Can we smell without an olfactory bulb?

BACKGROUND

Lack of an olfactory bulb (OB) is typically associated with anosmia.

METHODS

We present a patient with subnormal olfactory function in whom the OB could not be detected with magnetic resonance imaging (MRI).

RESULTS

Olfactory function was evaluated on two occasions. Orthonasal olfactory function was assessed with the "Sniffin' Sticks" test providing a score equivalent to hyposmia. Retronasal olfactory function was studied with "smell powders" indicating a decreased, but not absence of, olfactory function. Importantly, chemosensory event-related potentials were clearly present in response to olfactory and trigeminal stimuli.

CONCLUSION

This indicates that olfactory function may be present in some subjects even when an OB can not be detected with MRI.