Focal Cortical Dysplasia
Focal Cortical Dysplasia
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Authors: Paul Boyd, BS, George Washington University School of Medicine and Health Sciences
Melissa Tsuboyama, MD, Boston Children’s Hospital
Reviewed: February 2023 


Focal cortical dysplasia (FCD) occurs when neurons do not form normally during brain development. Neurons are a specific type of brain cell. 

Healthy neurons work together with:  

  • Other cell types. These include:  
    • Astrocytes (which support neurons) 
    • Oligodendrocytes (which cover neurons and allow them to communicate quickly)  
    • Microglia (which work as the brain’s immune system)  
  • Molecules called neurotransmitters.  

All of these coordinate to send electrical information from one region of the brain to another. 

Neurons in different parts of the brain are responsible for sending different types of information. They are involved in all the functions of the brain. These include functions such as: 

  • Talking 
  • Hearing  
  • Moving an arm or leg 

However, abnormally formed neurons in FCD do not work as they should. Instead, they may send abnormal electrical signals. These can cause seizures.  

Children with FCD have an increased risk of repeated seizures during their lifetime. (This is defined as a condition called epilepsy.) 


Disorder Overview


There are three different categories of FCD. The category depends on the way the neurons are formed and connected. Some characteristics of FCD can be seen on brain magnetic resonance imaging (MRI).  

However, the only way to diagnose a type of FCD for certain is to look at tissue under a microscope. The type of diagnosis is based on how the changes appear. Tests for genetic changes in the DNA of the tissue may also be used to help clarify the diagnosis. 

The three types of FCD are: 

Type I.

  • The cortex is the outer layer of the brain. It is made of neurons. The cortex is normally made of six horizontal layers of cells. In this type of FCD, it is not properly organized. The cells may be organized in vertical columns. There may also be a loss of the six layers.  
  • Changes may be harder to detect on brain MRI. 
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Type II.

  • Like in Type I, neurons are abnormally organized. There may be large neurons present. These are called balloon cells.  
  • Changes are more easily seen on brain MRI, as described below.
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Type III.

  • This type has the same changes as Type I.  
  • A second kind of abnormality is also present. For example, there may be: 
    • A tumor 
    • Brain scarring (such as in the hippocampus)  
    • Abnormal collections of blood vessels 
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Additionally, FCD may be divided into subgroups based on specific neuropathological findings. These subgroups include: 

  • Type I a and b 
  • Type II a and b 
  • Type III a, b, c, and d 

New categories of FCD have recently been suggested. These include: 

Mild malformations of cortical development (mMCDs).

  • There are more neurons present in the cortex than normal. 
  • However, these neurons are organized correctly. 
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mMCDs with oligodendroglial hyperplasia (MOGHE).

  • The white matter deep in the brain is primarily affected. The cortex may also be abnormal.  
  • There are more oligodendrocytes present than normal.
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No definite FCD on histopathology.

There is clinical suspicion of FCD. However, one of these two conditions applies: 

  • The classical features of FCD I, II, or III are not seen under the microscope. Features may also be ambiguous. 
  • There is incomplete sampling of the tissue, so an assessment cannot be made. 
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Importantly, FCD does not grow or spread to other parts of the brain over time. As your child’s brain develops, the FCD may become more clearly seen on brain MRI.  

Changes seen with MRI may include:  

  • Brightness of a particular region. This occurs on certain sequences. (Most often, the T2/FLAIR sequence is affected.) 
  • A bright streak or line. This is called a “tail.” It extends from the gray matter into the underlying white matter.  
  • Blurring between gray and white matter. There is a lack of clear definition. 


FCD is most commonly found on a brain MRI. An MRI is usually done when a child is undergoing testing to identify a cause for their epilepsy. Incidental FCD can sometimes be found that are not associated with seizures. Sometimes, children with FCD can have an “explosive” onset of seizures. This means that their seizures can:  

  • Start very suddenly 
  • Occur very frequently 
  • Be hard to control with medication (at least in the beginning)  

Seizures caused by FCD are called focal seizures. The abnormal electrical firing of the neurons starts in one particular region of the brain. It does not affect the entire brain at once. However, seizures can start in one area and spread to the rest of the brain. The presentation of a seizure depends on which part of the brain is involved.  

For example, FCD in the temporal lobe can cause seizures in which a person:  

  • Stares off. They may not be aware. 
  • Smacks their lips. 
  • Fumbles with their hands. They may perform other repeated, automatic movements. These can seem purposeful. 
  • Has a color change around their lips.  

