Lésions du lobe temporal

Comprendre le cerveau

Schéma en coupe du cerveau

Le cerveau est la partie principale du cerveau. Il se trouve à l'intérieur du crâne et sa surface ressemble à une noix. Il est divisé en deux parties : l'hémisphère droit, qui contrôle le côté gauche du corps, et l'hémisphère gauche, qui contrôle le côté droit du corps.

The cerebrum is also where you think and store your memory (especially long-term memory). Each hemisphere is subdivided into parts that are associated with certain functions. The main divisions are the frontal lobe, temporal lobe, parietal lobe and occipital lobe.

Le lobe temporal est impliqué dans :

• Comprendre et se souvenir de ce que l'on voit (vision).

• Comprendre la parole et le langage.

• Comprendre et gérer les émotions.

• Stocker et rappeler des souvenirs.

Les causes possibles des lésions du lobe temporal sont nombreuses. Les causes les plus courantes sont les suivantes :

• A stroke. A stroke usually affects other parts of the brain but may occur in the temporal lobe. Strokes can be caused by a blood clot, or a bleed.

• Brain tumours may affect the temporal lobe of the brain.

• A serious head injury or a surgical operation to remove a brain tumour may may also cause damage or injury to the temporal lobe.

• L'aggravation progressive du langage peut faire partie d'un type de démence appelé démence frontotemporale.

• Le lobe temporal peut être affecté par une infection du cerveau (encéphalite), en particulier l'encéphalite due au virus de l'herpès simplex.

D'autres maladies du cerveau, comme la sclérose en plaques, peuvent également affecter les lobes temporaux du cerveau.

Quelle est la fréquence des lésions du lobe temporal ?

Les lésions du lobe temporal sont peu fréquentes mais pas rares. Cependant, certaines lésions du lobe temporal peuvent être très petites et ne pas provoquer de symptômes évidents. Par conséquent, on ne connaît pas exactement la fréquence des lésions du lobe temporal.

The symptoms caused by temporal lobe lesions are usually much less obvious than when other parts of the brain are affected. For example, many strokes will cause muscle weakness (paralysis), often affecting one side of the body. However, the symptoms caused by a stroke affecting the temporal lobe will be much less obvious.

A temporal lobe lesion may cause various symptoms which may not be noticed by other people. These symptoms may include:

• Oubli.

• Problems with speech and language (especially understanding what is being said by others).

• Problems with vision.

• Temporal lobe lesions may also cause fits (seizures).

• Problems with hearing.

• Identifying objects.

• Learning new information and being unable to identify emotions in others.

• Temporal lobe lesions may also cause problems with memory and cause changes in your personality.
  

The symptoms you experience will depend on what is causing the problem in the temporal lobe. A stroke will usually cause a sudden onset of symptoms, but a brain tumour will often cause a slow onset and progression of symptoms.

The symptoms will also depend on whether only the temporal lobe is affected or whether other parts of the brain are also affected by the underlying condition.

Seizures which begin in the temporal lobe can cause a wide variety of symptoms.

• These symptoms may include different feelings, emotions, thoughts and experiences.

• These feelings may be familiar to you or you may have these feelings for the first time.

• You may suddenly remember something from your past or feel that everything around you is strange and unknown to you.

• You may feel that you have already experienced something that is actually happening for the first time (this is called déjà vu).

• You may also imagine voices, music, smells or tastes that are not really there (hallucinations).

Les symptômes de la crise peuvent être très légers et à peine perceptibles ou très graves et provoquer une grande frayeur. La crise peut également provoquer des sensations agréables et être plaisante.

Temporal lobe epilepsy can be treated with medicines that are used for epilepsy, but treatment will also depend on any underlying temporal lobe lesion. See the separate leaflet called Epilepsy with focal seizures for more details.

Comment les lésions du lobe temporal sont-elles diagnostiquées ?

L'élément le plus important pour établir le diagnostic d'un problème au niveau du lobe temporal est l'historique complet de vos symptômes. Il est également très utile d'obtenir l'historique de vos symptômes auprès d'un proche qui a vu ce qui se passe lorsque vous présentez les symptômes.

The symptoms may be very complicated and sometimes an assessment with a psychologist is needed to identify exactly what symptoms are due to the suspected temporal lobe lesion.

Temporal lobe lesions may cause you to be unable to see one area in your field of vision (this is called a visual field defect). Your visual fields will therefore also be tested.

The best way to find the cause of a temporal lobe lesion is by having an MRI scan of your brain. Any further investigations will depend on the underlying cause of the temporal lobe lesion. If an infection (for example, HSV encephalitis) is suspected, then blood tests and a lumbar puncture (where a sample of fluid is taken from around the spinal cord in your back) may be performed.

Existe-t-il des traitements pour les lésions du lobe temporal ?

Un psychologue peut souvent vous aider à surmonter certains des symptômes causés par une lésion du lobe temporal.

Le traitement dépendra par ailleurs de la cause de la lésion du lobe temporal.

The outcome will depend on the underlying cause and whether any other parts of the brain are also affected.

Young people, especially children, are able to use another part of the brain to take over the function of a damaged part of the brain, but this ability is lost as we become older. Therefore young people are more likely than older people to regain some of the brain function lost as a result of a temporal lobe lesion.

Peut-on prévenir les lésions du lobe temporal ?

There is a great deal we can do to reduce our risk of a stroke. See the separate leaflet called Cardiovascular disease (Atheroma) for more details.