Table 1

Quantitative and qualitative dysfunctions

HyposmiaReduced perception of smell, can be specific to one odorant or to all odours
AnosmiaComplete absence of perception of smell; usually trigeminal inputs remain, and some chemically irritating odours may still be perceived
Functional anosmiaOlfactory function is present, but is too poor to be useful in daily life
ParosmiaDistorted perception of odour in the presence of an odorous stimulus
PhantosmiaPerception of odour without an external stimulus