What is temporal lobe epilepsy (TLE)?
The features of seizures beginning in the temporal lobe can be extremely varied, but certain patterns are common. There may be a mixture of different feelings, emotions, thoughts, and experiences, which may be familiar or completely foreign. In some cases, a series of old memories resurfaces. In others, the person may feel as if everything – including home and family – appears strange. Hallucinations of voices, music, people, smells, or tastes may occur. These features are called “auras” or “warnings.” They may last for just a few seconds or may continue as long as a minute or two.
Experiences during temporal lobe seizures vary in intensity and quality. Sometimes the seizures are so mild that the person barely notices. In other cases, the person may be consumed with fright, intellectual fascination, or even pleasure.
The experiences and sensations that accompany these seizures are often impossible to describe, even for the most eloquent adult. And of course it is even more difficult to get an accurate picture of what people are feeling.
Tell me more
Dostoyevsky, the 19th-century Russian novelist, who himself had epilepsy, gave vivid accounts of apparent temporal lobe seizures in his novel The Idiot:
“He remembered that during his epileptic fits, or rather immediately preceding them, he had always experienced a moment or two when his whole heart, and mind, and body seemed to wake up with vigor and light; when he became filled with joy and hope, and all his anxieties seemed to be swept away for ever; these moments were but presentiments, as it were, of the one final second…in which the fit came upon him. That second, of course, was inexpressible. Next moment something appeared to burst open before him: a wonderful inner light illuminated his soul. This lasted perhaps half a second, yet he distinctly remembered hearing the beginning of a wail, the strange, dreadful wail, which burst from his lips of its own accord, and which no effort of will on his part could suppress. Next moment he was absolutely unconscious; black darkness blotted out everything. He had fallen in an epileptic fit.”
What are the types of temporal lobe epilepsy?
Temporal lobe epilepsy is the most common form of focal (partial) or location related epilepsy. It accounts for approximately 60% of all people living with epilepsy. There are two types of TLE. One involves the medial or internal structures of the temporal lobe; while the second, called neocortical temporal lobe epilepsy, involves the outer portion of the temporal lobe. The most common version of these two is medial temporal lobe epilepsy.
- Medial temporal lobe epilepsy often begins within a structure of the brain called the hippocampus or its surrounding structures. It accounts for almost 80% of all temporal lobe seizures.
- Medial temporal lobe epilepsy is also considered a syndrome, which means that a lot of different conditions can result in medial temporal lobe epilepsy. Individuals who have medial temporal lobe epilepsy have seizures by definition of temporal lobe origin.
- There are a lot of different older names for the seizures that occur in TLE, including, "psychomotor seizures," "limbic seizures," "temporal lobe seizures," "complex partial," and "simple partial." The modern name for these seizures is "focal onset," which is then characterized by whether the person stays aware or has impaired awareness.
- While medial temporal lobe epilepsy is a very common form of epilepsy, it is also frequently resistant to medications and associated with a particular finding on an MRI (magnetic resonance imaging). This finding is called hippocampal sclerosis (sclerosis means hardening) and it makes this a challenge to treat both medically and oftentimes surgical therapy is the best option for these individuals (See arrow in figure at the top of the page)
What is the outlook?
The overall prognosis for people with drug resistant medial temporal lobe epilepsy includes a higher risk for memory and mood difficulties. This in turn leads to impairments in quality of life and an increased risk for death, as observed in people who have frequent seizures failing to respond to treatment.
What are some risk factors for temporal lobe epilepsy?
Usually, the birth, labor, delivery, and development of individuals with medial temporal lobe epilepsy is normal. However, there are some common risk factors:
- Conditions often associated with TLE include head trauma with loss of consciousness, injuries during early childhood and birth, brain malformations, infections such as encephalitis or meningitis, and even some tumors within the temporal lobe.