Seizures from FCD can originate from a particular area of the brain and expand to include the whole brain. Symptoms include: 

  • Involuntary, sudden jerking movements of any part of the body. These typically occur on the side of the body opposite the side of the brain with FCD.  
  • Full body stiffening. 
  • Rhythmic jerking of both arms and legs. 
  • Eyes rolling back or up. 
  • Loss of consciousness 
  • Loss of bladder control. 

Seizures may be subtle or obvious. They generally look similar each time for a particular person. They may be very quick or last a long time.  

A neurologist may ask you many questions about what your child’s seizures look like. Taking videos of the events can be helpful. Further testing may be needed to confirm that the events you are seeing are seizures.  

Children with epilepsy, with or without FCD, can also have:  


FCD is caused by a change to neurons during brain development. Neurons are brain cells.  

Sometimes, these changes are due to a genetic condition. Other times, they occur randomly during fetal development.  

Testing can be done to try to figure out the cause of FCD. This includes blood or saliva tests from your child and sometimes from both biological parents. These tests look for spelling changes (mutations) in genes that can cause epilepsy 

Some of the genes associated with FCD include: 

  • MTOR 
  • AKT3 
  • PIK3CA  
  • DEPDC5 
  • TSC1 and TSC2 
  • NPRL2 and NPRL3 
  • REB 
  • SLC35A2 (which is associated with MOGHE) 

FCD may be inherited. Other times, it may only be present in your child. Therefore, it is important to talk to your child’s neurologist about your family history. Tell them whether any family members have had:  

  • Epilepsy 
  • Intellectual or developmental delays 
  • Any other conditions you feel may be relevant 


Initial Diagnosis 

For the initial diagnosis of FCD, the following tests may be used: 

Neurological examination.

  • A visit with a neurologist is the most important part of your child’s evaluation.  
  • The neurologist will ask many questions about your child’s development. They will ask if there have been any events that could be seizures. They will also want to know whether there are family members who have had similar symptoms. They may:  
    • Ask your child questions 
    • Ask them to move in different ways 
    • Interact with them 
    • Tap on their joints with a reflex hammer  
    • Look for birthmarks on their skin  
  • All these tasks provide information about how your child’s brain and overall nervous system are working. 
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Electroencephalogram (EEG).

  • An EEG is a test that measures the electrical activity of the brain surface. It can help identify whether there are certain regions of the brain that are more prone to seizures.  
  • Most commonly, metal discs called electrodes are placed on the scalp. These discs are connected to wires. They record brain activity. Often, video is also recorded to see what the patient is doing during the EEG.  
  • An EEG can last anywhere from twenty minutes to several days. It may be performed in your child’s neurologist’s office, at your home, or in the hospital. This tool allows the neurologist to understand the electrical functioning of the brain. 
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Magnetic resonance imaging (MRI).

  • MRI is a device that uses a large magnet to take detailed pictures of the brain.  
  • It may help to determine the extent of the FCD and any other differences in the way the brain formed. Such differences include: 
    • Blood vessel changes 
    • Strokes or scar tissue 
    • Tumors 
  • MRI is a tool that allows us to understand the anatomy of the brain.  
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Phase I Evaluation  

If an FCD is causing epilepsy that is difficult to treat with medication, more detailed testing may be done. This can determine if surgery to remove the FCD or at least the part of it causing seizures is an option.  

This type of testing is called a phase I evaluation. It evaluates whether your child may be a candidate for surgery. It does not mean you have to proceed with surgery. It is simply a way of finding out whether surgery is an option.  

The tests performed during a phase I evaluation depend on your child’s particular case. They usually include:  

  • Hospital admission. 
  • Long-term EEG monitoring (LTM). LTM captures typical seizures. 

Anti-seizure medications may be decreased or stopped while in the hospital. This can increase the chances of capturing seizures during this evaluation. Medication changes should never be done outside of the hospital unless discussed with your child’s neurologist.

Other specialized testing may also be performed using the tests below.  

  • Looking at sugar (glucose) uptake in the brain (PET scan) 
  • Blood flow changes in the brain at the beginning of a seizure (SPECT scan) 
  • Magnetic fields generated from the brain (MEG scan) 
  • A special MRI to determine the function of different parts of the brain (functional MRI).  

