Temporal lobe epilepsy usually manifests with either focal seizures with or without awareness impairment arising from the temporal lobe. It accounts for nearly two-thirds of focal onset 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 epilepsies, and many different names for them. The temporal lobe is involved with emotions, so temporal lobe epilepsy is often called psychomotor epilepsy. Other parts of the limbic system may be involved, so it may also be referred to as limbic epilepsy.
Sometimes, health-care providers refer to the precise location of the seizures. They discuss mesial or medial (inner) temporal lobe epilepsy and lateral (outer) temporal lobe epilepsy.
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, focal seizures with or without awareness impairment usually begin during childhood. The child nearly always has an aura (focal aware seizure), usually a rising sensation in the stomach. The child then stops what they are doing and stares, a phenomenon called behavioral arrest. Anxiety, déjà vu or strange sensations may also be reported. After some seconds, motor symptoms called automatisms may appear. These include behaviours such as repetitive lip smacking, chewing, swallowing or picking at the air or clothes. Each 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 gets older. At least one third of patients will develop drug resistant seizures (seizures that do not respond to anti-seizure medications).
It is not uncommon for children with this type of epilepsy to have a history of complex febrile seizures when they were younger, as well as a family history of epilepsy or febrile seizures.
Familial temporal lobe epilepsy
Familial temporal lobe epilepsy usually causes focal aware seizures with auditory, psychiatric or autonomic symptoms. Occasionally, it causes focal impaired awareness seizures or focal to bilateral tonic-clonic seizures.
On average, the seizures begin when the person is in their late teen years or earlier adulthood, although they can also begin in earlier adolescence or later adulthood.
The syndrome is probably caused by one of several different gene mutations.
What causes temporal lobe epilepsy?
Temporal lobe epilepsy is commonly caused by something called mesial temporal sclerosis. 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 prolonged 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.
Familial temporal lobe epilepsy is a genetic condition, usually inherited in an autosomal dominant pattern. This happens when one parent is affected with temporal lobe epilepsy and passes it to their child. It can manifest either with lateral or mesial symptoms. Seizure control can usually be achieved with medication, not requiring surgery.
How many other children have temporal lobe epilepsy?
Temporal lobe epilepsy is fairly common in teenagers and adults, accounting for nearly two-thirds of focal onset epilepsies in these age groups.
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. Brain imaging and EEG are also used to reach the final 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-seizure medications if there is no obvious cause for the seizures. However, if the child has mesial temporal sclerosis or another brain abnormality, 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 with no major risks of neurological deficits after surgery (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-seizure medications can reduce or stop seizures in 60% to 70% of people with temporal lobe epilepsy. There is a lower likelihood that seizures will be controlled with medications if the child:
- has an identified change in the brain as seen on MRI that is causing the child’s seizures
- has frequent focal to bilateral tonic-clonic 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% to 40% of children, it is important to recognize this fact early. In up to 90% of children, early surgery to remove the affected areas of the brain can stop the seizures and potentially help to improve behavior, cognition and social development. On the other hand, if surgery is delayed and a child has ongoing seizures during adolescence, the seizures can interfere with their education, behaviour and social development.
