Epilepsy involves seizures, resulting from the bursts of electricity in the brain, causing temporary abnormalities in muscle tone or movements (stiffness, twitching, or limpness), behaviors, or states of awareness.
Seizures are not all alike. A seizure can be a single event due to an acute cause, such as medication. When a person has recurring seizures, it is known as Epilepsy
Types of Seizures
There are four main types of seizure – focal, generalized, focal generalized combined, and unknown. The seizure type determines what kind of epilepsy a person has.
Different types of seizures affect the brain in different ways. For example, focal seizures affect only one part of the brain, whereas generalized seizures affect the entire brain. To be categorized as having epilepsy, a person must experience two or more unprovoked seizures. Some people can receive an epilepsy diagnosis if they have had one seizure and a doctor thinks they have a high likelihood of having another.
Classification of Seizures
Partial (focal) seizures:
- These seizures account for almost 60% of cases of epilepsy
- Simple partial seizures occur in about 15% of patients with seizures. Depending on the area of the cerebral cortex, symptoms may be motor, cognitive, sensory, autonomic, or affective. Consciousness is not impaired.
- Complex partial seizures, also known as psychomotor seizures, occur in approximately 35% of patients with seizures. Consciousness is partially or completely impaired, but no initial generalized tonic-clonic activity exists. Patients usually experience an aura, postictal confusion, or tiredness. They have no memory of the events during the seizure.
- Partial seizures evolving to generalized seizures begin locally but then generalise.
Generalized seizures:
- These seizures account for 40% of patients with epilepsy.
- Initial manifestations indicate involvement of both hemispheres, most commonly impairment of consciousness with bilateral motor involvement.
- Patients usually forget the events of the seizure.
- Sleep deprivation or drinking large amounts of alcohol can increase the excitatory response and increase the risk of generalized-onset seizures, especially in people with a genetic tendency to have them.
Diagnosis
The doctor needs to get an accurate seizure diagnosis to implement the most appropriate kind of treatment. Focal and generalized onset seizures usually have different causes and accurately diagnosing seizure types often helps identify the cause for the seizures.
The specialist may suggest having a test to check your brain activity called an electroencephalogram (EEG), or a brain scan to look for any problem in your brain. But if the tests show nothing, it is possible you still have epilepsy, and you may be diagnosed just based on your symptoms.
There are a variety of diagnostic tests:
- Neurological Examination:
This exam tests your behavior, movements, mental function, and other areas. It helps diagnose epilepsy and determine the type of epilepsy one might have.
- Neuropsychological tests:
These tests assess thinking, memory, and speech skills. The test results help determine which areas of the brain are affected by seizures.
- Genetic testing:
In some people with epilepsy, genetic testing may give more information about the condition and how to treat it. Genetic testing is most often performed in children but also may be helpful in some adults with epilepsy.
- Blood tests:
A blood sample can detect signs of infections, genetic conditions, or other conditions that may be associated with seizures.
There are brain imaging tests and scans that detect brain changes…
- Electroencephalogram (EEG):
This is the most common test used to diagnose epilepsy. In this test, small metal discs called electrodes are attached to your scalp with an adhesive or cap. The electrodes record the electrical activity of your brain.
If you have epilepsy, it’s common to have changes in the pattern of brain waves. These changes occur even when you’re not having a seizure. The doctor may monitor you on video during an EEG to detect and record any seizures. This may be done while you’re awake or asleep. Recording the seizures may help determine what kind of seizures you’re having or rule out other conditions.
You may get instructions to do something that can cause seizures, such as getting little sleep before the test.
- High-density EEG:
In a variation of an EEG test, you may have a high-density EEG. For this test, electrodes are placed closer together compared with a conventional EEG. High-density EEG may help more precisely determine which areas of your brain are affected by seizures.
- Computerized tomography (CT) scan:
A CT scan uses X-rays to obtain cross-sectional images of your brain. CT scans can detect tumors, or cysts in the brain that might be causing epilepsy.
- Magnetic resonance imaging (MRI):
An MRI uses powerful magnets and radio waves to create a detailed view of the brain. Like a CT scan, an MRI looks at the structure of the brain to detect what may be causing seizures. However, an MRI provides a more detailed look at the brain than a CT scan.
- Functional MRI (fMRI):
A functional MRI measures the changes in blood flow that occur when specific parts of the brain are working. This test may be used before surgery to identify the exact locations of critical functions, such as speech and movement. This allows surgeons to avoid those areas while operating.
- Positron emission tomography (PET):
PET scans use a small amount of low-dose radioactive material. The material is injected into a vein to help visualize the metabolic activity of the brain and detect changes. Areas of the brain with low metabolism may indicate places where seizures occur.
Diagnosis of the seizure type and where seizures begin gives you the best chance of finding an effective treatment!
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