A seizure is a sudden change in behavior or consciousness caused by abnormal electrical activity in the brain. Seizures occur when the nerve cells in the brain suddenly increase in activity, causing an electrical storm that can overwhelm the brain. This can result in different symptoms, depending on the area of the brain affected. These effects can range from slight changes in taste or smell to loss of consciousness and involuntary muscle contractions that affect the entire body.
Anything that disrupts the normal function of the brain can cause seizures. The most common condition associated with seizures is epilepsy. Epilepsy is characterized by a tendency to have recurring seizures. A single seizure does not mean a person is epileptic. Although roughly half of all seizures have no known cause, there are certain factors that can trigger seizures, such as brain trauma, genetic abnormalities, alcohol withdrawal or brain tumors. There are many different kinds of seizures. Generalized seizures can involve both sides of the brain simultaneously. Partial seizures involve only a specific area within the brain, but can expand, causing a generalized seizure.
Many times, seizures are isolated events and do not necessarily require treatment. However, some seizures are caused by chronic underlying conditions that may need treatment. In cases where the underlying cause is unknown, seizures can sometimes be controlled with medication.
A seizure is a sudden change in consciousness or behavior caused by abnormal brain electrical activity. Many are isolated events. Repeated seizures can occur without any obvious source of provocation. The condition of repeated seizures, regardless of whether there is an identifiable cause is defined as epilepsy. A single seizure does not mean a person has epilepsy.
Under certain circumstances, anyone can experience a seizure. As many as 10 percent of Americans have a seizure at some point in their lives, according to the Epilepsy Foundation. Seizures can occur at any age, although children are at greater risk for seizures than other age groups.
Seizures involve a sudden increase in electrical activity in the brain. The nerve cells, or neurons, produce electrochemical signals that instruct other parts of the body to do certain things, such as move or feel sensations. Neurons normally produce these signals at a rate of 80 per second.
A seizure occurs when something disturbs the pattern of electrochemical signals and causes the neurons to fire at a much faster rate, sometimes up to 500 signals per second. This storm of electrical activity in the brain can result in a seizure, possibly producing changes in mood or behavior, hallucinations, involuntary muscle contractions, loss of consciousness or involuntary movements. The specific course of a seizure depends on the area of the brain affected by this electrical activity.
Seizures are often followed by symptoms such as fatigue, drowsiness and confusion. It may take minutes or hours to return to full consciousness. Sleepiness may last for an hour or more, and a person can feel weak for up to two days following a seizure. Many people report a feeling of confusion or extreme tiredness. This is called the postictal syndrome.
Infants experiencing seizures can display repetitive movements, decreased alertness, weakness and irritability. Children who have seizures can fall into a deep sleep after the seizure ends. This is normal and enables the brain to recover after the stress of the seizure episode. They should not be awakened during this time.
A person who has experienced a seizure often has no memory of what happened during the seizure. In addition, some people can become agitated immediately following a seizure.
Seizures lasting longer than 5 minutes should be considered a medical emergency, according to the National Institute of Neurological Disorders and Stroke (NINDS). Prolonged unrelenting seizures, or status epilepticus, is life threatening. In these cases, recovery depends on how quickly the appropriate medical intervention is received. People with epilepsy have a greater risk of status epilepticus, although it can also occur in people with no prior history of seizures if an initial seizure progresses to status epilepticus.
Immediate medical attention should be sought if a person has no history of previous seizures, or if any of the following symptoms occur:
- Physical injury is sustained during the seizure
- Seizure lasts 5 minutes or longer
- There is failure to regain a normal level of consciousness within an hour after a seizure
Individuals who have seizures that result in impaired consciousness or motor functioning are advised not to drive, swim alone or participate in other activities that could be dangerous to themselves and others. Patients with infrequent seizures may not need to restrict their normal lives in any way. Most seizures do not result in death or permanent disability.
Pseudoseizures appear to be seizures, with muscle contractions and impaired consciousness, but they reveal no evidence of abnormal electrical activity in the brain. Pseudoseizures can be psychological or the result of certain medical conditions (e.g., Tourette syndrome, sleep disorders, cardiac disturbances). Some people with epilepsy can experience pseudoseizures in addition to actual seizures.
