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PubMed This is a summary of 19 peer-reviewed journal articles Updated
Neurology · Familial Focal Epilepsy with Variable Foci 1

Confirming the Diagnosis: EEG, MRI, and Genetics

At a Glance

FFEVF1 is evaluated through the seizure history and family pattern, EEG, epilepsy-protocol MRI, and genetic testing for a disease-causing DEPDC5 variant. A normal MRI or a genetic result of uncertain meaning does not by itself rule out the condition.

Diagnosing Familial Focal Epilepsy with Variable Foci 1 (FFEVF1) is often a detective process that combines clinical history, detailed brain imaging, and genetic testing [1]. Because the condition looks so different from person to person, doctors usually look for a specific family pattern: multiple relatives with focal epilepsy where the seizures start in different areas of the brain for each person [1][2]. A recognizable family history is very helpful, but it is not strictly required.

The diagnosis is typically supported when a multigene epilepsy panel (a blood or saliva test that looks at dozens of genes at once) identifies a specific, pathogenic alteration in the DEPDC5 gene [3]. It is important to know that finding a “Variant of Uncertain Significance” (VUS) does not confirm the diagnosis. A genetic counselor can help you interpret these results.

Brain Imaging: The Search for FCD

A high-quality MRI is a critical tool in managing FFEVF1. Its primary goal is to look for Focal Cortical Dysplasia (FCD), a small patch of abnormal brain tissue that can cause seizures [4].

  • Epilepsy-Protocol MRI: A standard brain MRI may miss subtle changes. Experts recommend a specialized “epilepsy protocol” (such as the HARNESS protocol), which uses a powerful 3-Tesla (3T) scanner and takes very thin, high-resolution 3D slices of the brain [5][6].
  • Normal MRI Results: It is very common—and important to remember—that a normal MRI does not rule out FFEVF1 [7]. Many people with the DEPDC5 gene have entirely normal brain imaging [7]. In some cases, a small area of FCD may exist but be too tiny for even a 3T scanner to see [8][9].

EEG: Tracking Electrical Activity

An EEG (electroencephalogram) records the brain’s electrical patterns. In FFEVF1, EEG findings are highly variable and do not always perfectly pinpoint the seizure-onset zone [10].

  • Focal Spikes: The EEG may show “spikes” or “sharp waves” in one specific area (the focus), which often matches where the seizures begin [11].
  • Multifocal Spikes: Some individuals show activity in several different areas of the brain [10].
  • Generalized Patterns: Occasionally, an EEG might look like “generalized” epilepsy (involving the whole brain at once), even though the seizures are actually focal [2].
  • Sleep Activation: Because many DEPDC5 seizures happen at night, a “sleep-deprived” EEG or a multi-day video-EEG is often used to capture the brain’s activity during sleep [12][13].

Advanced Testing for ‘Invisible’ Foci

If seizures are not controlled by medication (drug-resistant epilepsy) and the standard MRI is normal, doctors may use advanced tools to find the seizure focus [14]. These tests are often part of a “presurgical evaluation” to see if surgery could stop the seizures. They are not used as routine screening for asymptomatic carriers.

  • MEG (Magnetoencephalography): This highly sensitive test measures the magnetic fields produced by the brain’s electrical activity. It can sometimes pinpoint a focus that an MRI cannot see [1][11].
  • PET Scan (Positron Emission Tomography): A PET scan looks at how the brain uses sugar (glucose). A “cold spot” (hypometabolism) can indicate where the seizure-starting tissue is located, even if the brain structure looks normal [15].
  • MRI Post-Processing: Specialists can use computer software to analyze existing MRI scans in new ways (sometimes called a MAP scan), which can make subtle brain malformations much easier to see [16][17].
  • SEEG (Stereoelectroencephalography): In complex cases, doctors may place thin electrodes directly into the brain to map exactly where the seizures are coming from before deciding on a treatment [18][19]. Because this is an invasive procedure that carries risks of bleeding or infection, it is only done after a multidisciplinary team’s recommendation.

Common questions in this guide

How is FFEVF1 diagnosed?
Doctors combine the seizure history, family history, EEG, brain MRI, and genetic testing. A disease-causing change in DEPDC5 can support the diagnosis, but a recognizable family pattern is not required. The diagnosis is based on the complete clinical picture rather than one test alone.
Can FFEVF1 be present if my MRI is normal?
Yes. Many people with a DEPDC5-related form of FFEVF1 have normal brain imaging, and a very small area of focal cortical dysplasia may be too subtle for an MRI to show. A normal MRI does not rule out FFEVF1, although an epilepsy-protocol MRI may provide more detail.
What does a DEPDC5 variant of uncertain significance mean?
A variant of uncertain significance is a gene change whose health impact is not yet clear. It does not confirm FFEVF1 and usually cannot be used alone to guide medical decisions. A genetic counselor can explain the result and discuss whether updated interpretation or family testing is appropriate.
What can an EEG show in FFEVF1?
An EEG may show seizure-related spikes in one brain area, several areas, or sometimes a pattern that looks generalized even when the seizures are focal. Because seizures may occur at night, a sleep-deprived EEG or multi-day video EEG can be useful. EEG findings do not always identify the exact area where seizures begin.
What type of MRI is recommended for suspected FFEVF1?
An epilepsy-protocol MRI, often using a 3-Tesla scanner and thin, high-resolution 3D images, is designed to detect subtle focal cortical dysplasia. A standard MRI can miss small abnormalities. Review by a neuroradiologist who specializes in epilepsy may help identify findings that are easy to overlook.
What tests may be considered if seizures continue despite medication?
For drug-resistant epilepsy with a normal standard MRI, a presurgical evaluation may include a magnetic brain-activity scan called MEG, a PET scan, computer analysis of MRI images, or SEEG. A multidisciplinary team selects these tests to look for the seizure focus rather than using them for routine screening. SEEG places electrodes in the brain and carries risks such as bleeding or infection.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Did the genetic testing identify a pathogenic/likely pathogenic variant, or is it a Variant of Uncertain Significance (VUS)?
  2. 2.Was my child's MRI performed using an epilepsy protocol, and has it been reviewed by an epilepsy neuroradiologist?
  3. 3.How do the EEG findings correlate with the actual physical symptoms we are observing during a seizure?
  4. 4.Can we meet with a genetic counselor to discuss what these results mean for testing other family members?
  5. 5.If the current medications are not working and the MRI is clear, are we candidates for advanced imaging like MEG or PET?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

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This page explains EEG, MRI, and genetic testing in FFEVF1 for informational purposes only and does not constitute medical advice. Your epilepsy specialist and genetic counselor can interpret your results and recommend next steps.

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