Superficial siderosis acquired anosmia describes the loss of your ability to smell. It results from damage to the first cranial nerve and parts of the fifth cranial nerve. It is a very common symptom of Superficial siderosis with a slow progression. Most people will notice off odors or phantom smells at first. Over time, the dysfunction of your olfactory receptor neurons leads to the complete loss of your sense of smell.
Your sense of smell controls your concept of the more delicate qualities of taste. When you have anosmia, you can still distinguish salty, sweet, bitter, sour, and umami from the taste buds located on your tongue. When you lose your sense of smell, you lose the ability to enjoy the nuances of flavor. Eat chocolate ice cream with your eyes closed. A person with anosmia will tell you it’s cold, sweet, soft and creamy, but they are unable to tell it’s chocolate.
The first cranial nerve is responsible for qualitative odor sensations like flowers or fresh cut grass. The fifth cranial nerve controls the overtones of smell like warmth, coolness, sharpness, and irritation. An onion or ammonia will not only smell strong but will also cause a body response. For example, smell an onion and tears will form.
Damage to parts of the fifth cranial nerve that connects to the tongue is very rare. Even if you suffer complete anosmia you will still be able to distinguish stinging, burning, cooling and sharpness through the nerve endings in your tongue. The combined loss of both taste and smell is called ageusia.
Updated: November 9, 2020
Sources: Superficial siderosis is a rare neurologic disease characterized by progressive sensorineural hearing loss, cerebellar ataxia, pyramidal signs, and neuroimaging findings revealing hemosiderin deposits in the spinal and cranial leptomeninges and subpial layer. The disease progresses slowly, and patients may present with mild cognitive impairment, nystagmus, dysmetria, spasticity, dysdiadochokinesia, dysarthria, hyperreflexia, and Babinski signs. Additional features reported include dementia, urinary incontinence, anosmia, ageusia, and anisocoria. Superficial siderosis MedGen UID: 831707 •Concept ID: CN226971 •Finding Orphanet: ORPHA247245