Are small olfactory bulbs a risk for olfactory loss following an upper respiratory tract infection?

Considering the correlation between olfactory function and size of the human olfactory bulb (OB), it may be that OB volume is representative of the average number of functional olfactory receptor neurons in the nose. We observed a woman (64-year-old) with a 3-week history of hyposmia following an upper respiratory tract infection. Interestingly, both OB volumes were below the tenth percentile of the general population which seems to be difficult to explain by rapid, adaptive changes in the OB volume. It is hypothesized that small OBs may be a risk factor for acquiring olfactory loss.