Cortical activity during olfactory stimulation in multiple chemical sensitivity: a 18F-FDG PET/CT study

Purpose To investigate the differences in brain glucose consumption
during olfactory stimulation between subjects affected
by multiple chemical sensitivity (MCS) and a group of
healthy individuals.
Methods Two 18F-FDG PET/CT scans were performed in 26
subjects (6 men and 20 women; mean age 46.7±11 years)
with a clinical diagnosis of MCS and in 11 healthy controls (6
women and 5 men; mean age 45.7±11 years), the first scan
after a neutral olfactory stimulation (NS) and the second after
a pure olfactory stimulation (OS). Differences in 18F-FDG
uptake were analysed by statistical parametric mapping
(SPM2).
Results In controls OS led to an increase in glucose consumption
in BA 18 and 19 and a reduction in glucosemetabolismin
BA 10, 11, 32 and 47. In MCS subjects, OS led to an increase
in glucose consumption in BA 20, 23, 18 and 37 and a
reduction in glucose metabolism in BA 8, 9 and 10.
Conclusion The results of our study suggest that cortical
activity in subjects with MCS differs from that in healthy
individuals during olfactory stimulation.