Other symptoms related to seizures
In addition to the involuntary muscle contractions and impaired consciousness often seen with seizures, certain types of sensory and other abnormalities can occur with a seizure. These may appear when areas of the brain associated with processing sensory information or emotions are affected. These symptoms include:
- Visual changes (e.g., hallucinations)
- Abnormal tastes, smells
- Sense of déjà vu (feeling as if one is repeating a particular situation)
- Sudden, intense emotions (e.g., fear, joy)
Additional physical signs that can accompany a seizure include:
- Excessive blinking
- Drooping eyelids
- Trancelike state
- Incontinence (involuntary release of urine or stool)
- Biting of the cheek
- Clenching the jaw
- Irregular breathing
Types and differences of seizures
There are many different types of seizures. They are usually classified as being either partial seizures (also called focal seizures) or generalized seizures.
Partial seizures involve abnormal activity in specific parts of the brain. These types of seizures can occur at any age, although they occur slightly more frequently in adults than in children. Approximately 60 percent of patients with epilepsy experience partial seizures, according to the National Institute of Neurological Disorders and Stroke (NINDS).
Types of partial seizures include:
- Simple partial seizure. During a simple partial seizure, there is no alteration or loss of consciousness. People who have simple partial seizures can experience abnormal sensations such as inexplicable feelings of joy, anger or sadness. They may also see, hear, smell or taste things that are not really there.
- Complex partial seizure. During a complex partial seizure, an individual will experience a pronounced change or loss of consciousness. They may appear to be “out of it” or in a dreamlike state. They may also make repetitive movements that appear to be conscious, such as lipsmacking, picking at clothing, or repetitive motions with the hands.
Certain effects associated with partial seizures (e.g., abnormal sensations such as a flash of lights or unpleasant odors) can occur prior to the onset of a more severe seizure. When these effects act as a warning sign, they are known as an aura.
Generalized seizures involve both sides of the brain simultaneously and are often more severe than partial seizures. Types of generalized seizures include:
- Absence seizures (petit mal seizures). This kind of seizure involves a momentary change in a person’s state of consciousness. This short-term “absence” of conscious activity can be so mild it may not noticed by others. People who experience this type of seizure may suddenly have a blank look on their faces, appear to be staring off into space or drop something they were holding. Eyelids may droop or blink and muscles may twitch. Each episode lasts for just a few moments, making this type of seizure difficult to recognize and diagnose. Absence seizures most often occur during childhood and often resolve themselves as the child enters adolescence. Unexplained difficulties in school can suggest the possibility of absence seizures as the underlying cause.
- Tonic-clonic seizures (grand mal seizures). The most powerful type of seizure, it is also known as a convulsion. A person who experiences this type of seizure can fall to the floor and become unconscious as muscles tense up, eyes roll back in the head and saliva production increases. Seconds after falling, the person’s entire body can begin to shake violently and rhythmically. Labored breathing and loss of bladder or bowel control may follow. However, people who witness this kind of seizure should seek medical care if the person’s seizure lasts for more than 5 minutes or if seizures follow in succession without the person waking. This is the type of episode most people associate with the term seizure.
- Atonic seizures. Atonic seizures are sometimes called drop attacks because they involve a sudden loss of muscle function. During brief atonic seizures, the person may only experience a quick drop of the head. Longer seizures may result in the person collapsing and falling to the floor. This type of seizure can be particularly dangerous because of the risk of the head injury or broken bones from the fall.
- Myoclonic seizures. A myoclonic seizure is one in which the muscles of a part of the body or the entire body suddenly and briefly contract and partially release, much like the jerking sensation some people experience as they are falling asleep. This type of seizure often occurs at the same time as other generalized seizures.
Potential causes of seizures
Anything that disrupts the normal functioning of the brain can cause a seizure.
Seizures can occur as a sign of a wide variety of medical conditions (e.g., cerebral palsy, Alzheimer’s disease, muscular dystrophy), illnesses (e.g., heatstroke, kidney failure) or due to use of certain medications. Patients should carefully read product labels of all medicated substances (including medicated shampoos) for possible adverse reactions that may include seizures.
However, because of the complex nature of the brain, roughly half of all seizures have no known cause. Unprovoked, repeated seizures may be characteristic of many forms of epilepsy.
Conditions and situations that may provoke seizures include:
- Brain injury. People who have experienced brain trauma, such as severe head injury or stroke, are at a high risk of having a seizure. This usually happens within weeks of the head injury, although some people can have seizures months after the injury. People with head injuries are more likely to have recurrent seizures.
