Odourless

Synonyms in a broader sense

Odorlessness, odor blindness

Definition

Odorlessness (anosmia) is the complete absence or loss of the sense of smell. A deterioration of the sense of smell is called hyposmia. Odorlessness (anosmia) can have various causes.

On the one hand, the olfactory cells in the nose can be damaged, but on the other hand, the flow of air to the cells can also be disturbed by a blockage in the nose. Furthermore, brain-organic disturbances in sensory processing are also conceivable. Congenital odourlessness can have genetic causes (Kalmann syndrome).

Possible injuries are fractures at the base of the skull (skull base fracture), as the olfactory sensory cells leak out there. More common, however, are injuries caused by viruses in the course of a cold. A blockage of the airflow can be caused by mucous membrane proliferations (polyps), foreign bodies or swelling of the nasal mucosa due to sinusitis or allergies. Odorlessness can also occur in the context of depression or dementia.

Symptoms

Patients with odourlessness suffer, in addition to the loss of their sense of smell, from a limitation of their sense of taste. Since only the basic tastes (sweet, sour, salty, bitter, hearty) are perceived by the tongue and more complex tastes are actually olfactory impressions, food tastes much easier for anosmic patients than for healthy people. This can lead to a reduced willingness to eat and to malnutrition.

Diagnosis

In an olfactory test (olfactometry), the patient with odourlessness is presented with a series of olfactory substances that he or she is supposed to identify. These include substances that are not perceived by the olfactory cells, but which produce a sensory perception via the normal mucous membrane.