The epilepsies are a spectrum of brain disorders ranging from severe, life-threatening and disabling, to ones that are much more benign. In epilepsy, the normal pattern of neuronal activity becomes disturbed, causing strange sensations, emotions, and behavior or sometimes convulsions, muscle spasms, and loss of consciousness. The epilepsies have many possible causes and there are several types of seizures. Anything that disturbs the normal pattern of neuron activity—from illness to brain damage to abnormal brain development—can lead to seizures. Epilepsy may develop because of an abnormality in brain wiring, an imbalance of nerve signaling chemicals called neurotransmitters, changes in important features of brain cells called channels, or some combination of these and other factors. Having a single seizure as the result of a high fever (called febrile seizure) or head injury does not necessarily mean that a person has epilepsy. Only when a person has had two or more seizures is he or she considered to have epilepsy. A measurement of electrical activity in the brain and brain scans such as magnetic resonance imaging or computed tomography are common diagnostic tests for epilepsy.
Causes of epilepsy vary by age of the person. Some people with no clear cause of epilepsy may have a genetic cause. But what’s true for every age is that the cause is unknown for about half of everyone with epilepsy.
- Some people with no known cause of epilepsy may have a genetic form of epilepsy. One or more genes may cause the epilepsy or epilepsy may be caused by the way some genes work in the brain. The relationship between genes and seizures can be very complex and genetic testing is not available yet for many forms of epilepsy.
- About 3 out of 10 people have a change in the structure of their brains that causes the electrical storms of seizures.
- Some young children may be born with a structural change in an area of the brain that gives rise to seizures.
- About 3 out of 10 children with autism spectrum disorder may also have seizures. The exact cause and relationship is still not clear.
- Infections of the brain are also common causes of epilepsy. The initial infections are treated with medication, but the infection can leave scarring on the brain that causes seizures at a later time.
- People of all ages can have head injuries, though severe head injuries happen most often in young adults.
- In middle age, strokes, tumors and injuries are more frequent.
- In people over 65, stroke is the most common cause of new onset seizures. Other conditions such as Alzheimer’s disease or other conditions that affect brain function can also cause seizures.
A seizure is the clinical manifestation of epilepsy. This occurs basically due to excessive firing of the neurons and fast spread of these impulses over the brain. Thus there are two phenomenons in the pathophysiology of a seizure:-
- hyper-excitability of a neuron
- hyper synchronization
Hyper synchronization means that a hyper-excitable neuron leads to excessive excitability of a large group of surrounding neurons. This means that when a large electrical impulse is generated in one part of the brain from a focus of tissues millions of neurons in the brain fire excessively in addition bringing on a seizure.
Seizure is defined as an “involuntary alteration of behavior with or without loss of consciousness accompanied by an abnormal electrical discharge in the brain.”
Because epilepsy is caused by abnormal activity in brain cells, seizures can affect any process your brain coordinates. Seizure signs and symptoms may include:
- Temporary confusion
- A staring spell
- Uncontrollable jerking movements of the arms and legs
- Loss of consciousness or awareness
- Psychic symptoms
Symptoms vary depending on the type of seizure. In most cases, a person with epilepsy will tend to have the same type of seizure each time, so the symptoms will be similar from episode to episode.
Doctors generally classify seizures as either focal or generalized, based on how the abnormal brain activity begins.
When seizures appear to result from abnormal activity in just one area of your brain, they’re called focal (partial) seizures. These seizures fall into two categories.
- Focal seizures without loss of consciousness (simple partial seizures). These seizures don’t cause a loss of consciousness. They may alter emotions or change the way things look, smell, feel, taste or sound. They may also result in involuntary jerking of a body part, such as an arm or leg, and spontaneous sensory symptoms such as tingling, dizziness and flashing lights.
- Focal dyscognitive seizures (complex partial seizures). These seizures involve a change or loss of consciousness or awareness. During a complex partial seizure, you may stare into space and not respond normally to your environment or perform repetitive movements, such as hand rubbing, chewing, swallowing or walking in circles.
Symptoms of focal seizures may be confused with other neurological disorders, such as migraine, narcolepsy or mental illness. A thorough examination and testing are needed to distinguish epilepsy from other disorders.
Seizures that appear to involve all areas of the brain are called generalized seizures. Six types of generalized seizures exist.
- Absence seizures. Absence seizures, previously known as petit mal seizures, often occur in children and are characterized by staring into space or subtle body movements such as eye blinking or lip smacking. These seizures may occur in clusters and cause a brief loss of awareness.
- Tonic seizures. Tonic seizures cause stiffening of your muscles. These seizures usually affect muscles in your back, arms and legs and may cause you to fall to the ground.
- Atonic seizures. Atonic seizures, also known as drop seizures, cause a loss of muscle control, which may cause you to suddenly collapse or fall down.
- Clonic seizures. Clonic seizures are associated with repeated or rhythmic, jerking muscle movements. These seizures usually affect the neck, face and arms.
- Myoclonic seizures. Myoclonic seizures usually appear as sudden brief jerks or twitches of your arms and legs.
- Tonic-clonic seizures. Tonic-clonic seizures, previously known as grand mal seizures, are the most dramatic type of epileptic seizure and can cause an abrupt loss of consciousness, body stiffening and shaking, and sometimes loss of bladder control or biting your tongue.
Knowing if a person is having a seizure and diagnosing the type of seizure or epilepsy syndrome can be difficult. There are many other disorders that can cause changes in behavior and can be confused with epilepsy. Since the treatment of seizures depends on an accurate diagnosis, making sure that a person has epilepsy and knowing what kind is a critical first step.
What happens during a seizure is one of the most important pieces of information. And, since seizures rarely happen in a doctor’s office, the information given to the doctor and other health care professionals by you or other witnesses is extremely important. Yet, even with accurate descriptions of events, other tests are needed to learn more about the brain, what is causing the events and where the problem is located.
Once epilepsy is diagnosed, it is important to begin treatment as soon as possible. For about 70 percent of those diagnosed with epilepsy, seizures can be controlled with modern medicines and surgical techniques. Some drugs are more effective for specific types of seizures. An individual with seizures, particularly those that are not easily controlled, may want to see a neurologist specifically trained to treat epilepsy. In some children, special diets may help to control seizures when medications are either not effective or cause serious side effects.