What is Cortical Dysplasia?
Cortical dysplasia is a brain disorder in which nerve cells in the outer layers of a baby’s brain do not develop properly during pregnancy. As a result of the abnormal development, connections between brain cells do not work as they should, and the child experiences seizures.
The most common type of cortical dysplasia is focal cortical dysplasia (FCD). It is one of the most common causes of epileptic seizures in children.
Types of FCD
FCD is categorized into different types depending on the location of abnormal brain development. The types include:
- Type I. This type usually involves problems in the brain’s temporal lobe. Often, people with this type of FCD don’t begin having seizures until adulthood.
- Type II. This more severe type typically involves both the temporal and frontal lobes. In these cases, seizures usually begin in childhood.
- Type III. This type involves abnormal development in the same areas as Type I or Type II, but it also involves a problem in another part of the brain. A brain injury sometimes causes the associated brain damage in childhood.
Types of Seizures
The most common seizure types in FCD include:
- Tonic-clonic seizures were previously known as grand mal seizures. They are the most dramatic type of epileptic seizure. Tonic-clonic seizures can cause loss of consciousness, body stiffening and shaking, loss of bladder control, or tongue-biting.
- Absence seizures. Previously known as petit mal seizures, these seizures usually happen in children. Seizures vary in frequency and duration from a few seconds to several minutes. Absence seizures may look like short attention blackouts or daydreaming. A child may seem momentarily confused or unaware of their surroundings. Absence seizures last up to 20 seconds and can occur very often (up to hundreds of times a day).
What Causes Cortical Dysplasia?
In most cases, the exact cause of FCD is unknown. The conditions that lead to abnormal brain development usually happen before birth, but external factors and events after delivery may also play a role in some cases.
Some possible causes of FCD include:
- Genetics. Epilepsy sometimes runs in families. Specific genes may make someone more sensitive to environmental conditions that can lead to seizures.
- Head injury can cause epilepsy. Seizures may go away after the acute injury calms down. However, seizures can also occur later on, driven by scarring in the brain after an injury.
- Brain disorders. Conditions like a brain tumor or stroke can cause epilepsy.
- Prenatal conditions. Before birth, brain damage can develop from an infection, poor nutrition, or oxygen deficiency. This damage can cause epilepsy.
- Developmental health conditions. Developmental disorders such as autism spectrum disorder can cause epilepsy.
- Childhood seizures. High fevers in children are associated with seizures. Usually, children with seizures caused by high fevers don’t develop epilepsy. The risk increases if a child has a prolonged seizure, another nervous system condition, or a family history of epilepsy.
Is Cortical Dysplasia Hereditary?
The majority of FCD cases do not seem to be inherited. However, the condition does run in some families, suggesting that there is sometimes a genetic component involved. In addition, some studies have found specific genes, such as one called DEPDC5, that are associated with familial cases of FCD.
How Is Cortical Dysplasia Detected?
Epilepsy is diagnosed when someone has two unprovoked seizures (or one unprovoked seizure with the likelihood of more).
- Many people with epilepsy have more than one type of seizure. The earlier someone is diagnosed, the sooner the seizures can be addressed and treated.
- Anyone who has had a seizure — or suspects they might have had one — should see a doctor.
- A primary care provider will refer someone suspected of having a seizure to a neurologist, a doctor with special training in disorders of the brain, including epilepsy.
How Is Cortical Dysplasia Diagnosed?
To diagnose epilepsy, the doctor will go over the symptoms and medical history. The doctor may order tests to figure out why someone is having seizures, such as:
- A neurological exam. A doctor tests a person’s behavior, motor skills, and mental capabilities to determine if they have epilepsy.
- Blood tests. A specialist may take a blood sample to check for signs of infections, genetic conditions, or other conditions that might cause seizures.
- Electroencephalogram (EEG) is the most common test used to diagnose epilepsy. During this test, doctors attach electrodes to a person’s scalp, which record the brain’s electrical activity. If someone has epilepsy, it’s common to have changes in the typical pattern of brain waves, even while not having a seizure.
- The doctor may monitor a patient on video while conducting an EEG to record any seizures they experience, either awake or asleep. This can help determine the type of seizures.
- Computerized tomography (CT) scan. A CT scan uses X-rays to reveal if anything else in the brain — such as tumors or bleeding — may be causing seizures.
