Background:In this study, the authors compared the right and left olfactory bulb volumes by magnetic resonance image findings of patients with unilateral concha bullosa (CB).Methods:The cranial magnetic resonance imaging studies of 24 patients having unilateral CB were reviewed. There were 10 males and 14 females ranging in age from 29 to 51 years (mean age, 2915.2 years). The volumes of both olfactory bulbs (contralateral and ipsilateral to the concha bullosa side) were calculated by using the computer program.Results:The average values for olfactory bulb volumes were 46.57 +/- 8.03 mm(3) in the CB side of the nasal cavity and 54.80 +/- 10.031 mm(3) in the normal side of the nasal cavity. We found a statistically significant difference in olfactory bulb volume between the contralateral and ipsilateral to the concha bullosa side of the patients (t=-3.08 and P<0.01 for CB side, t=-3.47 and P<0.01 for left normal side).Conclusion:Our results may point out a possible relationship between CB and ipsilateral decreased olfactory bulb volume, yet the exact mechanism still remains unclear. Decreased nasal air flow on the CB side may be attributed to the pathophysiologic mechanism of this finding. Also, the significant reduction in olfactory bulb volumes ipsilateral to CB compared with the contralateral olfactory bulb volumes seems to support our hypothesis.