title: Assessment of cerebral blood flow in patients with multiple chemical sensitivity using near-infrared spectroscopy--recovery after olfactory stimulation: a case-control study.
abstract: OBJECTIVE
  Multiple chemical sensitivity (MCS) is a chronic acquired disorder characterized by non-specific symptoms in multiple organ systems associated with exposure to odorous chemicals. We previously observed significant activations in the prefrontal cortex (PFC) during olfactory stimulation using several different odorants in patients with MCS by near-infrared spectroscopy (NIRS) imaging. We also observed that the patients with MCS did not adequately distinguish non-odorant in the late stage of the repeated olfactory stimulation test. The sensory recovery of the olfactory system in the patients with MCS may process odors differently from healthy subjects after olfactory stimulation.
  
  
  METHODS
  We examined the recovery process of regional cerebral blood flow (rCBF) after olfactory stimulation in patients with MCS. NIRS imaging was performed in 6 patients with MCS and in 6 controls. The olfactory stimulation test was continuously repeated 10 times. The study also included a subjective assessment of the physical and psychological status and of the perception of irritating and hedonic odors.
  
  
  RESULTS
  After olfactory stimulation, significant activations were observed in the PFC of patients with MCS on both the right and left sides compared with controls. The activations were specifically strong in the orbitofrontal cortex (OFC). Compared with controls, autonomic perception and feelings identification were poorer in patients with MCS. OFC is associated with stimuli response and the representation of preferences.
  
  
  CONCLUSIONS
  These results suggest that a past strong exposure to hazardous chemicals activates the PFC during olfactory stimuli in patients with MCS, and a strong activation in the OFC remains after the stimuli.
authors: Department of Environmental Medicine and Behavioral Science, Kinki University Faculty of Medicine, Osakasayama, Osaka, 589-8511, Japan, kenazuma@med.kindai.ac.jp.
authors: Kenichi
authors: K
authors: Azuma
authors: Iwao
authors: I
authors: Uchiyama
authors: Mari
authors: M
authors: Tanigawa
authors: Ikuko
authors: I
authors: Bamba
authors: Michiyo
authors: M
authors: Azuma
authors: Hirohisa
authors: H
authors: Takano
authors: Toshikazu
authors: T
authors: Yoshikawa
authors: Kou
authors: K
authors: Sakabe
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D018777:Multiple Chemical Sensitivity / Q000209:etiology / Q000503:physiopathology*; D009812:Odorants / Q000032:analysis*; D010812:Physical Stimulation; D019265:Spectroscopy, Near-Infrared