Submitted on February 14, 2005
Accepted on September 22, 2005
Effects of mandibular advancement on brain activation during inspiratory loading in healthy subjects: a functional magnetic resonance imaging study
Koji Hashimoto1, Takashi Ono1*, Ei-ichi Honda2, Keiko Maeda1, Hideo Shinagawa3, Satoru Tsuiki1, Shigetoshi Hiyama1, Tohru Kurabayashi4, and Kimie Ohyama1
1 Maxillofacial Orthognathics, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
2 Oral/Maxillofacial Radiology, The University of Tokushima, Tokushima, Tokushima-shi, Tokushima, Japan; Oral/Maxillofacial Radiology, Graduate Schoot, The University of Tokushima, Tokushima, Tokyo, Japan
3 Maxillofacial Orthognathics, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan; Tokyo Metropolitan Institute of Gerontology, Bunkyo-ku, Tokyo, Japan
4 Oral/Maxillofacial Radiology, The University of Tokushima, Tokushima, Tokushima-shi, Tokushima, Japan
* To whom correspondence should be addressed. E-mail: t-ono.mort{at}tmd.ac.jp.
Oral appliances have been a popular treatment option for subjects with obstructive sleep apnea. However, little information is available on how brain activation induced by respiratory challenge is modulated by mandibular advancement with these appliances. We hypothesized that the brain activation caused by respiratory stress may be alleviated by mandibular advancement. Respiratory stress was induced in 12 healthy subjects by resistive inspiratory loading. The effects of mandibular advancement during resistive inspiratory loading were assessed subjectively using a visual analogue scale. These effects were also evaluated objectively using blood-oxygenation-level-dependent functional magnetic resonance imaging. The score for the visual analogue scale significantly decreased with mandibular advancement. Cortical deactivation in association with mandibular advancement was localized to several specific regions including the left cingulate gyrus and the bilateral prefrontal cortices. These regions are known to be involved in respiratory control. Our results suggest that mandibular advancement with an oral appliance appears to be useful for reducing respiratory stress, based on both subjective and neuronal criteria.
