Imagine not being able to smell red roses or the aroma of freshly baked bread. Picture never being able to taste your favourite cuisine or a good wine ever again. This is a sad fact of life for many people after a brain injury.

Out of the five senses, smell is often viewed as the least important. It is often only when the sense is gone or severely diminished, that we come to appreciate its importance to our quality of life. The loss of ability to perceive smell is referred to as 'Anosmia'. The sense of smell originates from the olfactory nerves which sit at the base of the brain’s Frontal Lobes, right behind the eyes and above the nose. [1]

A Traumatic Brain Injury can result in damage to areas connected to smell perception. Such damage often occurs without Physical damage to the nose. Our sense of taste is closely associated with our sense of smell, so impaired smell will often lead to a reduction in taste. Sufferers, however, may still be able to experience the taste of salt, sour, sweetness and bitterness, as these senses are received by receptors in the tongue [6]. The likelihood of experiencing Anosmia has been found to increase with the severity of brain injury. [1]

How does damage to areas responsible for smell occur?

A blow to the head can cause Anosmia by injury to the olfactory nerve. This nerve sits between the frontal lobe and bony protrusions from the skull and is vulnerable to trauma. Damage to the area may occur through shearing and/or stretching of the olfactory nerves and brain contusion or hemorrhage within the olfactory-related brain regions [2][3]. A blow to the head can also cause anosmia by damage to smell processing cells in the anterior Temporal Lobes or by mechanical damage to nasal structures.

Will It Go Away?

Anosmia can be temporary or permanent. If the sensory cortex has been bruised, a gradual Recovery of sensation may occur. When damage has occurred to the olfactory nerves or tracts in the brain that is involved in processing sense of smell the chance of full recovery is smaller. Some olfactory Neurons may be able to regenerate following trauma, which may mean that loss of smell may be recovered.[4] A common belief is that if recovery is to occur it will happen in the first three months for the majority of people with anosmia. For others recovery may occur gradually over a number of years. [6]

What impact could anosmia have on daily life?

Loss of smell and taste is associated with reduced quality of life – the sense of smell is associated with many pleasures of life, including the ability to smell fine foods, perfumes, or with the sent of a loved one. It is also thought to be involved in more subtle human communication and sexual activity. [5]

Impact on food consumption

Our sense of flavour is a mixture of both smell and taste perception. Since the ability to taste and enjoy food and drink depends on our sense of smell, anosmia often leads to reduced appetite and weight loss. In some patients it leads to weight gain, because they eat food with a high salt and fat content to gain any enjoyment.

Impaired ability to detect danger

Smell has a survival function allowing us to detect early indicators of danger, such as the smell of smoke, fuel and dangerous chemicals [2].

Lack of understanding and sympathy

The importance of anosmia is often underestimated and doctors may provide little information on it, due to a perception that it is a trivial condition. Make sure you get the level of information you need.

What Can I Do?

There is currently no fixed treatment for Anosmia, however there are small things that can make a difference. Find ways to make eating fun again. The texture of different foods becomes very important, particularly how you combine them. Mix half-cooked vegetables with cooked ones for a texture comparison. Eat a hot meal with a cold salad for different temperature experiences. Try spicy food from Eastern cuisines that cause sensations on the tongue. The object is to take some time to make meals interesting and fun, so it is still appealing to eat and feel satisfied afterwards.

If you have lost your sense of smell you may need to take some extra steps to become safety conscious. Install plenty of smoke detectors if you can’t smell smoke in the house. Switch to electricity instead of gas. Read labels carefully in case you are using strong chemicals that requires ventilation. Use visible labels for expiry dates on food.

References and Further Information

Anosmia Foundation: http://www.anosmiafoundation.org/details.shtml