- High fever. This is an especially common cause of seizures in children, where it is called a febrile seizure. A febrile seizure occurs when a sudden and severe spike in a child’s temperature of 102 degrees Fahrenheit (38.9 degrees Celsius) or more triggers a seizure. Febrile seizures most often affect children between the ages of 6 months and 3 years. In most cases, they are associated with a viral or bacterial infection. Although febrile seizures typically strike when a child’s temperature is rising, they also can occur as the child’s temperature drops. Febrile seizures can be more common in those with a family history of seizures or epilepsy. However, they rarely indicate a child will develop chronic epilepsy.
- Genetic abnormalities. Some types of seizures have been found to run in families and are thought to be caused by genetic abnormalities. There are many genes that have been linked to seizures. However, only a small proportion of seizure types are believed to develop as a direct result of genetic abnormalities. Instead, studies have shown that people with certain genetic abnormalities are more susceptible to seizures caused by other factors, such as brain trauma.
- Infections. Certain infections such as meningitis, encephalitis and brain abscess can result in either isolated or recurrent seizures. In some cases, successful treatment of the underlying infection can stop the seizures. However, some infections may cause irreparable damage to cells in the brain.
- Tumors or brain lesions. Tumors or brain lesions, which can cause pressure to build in the brain, can disrupt the function of neurons. Seizures that are caused by tumors or brain lesions usually begin as partial seizures but may develop into generalized seizures as the tumor or lesion grows. Surgery can sometimes be used to remove the tumor or lesion. Such surgery can reduce or eliminate seizures. The presence of other structural abnormalities in the brain can also cause seizures.
- Metabolic abnormalities. Seizures can be caused by a wide variety of metabolic problems. This includes diabetes, an electrolyte imbalance, kidney failure and nutritional deficiencies. Abnormal blood sugar levels such as low blood sugar (hypoglycemia) or high blood sugar (hyperglycemia) can provoke seizures.
- Substance abuse and withdrawal. Heavy drinking or withdrawal after a period of heavy drinking can cause seizures. Both intoxication and withdrawal from alcohol can interfere with the activity of neurons in the brain. Seizures are more likely to occur within six hours to four days of stopping drinking, according to the National Institute on Alcohol Abuse and Alcoholism. The use of certain illegal drugs (e.g., cocaine, amphetamines, heroin) can also cause seizures. Withdrawal symptoms from these drugs can also include seizures.
- Reactions to certain medications. Some types of medication, such as some chemotherapy drugs, can cause seizures. This may be due to an adverse side effect of the medication, an allergy of the patient, or due to consumption of toxic levels of the medication. Patients should consult their physicians about the risks involved with taking certain medications, whether prescription or over-the-counter remedies.
- Eclampsia. Eclampsia is a rare condition in pregnant women that results in seizures. It is unclear what causes the seizures, although various factors, including neurological ones, may be involved. Eclampsia is usually accompanied by other complications during pregnancy, such as high blood pressure and excessive weight gain.
Diagnosing causes of seizures
Patients who experience a seizure for the first time should seek medical attention for proper diagnosis and appropriate treatment. In some cases, patients may be referred to a neurologist. Visiting a physician will also help establish a record of events surrounding the seizure in case the patient experiences additional seizures or appears to have a seizure disorder.
A physician will begin by compiling a patient’s medical history. This can include questions about the seizure, including:
- Date and time of seizure
- Seizure duration
- Body parts affected
- Type of movement or symptoms involved
- Circumstances immediately preceding the seizure
Because a patient may have no memory of what occurred during the seizure, people who witnessed the seizure may be asked about it. Written accounts by witnesses to the seizure can help a physician identify the underlying cause.
Patients are advised to tell their physicians about all current or suspected medical conditions and all medications being taken, including prescription and over-the-counter drugs, herbal remedies and dietary supplements.
A physical examination will be performed. This will include taking the patient’s blood pressure and heart rate to identify any potential abnormalities that may be contributing to the patient’s symptoms.
When a person experiences a seizure for the first time, a physician may conduct certain tests to help identify the cause of the seizure. The most common test used is the electroencephalogram (EEG). During an EEG, electrical activity in the brain is monitored through electrodes that are placed on the scalp so that any abnormalities can be noted. A physician may request that the EEG be performed while the patient is sleeping or over a period of days to obtain the most accurate results of the patient’s brain activity. However, a normal EEG does not necessarily rule out seizures.
