Centrally-Mediated Abdominal Pain Syndrome (CAPS) — formerly known as functional abdominal pain syndrome (FAPS) — is a complex condition characterized by severe and often continuous pain in the abdomen for at least six months with no apparent physical cause.
As the name suggests, the most common symptom of centrally mediated abdominal pain syndrome is chronic, often continuous abdominal pain that can be severe to the point of being all-consuming. Unlike other gastrointestinal disorders like irritable bowel syndrome that can cause abdominal pain, the pain caused by CAPS is rarely related to experiencing a physiological event like eating, menstruation or having a bowel movement.
CAPS patients also usually don’t have abnormal X-rays or laboratory findings that show a physical problem or cause of their pain and other symptoms. CAPS also doesn’t usually impact gut function or motility, which is the speed at which food moves through the GI tract as it is digested.
The gastrointestinal pain of CAPS can be so intense that it can become a main focus of the patient’s life, affecting not only their quality of life but also their ability to perform a job. Because of this, CAPS can have a major economic impact on patients’ ability to make a living.
The exact cause of Centrally-Mediated Abdominal Pain Syndrome isn’t well understood. Some people can develop CAPS symptoms with no apparent underlying cause. For others, however, the onset of symptoms can happen after issues like abdominal infections, abdominal trauma or surgery involving the abdomen.
In some cases, certain high-stress events that induce powerful emotions can also trigger the onset of CAPS, including:
Divorce
Physical or sexual abuse
The death of someone important to you
CAPS is considered a functional GI disorder, which means that it is believed to be related to an issue with how gastrointestinal pain signals carried by nerve impulses are transmitted between the brain and gut.
Other functional gastrointestinal disorders include Irritable Bowel Syndrome (IBS), functional constipation and functional dyspepsia, though CAPS and these functional disorders aren’t thought to be directly related.
The specific symptoms experienced by those with CAPS are often different for every patient. However, common symptoms and characteristics include:
Frequently-recurrent abdominal pain or continuous abdominal pain lasting more than six months
Severe abdominal pain: CAPS symptoms often include chronic, continuous abdominal pain, meaning there is no way to find relief from it. The chronic abdominal pain caused by CAPS can be severe and debilitating, often causing disruption to a patient’s quality of life. The pain can also impact a person’s ability to work, which can have a major economic impact on their financial well-being and ability to provide for their family.
Symptoms that are unrelated to gut events: In many other disorders that cause chronic abdominal pain, the pain often lessens or becomes more severe after certain physiological events like eating or defecation. Because a functional abdominal pain syndrome like CAPS is related to issues with nerve impulses and nerve sensitivity, the pain experienced by CAPS sufferers is rarely altered by these gut-related events.
Symptoms that are unrelated to the menstrual cycle: In women with chronic bowel disorders like inflammatory bowel disease (IBD), Crohn’s disease, irritable bowel syndrome or ulcerative colitis, the spike in certain hormones during menstruation can make symptoms worse. In women with CAPS, chronic pain in the abdomen and other symptoms are usually unchanged by the menstrual cycle
Heightened sensitivity to abdominal pressure and bloating: Symptoms experienced by those with CAPS sometimes include what’s called visceral hyperalgesia, which is hypersensitivity and a chronic pain response to what should be normal intraluminal distention of the GI tract. Intraluminal distention refers to internal pressures caused by gas, air, water and feces.
Repeated quality-of-life disruptions due to severe abdominal pain: Due to the recurrent abdominal pain caused by centrally mediated abdominal pain syndrome, the disorder can have a huge impact on a patient’s quality of life, including impacting their ability to hold a job, economic wellness, sexual health, social life, education and more.
Like many functional bowel disorders, CAPS can be difficult to diagnose because it usually causes few symptoms other than severe, debilitating abdominal pain.
If you visit your doctor with functional abdominal pain and other symptoms that suggest you might have CAPS, you’ll likely be given a through physical exam and evaluation, including being asked to give a detailed history of your health and symptoms. This examination will likely lead to blood tests, imaging tests and scans to rule out other conditions, including other functional GI disorders that can result in gastrointestinal symptoms like severe abdominal pain. If no other cause is found, you may be evaluated for CAPS.
CAPS is diagnosed through what’s known as the Rome IV diagnostic criteria. Established in 2016, the criteria establishes five features that must be present to confirm a diagnosis of CAPS.
To meet the Rome IV requirements, symptoms must have been present for at least 3 months before the evaluation, with the onset of symptoms at least 6 months before. Criteria include:
Chronic, continuous abdominal pain, or pain which is nearly continuous
No change (or only occasional change) in the patient’s abdominal pain when experiencing physiological events like eating, defecation or menstruation
The chronic abdominal pain experienced by the patient limits some aspect of their day-to-day function, including impacting their ability at work, during intimacy, during social or leisure, during family life, etc.
The pain is not feigned, meaning it is not being “made up” by the patient
The pain is not due to any structural or functional gastrointestinal disorder or medical condition. This is usually confirmed through medical imaging and laboratory findings. Structural gastrointestinal disorders that can cause abdominal pain include conditions like peptic ulcer disease and chronic pancreatitis.
There is currently no cure for CAPS, but your physician can help you take steps that might help you better control your pain and lessen severe symptoms. Treatment and management tools that can potentially help patients suffering with CAPS include:
Stress management and relaxation training: The pain from CAPS can often be debilitating, but through techniques like mediation and deep relaxation, patients can potentially learn how to focus their attention away from the pain, improving their ability to manage daily activities.
Cognitive behavioral therapy (CBT): Cognitive Behavioral Therapy is a short-term form of therapy that works to help patients recognize and change potentially damaging behaviors, thoughts and perceptions that might be triggering or influencing their pain levels, triggering their pain or other symptoms. In treating chronic pain, CBT is sometimes utilized with psychiatric medication.
Drug treatments to help control your pain: To help manage the severe pain that’s often a feature of CAPS, your doctor may prescribe an anti-depressant medication at a low dose. This medication is prescribed not for mental health treatment or emotional factors, but as a pain reliever. Though it is not a well-known quality of these drugs, some psychotropic medicines like tricyclic antidepressants (TCAs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) have the ability to reduce severe pain in some cases.