History & Physical Examination
A careful, thoughtful, and compassionate exposure and psychosocial history is critical. Although the etiology of MCS is controversial, the patient may be suffering from disabling symptoms and frustrated by the lack of definitive answers from clinicians and sometimes is desperately seeking advice and counsel regarding treatment. Approaching the history with the suspicion that the patient with MCS is suffering from a psychiatric disorder, is malingering, or is seeking monetary benefits is not helpful in establishing a therapeutic relationship. Acknowledgment of symptoms and the establishment of a trusting relationship should not necessarily be avoided because the etiology is uncertain or patient motivation is suspect. Where the diagnosis is suspect or contested, an adversarial relationship sometimes may emerge in the provider-patient context that may erode trust, challenge the provider's capacity to treat the patient, and interfere with the therapeutic goals.
A history should be obtained of symptom onset in relationship to acute or chronic exposures. One standardized questionnaire called the Quick Environment Exposure Sensitivity Inventory (QEESI) has been developed that can assist clinicians in evaluating patients and populations for chemical sensitivity. Attention should be paid to respiratory, dermal, neurologic, and systemic symptoms. Most patients with MCS report general systemic symptoms such as difficulty concentrating, fatigue, lethargy, forgetfulness, and irritability. Myalgias, gastrointestinal complaints, headache, burning eyes, and hoarseness or loss of voice also are reported commonly. These various symptoms are provoked by exposure to low-level airborne contaminants such as perfumes, colognes, cleaning solutions, smoke, gasoline, exhaust fumes, and printing inks. Duration and severity of symptoms should be recorded, particularly in relationship to repeated exposures in the workplace or environment (eg, improvement away from work or on weekends/vacations with worsening symptoms at work). An occupational history should be obtained, including past employment and exposure to chemicals, dusts, or fumes. Recent and past chemical exposures should be identified by product names or material safety data sheets, and any environmental monitoring data should be reviewed if available.
Symptoms of headache, fatigue, lethargy, myalgias, and trouble concentrating may persist for hours to days or even weeks, with typical “reactions” reported after exposures to airborne chemicals. Often the individual with MCS will have already identified a variety of chemicals that result in symptoms and will have initiated an avoidance regimen. Varying degrees of restrictions in social and work activities may be reported, including problems driving an automobile, grocery shopping, wearing certain types of clothing, or staying away from office buildings or other workplaces.
The physical examination often is normal in patients with MCS, but particular attention should be paid to examination of the respiratory tract, skin, and nervous system.
Although routine laboratory evaluations usually do not reveal any consistent diagnostic abnormalities, it is essential to rule out other nonoccupational diseases through a comprehensive history, review of previous records, and appropriate diagnostic studies. The presence of asthma and/or allergic disorders should be considered carefully and an appropriate workup undertaken. A few patients may have increased airway responsiveness and develop symptoms of chest tightness or shortness of breath on exposure to low-level environmental contaminants. Pulmonary function testing with nonspecific airway challenge testing may be indicated depending on history and symptoms. As suggested by the clinical history, confirmatory serologic and/or skin testing for common aeroallergens may be useful. If contact dermatitis is suspected, diagnostic level IV patch testing should be performed.
If a focal neurologic defect is suggested by history or physical examination, additional neurodiagnostic testing may be indicated. One patient with symptoms of altered odor sensitivity was found to have papilledema and a visual-field defect and was determined to have a treatable occipital lobe meningioma. Single-photon-emission computed tomographic or positron-emission tomographic studies of brain perfusion, computerized electroencephalographic analysis, or visual-evoked response and brain stem auditory-evoked response have not revealed consistent neurotoxic or neuroimmunologic brain changes in patients with MCS and should be used primarily to confirm clinical findings.
Additional psychological evaluation should be considered if the history suggests the presence of significant psychiatric disorder. Psychiatric consultation and/or treatment may be advised regardless of the etiology of MCS because many patients may have significant psychiatric morbidity with this disorder. Caution is advised in the interpretation of neuropsychological test results because these techniques are very sensitive but not specific. Abnormal test results could be a result of a neurologic, medical, or neuropsychiatric disorder. Neuropsychological studies have not shown significant differences between MCS patients and controls on tests of verbal learning, memory functioning, and psychomotor performance.
The capsaicin inhalation test has been used to assess sensory hyperreactivity in patients with MCS, but this test is not widely available for routine use, and its correlation with symptoms and response to treatment is not reliable for diagnosing MCS. The capsaicin concentration causing five coughs or more (C5) can be used to verify presence of lower airway symptoms related to odorous chemicals.
There is no convincing evidence that MCS is caused by a disturbance of heme synthesis, and tests for porphyrin metabolism in blood, urine, or stool specimens have not been correlated with clinical symptoms.
Several controversial techniques have been employed for the diagnosis of MCS, including provocation-neutralization testing, chemical and food challenges, inhalant challenges, serologic testing for Epstein-Barr virus antibodies and various autoantibodies, blood testing for organic hydrocarbon and pesticides, and hair testing for heavy metals. Many of these tests have no diagnostic utility. There is no evidence linking MCS to past infection with the Epstein-Barr virus. There is no association between MCS and levels of organic hydrocarbons or pesticides in blood or fatty tissue, and knowledge of minute residues of these chemicals may serve only to mislead and alarm the patient. Unless specific exposures are suspected, the use of biomarkers (eg, detailed profiles in serum of lipid-soluble toxins and their metabolites or heavy metals in the hair matrix) have little role in the diagnosis of patients with MCS. These tests have not been correlated with any pathologic consequences in MCS or control groups.
