Partial seizures (focal seizures)
- Reviewed by Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
What are partial seizures?
Nerve cells in the brain normally pass signals among themselves using both electrical current and chemicals. In a seizure, the brain's electricity is not passed in an organized way from one cell to the next, but spreads over a cluster of cells or the whole brain all at once. When only a portion of the brain is involved, the seizures are called partial seizures or focal seizures. These seizures vary tremendously in their effects on the person's movement, sensation, or behavior depending on which area of the brain is involved.
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Some partial seizures are associated with a change in consciousness, even though the person might appear to be awake and his or her eyes may be open. In this type of seizure, called a complex partial seizure, the affected person is unaware of the people nearby during the event, is not aware of his or her own movements or behaviors during the seizure, and does not remember the seizure after it occurs. When the person having a partial seizure is aware of having a seizure, is aware of his or her surroundings, and remembers the event afterward, the seizure is classified as a simple partial seizure.
Sometimes a seizure may begin as a partial seizure but change partway through the event to involve the whole brain, ending with arm and leg movements on both sides and loss of consciousness. When this happens, it is called a generalized seizure. A person who has seizures repeatedly is said to have epilepsy. In many cases, the cause of focal seizures cannot be found. Sometimes, epilepsy can be caused by scar tissue or a brain infection that can interfere with the brain's electrical signaling. Scar tissue in the brain can be caused by head injury, tumor, stroke, or surgery.
Other causes or triggers of focal seizures include fever (especially in children), diabetes, use of drugs or alcohol (or withdrawal), and genetic factors. Rarely, epilepsy is caused by an autoimmune disease such as lupus.
Symptoms of a partial seizure
A partial seizure can imitate any type of behavior or sensation that the brain can cause, depending on the part of the brain that the seizure activates. Seizures tend to occur in the same area of the brain over and over, so symptoms in one person seem very similar from one time to the next. Examples of the symptoms of partial seizures include:
- abrupt jerking muscle movements in an arm or leg
- chewing or other mouth or tongue movements, or pulling or fumbling with clothing without a purpose
- a blank stare with no apparent awareness of one's surroundings
- a sudden feeling of fear, joy, or rage that comes without reason
- repeating a phrase or word
- a change in vision or a hallucination (seeing something that is not real)
- a sensation of smell or taste, usually unpleasant, that does not come from a real object or food
- sudden loss of balance or dizziness
- disorientation or confusion (following the seizure).
Diagnosing partial seizures
Partial seizures can be difficult to diagnose with certainty because they vary so much from one person to another. It is helpful for the doctor to hear a detailed description from the person who is experiencing the events and from people who have seen them occur. The doctor will also review any medical history of problems that can result in brain injury, including brain injury before or during birth. A physical examination with testing of neurological function will check for evidence of brain disease or brain injury that could result in seizures.
Usually, the brain's electrical activity pattern is tested with an electroencephalogram (EEG) to see if any areas of the brain are conducting electricity in an abnormal way. If the EEG is abnormal, it can confirm suspicions that seizures are occurring. A normal EEG is much less helpful, since many patients with recurrent seizures have normal EEGs in between events.
Expected duration of partial seizures
If seizures are suspected, a brain scan — preferably a magnetic resonance imaging (MRI) scan — will be used to check for scar tissue or structural abnormalities in the brain that could be causing the seizures.
A seizure usually lasts no longer than a minute or two. Seizures lasting longer than five minutes require emergency medical attention. Disorientation or confused thinking may follow a seizure, and this can last for several minutes.
Preventing partial seizures
If you have epilepsy, the best way to prevent seizures is to take prescribed antiseizure medicines without missing doses. You should also get enough sleep each night, don't fast, and avoid drinking too much alcohol. Even when medicine is working well, however, some seizures cannot be prevented.
Treating partial seizures
A variety of medicines can be used on a long-term basis to prevent seizures or decrease their frequency. Two of the most commonly used medicines to treat partial seizures are carbamazepine (Tegretol and other brand names) and lamotrigine (Lamictal, Subvenite). Other choices include valproate (Depakote, others), gabapentin (Neurontin), topiramate (Topamax, others), levetiracetam (Keppra, others), oxcarbazepine (Trileptal and Oxtellar XR), and lacosamide (Vimpat and Motpoly XR).
Antiseizure medicines require close supervision by a doctor so that the dose can be adjusted as needed and side effects monitored. If you are treated with an antiseizure medicine, do not stop taking the medicine abruptly because seizures can be triggered by this sudden withdrawal.
If you have seizures, even if you are taking medication, you should avoid driving a motor vehicle until seizures are completely controlled. After a period of good seizure control, it may be reasonable to consider driving again. However, it is important to check local laws and discuss your options with your physician. Driving restrictions for people with seizures vary in the United States from state to state, with requirements for a seizure-free period ranging from 3 to 12 months.
When to call a professional
If you are experiencing periodic episodes that could be seizures, you should be evaluated by a doctor. If you are a woman who is considering pregnancy, discuss your seizure history and your medications with your doctor before attempting to get pregnant.
Prognosis
If you have epilepsy and it is not caused by a treatable condition such as infection, your tendency to have seizures may be lifelong and may require long-term treatment with medicines. Children with partial seizures frequently stop having seizures as they grow older, and they may not require continuing treatment.
Additional info
Epilepsy Foundation
https://www.epilepsy.com/
American Academy of Neurology (AAN)
https://www.aan.com/
About the Reviewer
Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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