- Magnetic resonance imaging (MRI). An MRI uses powerful magnets and radio waves to create a detailed view of the brain. Like a CT scan, MRI can also show if any brain abnormalities could be causing seizures.
- Positron emission tomography (PET). During a PET scan, the doctor injects a small amount of low-dose radioactive material into the vein. This material helps doctors observe active areas in the brain for anything abnormal.
- Single-photon emission computerized tomography (SPECT). This test is typically used to pinpoint where seizures arise in the brain. A small amount of low-dose radioactive material is injected into a vein. SPECT creates a 3D map of the brain’s blood flow.
How Is Cortical Dysplasia Treated?
The best course of treatment for FCD depends on the severity of the condition, the location of the problem in the brain, and how a patient responds to specific treatment options.
Medication is usually the first choice for treating most types of epilepsy. However, the seizures of FCD are often resistant to anti-seizure medications. Only about 20% of people with FCD will experience relief from seizures treated with medication alone.
If medications don’t control seizures, surgery may help. During epilepsy surgery, a surgeon removes the area of the brain where the seizures begin.
Doctors usually perform surgery when tests show that seizures originate in a small, well-defined area of the brain that doesn’t interfere with crucial functions such as speech, language, motor function, vision, or hearing.
When surgery is an option for FCD, it can be very effective. As many as 80% of children who undergo surgery are free from seizures afterward.
In addition to medications and surgery, additional therapies offer options for epilepsy:
- Ketogenic diet. Some children with epilepsy can reduce seizures by following a strict diet high in fats and low in carbohydrates. The “ketogenic” diet allows the body to use fat, rather than carbohydrates, for energy. After a few years, some children may be able to stop the ketogenic diet and remain seizure-free.
- Vagus nerve stimulation can often reduce seizures by 20-40%. The doctor implants a device called a vagus nerve stimulator underneath the skin of the chest. It’s similar to a heart pacemaker. Wires from the stimulator are connected to the vagus nerve in the neck. The battery-powered device sends bursts of electrical energy through the vagus nerve to the brain. Potential side-effects from vagus nerve stimulation include throat pain, hoarse voice, shortness of breath, or coughing. After vagus nerve stimulation, people often still need to take anti-seizure medication, though they may be able to lower the dose.
How Does Cortical Dysplasia Progress?
As epilepsy progresses, people may exhibit various symptoms, including sensations of déjà vu, twitching on one side of the body, acting confused, or having difficulty speaking. In addition, recurrent seizures are believed to cause progressive brain injury, sometimes resulting in loss of cognitive ability and “kindling” further seizures in the affected region of the brain.
How Is Cortical Dysplasia Prevented?
In most cases, epilepsy can’t be prevented. But once it’s diagnosed, it can be addressed and managed.
Changes in diet have been shown to improve seizures in children. However, some people may need treatment for the rest of their lives to control their seizures.
Sometimes, seizures go away. Epilepsy is considered to be resolved for people who have remained seizure-free for the past ten years, with no seizure medications for the past five years.
Cortical Dysplasia Caregiver Tips
The most important thing you can do for a loved one with epilepsy is to be supportive. Epilepsy is a common condition. Some seizures rarely cause problems.
Overall, the chance of injury is higher for people with uncontrolled seizures. Bruises, cuts, burns, and falls are all common injuries. Less common concerns include breathing problems, drowning (due to a seizure while swimming or bathing), car accidents (many states restrict driver’s licenses for those with epilepsy), and pregnancy complications.
Rolling someone with an active tonic-clonic seizure onto their side helps prevent fluids from getting into the lungs. Putting fingers, a bite block, or a tongue depressor in the mouth is not recommended.
It’s essential to help a loved one with epilepsy track how often seizures occur. It’s especially crucial when trying a new treatment, like a new medication or a different dosage.
Caregivers should also be aware of the rare, but life-threatening complications of epilepsy, including:
- Status epilepticus, a state of continuous seizure activity lasting more than five minutes. People with status epilepticus have an increased risk of permanent brain damage and death.