- The most common risk factor is having had a seizure associated with fever. Approximately two-thirds of people with TLE have had a febrile seizure without an infection before the onset of focal with impaired awareness (complex partial) seizures. Nearly 75% of these febrile seizures were considered to be either prolonged or have complex features. For example, the febrile seizures may be longer than usual (lasting 15 minutes or longer) or have a very clear neurological abnormality, such as weakness in an arm or a funny posturing that suggests an abnormality in the brain.
- Despite the fact that febrile seizures are a common risk factor for people with medial temporal lobe epilepsy, it is important to know that simply having had a seizure during a fever does not significantly increase the risk of epilepsy above that of the general population.
When does TLE usually develop?
Medial temporal lobe epilepsy usually begins at the end of a first or second decade in most people, following either a seizure with fever or an early injury to the brain. In women, hormonal influences during their menstrual cycle and ovulation may lead to reports of increased seizures during their menstrual cycle.
What type of seizures are seen?
- Seizures in TLE include focal aware (simple partial) seizures, such as auras, and focal impaired awareness (complex partial) seizures.
- The most common auras are déjà-vu experiences or some gastrointestinal upset. Feelings of fear, panic, anxiety, or a rising epigastric sensation or butterflies with nausea are also other ways in which auras present in medial temporal lobe epilepsy. Some people also report a sense of unusual smell; this may raise a possibility of a hippocampal abnormality or a tumor in that area.
- Focal impaired awareness (complex partial) seizures can be associated with a fixed stare, impaired consciousness, fumbling with their fingers, or lip-smacking movements that last 30 to 60 seconds. There can be a posture change in an arm that also can help identify the location in the brain of these seizures. Some people also speak gibberish or lose their ability to speak in a sensible manner. Some individuals report difficulty with the language, particularly if the seizures are coming from the dominant temporal lobe. Some people may have a generalized tonic-clonic jerking and this can lead to weakness after the seizure has stopped.
- Some individuals can also have prolonged seizures and in some rare situations, status epilepticus may occur.
How is TLE diagnosed?
- The diagnosis of medial temporal lobe epilepsy is still by listening to a person describe their seizures or hearing observations of a witness.
- An MRI of the brain is considered the standard radiology procedure to see the characteristic abnormalities associated with medial temporal lobe epilepsy.
- An EEG (electroencephalogram) is also essential. The results often show anterior temporal spike or sharp waves, which can occur in both wakefulness and/or sleep.
- Sometimes recording seizures in a video EEG monitoring unit is needed. This is often done to locate seizures and determine if surgery could be helpful.
How is TLE treated?
- Most people with focal seizures will respond to medical treatment with appropriate anti-seizure drugs. However, almost a third of people may not respond to therapy.
- These people may report problems with memory, socialization, and a fear of leaving their home.
- They may restrict their daily activities, which leads to a decrease in quality of life.
- If seizures fail to respond to medication, then surgical approaches are an appropriate option. In individuals where the MRI shows hippocampal sclerosis in the medial temporal lobe and EEGs show abnormalities in that same area, seizures may be cured by surgery. In some cases, up to 70% of people can be rendered seizure-free through surgery with minimal problems afterwards.
- If surgery is not possible or doesn't work, devices such as vagus nerve stimulation or responsive neurostimulation may help.
- It is important to understand and recognize the features of medial temporal lobe epilepsy and how responsive treatments such as surgery and medications can be.
- Talking with your health care team about what happens before, during, and after a seizure can help with making the right diagnosis and finding the best treatment plan.
- Consider seeing a neurologist who specializes in epilepsy (called an epileptologist) or having an evaluation at an epilepsy center to explore all treatment options, including surgery, devices, and dietary therapy.
Important Tips about Temporal Lobe Epilepsy
- Most common form of focal or partial epilepsy
- Surgery may be an option for individuals who fail to respond to medications.
- MRI and EEG are important tests in the diagnosis of this condition.
- Individuals may report worsening short term memory and quality of life if seizures are not controlled.