Additional tests may be performed to rule out other conditions or causes of a patient’s seizures. Imaging tests such as computed tomography scans or magnetic resonance imaging may identify lesions or structural damage in the brain that may be causing the seizures. Blood tests can detect the presence of infection or conditions such as diabetes or kidney failure. A spinal tap may also be performed to identify the presence of certain types of infections.
Treatment and prevention of seizures
In many cases, a seizure is an isolated event that does not recur and does not necessitate treatment. However, if a person experiences recurrent seizures or if the seizure indicates a serious condition, treatment may be necessary.
Treatments vary depending on the cause of the person’s seizures. It may involve treating the underlying cause, such as performing surgery for brain injuries or prescribing medications for metabolic disorders such as diabetes.
Seizures with an avoidable trigger (e.g., alcohol or certain illegal drugs) may be remedied by avoiding the precipitating factor.
If a person is diagnosed with epilepsy or other seizure disorders, a physician may prescribe anticonvulsant medications that prevent nerve cells in the brain from firing in an abnormal manner. This helps control the seizures if the medication is taken regularly. Over time, the person may be tapered off the drug to determine if the seizures have been permanently brought under control.
A physician may suggest a treatment method called vagus nerve stimulation. The vagus nerve is a cranial nerve that originates in the brain stem and controls numerous organs. People with epilepsy that cannot be controlled through medication can have a device (similar to a pacemaker) surgically implanted into the skin that stimulates the left vagus nerve through a series of small electric shocks. These shocks can reduce seizures in people with epilepsy by up to 40 percent, according to the National Institute of Neurological Disorders and Stroke (NINDS).
Surgery on the part of the brain where the seizures occur is also possible for patients with epilepsy. If an identifiable area (called the seizure focus) can be found in the area of the brain where the seizures arise, surgery to remove that part of the brain can provide relief from epilepsy in many instances.
Specialized epilepsy treatment centers also offer another type of brain surgery as a potential option to manage epilepsy. When appropriate, brain surgery can be done while the patient is under local anesthesia, but awake in order to monitor crucial neurologic functions while the surgery takes place.
In many cases, the cause of seizures is unknown, making them difficult to prevent. However, certain measures can be taken to avoid head injuries, which are known to cause seizures. People should always wear appropriate protection when riding bicycles or motorcycles, or when playing contact sports. Additionally, people should avoid binge drinking (consuming large amounts of alcohol in a short space of time) or using illegal drugs, which can lead to seizures.
Treating the cause of seizures may prevent seizures from occurring. Anticonvulsant medications may help prevent or reduce the likelihood of future seizures. Patients should follow their physician’s instructions regarding their medications. One of the most common causes of seizures in people who have been seizure-free for months or sometimes years, is non-compliance with their medication schedules.
First aid for seizures
Witnessing a seizure can be distressing. Often, people do things that make the situation worse, or do not know how to react. Friends and family of a person who has seizures will be instructed by a physician on what to do during a seizure. Otherwise, there are certain things bystanders can do or avoid to prevent additional harm to the person having a seizure.
- Do not place anything in the person’s mouth. This can increase the risk of choking.
- Do not restrain the person.
- Clear the area. Move any furniture or objects out of the way that may cause harm. This includes objects on tables or stands that may be knocked over.
- If vomit or mucus are present, turn the person on his or her side to prevent inhaling or choking on their own vomit. After the seizure is over, the patient may be gently rolled onto their side to keep their respiratory tract clear of mucus if they sleep for a short while after the attack.
Mouth-to-mouth resuscitation is rarely required after a seizure. In most cases, the person returns to normal within minutes.
Questions for your doctor regarding seizures
Preparing questions in advance can help patients have more meaningful discussions with healthcare professionals regarding their condition. Patients may wish to ask their doctor the following seizure-related questions:
- What type of seizure did I have?
- Will you need to speak to people who witnessed the seizure to confirm your diagnosis?
- What could have caused my seizure?
- Do I have epilepsy?
- How will you identify any underlying medical conditions that may be related to my seizure?
- What kind of treatment do you recommend for me? Are there risks involved?
- How long will I require treatment?
- Is there a chance I could have another seizure?
- What should I do if I have another seizure?
- What can I do to reduce my risk of seizures?
- What should I do if my child or loved one has a seizure?