Dysosmia in Covid-19 Patients
While most patients who experience Covid-19 experience loss of smell (hyposmia) either transiently or on a chronic basis there is another whole class of sensory loss they experience. Covid-19 patients experience distortions of smell and taste (dysosmia/dysgeusia) entirely without any loss of smell or taste or associated with the smell and taste loss.
These distortions are similar to those described previously among many other patients who report taste and smell dysfunction. These distortions fall into two major categories — phantom odors (phantosmias) or tastes (phantageusias) or distorted smell and taste associated with the intake of food or drink (aliageusia) or with the smell of external odor (aliosmia).
Phantom smells (phantosmias) refer to the presence of an usually obnoxious odor which appears spontaneously in absence of any external odor. This sensation can be intermittent or persistent, can be very strong or mild and usually occurs without any external stimulus. These odors are usually obnoxious with a rotten, metallic, burned or chemical character. Similar characteristics can occur for phantageusia with persistent or transient taste sensations that occur in absence of any oral stimulus. These tastes are also commonly strong and obnoxious, usually described as rotten, metallic, burned or chemical similar to descriptions of phantosmia.
Patients may experience either phantosmia or phantageusia or both simultaneously which causes severe discomfort with loss of appetite and significant weight loss. On occasion patients may experience phantosmia, phantageusia, aliosmia and aliageusia which makes life extremely difficult to experience due to the persistence of these abnormal obnoxious sensations.
We have developed specific therapies to inhibit these obnoxious sensations dependent upon their character and persistence.
The major mechanism causing these distortions relates to decreased brain gamma-aminobutyric acid (GABA). If this moiety were increased the sensations are attenuated and the symptoms are decreased.
See Henkin RI, Potolicchio SJ, Levy LM. Olfactory hallucinations without clinical motor activity: a comparison of unirhinal with birhinal phantosmia. Brain Sci. 2013;3:1483-1553 for more information.