The symptoms of a focal onset seizure, whatever the type, depend on the area of the brain that’s affected. Doctors divide the brain into lobes or regions. Each has different functions that are interrupted during a seizure.
In the temporal lobe
If the temporal lobe is affected during the seizure, it can cause:
- lip smacking
- repeated swallowing
- déjà vu
In the frontal lobe
Seizures in the frontal lobe can cause:
- difficulty speaking
- side-to-side head or eye movements
- stretching of the arms in an unusual position
- repeated rocking
In the parietal lobe
A person with a focal onset seizure in the parietal lobe may experience:
- numbness, tingling, or even pain in their body
- vision changes
- a feeling as if their body does not belong to them
In the occipital lobe
Focal seizures in the occipital lobe can cause:
- visual changes with eye pain
- a feeling as if the eyes are rapidly moving
- seeing things that aren’t there
- fluttering eyelids
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People who have experienced a traumatic brain injury in the past are at greater risk of focal onset seizures. Other risk factors for these seizures include a history of:
- brain infection
- brain tumor
Age can also be a risk factor. People are more likely to have a seizure in early childhood or after age 60, according to the Mayo Clinic. However, it’s possible a person could have no risk factors and still have a focal onset seizure.
A doctor will start by asking about your medical history and conducting a physical exam. Sometimes a doctor will make the diagnosis based on the explanation of your symptoms. However, focal onset seizures can cause symptoms that are similar to other conditions. Examples of these conditions include:
- psychiatric illnesses
- migraine headaches
- pinched nerve
- transient ischemic attack (TIA), which is a warning sign for stroke
The doctor will try to rule out other conditions while determining if your symptoms could mean you are having focal onset seizures.
A doctor may also use diagnostic tests to determine if a person could be having seizures. Examples of these tests include:
Electroencephalogram (EEG): This test measures and locates the region of abnormal electrical activity in the brain. However, because a person with focal onset seizures likely doesn’t have constant disturbances in electrical activity, this test may not detect this seizure type unless they later generalize.
Magnetic resonance imaging (MRI) or computed tomography (CT): These imaging studiescan help a doctor identify potential underlyingcauses associated with focal onset seizures.