Multiple Chemical Sensitivity: A Clinical Perspective.

Objective: The etiology of multiple chemical sensitivity (MCS) is still debated, which is an obstacle to assessing treatment options. An analysis of the scientific literature combined with the clinical experience can suggest some avenues.

Methods: The etiology of MCS and its underlying mechanisms were reviewed from the scientific literature to identify the main factors contributing to its development. The results of the studies involving biomarkers and cerebral imaging techniques on MCS subjects were compared with those performed on subjects having the comorbidities of MCS. From the scientific literature and the experience in a clinical setting in occupational and environmental medicine, distinct types of MCS were looked for, with the application of the underlying mechanisms. The potential effectiveness of available treatments was also reviewed.

Results: Among many factors, unresolved emotional traumas causing chronic and acute stress reactions play an important role in the development of MCS and can be the basis for effective treatment. We identified three types of clinical presentations, called the accidental type, following a toxic exposure causing an associated emotional trauma, the associative type, following a repeated innocuous exposure in a threatening context, and the developmental type, following a traumatic childhood/adolescence causing hypervigilance and chronic stress/trauma-related disorders. We presented real cases to illustrate these types and the mechanisms behind their development, as well as effective resolution.

Conclusions: MCS and its comorbidities could be treated effectively when the underlying emotional trauma(s) are targeted using trauma-focused psychotherapy and other therapies. Diagnostic criteria, principles of treatment and prevention, and avenues for research were derived from this analysis.