Epilepsy is an ongoing disorder of the nervous system that produces sudden, intense bursts of electrical activity in the brain. These bursts cause seizures, which may briefly affect muscle control, movement, speech, vision and awareness. People with epilepsy have repeated seizures, usually without warning and for no clear reason. If epilepsy is not treated, seizures may occur throughout a person's life and in some cases become more severe and more frequent over time.
There are two types of epileptic seizures. Partial seizures begin in a specific location in the brain and may affect only awareness or only one side or part of the body. Generalized seizures begin over the entire surface of the brain and may affect the entire body. Partial and generalized seizures are often treated differently.
Many types of epilepsy can cause partial or generalized seizures. Classifying those types is difficult because they can have more than one cause and can affect individuals in different ways.
Causes and Risk Factors
Although epilepsy is sometimes the result of another condition, many cases have no known cause. Epilepsy most often begins in childhood or after the age of 60, but it can develop at any age. Several conditions can damage the brain and cause epilepsy, including a serious head injury, stroke, hardening of the arteries in the brain, brain tumor, brain infection (meningitis or encephalitis) and Alzheimer's disease.
Such damage can affect the brain's electrical system, causing the type of electrical activity that triggers seizures. Tumors, scar tissue from injury or disease or abnormal brain development may damage a specific area of the brain and cause partial seizures.
In many cases, there is no known cause of epilepsy. Children are more likely than adults to develop the disorder from an unknown cause. A family history of epilepsy may sometimes be a factor, although experts are not sure how the disease is passed from parent to child.
Making an accurate diagnosis is vital in planning the correct treatment to control seizures. Misdiagnosis followed by the wrong treatment is one reason why people sometimes keep having seizures. Inappropriate treatment also results in unnecessary side effects from medication. However, diagnosing epilepsy can be difficult, and the doctor needs to determine:
- If the event was actually a seizure or something else. Several conditions can appear to be seizures but are not (e.g., breath-holding spells, migraine headaches, muscle twitches or tics, sleep disorders, or psychogenic seizures). Taking antiepileptic medications to treat events that are not seizures can put the patient at needless risk.
- The type of seizure and if it was caused by epilepsy
- A detailed medical history, which often provides the best clues about epileptic seizures. What happens just before a seizure, during a seizure and right after a seizure can help the doctor make a diagnosis. Taking a medical history can help rule out non-epilepsy conditions that might have caused the seizures.
- Complete blood counts (CBC) to check for infection, abnormal electrolyte levels (such as magnesium, potassium and calcium), signs of kidney or liver malfunction and other common problems
- A lumbar puncture (sometimes called a spinal tap) to rule out infections, such as meningitis and encephalitis
- Toxicology screenings for poisons, illegal drugs or other toxins
The most useful test in confirming epilepsy is electroencephalalography (EEG). An EEG records electrical activity in the brain through wires taped to the patient's head and hooked to a computer. The computer records the brain's electrical patterns. If the patient has epilepsy, the EEG may show abnormal spikes or waves in electrical activity patterns. Different types of epilepsy cause different patterns.
Video and EEG monitoring can be performed at the same time to record seizures on videotape and computer so that the doctor can see what happens just before, during and right after a seizure. The video records what the body is doing, and the EEG records the electrical activity occurring in the brain. Such monitoring may be used prior to surgery or when repeated EEG tests have not provided enough clues as to the type of seizure or to diagnose psychogenic seizures.
Magnetic resonance imaging (MRI) and computed tomography (CT) scans may be used to evaluate the cause and the location of a possible source of epilepsy within the brain. The scans can reveal scar tissue, tumors or structural problems in the brain. These tests also may be used before epilepsy surgery to pinpoint the exact location of a problem in the brain.
For most people with epilepsy, treatment can reduce or prevent seizures and allow many patients to remain free of seizures for the rest of their lives.
Uncontrolled seizures can have a big impact on lifestyle, restricting the individual from driving and limiting their work and leisure time activities. Although seizures themselves usually are not physically harmful to people who have epilepsy, they carry a risk of injury and death. The risk is greater for people who have many seizures, depending on the type of seizure they have. Unexpected seizures can cause falls, drowning or other accidents, and a lengthy seizure condition (status epilepticus) can lead to coma or death. By reducing or stopping seizures, treatment may greatly improve the patient's quality of life and safety.
A correct diagnosis is vital to effectively treat epilepsy. Decisions about treatment are based first on the type of epilepsy and the kinds of seizures that occur. Treatment that controls one kind of seizure may have no effect on other kinds of seizures. Age, health and lifestyle are also important factors. Treatment options include:
- Medication. This is the first and most common approach to treating epilepsy. Antiepileptic medications do not cure epilepsy, but they help prevent seizures in well over half of the people who take them.
- Brain surgery. Some patients with partial epilepsy do not respond to medication but have great success with surgery. Surgery is highly effective in treating many pediatric epilepsies that have not responded to other medical therapies.
- Vagus nerve stimulator. This device is used with medication or surgery to reduce seizures.
- Ketogenic diet. A high-fat diet has been used with some success to treat people (especially children) who have severe, uncontrolled seizures. However, some doctors may not support its use.