- Sudden unexpected death in epilepsy (SUDEP). People with epilepsy also have a small risk of sudden unexpected death. However, the risk is very low (about 1% of people with epilepsy), and the cause is unknown. People whose seizures aren’t controlled by medications or who have frequent tonic-clonic seizures have a higher risk of SUDEP.
Many people with epilepsy also suffer from other brain and mental health-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with epilepsy:
Cortical Dysplasia Brain Science
At least in some cases, FCD is a type of condition called a neuronal migration disorder. Brain cells are created during early fetal development near the brain’s center and then migrate outward toward their normal final position in layers on the brain’s outer surface. In neuronal migration disorders, the cells don’t move as they should, and as a result, the outer layers of the brain develop abnormally. The abnormal development interferes with brain cell function in specific areas, causing FCD seizures.
Cortical Dysplasia Research
Title: Use of a Tonometer to Identify Epileptogenic Lesions During Pediatric Epilepsy Surgery
Principal Investigator: Aria Fallah, MD
University of California, Los Angeles
Los Angeles, CA
Refractory epilepsy, meaning epilepsy that no longer responds to medication, is a common neurosurgical indication in children. In such cases, surgery is the treatment of choice. Complete resection of affected brain tissue is associated with the highest probability of seizure freedom. However, epileptogenic brain tissue is visually identical to normal brain tissue, complicating complete resection. Modern investigative methods are of limited use.
An important subjective assessment during surgery is that affected brain tissue feels stiffer. However, there is currently no way to determine this without committing to resecting the affected area. It is hypothesized that intraoperative use of a tonometer (Diaton) will identify abnormal brain tissue stiffness in the affected brain relative to a normal brain. This will help identify stiffer brain regions without having to resect them.
The objective is to determine if intra-operative use of a tonometer to measure brain tissue stiffness will offer additional precision in identifying epileptogenic lesions.
In participants with refractory epilepsy, various locations on the cerebral cortex will be identified using standard pre-operative investigations like magnetic resonance imaging (MRI) and positron emission tomography (PET). These are presumed normal and abnormal brain areas where the tonometer will be used during surgery to measure brain tissue stiffness. Brain tissue stiffness measurements will then be compared with the results of routine pre-operative and intra-operative tests. Such comparisons will help determine if and to what extent intra-operative brain tissue stiffness measurements correlate with other tests and help identify epileptogenic brain tissue.
Twenty-four participants have already undergone intra-operative brain tonometry. Results in these participants are encouraging: abnormally high brain tissue stiffness measurements have consistently been identified and significantly associated with abnormal brain tissue.
If the tonometer adequately identifies epileptogenic brain tissue through brain tissue stiffness measurements, it is possible that resection of identified tissue could lead to better postoperative outcomes, lowering seizure recurrences and neurological deficits.
Title: Study of Predictive Biomarkers for Rational Management of Drug-resistant Epilepsy Associated With Focal Cortical Dysplasia (SPREAD)
Principal Investigator: Edouard Hirsch
Focal Cortical Dysplasias (FCDs) are neurodevelopmental disorders that represent a major cause of early-onset drug-resistant epilepsies with cognitive and behavioral impairments, carrying a lifelong perspective of disability and reduced quality of life. Despite a major medical and socio-economic burden, rational therapeutic strategies are still being debated. Surgical removal of the epileptogenic brain area (Epileptogenic Zone) is the most successful treatment, yet it fails to control FCD-associated seizures in as much as 40% of cases. Precise definition and complete resection of the Epileptogenic Zone are the main determinants of outcome. In current practice of French centers, up to 80% of FCD patients require an intracranial EEG (icEEG) recording to define the epileptogenic zone accurately. However, the indications for icEEG in MRI-visible FCD remain empirical and are essentially based on expert opinion.
Title: Genetic and Electrophysiologic Study in Focal Drug-resistant Epilepsies (GENEPHY)
Principal Investigator: Georg Dorfmüller, MD
Fondation Ophtalmologique Adolphe de Rothschld
Brain somatic mutations in genes belonging to the mTOR pathway are well recognized in malformations of cortical development, such as focal cortical dysplasia or hemimegalencephaly. The present study aims to search for brain somatic mutations in paired blood-brain samples from children undergoing epilepsy surgery at the Rothschild Foundation, Paris. Patients and their parents will be recruited to identify genetic abnormalities both in lymphocytic and cortical DNA.