The information gathered is then reviewed by a team of neurologists. This team includes: 

  • Epilepsy specialists (epileptologists) 
  • A neurosurgeon  
  • A neuroradiologist (a doctor who reads and interprets brain images)  
  • A neuropsychologist 

Together, they come to an agreement as to whether surgery to remove the FCD is an option. 

Phase II Evaluation

There are times when further testing needs to be done. This is needed to determine: 

  • If the FCD can be removed  
  • What part of the FCD is safe to remove 

Additional testing occurs in the form of a phase II evaluation. This involves EEG monitoring within the brain. There are two types of intracranial EEG monitoring that may be used. They are: 

Stereotactic EEG (sEEG).

  • A neurosurgeon carefully inserts thin wires with electrode contacts into specific areas of the brain.  
  • The goal is to record electrical activity of those brain regions. 
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Grids and strip electrodes.

  • A neurosurgeon places rows of electrodes directly onto the surface of the brain.  
  • This records electrical activity from those regions. 
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Similar to what was described in the LTM testing during a phase I evaluation above, anti-seizure medication may be decreased or stopped. This is done in order to capture seizures while the sEEG or grids and strip electrodes are implanted.  

The brain may be electrically stimulated through these electrodes. This shows which function is activated. Functions include muscle movement, sensation, and language. In addition, it can identify whether they overlap with the area where seizures are starting. 


Medication is not used to treat FCD or make it go away. Instead, treatment is centered around the seizures that FCD can cause. If FCD does not cause seizures, anti-seizure medication may not be needed. 

Anti-seizure medication is the main treatment for epilepsy. It can reduce the number and severity of seizures. In two-thirds of patients with epilepsy, the first and/or second medicine can stop the seizures completely. Your child’s neurologist will work closely with you to determine the best medication(s) for your child. They always balance the risk of side effects with the safety and well-being of your child.  

Unfortunately, a third of people with epilepsy have “refractory epilepsy.” This means that they continue to have seizures despite having tried two or three reasonable anti-seizure medications at good doses. Most likely (but not always), other medications will not allow them to achieve seizure freedom. However, they can help them to get better control of their seizures.  

Many patients with FCD have refractory epilepsy. If one medication fails to control seizures, your neurologist may discuss whether epilepsy surgery is a treatment option. Reducing the number and intensity of seizures is important in keeping patients with FCD safe.  

In these scenarios, other treatment options are discussed in addition to anti-seizure medication. These include:  


  • First, extensive testing and discussions will occur (as outlined above).  
  • If your child is found to be a good surgical candidate, a neurosurgeon with expertise in treating patients with epilepsy can perform the surgery.  
  • The goal is to remove or disconnect the area of the brain (such as the FCD) causing the seizures. Please see the Pediatric Epilepsy Surgery Alliance website for more information. 
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Brain stimulation.

  • Sometimes, a child’s seizures come from many different areas (possibly from multiple FCDs). Or, they may come from an area that overlaps with critical function (like language). In this case, the risks of surgery may outweigh any possible benefit to your child.  
  • In some of these cases, a device that stimulates the brain may be implanted. There are several different types of stimulators. These include:  
    • Deep brain stimulation (DBS) 
    • Responsive neurostimulation (RNS) 
    • Vagus nerve stimulation (VNS)  
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Diet therapy.

  • Medical diets can improve seizure control for some children with epilepsy. Such diets include: 
    • A ketogenic diet 
    • A modified Atkins diet 
    • A low-glycemic index diet  
  • A thorough evaluation including blood and urine testing should be done before starting one of these diets. This ensures they are safe to try. Blood and urine monitoring are often needed while on the diet.  
  • You and your child will meet with a dietician and neurologist who specializes in diet therapy for epilepsy. It is important that you do not start any of these diets without the supervision of a medical team. This ensures it is done safely and properly.  
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Seizure freedom can be achieved in children with FCD. The outcome will largely depend on:  

  • How responsive the seizures are to anti-seizure medication 
  • Where the FCD is in the brain 
  • How much of the FCD can be safely removed during epilepsy surgery  

It is important that your child take any prescribed anti-seizure medication according to their neurologist’s instructions. If applicable, following a prescribed diet plan as instructed is also important. 

