Welcome back!
Last time we talked about the process of evaluating GI symptoms in general. Now let’s get into some specific problems. Like, exactly what the heck is irritable bowel syndrome (IBS)?
For one thing, IBS is a syndrome and thus different from a disease. A syndrome is a group of symptoms that may or may not have a single underlying cause. So who cares? Good question. For one thing, it is usually easier to find an effective treatment or even a cure for a problem if you know what starts the process in the first place. The point is IBS is characterized by recurrent abdominal pain and irregular stools, AND the pain changes with your BMs OR your BMs are different (harder, looser, more or less frequent) from what they used to be. Got that? This is basically what we refer to as the Rome IV criteria. Why Rome? That’s where- in Rome, Italy, a group of experts in the field first met in 1989 to agree upon and establish what IBS is and how it is diagnosed. With this agreement, the GI community could then study this common condition and work on treatments.
Prior to the first criteria (Rome 1) published in 1992, IBS was considered a “diagnosis of exclusion”. ‘Well, you ain’t got cancer and you ain’t got celiac and you ain’t got Crohn’s, so it must be IBS’. That is so ‘80s. If you were ever told such a thing, you need to find a new doctor. By applying the highly accurate and reliable (80% sensitivity and specificity) Rome IV criteria, we can confidently diagnose IBS based on symptoms alone. Then just a few simple tests – CBC (complete blood count), celiac blood screen, and 2 measures of gut inflammation (1 blood, 1 stool). If these are negative (normal), then no further tests (like a scope) may be needed.
There are three categories of IBS: IBS-D (diarrhea predominant), IBS-C (constipation predominant) and IBS-M (mixed; a little of both). If you think about your own bowel pattern (who doesn’t?), you can probably put yourself into one of these categories.
So what causes IBS in the first place? If I don’t have cancer or gut inflammation, why can’t I have regular daily BMs without pain? Wow, talk about your million dollar questions. Think of your GI tract as a long (about 25 feet!) muscular tube that is always contracting to move things through. But the rate at which it contracts changes throughout the day and night, mostly in response to eating. The large intestine does its own thing, different but in tune with the small intestine. And don’t forget the stomach and esophagus, on the front end but also in synch. One thing that happens is this coordinated peristalsis is thrown off schedule, sometimes too fast, sometimes too slow. This can result in irregular stools, too hard or too loose.
But what about the pain, you say? I sincerely hope that as you are reading this, you are feeling good and not having any abdominal discomfort. But I guarantee you that your gut is cranking away. So what causes us to feel this peristalsis at some times and not at others? It could be because the contractions are stronger than “normal” or because of spasm, that is, two or more segments contracting at the same time. But also important is the concept of hypersensitivity. That is, patients with IBS may perceive normal peristalsis as painful or crampy or bloated. Why? Well, the brain-gut axis is very complex. Our “abdominal brain” (AKA enteric nervous system) talks to our central nervous system (AKA brain brain) in many different ways. That means there are many places in this supply chain where errors can occur.
You may have also heard of the gut microbiome, or the trillions of bacteria that reside within us. (As an aside, take a minute to think of your GI tract as actually being the outside world tunneling its way through your body. No, really. Wow! Kinda blows your mind, doesn’t it?) A “healthy” microbiome is important for normal gut function and our immune system tolerates, or coexists, with these bugs. If “bad” bacteria take over, or if our immune tolerance of the “good” is altered, problems can ensue. As I said in the last blog, exactly how this occurs gets pretty complicated. So more good bacteria, right? Unfortunately, probiotics don’t really work for IBS. Another example of how not every logical idea ends up really working in a complex biological system such as the human organism. That’s medicine for you.
So, that’s a lot of info on IBS pathophysiology. Next time we’ll talk about symptoms and treatment, including diet, medication and even hypnotherapy.
Until then, Happy Holidays and Na Zdrowie!!