Exploring the contributing factors to multiple chemical sensitivity in patients with migraine

Objective Multiple chemical sensitivity (MCS) is a form of chemical intolerance in which various systemic symptoms are triggered by exposure to a variety of chemical substances. Although migraine has been associated with central sensitivity syndrome, the relationship between MCS and migraine has not been studied. We assessed the frequency of MCS and its related factors in patients with migraine. Methods We performed a cross-sectional study that included 95 patients (14 M/81 F; age, 45.4 +/- 12.4 years) out of 100 consecutive patients with migraine from our outpatient headache clinic. MCS was defined as having a combination of Q1 >= 30, Q3 >= 13, and Q5 >= 17 on the quick environment exposure sensitivity inventory (QEESI; Japanese version). Central sensitization inventory-A scores >40 were considered an indication of central sensitization. Headache-related disability and psychological distress were evaluated with the Migraine Disability Assessment score (MIDAS) and Kessler Psychological Distress Scale (K6), respectively. Results MCS was identified in 20% of patients with migraine; however, none had previously been diagnosed with MCS. The MCS-positive group had higher rates of photophobia, osmophobia, visual aura, sensory aura, and central sensitization and higher MIDAS and K6 scores than the MCS-negative group. A logistic regression analysis showed that osmophobia, sensory aura, and central sensitization were significant contributors to MCS. Conclusion We showed that MCS was observed in 20% of patients with migraine, and our study results may indicate a possible association of MCS with central sensitization and hypersensitivity-related symptoms in patients with migraine.