The Olfactory Nerve.
The olfactory nerve may be affected in its nasal origin, in the mucous membrane, by a disturbance at the bulb, at some point in the course of the tract, or at its origin in the brain. The result is an increased, diminished, or perverted function of the sense of smell.
Hyperosmia is an abnormally acute sense of smell, and is generally found in hysteria, neurasthenia, and insanity.
Parosmia.—Perversion of the sense of smell may be confined to one or many odors, and, like hyperosmia, occurs most frequently in neurasthenia and in the insane.
Anosmia.—Loss of the sense of smell, may be due to acute or chronic rhinitis, bone disease, or lesions of the brain.
Treatment.—The treatment depends entirely upon the cause. When due to organic changes, medication is unsatisfactory.