Temporal lobe epilepsy is a disease involving recurrent seizures arising from the temporal lobe of the brain. These types of seizures often arise during childhood, but they may not become intractable until after puberty. Temporal lobe seizures are often resistant to antiseizure medications. Surgery may be an option for some patients with this disorder.
The temporal lobe is the portion of the brain that processes emotions, fight-or-flight reactions and short-term memory. Many patients who have temporal lobe seizures may experience a warning feeling prior to the seizure, which can include fear, déjà vu experiences, evolutions or hallucinations of taste or smell. Patients who have temporal lobe seizures usually remain partially conscious during a seizure, but they lose awareness of their surroundings and oftentimes do not remember what happened. These types of seizures, referred to as complex partial seizures, are often described as “staring spells.” Many patients with temporal lobe epilepsy have these spells for many years prior to the diagnosis of their seizures. A temporal lobe seizure usually lasts 15 seconds to two minutes. Characteristic signs and symptoms of temporal lobe seizures include: loss of awareness of surroundings, lip smacking, staring, repeated swallowing or chewing (oral automatisms) and pointless movements of the arms such as fidgeting with their clothes. Many patients experience a brief period of confusion and possibly difficulty speaking following their seizure. On rare occasions, these complex partial seizures may evolve into a grand mal (tonic-clonic) seizure. These types of seizures are characterized by generalized convulsions and a complete lack of consciousness.
All seizure disorders should be evaluated by a neurologist. At our institution, we have a specialized epilepsy team, which consists of specially trained epilepsy neurologists (epileptologist). The team also consists of social workers, neuropsychologists, neurophysiologists, and a neurosurgeon. An electroencephalogram “EEG” is the standard diagnostic study for an initial evaluation of epilepsy. The EEG displays the electrical activity of the brain by placing small electrodes to the scalp. For intractable seizures, such as those with recurrent temporal lobe epilepsy, a visit to the Epilepsy Monitoring Unit (EMU) is indicated. In this specialized facility, the patient is admitted to the unit where there is continuous EEG monitoring. The purpose of this testing is to observe seizures under a carefully controlled setting for diagnostic purposes. In temporal lobe epilepsy, the EEG frequently reveals the seizures to arise from the temporal portion of the brain. Other diagnostic studies are often performed during the epilepsy monitoring stay including an MRI to possibly identify structural defects in the brain, which could be causing the seizures. In temporal lobe epilepsy, the hippocampus portion of the temporal lobe may have an abnormal appearance or be diminished in size (atrophic). When either of these features is delineated on MRI, a diagnosis of mesiotemporal sclerosis is made. When this radiological abnormality is identified on the same side as a temporal lobe seizure focus, it is considered a positive indicator for surgery outcome. Frequently, PET scans and SPECT scans are performed to evaluate the seizure focus. PET scans use injected radioactive material to he lp visualize active areas of the brain. PET scans can often show a diminished metabolism in a portion of the brain, which is plagued by recurrent seizures. SPECT scans are often performed using injected radioactive materials and are often performed during a seizure as well as in between seizures. Frequently, SPECT scans show increased activity during a seizure involving the area of the brain, which is the focus of the seizure. Performed in between seizures, they show a decrease in activity in the seizure focus, similar to a PET scan.
Neuropsychological testing is performed in all patients who are considered possible candidates for temporal lobe seizure surgery. This testing involves a battery of tests conducted by a specially trained neurophysiologist. This testing provides a functional evaluation of the processing functions of the various portions of the brain. Patients with temporal lobe epilepsy often have diminished functioning on the side of the brain that harbors the seizure focus.
Numerous medications are available to treat temporal lobe seizures. Many patients with temporal lobe epilepsy do not achieve sufficient seizure control with medications alone. If patients do not respond well to the initial two seizure medicines, it is less likely that they will respond to additional medications. Additionally, seizure medicines have side effects, which include fatigue, dizziness, and weight loss.
Surgery to remove the portion of the temporal lobe that is causing the seizures is often effective. Success rates range between 65% to 90%, depending on the cause of the temporal lobe seizures. This surgery, temporal lobectomy, is not an option for every patient with temporal lobe seizures. The ideal candidate for this type of surgery is one who has intractable seizures, which have been demonstrated to arise from only the temporal lobe on only one side of the brain. This determination is made through the Epilepsy Monitoring Unit evaluation.