Temporal Lobe Epilepsy
What Is It?
Temporal lobe epilepsy (TLE) is a general term for a set of conditions which give rise to recurrent seizures originating from the temporal lobe of the brain. The term is used generally to refer to any epilepsy originating in the temporal lobe but can include several different underlying pathologies that cause the seizures.
One subclassification separates the temporal lobe epilepsies into mesial (or medial) and lateral types. Mesial refers to seizures that originate from the medial part of the temporal lobe, particularly structures known as the hippocampus, amygdala and parahippocampal gyrus, whereas lateral refers to seizures which originate from the more lateral, superficial parts of the lobe.
There are numerous pathologies that can affect the temporal lobe and cause seizures, such as vascular malformations, brain tumors, infection and trauma. However, the most common pathologic finding in patients who present with typical termporal lobe epilepsy is known as hippocampal sclerosis or mesial temporal lobe sclerosis. The term sclerosis refers to the hardening of the hippocampus structures manifested as a smaller hippocampus on neuroimaging studies such as MRI. This sclerosis is evidence of some damage to the cells in the hippocampus in the temporal lobe, but in most cases the underlying cause of the damage is unknown.
The cause of hippocampal sclerosis and the resulting temporal lobe seizures is generally unknown. Most children who present with febrile seizures generally do not develop a chronic epilepsy condition in later life. However, a subset of these patients do go on to develop temporal lobe epilepsy in adulthood.
What Types of Symptoms Are Typical?
Patients with temporal lobe epilepsy present most frequently with recurrent partial seizures
. These seizures, which affect only part of the brain, can occur without an effect on the patient's level of consciousness (termed a simple partial seizure
) or with a concomitant loss or alteration of consciousness (termed a complex partial seizure
). In a smaller set of patients with temporal lobe epilepsy, the seizure activity can spread to involve most of the brain on both sides, known as a partial seizure with secondary generalization
Because of the involvement of the temporal lobe, there are some common manifestations of temporal lobe seizures. For example, an aura of some type precedes the seizure in many cases. This can include olfactory and/or gustatory illusions or hallucinations. Visual illusions or hallucinations can also occur. Psychological symptoms, such as fear or anxiety, can also occur, presumably due to involvement of the amygdala and other temporal structures involved in these emotions. Each patient's set of specific symptoms they experience with a seizure vary and can include these as well as other manifestations.
How Is The Diagnosis Typically Made?
In a patient with recurrent seizures, the work up will generally involve a complete neurological examination followed by imaging studies such as CT scan
and MRI scan
. These studies help to determine if there is a lesion which can be seen to explain the epilepsy. Hippocampal sclerosis, the most common cause of TLE, although subtle, can often be seen on a good quality MRI.
Electroencephalogram is generally also performed to identify the seizure activity and attempt to localize the seizures in the brain. Typical partial seizures arising from the temporal lobe can often be localized to the general area. However, in some patients additional testing, such as MEG, PET scan or implanted electrodes, may be required to confirm the origin and hone in on its precise location.
What Are Some Common Treatments?
As with other forms of epilepsy, management of temporal lobe epilepsy can include both medical and surgical treatments which attempt to decrease or eliminate the occurrence of seizures. In general, most patients are first started on various anti-epileptic medications
. If this medical treatment alone is not sufficient to adequately control seizures, surgical treatments are also considered. If the source of the seizures is positively identified on testing to be the temporal lobe, the most common procedure used to treat this condition is a temporal lobectomy. A temporal lobectomy surgically removes part of the temporal lobe. The specific structures removed and how much of the lobe is removed depends on the specific procedure and the patient's underlying pathology.
For more information about treatment for epilepsy in general, see the Epilepsy Treatment page.
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This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.