Mesial Temporal Sclerosis Fast Facts

Mesial temporal sclerosis (MTS) is a condition characterized by scarring and deterioration of the inner part of the brain’s temporal lobe.

MTS is the most common cause of temporal lobe epilepsy.

MTS may be caused by head trauma, infections, or disruption of the oxygen supply to the brain. In some cases, the cause of the condition is unknown.

Some studies suggest that MTS may be, in some cases, caused or aggravated by seizures.

MTS may cause cognitive and behavioral symptoms as well as seizures.

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MTS may be caused by head trauma, infections, or disruption of the oxygen supply to the brain.

What is Mesial Temporal Sclerosis?

Mesial temporal sclerosis (MTS) is a brain condition characterized by scarring and loss of nerve cells deep inside the brain’s temporal lobe. The condition is also referred to as hippocampal sclerosis. This part of the brain is responsible for multiple functions, including the regulation of emotions and memory.

MTS is commonly associated with seizure disorders, and the condition is thought to be the most common cause of temporal lobe epilepsy. In addition, research has suggested that in some cases, MTS may be caused by prolonged seizures.

Symptoms of MTS

MTS typically causes focal seizures, which are seizures confined to one area of the brain. Symptoms of these seizures sometimes include behavioral or cognitive effects. Common symptoms include:

  • Odd feelings or emotions, such as deja vu, extreme happiness, or unexplained fear
  • Confusion
  • Memory loss
  • Speech difficulties
  • Muscle spasms or convulsions

What Causes Mesial Temporal Sclerosis?

In many cases, MTS seems to be caused by an event or condition that causes stress or damage to the brain. These kinds of events can include:

  • Traumatic brain injury
  • Brain infection or inflammation
  • Stroke
  • Brain tumor
  • Oxygen deprivation
  • Seizure activity

Although it has long been known that MTS is a common cause of seizures, more recent research has suggested that the condition can also be caused by seizure activity. Prolonged seizures or complex febrile seizures (seizures caused by fever) have been associated with MTS in studies.

In some cases, the cause of MTS remains unknown.

Is Mesial Temporal Sclerosis Hereditary?

In most cases, MTS does not appear to be an inherited condition. It is often caused by an external event or situation and doesn’t appear to have a genetic origin. Some studies have found cases of temporal lobe epilepsy that runs in families, but no MTS was present in these cases.

How Is Mesial Temporal Sclerosis Detected?

MTS is rarely diagnosed in children under the age of 10, and most children diagnosed with epilepsy have no evidence of the condition. It is most commonly diagnosed at or after adolescence.

Because MTS is commonly associated with focal seizures affecting the temporal lobe, symptoms of this type of seizure may suggest that the condition is present. Focal seizure symptoms may include:

  • Odd emotional experiences or memories
  • Sensory effects
  • Muscles spasms or jerking movements affecting one part of the body

How Is Mesial Temporal Sclerosis Diagnosed?

A doctor may suspect MTS if a patient presents symptoms of temporal lobe epilepsy and has experienced any of the conditions known to be associated with MTS. The tool doctors most commonly use to diagnose MTS is a magnetic resonance imaging (MRI) scan. This scan creates images of the brain and can show the scarring and damage of the temporal lobe characteristic of MTS.


How Is Mesial Temporal Sclerosis Treated?

The seizures associated with MTS are often resistant to the anti-seizure medication typically used to treat other types of epilepsy.

A surgical procedure called a temporal lobectomy is often effective, especially if only one side of the brain is affected. In this procedure, surgeons remove the scarred part of the temporal lobe. The surgery has a high success rate for eliminating seizures, and patients usually don’t experience any new neurological symptoms.

How Does Mesial Temporal Sclerosis Progress?

MTS seems to get progressively worse after the initial condition that causes scarring of the temporal lobe. In a metabolic process that is not yet completely understood, nerve cells in the affected area are susceptible to further damage, and they may eventually die, leading to the deterioration of the temporal lobe.

How Is Mesial Temporal Sclerosis Prevented?

One way to help prevent MTS is to avoid the conditions that cause it and treat them promptly when they occur. These conditions include:

  • Infections
  • Head injuries
  • Tumors
  • Stroke

Studies have suggested that prolonged seizure activity can be an initial cause of MTS and a factor that worsens existing MTS. Therefore, effective and early control of seizures plays a crucial role in preventing MTS and lowering the risk of significant complications in the future.

Mesial Temporal Sclerosis Caregiver Tips

  • Keep a diary of your child’s symptoms and be alert for seizure activity. Early diagnosis and intervention can lessen the long-term impact of MTS. Consult your doctor right away when you see any of the disorder’s warning signs.
  • Find support from people who know what you’re going through. The Epilepsy Foundation operates a 24/7 helpline through which you can find information and links to support resources.

