What to Expect If You Have Focal Seizures

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Most people do not know for sure if they experienced a seizure, particularly if they have not had one before. It can also be very difficult for you to know if your seizure was a focal seizure or a generalized seizure, and you're likely anxious to learn what both of these mean.

Focal seizures are seizures that arise as the result of abnormal electrical activity in a particular region in the brain. The brain normally works to take care of tasks such as producing thoughts and movements when brain cells "talk" to each other by sending electrical signals.

When the electrical signals fire erratically, the brain may produce unwanted activities, such as seizures.

The symptoms and manifestations of seizures have characteristic features, which often provide insight about the cause of the seizures and help to determine whether they are focal or generalized. The treatment of recurrent seizures is often guided by whether they are focal seizures or generalized seizures.

What Is a Focal Seizure?

Seizures are involuntary (not on purpose) alterations in consciousness or movement caused by abnormal, erratic electrical activity in the brain. Focal seizures (also known as partial seizures) are called focal because the electrical activity begins in a small region in the brain and may or may not spread to involve a larger area of the brain. Sometimes, focal seizures begin in a small part of the brain and rapidly involve both sides of the brain—but they are still considered focal seizures if they originated in one region of the brain.

Symptoms of focal seizures can include involuntary movements or twitches of a small part of the body, jerking of the whole body, convulsions, decreased alertness, or complete lack of awareness.

Focal Seizures vs. Generalized Seizures 

The other type of seizure is called a generalized seizure, which is a seizure that begins with widespread abnormal electrical activity in the brain.

 Because a focal seizure can spread rather quickly, causing intense symptoms, sometimes a focal seizure and a generalized seizure can appear to be very similar.

The main differences between focal and generalized seizures include:

  • A focal seizure may begin with symptoms such as spasms or muscle tightness on one side of the face, arm, or leg before the symptoms begin to involve changes in consciousness or more widespread involuntary movements. A generalized seizure manifests with generalized symptoms, such as loss of consciousness or whole body convulsions from the start.
  • A focal seizure can produce residual symptoms of weakness such as Todd’s paralysis after the seizure is over, while a generalized seizure typically does not.
  • A person who has focal seizures may have erratic electrical activity in one specific area on electroencephalogram (EEG) testing, while a person with generalized seizures is expected to have a more widespread pattern of irregularity.
  • A focal seizure may be associated with abnormalities on brain imaging tests that correspond to the initial seizure symptoms or the EEG pattern. A generalized seizure is not typically associated with such a correlation between brain imaging and seizure symptoms or EEG patterns.

    In general, if you have focal seizures that begin in one part of the brain, it is possible to have focal seizures originating from another region of the brain as well. It is also possible to experience both focal seizures and generalized seizures.

    Symptoms

    The symptoms of a focal seizure can vary and may begin with mild twitching, jerking, or spasms of one part of the body. Over a few seconds or minutes, the symptoms may increase or may subside on their own as the erratic electrical activity in the brain spreads or resolves.

    The seizure may become more severe so rapidly that the first noticeable manifestation of a focal seizure can actually appear to be quite intense, and may not appear to be focal at all.

    Initial symptoms of a focal seizure can include: 

    • Face, head, arm, leg or body twitches, spasms or jerking
    • Unusual or erratic eye movements
    • Mumbling or drooling
    • Decreased awareness
    • Loss of consciousness

    Causes

    Focal seizures are triggered by an area of the brain that is prone to erratic electrical activity. These electrical activity abnormalities may be present from birth, and sometimes focal seizures may begin due to brain damage at any time during childhood or adulthood.

    Common causes of focal seizures include:

    Diagnosis

    Focal seizures are diagnosed by a combination of features, which include:

    • Medical history: If you have started to have seizures after experiencing severe head trauma or after being diagnosed with a brain tumor, there is a strong chance that they are focal seizures.
    • Description of the seizure: Your doctor may not have witnessed your seizure, and if you recall experiences such as unusual sensations or movements of one part of your body, this is suggestive of a focal seizure. Similarly, if witnesses observe movements in one part of your body prior to or during your seizure, this also can support a diagnosis of focal seizures. If you experienced residual paralysis for a short time after having a seizure, this also may mean that it was a focal seizure.
    • Physical examination: Your physical examination can help your doctor determine if you have had a medical condition that could have predisposed you to focal seizures, such as a stroke.
    • Brain imaging tests: Sometimes a brain imaging test can show an area of brain injury or disease that corresponds to a focal seizure. However, often, focal seizures are not associated with correlations on brain imaging tests.
    • EEG: Focal seizures may be associated with a focal area of irregular electrical activity on an EEG, particularly right before, during, or after the seizure.

    Treatment

    There are several treatment options for focal seizures. These include:

    • Medication: There are a number of prescription anti-seizure medications that are effective in controlling seizures.
    • Surgery: Removal of the lesion if there is a removable lesion causing the seizures, such as a tumor.
    • Epilepsy surgery: There are a number of surgical procedures that can prevent recurrent seizures for some people who have epilepsy.

    Prognosis

    If you have focal seizures, they may recur or they may improve on their own. It is difficult to predict the severity and frequency of future seizures. If you have had one or more seizures, it is important to get medical attention. Your medical team will do a thorough evaluation to see if you need to take medication or have surgery for seizure prevention.

    Overall, most people with focal seizures either improve on their own or experience good seizure control with medical or surgical treatment.

    Classification

    According to the 2017 classification of seizures by the International League Against Epilepsy, there are several categories of focal seizures. These classifications are based on several factors, including the following.

    • Awareness: Can be normal or decreased.
    • Physical Movements: The seizure may or may not be associated with involuntary movements. Motor symptoms associated with focal seizures are classified as atonic, automatisms, clonic, epileptic spasms, or hyperkinetic, myoclonic, or tonic activity. Non-motor symptoms associated with focal seizures are classified as autonomic, behavior arrest, cognitive, emotional, or sensory dysfunction.

    A Word From Verywell

    Seizures are understandably very worrisome for you and your loved ones. If you experience a seizure, it is important that you receive prompt medical attention. In the immediate stage, your medical team will work to ensure that your seizure does not last for long, possibly initiating medication to stop the seizure.

    Once you are stable, your doctors will work to diagnose the cause or type of your seizure and may start you on a long-term treatment plan to prevent further seizures, if necessary. While having a seizure is stressful, it is important for you to know that focal seizures are generally manageable with medication or surgery.

    Sources:

    The New Classification of Seizures by the International League Against Epilepsy 2017, Fisher RS, Curr Neurol Neurosci Rep. 2017 Jun;17(6):48. doi: 10.1007/s11910-017-0758-6.