I would typically do can be run relatively inexpensively, and then we encourage a positive diagnostic strategy. You make a diagnosis based on the presence of the appropriate symptoms and proceed accordingly with the treatment of that individual.

Brian Lacy:

Greg, wonderful. So I know you see a lot of very complicated patients sent for third, fourth, fifth, even sixth opinions. And let's take somebody with several year history of chronic abdominal pain and any test you can imagine, every blood work, upper endoscopy, colonoscopies, CAT scans, ultrasounds, mesenteric duplex, every test you can imagine is normal. So how do you explain the presence of abdominal pain to that patient where every test is normal or negative?

Dr. Greg Sayuk:

Right. Well, this of course is a frustration for patients often because they've become conditioned to expect that every diagnosis is based on a specific test. And in this particular case, we often don't have a specific tool or test to make a definitive diagnosis. So again, we rely on symptoms to make a diagnosis appropriately. The explanation, I think, in terms of why the patient is experiencing these symptoms gets back to providing a very simple layman explanation of this concept of visceral hypersensitivity. This concept of the gut-brain access wherein stimuli signals that are deriving from the gut are communicated through the spinal cord to the brain, where of course, all of these things are perceived at an inappropriate level.

So I tell the patients that fortunately, for the most part, your gut is functioning normally, your transit may be slightly different or enhanced, but for the most part, we're not talking about an inflammatory disorder, we're not talking about a structural change to your gut. It's really more of a miscommunication of the signals from your gut to your brain, and at some point along the way, that amplitude of those signals is upregulated, so you're perceiving functions of your gut that for a normal individual might go completely at the subconscious, the subcognitive level. And so that's really a starting point which transitions us into some of the approaches that we may recommend to try to address that hypersensitivity for the individual.

Brian Lacy:

Greg, that's great. I sometimes take a simpler approach and just say, "Your gut is extra sensitive. None of these tests look at nerve sensitivity, that's why all these tests are normal," and move from there. But your explanation is much better than mine.

Speaker 3:

Be sure to join us for part two of this podcast as doctors Lacy and Sayuk discuss treatment options for patients with chronic abdominal pain.

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