Blinded provocation testing has been employed in research studies but has not been evaluated rigorously as a useful diagnostic technique for individual patients. In a double blind placebo controlled trial, patients with MCS and controls underwent exposure sessions (solvent mixture and clean air in random order, double-blind) in a challenge chamber. There were no differences between the groups with regard to sensitivity, specificity, and accuracy were found. Cognitive performance was not influenced by solvent exposure, and did not differ between the groups. Likewise, immunologic testing has not been shown to be diagnostic for specific chemical exposure or associated illness.
In the absence of other concurrent medical conditions suggested by history, physical examination, or routine laboratory testing, the diagnosis of MCS relies on the patient's history of multiple symptoms triggered by low-level chemical exposures.
Patients with MCS should be advised that, as with a chronic illness, treatment is not directed at a “cure” but rather at accommodation. Care should emphasize relief of symptoms and a return to active work and home life. These treatment strategies entail a treatment alliance between patient and clinician without judgment regarding the etiology of MCS. Ethnographic studies have shown that many MCS patients manage their symptoms through a combination of prevention/avoidance, detoxification, and emotional self-care. In addition to symptoms and the ongoing difficulty in living with this condition, social relationships and daily life may be affected greatly. For some individuals, education regarding general principles of toxicology (eg, routes of exposure of toxic chemicals and routes of elimination) may be reassuring if they are concerned about long-term storage of chemicals in the body and the fear of ongoing damage. Elimination of exposures at home, workplace, or school through a variety of strategies (including room air filters) often is implemented by patients. In one case series of MCS patients from an occupational health practice, improvement in symptoms was associated with self-reported avoidance of specific substances or materials. Two of the three most highly rated treatments as reported by a large series of MCS patients were creating a chemical-free living space and chemical avoidance. While many patients report empirical improvement of symptoms, avoidance of low-level irritants has not been tested in controlled scientific studies. In some patients, avoidance may reinforce the notion of disability and lead to further isolation, powerlessness, and discouragement.
Although it is not clear whether psychological symptoms are the cause of MCS or simply accompany the diagnosis, specific cognitive and behavioral interventions may be most useful in the treatment of MCS. A biopsychosocial model of illness conceptualizes a close correlation between physical and psychological diseases. MCS may be a heterogeneous disorder with more than one causal mechanism. Significant psychophysiologic symptoms may occur after exposure to low-level volatile compounds in persons with and without coexisting or preexisting psychiatric illness. Similar to techniques used in other functional syndromes, behavioral strategies such as response prevention, systemic desensitization, graduated exercise regimens, and progressive relaxation may help patients to regain normal activities, minimize role impairment, and curtail sick behaviors.
Improving the patient's understanding of the role of stress on illness and enhancing coping mechanisms for the impact on daily life may be helpful. Biofeedback-assisted relaxation training and cognitive restructuring have been reported with some success in MCS patients. Adults with MCS who completed an 8-week mindfulness-based cognitive therapy program (MBCT) generally reported benefiting in terms of improved coping strategies and sleep quality. Treatments with demonstrated efficacy in panic disorder also may be of benefit in MCS, and conversely, treatments that reinforce anticipatory anxiety and avoidance behavior may be detrimental.
Pharmacologic treatment for specific symptoms suggestive of depression or anxiety, in conjunction with other behavioral techniques, may offer some relief as part of an overall treatment program. In addition, antidepressants sometimes alleviate somatic symptoms (particularly pain and insomnia) and may improve the functional status of some MCS patients. One case report demonstrated dramatic improvement in a patient with MCS who received a selective serotonin reuptake inhibitor.
Patients in whom panic responses may be at least a contributing factor to symptoms might be responsive to intervention with psychotherapy to enable their desensitization or deconditioning of responses to odors or other triggers. These patients also may be helped by anxiolytic medications, relaxation training, and counseling for stress management.
A number of controversial methods have been used for the treatment of MCS, including elimination or rotary diversified diets, vitamins or nutritional supplements, oxygen, antifungal and antiviral agents, thyroid hormone supplement, supplemental estrogen or testosterone, transfer factor, chemical detoxification through exercise and sauna treatment, intravenous gamma-globulin, and intracutaneous or subcutaneous neutralization. A specially designed chemical-free environmental control unit has been used as a method to decrease blood pesticide levels and improve symptoms as well as intellectual and cognitive function. Controversial treatment methods offer hope of improvement to many individuals with MCS, and some patients do report symptom improvement over time. Many of these treatment methods are expensive and rarely are covered by health insurance. These treatment methods have not been validated through carefully designed, controlled trials, may have unwanted side effects, and may serve to reinforce counterproductive behaviors. Patients should be advised that such treatments are controversial, have not been subject to controlled clinical trials, and are not recommended by most medical professional organizations.
Follow-up studies indicate that up to half of MCS patients may improve over a period of years, but the majority continue to remain symptomatic with a major impact on career, marriage or family and other common daily activities.