Medically UnexplainedSymptoms: A TreacherousFoundation for SomatoformDisorders?

Joel E. Dimsdale, MD

KEYWORDS

• Psychiatric diagnosis • Medically unexplained • Pain

In the DSM-IV, medically unexplained symptoms (MUS) form the key defining featureof somatoform disorders. There are problems, however, in making MUS the “foun-dation” of diagnosis. I first discuss five problems that result from defining a diagnosison the basis of the absence of a sign or symptom—in essence, a “negative” symptom.Then I suggest an alternative to MUS-based diagnoses.

PROBLEMS WITH MEDICALLY UNEXPLAINED SYMPTOMS

1. The quality of the evaluation. On the face of it, MUS sounds affectively neutral butthe term sidesteps the quality of the medical evaluation itself. A number of factorsinfluence the accuracy of diagnoses. Most prominently, one must consider howthorough was the physician’s evaluation of the patient. How adequate was thephysician’s knowledge base in synthesizing the information obtained from thehistory and physical examination? The time pressures in primary care make itdifficult to comprehensively evaluate patients and thus contribute to delays andslips in diagnosis. Similarly, physicians can wear blinders or have tunnel vision inevaluating patients.1 Just because a patient has previously had MUS is noguarantee that the patient has yet another MUS. As a result of these factors, thereliability of the diagnosis of MUS is notoriously low.2

2. The state of medical knowledge. The considerations just posed pertain to how adiagnosis of MUS is reached. However, diagnoses are shaped by the state ofmedical knowledge at the time when the patient is evaluated. One “sees” whatone is prepared to see or understand. If one has no tools for recognizing hepatitisC, for instance, one will not make that diagnosis until very late in the progressionof the infection. New diseases are constantly arising, either totally new diseasesor, more commonly, diseases that have previously not been well understood.

Department of Psychiatry, University of California, San Diego, 9500 Gilman Drive, Mail Code0804, La Jolla, CA 92093-0804, USAE-mail address: jdimsdale@ucsd.edu

Psychiatr Clin N Am 34 (2011) 511–513doi:10.1016/j.psc.2011.05.003 psych.theclinics.com

0193-953X/11/$ – see front matter © 2011 Elsevier Inc. All rights reserved.

512 Dimsdale

3. Nonspecific symptoms as harbingers of undiagnosed illness. Many illnessespresent initially with nonspecific signs such as fatigue, long before the diseaseprogresses to the point where laboratory and physical findings can establisha diagnosis. Thus, there is always the possibility that a patient’s MUSrepresents an as-yet-undiagnosed disease. Interestingly, new technologiesinevitably facilitate diagnosing diseases earlier in their course. Cancer screen-ing with contemporary imaging allows the detection of smaller tumors.Advances in drug development (eg, conscious sedation) and bioinstrumenta-tion development (eg, endoscopy) now facilitate examination of areas of thebody previously “accessible” only with the use of general anesthesia. Similaradvances in assay development allow simple screening with blood sampling.All of these sorts of technologies facilitate early detection and thus provide apowerful tool for understanding early nonspecific symptoms presented inconjunction with an undiagnosed disease.Obstructive sleep apnea provides an interesting example of revolutionarychanges in perspective brought about by new ways of screening for disease.Once recognized in the severe form only, sleep apnea is now recognized to bea common disorder. Its initial presentation can frequently include nonspecificcomplaints of fatigue or sleepiness. How often is the undiagnosed apneicthought to have an MUS? Is it then appropriate to diagnose such a patient witha somatoform diagnosis? Is this helpful? To the extent that one believes thatpsychiatric intervention is good for all kinds of distress and for all chronicdisease, such a diagnosis might facilitate referral and treatment. However, thequestion is, which is the most proximal therapy for such a patient— continu-ous positive airway pressure (CPAP) treatment or psychiatric referral (orboth)?

4. Mind-body dualism. The implication of the MUS label is that we are telling thepatient that “it’s all in your head.” Of course, that statement is quite literally true.Symptoms are processed in the brain, whether they are pain signals from acompound fracture, back spasm, or enteric distress. They are “authentic” and feltby the patient. The task of medicine is to diagnose the symptom’s source and toprovide appropriate treatment. Unfortunately, the implication of the “all in yourhead” statement is that the patient is causing or misreporting the symptom,wasting the doctor’s time, or some other similarly dismissive conclusion. It is nowonder that patients are unhappy with somatoform diagnoses.3

5. Heterogeneity of disease. One needs to acknowledge that diseases are veryheterogeneous. That heterogeneity may account for the variance in response tointervention. Histologically, similar tumors have different surface receptors, whichaffect response to chemotherapy. Particularly in chronic disease presentationssuch as irritable bowel syndrome or chronic fatigue syndrome, the heterogeneityof the illness makes it perilous to diagnose all such patients as having MUS andan underlying somatoform disorder.

AN ALTERNATE FORMULATION

It is true that some people are more sensitive to pain than others. That sensitivity mayrepresent a different neural sensory amplification threshold that may be hard-wiredand/or learned. One anticipates that considerable neural imaging research in thesetopics (see article by Stuart W.G. Derbyshire elsewhere in this issue for furtherexploration of this topic) will be carried out in the next 10 years. However, sensitivityto symptoms also reflects the patient’s thoughts, feelings, and behaviors. The

cognitive attributions of the meaning of symptoms shape the patient’s help-seeking

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513Problems with Medically Unexplained Symptoms

behavior (eg, headache interpreted as an aneurysm). Alternatively, the symptoms maybe amplified by emotions (particularly depressive symptoms) or may be behaviorallyreinforced by solicitousness from family. Grounding a psychiatric diagnosis andintervention on positive features such as thoughts, feelings, and behaviors seemsmore productive than basing psychiatric diagnosis and intervention on MUS—the“absence” of a medical explanation for the symptoms.

SUMMARY

Patients present with an admixture of symptoms, preconceptions, feelings, andillnesses. The task of psychiatric diagnosis is to attend to the patient’s thoughts,feelings, and behaviors that are determining his/her response to symptoms, be theyexplained or unexplained. One hopes that future psychiatric diagnosis will focus onsuch features as opposed to MUS.

REFERENCES

1. Dimsdale JE. Delays and slips in medical diagnosis. Perspect Biol Med 1984;27:213–20.

. Rief W, Rojas G. Stability of somatoform symptoms: implications for classification.Psychosom Med 2007;69:864–9.

. Dimsdale J, Sharma N, Sharpe M. What do physicians think of somatoform disorders?Psychosomatics 2011;52:154–9.