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Medically unexplained physical symptoms (MUPS or MUS) are symptoms for which a treating physician or other healthcare providers have found no medical cause, or whose cause remains contested. In its strictest sense, the term simply means that the cause for the symptoms is unknown or disputed—there is no scientific consensus. Typically, the possibility that MUPS are caused by prescription drugs or other drugs is ignored. However, in practice, most physicians and authors who use the term consider that the symptoms most likely arise from psychological causes. It is estimated that between 15% and 30% of all primary care consultations are for medically unexplained symptoms. A large Canadian community survey revealed that the most common medically unexplained symptoms are musculoskeletal pain, ear, nose, and throat symptoms, abdominal pain and gastrointestinal symptoms, fatigue, and dizziness. The term MUPS can also be used to refer to syndromes whose etiology remains contested, including chronic fatigue syndrome, fibromyalgia, multiple chemical sensitivity and Gulf War illness.
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Many patients presenting with medically unexplained symptoms also meet the diagnostic criteria for anxiety and/or depression. The likelihood of meeting such criteria increases with the number of unexplained symptoms reported. However, anxiety and depression are also very common in individuals with medically explained illnesses, and again, the likelihood of a person receiving one of these diagnoses increases with the number of symptoms reported. Consequently, on the current evidence, we cannot infer that anxiety or depression are causes of medically unexplained physical symptoms.
Physical symptoms have been associated with adverse psychosocial and functional outcome across different cultures, irrespective of etiology (either explained or unexplained).
Doctor-patient relations
The lack of known etiology in MUPS cases can lead to conflict between patient and health-care provider over the diagnosis and treatment of MUPS. Most physicians will consider that MUPS most probably have a psychological cause (even if the patient displays no evidence of psychological problems). Many patients, on the other hand, reject the implication that their problems are "all in their head", and feel their symptoms have a physical cause. Diagnosis of MUPS is seldom a satisfactory situation for the patient, and can lead to an adversarial doctor-patient relationship. The situation may lead a patient to question the doctor's competence.
A 2008 review in the British Medical Journal stated that a doctor must be careful not to tell a patient that nothing is wrong, "as clearly this is not the case." The symptoms that brought the patient to the doctor are real, even when the cause is not known. The doctor should try to explain the symptoms, avoid blaming the patient for them, and work with the patient to develop a symptom management plan.
Evaluation
When a cause for MUPS is found, the symptom(s) are no longer medically unexplained. Some cases of ulcers and dyspepsia were considered MUPS until bacterial infections were found to be their cause. Similarly, in illnesses where long diagnostic delays are common (e.g., certain types of autoimmune disease and other rare illnesses), the patients' symptoms are classifiable as MUPS right up until the point where a formal diagnosis is made (which, in some instances, can take upwards of five years). Even when a person has received a confirmed medical disease diagnosis, they may nonetheless be considered to have MUPS, if they present with symptoms that are either not fully explained by their disease diagnosis, or are considered by the physician to be more severe than would be predicted by their disease. For example, severe fatigue in patients with systemic lupus erythematosis (SLE) has been interpreted as MUPS because the fatigue cannot be clearly linked to any of the known biological markers for SLE.
Treatment
Just as little is known about the mechanisms that cause MUPS, also little is known about how to treat them. There have been a number of efforts to treat MUPS with various forms of psychotherapy. However, very few of these studies meet the minimum quality standards required for assessing a medical treatment intervention (one of these is that patients should be allocated to either a treatment condition or another condition that controls for the placebo effect). Nevertheless, there have been some suggestions that Cognitive behavioral therapy may be useful in fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome (IBS), unexplained headaches, unexplained back pain, tinnitus, and non-cardiac chest pain. As of 2006, CBT had not been tested for menopausal syndrome, chronic facial pain, interstitial cystitis, or chronic pelvic pain.
Some high quality studies have been conducted examining the effectiveness of antidepressants in MUPS. Those antidepressants that have been investigated include tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). For example, TCAs have effects on IBS, fibromyalgia, back pain, headaches, and possibly tinnitus, and single studies show a possible effect in chronic facial pain, non-cardiac chest pain, and interstitial cystitis. SSRIs are usually not effective or have only a weak effect. One exception is menopausal syndrome, where SSRIs are "possibly effective" as well as a third class of antidepressants, the serotonin-norepinephrine reuptake inhibitors (SNRIs).
Theories
There is no consensus as to what causes MUPS. However, a number of theories have been put forward. Many of these share the common assumption that MUPS are somehow caused by psychological distress or disturbance. One classical theory is that MUPS arise as a reaction to childhood trauma in vulnerable individuals. More contemporary theories place less emphasis on trauma and suggest that an individual's personality and psychological characteristics play a central role. For example, it has been suggested that people who suffer from anxiety or depression and/or who focus excessively on their body might be particularly prone to these symptoms.
For certain MUPSs that occur within recognized syndromes (e.g. chronic fatigue syndrome and fibromyalgia), there is wide disagreement across disciplines as to the causes of the symptoms. Research in the domains of psychology and psychiatry frequently emphasizes psychological causal factors, whereas research in the biomedical sciences – relating to immunology and rheumatology, for example – commonly emphasizes biological factors.