Temporal lobe epilepsy syndromes feature simple or complex partial seizures arising from the temporal lobe. They account for nearly two-thirds of partial epilepsies in teenagers and adults. Because the temporal lobe is involved with emotions and memory, these seizures often produce emotions such as fear, joy, or anger or memory phenomena such as déjà vu (a feeling of having seen something before, even though it is new to you) or jamais vu (a feeling that you have never seen a familiar object or place before).
What are the different temporal lobe epilepsies?
There are many different temporal lobe epilepsy syndromes, and many different names for them. Because the temporal lobe is involved with emotions, temporal lobe epilepsy is often called psychomotor epilepsy. Because other parts of the limbic system may be involved, it may also be referred to as limbic epilepsy. Sometimes, doctors refer to the precise location of the seizures. They discuss mesial or medial (inner) temporal lobe epilepsy and lateral (outer) temporal lobe epilepsy.
What causes temporal lobe epilepsy?
Two temporal lobe epilepsies are discussed here:
- temporal lobe epilepsy with mesial temporal sclerosis
- familial temporal lobe epilepsy.
Temporal lobe epilepsy is usually caused by a problem such as mesial temporal sclerosis. However, familial temporal lobe epilepsy is a genetic condition with autosomal dominant inheritance.
Mesial temporal sclerosis is a condition in which the mesial temporal region, the hippocampus, the amygdala and the uncus shrink and develop scar tissue, often with changes in the shape of the surrounding neurons. The cause is not clear. It is possible that febrile seizures in early childhood or continuing seizures contribute to the damage. Mesial temporal sclerosis is also called hippocampal sclerosis.
Other problems, including tumours, tangles of blood vessels, or congenital brain malformations, may cause similar seizures.
What are the features of temporal lobe epilepsy?
Temporal lobe epilepsy with mesial temporal sclerosis
Temporal lobe epilepsy with mesial temporal sclerosis is the most common form of epilepsy in adults. In this condition, complex partial seizures usually begin during childhood. The child nearly always has an aura, usually a rising sensation in the stomach. The child then stops what they are doing and stare. They may feel anxiety, déjà vu or a strange sensation in their head. They may have automatisms such as lip smacking, chewing, swallowing or picking at the air or their clothes. The seizure usually lasts between 30 and 90 seconds. The child may be confused or have difficulty speaking for a few minutes after the seizure.
The seizures may respond to medications at first and the child may do well for several years, but the seizures often return when the child is older. At least a third of the time, the seizures do not respond to treatment.
Children with this type of epilepsy often had complex febrile seizures when they were younger, and may have a family history of epilepsy or febrile seizures.
Familial temporal lobe epilepsy
Familial temporal lobe epilepsy usually causes simple partial seizures with psychic or autonomic symptoms. Occasionally, it causes complex partial seizures or secondarily generalized seizures.
The seizures begin when the person is 19 years old, on average, although they can also begin in adolescence or adulthood.
The syndrome is probably caused by one of several different gene mutations.
How many other children have temporal lobe epilepsy?
Temporal lobe epilepsy is fairly common. It accounts for nearly two-thirds of partial epilepsies in teenagers and adults.
How do you know that a child has temporal lobe epilepsy?
A diagnosis of temporal lobe epilepsy is made on the basis of the seizure description. This may be combined with brain imaging findings and EEG to reach the diagnosis. Mesial temporal sclerosis, which is often associated with temporal lobe epilepsy, is diagnosed with MRI.
How is temporal lobe epilepsy treated?
Temporal lobe epilepsy is normally treated with anti-epileptic drugs if there is no obvious cause for the seizures. However, if the child has mesial temporal sclerosis or another brain problem, or if the seizures do not respond to two different anti-epileptic medications, they will be considered for surgery to remove the area of the brain in which the seizures begin.
Surgery is more likely to be successful if:
- it is performed soon after the child starts having seizures
- there is an abnormality visible on brain imaging (MRI) that is associated with the seizures
- the area of the brain in which the seizures begin can be completely removed (this depends on how close the area is to other areas that control movement or language).
What is the outlook for a child with temporal lobe epilepsy?
Anti-epileptic drugs can reduce or stop seizures in 60 per cent to 70 per cent of people with temporal lobe epilepsy. There is less chance that seizures will go away if the child:
- has symptomatic epilepsy
- has frequent generalized seizures
- continues to have seizures after trying two or more anti-epileptic medications
- has an abnormal EEG between seizures.
If a child’s seizures are not controlled by medication, which is the case in 30 per cent to 40 per cent of children, it is important to recognize this fact early. In up to 80 per cent to 90 per cent of children, early surgery to remove the affected areas of the brain can stop the seizures and in some cases enhance social development. On the other hand, if surgery is delayed and a child has seizures for a long time during adolescence, they can interfere with their education, behaviour and social development.