Causes of anosmia
Common conditions such as rhinitis, sinusitis or nasal polyps can cause a temporary loss of sense of smell. It can also be caused by degeneration of the sensitive cells for the reception of smell in the nose after a severe ‘cold’ or influenza. Smell can also be affected by a head injury, certain medications and medical conditions. Very rarely a tumour of the nerve for smell (olfactory nerve) can affect the sense of smell. Loss of sense of smell will require assessment and investigations as appropriate.
Rhinitis literally means inflammation of the nose and refers to the inside lining of the nose. The inflammation causes swelling of the lining, excess mucus production and irritation. The swelling causes the sensation of blockage and the excessive mucus production leads to a runny nose and/or too much mucus going backwards from the nose to the throat known as post nasal drip. If the rhinitis is caused by an allergy then the patient may experience itching of the nose, eyes and throat. Rhinitis also causes sneezing.
Rhinitis is a very common condition. The severity of symptoms is extremely variable, however. Some people have mild nose irritation which comes and goes and causes little trouble and others have severe symptoms causing discomfort, distress and difficulty carrying out daily activities.
WHAT CAUSES RHINITIS?
The causes of persistent rhinitis can be divided into allergic and non-allergic.
The most common allergies causing rhinitis are pollen (hay fever), house dust mite and pets, most commonly cats. Hay fever is seasonal and occurs during a particular period each year.
Symptoms of allergy in the nose are due to the immune system reacting to the allergen (the individual cause of the allergy). Cells in the lining of the nose release histamine and other chemicals when they come into contact with the allergen. This causes inflammation in the nose with swelling, excess mucus production and irritation. Allergic rhinitis can be associated with asthma and eczema and can run in families.
Rhinitis commonly occurs without an allergic cause and there is often no identifiable cause for the condition. Many factors can influence the nasal lining however including:
- Changes in temperature or humidity
- Hormonal changes e.g. during pregnancy
- Food and drink, e.g. alcohol
- Emotion such as stress and anxiety
- Medication. Some medications can have side effects on the nose e.g. blood pressure medication and the contraceptive pill
- Use of decongestants
Rhinitis medicamentosa is the name given to rhinitis that can occur due to the overuse of nasal decongestant sprays. These sprays are used to relieve a blocked nose and they reduce swelling inside the nose by causing blood vessels in the nose to constrict. However, with prolonged use, they cause rebound nasal congestion which is more severe than the original swelling. The temptation is to use yet more decongestant and a vicious circle can be set up. A similar problem can occur in people who abuse cocaine.
In some people, no cause for their persistent rhinitis is found and it is called idiopathic or vasomotor rhinitis.
WILL I REQUIRE A TEST FOR RHINITIS?
You may require allergy tests if allergic rhinitis is suspected. These can be in the form of skin prick tests or blood tests.
WHAT IS THE TREATMENT FOR RHINITIS?
The commonly used treatment options for allergic rhinitis include:
- Avoiding the cause of the allergy
- Antihistamine tablets
- Steroid nose sprays
- Steroid nose drops and tablets (for limited periods)
- Nasal Douching (this involves spraying salt water into the nose)
In some cases, other forms of medication are required. Severe allergic rhinitis can sometimes be treated with immunotherapy. This consists of a course of tablets or injections which modify your immune system in order to prevent the allergic reaction from occurring.
The main form of treatment for this is a steroid nasal spray although sprays to reduce secretion from the nose and nasal douching are also used.
This can be indicated when medical treatment has failed or if the rhinitis is associated with sinusitis (see the section on sinusitis) or large adenoids (see the section on adenoids). Nasal surgery for rhinitis involves reducing the size of the nasal turbinates. These are extensions of the side wall of the nose which become swollen in rhinitis.
The sinuses are air-containing cavities situated in the cheeks, between the eyes and in the forehead. They produce mucus which drains into the nose and can be regarded as extensions of the nose. Rhinitis can be associated with blockage and inflammation of the sinuses (sinusitis).
Sinusitis can be ‘acute’, for example, when associated with a cold or flu or ‘chronic’ when the condition is ongoing.
WHAT INVESTIGATIONS DO YOU PERFORM FOR SINUSITIS?
As well as allergy tests the patient will require imaging of the sinuses to confirm the diagnosis. This is usually a CT scan although sometimes an MRI is performed.
WHAT DOES SINUSITIS TREATMENT INVOLVE?
Treatment consists of:
- Treating associated rhinitis
- Decongestants (short term use only)
- Steroids (sprays and drops mainly but occasionally a course of tablets)
- Nasal douching (this involves passing salt water through the nose to remove secretions and allergic particles)
- Surgery (when medical treatment is not successful)
Surgery involves opening the drainage points from the sinuses to the nose and removing inflamed tissue. The aim of the surgery is to enable the sinuses to secrete mucus freely into the nose without obstruction and to allow the lining of the sinuses to become healthy.
Surgery is performed using small endoscopes that project an image of the inside of the nose and sinuses onto a television monitor allowing the surgeon to operate with fine instruments inside the nose using the monitor as a guide. This is called endoscopic sinus surgery or functional endoscopic sinus surgery (FESS). No cuts are made on the outside of the nose or face. Sometimes small balloons are used to dilate passages between the nose and sinuses in a procedure called balloon sinuplasty.
These are ‘grape-like’ swellings inside the nose. They usually arise from the sinuses. Treatment consists of steroids which often shrink the polyps. If they are not controlled with medication then surgery to remove them will be offered.
They can be associated with asthma and sensitivity to non-steroidal anti-inflammatory drugs.
Polyps usually occur on both sides of the nose. If they occur on one side only they require investigation to exclude cancer of the nose and sinuses although a polyp in one side of the nose is often benign and not cancerous.
SURGERY FOR NASAL POLYPS
Polyps are often removed during sinus surgery which is usually performed under general anaesthetic (patient asleep) as a day case. Polypectomy can be performed alone under local anaesthetic (patient awake) when the inside of the nose is numbed before surgery. Polyps themselves are not actually sensitive and an instrument called a microdebrider can be used to detach the polyp and suction it out of the nose.