The goal of any treatment intervention is to:  

  • Keep your child safe 
  • Help them reach their maximum potential 
  • Optimize their quality of life


Pediatric Epilepsy Surgery Alliance  

The Pediatric Epilepsy Surgery Alliance (formerly known as The Brain Recovery Project) enhances the lives of children who need neurosurgery to treat medication-resistant epilepsy. They empower families with research, support services, and impactful programs before, during, and after surgery. PESA’s programs include research-based, reliable information to help parents and caregivers understand when a child’s seizures are drug-resistant; the risks and dangers of seizures; the pros and cons of the various neurosurgeries to treat epilepsy; the medical, cognitive, and behavioral challenges a child may have throughout life; school, financial aid, and life care issues. PESA’s resources include a comprehensive website with downloadable guides, pre-recorded webinars, and virtual workshops; an informative YouTube channel with comprehensive information about epilepsy surgery and its effects; a private Facebook group (Education After Pediatric Epilepsy Surgery) with over 300 members; Power Hour (bi-monthly open forums and live virtual workshops on various topics); and free school training to help your child’s education team understand the impact of their epilepsy surgery in school. Their Peer Support Program will connect you with a parent who has been there. The Pediatric Epilepsy Surgery Alliance also hosts biennial family conferences and regional events that allow families to learn from experts, connect with other families, and form lifelong friendships. They also provide a travel scholarship of up to $1,000 to families in need to fund travel to a level 4 epilepsy center for a surgical evaluation. 

In addition, PESA has resources for medical professionals to assist in helping clinicians help the parents of their patients find the resources they need after surgery. Educators and therapists will also find helpful resources and information, including videos, guides, and relevant research. Patients who have undergone surgery are encouraged to register with the Global Pediatric Epilepsy Surgery Registry to help set future research priorities. 

Epilepsy Leadership Council 

The Epilepsy Leadership Council is made up of individuals representing organizations serving individuals with epilepsy and their families, as well as professionals, and governmental organizations. The mission is to develop and coordinate among its members shared projects that will have a positive impact on the lives of individuals with epilepsy, focusing on those areas where working together produces greater efficiency and impact than working independently. 

For a list of more than 40 professional societies, patient advocacy organizations, and governmental agencies, please click here. 

Child Neurology Foundation (CNF) solicits resources from the community to be included on this webpage through an application process. CNF reserves the right to remove entities at any time if information is deemed inappropriate or inconsistent with the mission, vision, and values of CNF. 


These are clinical trials that are recruiting or will be recruiting. Updates are made daily, so you are encouraged to check back frequently. is a database of privately and publicly funded clinical studies conducted around the world. This is a resource provided by the U.S. National Library of Medicine (NLM), which is an institute within the National Institutes of Health (NIH). Listing a study does not mean it has been evaluated by the U.S. Federal Government. Please read the NLM disclaimer for details.  

Before participating in a study, you are encouraged to talk to your health care provider and learn about the risks and potential benefits.  

For more information about participation in clinical trials, check out our education hub on the topic here

Information for research and clinical trials specific to Focal Cortical Dysplasia can be found on the Pediatric Epilepsy Surgery Alliance website. 

The information in the CNF Child Neurology Disorder Directory is not intended to provide diagnosis, treatment, or medical advice and should not be considered a substitute for advice from a healthcare professional. Content provided is for informational purposes only.  CNF is not responsible for actions taken based on the information included on this webpage. Please consult with a physician or other healthcare professional regarding any medical or health related diagnosis or treatment options. 



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Jesus-Ribeiro J, Pires LM, Melo JD, Ribeiro IP, Rebelo O, Sales F, Freire A, Melo JB. Genomic and Epigenetic Advances in Focal Cortical Dysplasia Types I and II: A Scoping Review. Front Neurosci. 2021 Jan 22;14:580357. PMID: 33551717; PMCID: PMC7862327. 

Najm I, Lal D, Alonso Vanegas M, Cendes F, Lopes-Cendes I, Palmini A, Paglioli E, Sarnat HB, Walsh CA, Wiebe S, Aronica E, Baulac S, Coras R, Kobow K, Cross JH, Garbelli R, Holthausen H, Rössler K, Thom M, El-Osta A, Lee JH, Miyata H, Guerrini R, Piao YS, Zhou D, Blümcke I. The ILAE consensus classification of focal cortical dysplasia: An update proposed by an ad hoc task force of the ILAE diagnostic methods commission. Epilepsia. 2022 Aug;63(8):1899-1919. Epub 2022 Jun 15. PMID: 35706131; PMCID: PMC9545778.

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