What is a smell disorder?
You can read more about exactly how the sense of smell works on www.kno.nl. There are various types of smell disorders, such as a reduced, altered or heightened perception of odours, or a complete absence of smell. Numerous other variants of smell disorders also exist.
A normal sense of smell is called normosmia; the general term for a disturbed sense of smell is dysosmia. When smell is reduced due to ageing, we call this presbyosmia.
Classification by cause
We speak of a conductive smell disorder when a blockage of (part of) the nose prevents odour molecules from reaching the olfactory organ; this is also called a respiratory disorder. If the olfactory organ or the sense of smell's nervous system itself is affected, we speak of a perceptive smell disorder.
Causes and diagnosis
A smell disorder can have many different causes. To treat the complaint properly, it's important to identify the cause.
Possible causes
Most often, a smell disorder is caused by a viral upper respiratory infection; the sense of smell usually returns on its own. Surgery on the sinuses, certain medications, smoking, or a blow to the head can also affect smell. A smell disorder is also common with nasal congestion, for example due to nasal polyps, chronic sinusitis or a deviated nasal septum, and with conditions such as Parkinson's and Alzheimer's, where it's often an early symptom. In roughly 20% of cases, no clear cause is found.
Medical history
Loss of smell is a serious complaint that deserves a thorough assessment of its severity and nature. In cases of persistent loss of smell, the GP usually refers you to an ENT doctor. We ask in detail when and how the symptoms started: was there anything preceding it, such as a respiratory infection, surgery or medication use; how quickly did it develop; is the smell completely or partially gone; are there accompanying symptoms such as a blocked nose; and does the family have a history of smell disorders?
ENT examination
Besides discussing your symptoms, we carry out a thorough ENT examination. Using a nasal endoscope, we examine the inside of the nose: is the structure abnormal, are there nasal polyps, or are there signs of chronic sinusitis? We particularly check whether access to the olfactory epithelium, high in the nose, is clear. The oral cavity is also examined, since infections there can cause unpleasant smell sensations.
Further investigation
A CT scan of the sinuses, an MRI of the brain, or blood tests are only carried out if needed. To objectify the extent of smell loss, we use smell tests: identification tests (you recognise test odours, for example with the Sniffin' Sticks test), threshold tests (the minimum detectable concentration of an odorant), and discrimination tests (can you distinguish between different odours).
Treating the cause, easing the symptoms
Treatment options depend on the nature of the smell disorder.
Conductive smell disorder
If the smell disorder is caused by nasal congestion, for example due to nasal polyps or chronic sinusitis, smell often improves after treatment with medication or surgery. This effect isn't always permanent: in some patients, symptoms return within a year.
Perceptive smell disorder
There is currently no effective treatment for a perceptive smell disorder. After a respiratory infection (post-viral anosmia), spontaneous recovery often occurs, usually within 3 to 6 months of the first unusual smell sensations. After head trauma, loss of smell is usually permanent.
Coping with loss of smell
If no treatment is possible, adjusting your diet can help: spicier and more seasoned food with attention to sweet, sour, salty and bitter, and warm, flavourful dishes rather than boiled vegetables. Don't use too much salt and sugar. For safety, install smoke and gas detectors at home.
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Frequently asked questions
Noticing your sense of smell is fading?
For an appointment at De KNO Praktijk Nijmegen you need a referral from your GP. Discuss your symptoms with your GP; they assess whether a referral is needed. With the referral, you contact us and we schedule your consultation.