IBS and Non-GI Functional Disorders

“Unexplained” Symptoms and “Functional” Disorders

People usually go to healthcare providers with symptoms, not with the names of diseases or conditions (diagnoses). The healthcare provider’s task is to make sense of the patient’s complaints within the framework of medical diagnoses and recognized diseases such as IBS and other functional disorders. 

Your healthcare provider will begin by taking your family history, conducting a physical examination, and run some diagnostic tests. This is completed when the symptoms are diagnosed and treated.

A significant percentage of patients who consult with healthcare providers in primary care or even specialist clinics have symptoms that remain unexplained even after all the diagnostic process has been exhausted.

Modern medicine focuses on structural (often called “organic”) diseases, that is diseases that have a basis in the structure or anatomy of the body systems rather than functional disorders that have a basis in how the systems work.

Examples of structural abnormalities in the gastrointestinal tract are:

  • ulcers
  • inflammation
  • infection
  • cancer.

Examples of functional abnormalities are disordered motility (where nerves or muscles in any part of the digestive tract do not function with their normal strength and coordination).. This can lead to hypersensitivity to pain (where persons sense or perceive pain or discomfort more easily, or at lower levels than is considered normal).

Most diagnostic tests (laboratory tests, radiology, endoscopy, and isotope scans) are designed to identify structural problems, but not disorders of function.

There are many examples of functional disorders in the gastrointestinal (GI) tract. The best-studied and most common of these are irritable bowel syndrome (IBS), and non-ulcer dyspepsia or functional dyspepsia.

Non-gastrointestinal Functional Disorders Common Unexplained Symptoms
– Fibromyalgia (FMS)
– Chronic fatigue syndrome (CFS)
– Migraine and tension headaches
– Temporomandibular joint disorder (TMJ)
– Post-traumatic stress disorder (PTSD)
– Chronic pelvic pain (CPP)
– Interstitial cystitis and dysuria (pain on urination)
– Non-cardiac chest pain (NCCP)†
– Multiple chemical sensitivities
– Headache
– Dizziness
– Palpitations
– Back and muscle pain
– Shortness of breath
– Dysuria (pain on urination)
– Fatigue/ sleeping problems
– Jaw pain
– Dry mouth
– Sexual-related disorders
– Exacerbation of IBS during menses
– Somatization disorder
– Psychological co-occurrence
– Depression/Anxiety/ panic disorders
*The distinction between disorders and unexplained symptoms (see Table 2) is not always clear-cut.
†In some patients NCCP has a gastrointestinal basis.
*The distinction between disorders and unexplained symptoms is not always clear-cut.

The Coexistence of IBS with FMS and Other Functional Disorders

A study was conducted of 127 chronic fatigue patients who had a non-fatigued twin. Coexisting conditions such as fibromyalgia, IBS, TMJ, interstitial cystitis, chronic pelvic pain, tension headache, multiple chemical sensitivities and other functional disorders were significantly more prevalent in the twin with chronic fatigue syndrome than in the control twin. Other data this study found:

  • Up to 70% of fibromyalgia (FMS) patients have chronic fatigue syndrome (CFS) and
  • 35–70% of patients with CFS have FMS
  • Fifty-eight to 92% of CFS patients have IBS

In a study conducted in Israel, Sperber et al. showed that found that

  • 31.6% of IBS patients met the diagnostic criteria for fibromyalgia, and
  • 32% of women with fibromyalgia also suffered from IBS

Functional Disorders in Various Body Systems

In the mid-19th century George Miller Beard, an American neurologist coined the term “neurasthenia” for a disorder that has also been known at times as Beard’s disease. He described patients with unexplained chronic fatigue and lassitude, which he referred to as nervous exhaustion. He reported that these patients had many additional signs and symptoms, including insomnia, back pain, nervousness, anxiety, depression, headache, difficulty in concentrating, reduced sexual impulse, abdominal pain, bloating and excess gas, diarrhea, and lack of appetite. Although he described patients of both sexes, he reported that neurasthenia had a female predominance.

This was an early description of a generalized functional disorder with associated psychological elements and evidence of somatization disorder (SD). These associations have gained recognition over the years for their potential contribution to the understanding and treatment of IBS.

Somatization disorder is a chronic condition with multiple physical complaints or symptoms and no recognizable physical abnormality. It is much more prevalent among women than men and usually begins at a young age (up to 30 years of age). Stress often worsens symptoms.   Learn more about stress and IBS

Source: IFFGD Publication #207, by Ami D. Sperber, MD.

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