Many people with MTS also suffer from other brain-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with MTS:

  • As many as a third of people with MTS experience mood disorders such as depression.
  • People with MTS are at increased risk for epilepsy-related psychiatric conditions such as interictal dysphoric disorder and postictal psychosis.

Mesial Temporal Sclerosis Brain Science

Researchers are working to understand the causes of MTS and the biochemical processes that may make the condition worse. Some scientists believe that the condition arises when an event triggers the release of excessive amounts of glutamate in the brain. Glutamate is a chemical vital to communication between brain cells, but studies have found that an event such as a brain injury can cause an imbalance of the chemical in the brain.

The glutamate imbalance may lead to a complex metabolic process that is damaging to nerve cells. In particular, the process may allow toxic amounts of calcium to enter brain cells, causing damage and, ultimately, cell death. As cells in the temporal lobe die, the symptoms of MTS result.

Mesial Temporal Sclerosis Research

Title:  Surgery as a Treatment for Medically Intractable Epilepsy

Stage: Recruiting

Principal investigator: Kareem A Zaghloul, MD

National Institute of Neurological Disorders and Stroke (NINDS)

Bethesda, MD

Background: Medically intractable epilepsy is the term used to describe epilepsy that medication cannot control. Many people whose seizures do not respond to medication will respond to surgical treatment, relieving seizures completely or almost completely in one-half to two-thirds of patients who qualify for surgery. The tests and surgery performed as part of this treatment are not experimental. Still, researchers are interested in training more neurologists and neurosurgeons in epilepsy surgery and care to better understand epilepsy and its treatment.

Objectives: To use surgery as a treatment for medically intractable epilepsy in children and adults.

Eligibility: Children and adults at least eight years of age who have simple or complex partial seizures (seizures that come from one area of the brain) who have not responded to medication and are willing to have brain surgery to treat their medically intractable epilepsy.

Design: Participants will be screened with a medical history, physical examination, and neurological examination. Imaging studies, including magnetic resonance imaging and computer-assisted tomography (CT), may also be conducted as part of the screening. Participants who do not need surgery or whose epilepsy cannot be treated surgically will follow up with a primary care physician or neurologist and will not need to return to the National Institutes of Health for this study.

Before the surgery, participants will have the following procedures to provide information on the correct surgical approach.

Video electroencephalography monitoring to measure brain activity during normal activities within a 24-hour period. Three to four 15-minute breaks are allowed within this period.

Wada test to evaluate speech, comprehension, and memory centers of the brain, using a contrast dye to study the brain’s blood vessels and a short-term anesthetic administration procedure to test the effects on areas of speech and memory.

Depth electrodes and/or brain surface electrodes measure brain activities and determine the part of the brain responsible for the seizures (seizure focus).

Participants will have a surgical procedure at the site of their seizure focus. Brain lesions, abnormal blood vessels, tumors, infections, or other areas of brain abnormality will be either removed or treated in a way that will stop or help prevent the spread of seizures without affecting irreplaceable brain functions, such as the ability to speak, understand, move, feel, or see.

Participants will return for outpatient visits and brain imaging studies two months, one year, and two years after surgery.


Title:  Stereotactic Laser Ablation for Temporal Lobe Epilepsy (SLATE)

Stage: Recruiting

Principal investigator: Robert Gross, MD, PhD

Emory University

Atlanta, GA

The study is designed to evaluate the safety and efficacy of the Visualase MRI-guided laser ablation system for mesial temporal epilepsy (MTLE).

The purpose of the study is to evaluate the safety and efficacy of the Visualase MRI-guided laser ablation system for necrotization or coagulation of epileptogenic foci in patients with intractable mesial temporal lobe epilepsy.

The study will include approximately 150 adult patients with drug-resistant MTLE treated at selected epilepsy centers across the United States. After the Visualase procedure, patients will be followed for 12 months and evaluated for freedom from seizures, quality of life, adverse events, and neuropsychological outcomes.


Title:  Electrophysiologic Biomarkers in MTLE Patients

Stage: Not Yet Recruiting

Principal investigator: Robert Gross, MD, PhD

Emory University

Atlanta, GA

The investigators plan to enroll individuals with medial temporal lobe epilepsy undergoing surgical workup with clinically implanted intracranial electrodes. The study intends to administer computerized memory tasks and stimulation during the intracranial Electroencephalography (EEG) monitoring period.

This is a nonrandomized interventional trial that will apply brain stimulation via clinically implanted intracranial electrodes to subjects with medial temporal lobe epilepsy to identify biomarkers related to the pre-ictal state; to perform an acute parameter search to determine the stimulation pattern that most effectively modifies these biomarkers and to identify changes in memory (free recall) during asynchronous distributed multi-electrode stimulation (ADMES).

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