Olfactory and gustatory dysfunction
Olfactory and gustatory dysfunction spans sinonasal, post-viral, post-traumatic, neurodegenerative, medication-induced, and congenital causes; most patients who complain of losing their sense of taste are actually losing their sense of smell, since flavor perception is predominantly retronasal olfaction.
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What this article covers
- Overview
Olfactory and gustatory dysfunction is a symptom complex, not one disease: reduced or absent smell (hyposmia, anosmia), distorted smell (parosmia, phantosmia), and reduced, absent, or distorted taste…
- Epidemiology
Sinonasal disease is the most common identifiable cause: allergic rhinitis and chronic rhinosinusitis, with or without polyps, are also the most likely to fully reverse with treatment.
- Risk factors
Chronic sinonasal inflammation: allergic rhinitis, vasomotor rhinitis, and chronic rhinosinusitis with nasal polyps; polyps are especially linked to asthma and aspirin/NSAID sensitivity (Samter…
- Pathophysiology
Conductive (sinonasal) loss: mucosal edema, polyps, or purulent secretions block odorant molecules from reaching the olfactory epithelium high in the nasal vault; smell normalizes once the obstruction or inflammation is treated.
- Clinical features
Reduced or absent sense of smell (hyposmia/anosmia) is the hallmark, frequently reported as "loss of taste".
- Differential diagnosis
Anterior skull base or nasal cavity tumor: unilateral, progressive olfactory loss without obstruction or discharge; the most dangerous cause to miss, requiring imaging rather than empiric treatment.
- Diagnosis
There is no single confirmatory laboratory test; the diagnosis is established by an objective deficit on standardized psychophysical smell testing after a conductive cause is excluded.
- Management
First, treat any identified sinonasal cause, the most reversible category.
- Complications
Missed or delayed diagnosis of a dangerous underlying cause, most importantly an anterior skull base tumor presenting only as unilateral progressive anosmia.
- Prognosis
Sinonasal causes have the best prognosis: allergic rhinitis and nasal polyps frequently normalize with anti-inflammatory therapy, though polyps recur and surgery is not curative.
- Prevention
Treat allergic and inflammatory sinonasal disease proactively with daily intranasal corticosteroid therapy to reduce polyp formation before chronic olfactory loss develops.
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