Epilepsy is a disorder with many possible causes. 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, or some combination of these factors. Researchers believe that some people with epilepsy have an abnormally high level of excitatory neurotransmitters that increase neuronal activity, while others have an abnormally low level of inhibitory neurotransmitters that decrease neuronal activity in the brain. Either situation can result in too much neuronal activity and cause epilepsy. One of the most-studied neurotransmitters that plays a role in epilepsy is GABA, or gamma-aminobutyric acid, which is an inhibitory
neurotransmitter. Research on GABA has led to drugs that alter the amount of this neurotransmitter in the brain or change how the brain responds to it. Researchers also are studying excitatory neurotransmitters such as
glutamate.
In some cases, the brain's attempts to repair itself after a head injury, stroke, or other problem may inadvertently generate abnormal nerve connections that lead to epilepsy. Abnormalities in brain wiring that occur during brain development also may disturb neuronal activity and lead to epilepsy.
Research has shown that the cell membrane that surrounds each neuron plays an important role in epilepsy. Cell membranes are crucial for a neuron to generate electrical impulses. For this reason, researchers are studying details of the membrane structure, how molecules move in and out of membranes, and how the cell nourishes and repairs the membrane. A disruption in any of these processes may lead to epilepsy. Studies in animals have shown that, because the brain continually adapts to changes in stimuli, a small change in neuronal activity, if repeated, may eventually lead to full-blown epilepsy. Researchers are investigating whether this phenomenon, called kindling, may also occur in humans.
In some cases, epilepsy may result from changes in non-neuronal brain cells called glia. These cells regulate concentrations of chemicals in the brain that can affect neuronal signaling.
About half of all seizures have no known cause. However, in other cases, the seizures are clearly linked to infection, trauma, or other identifiable problems.
Genetic Factors
Research suggests that genetic abnormalities may be some of the most important factors contributing to epilepsy. Some types of epilepsy have been traced to an abnormality in a specific gene. Many other types of epilepsy tend to run in families, which suggests that genes influence epilepsy. Some researchers estimate that more than 500 genes could play a role in this disorder. However, it is increasingly clear that, for many forms of epilepsy, genetic abnormalities play only a partial role, perhaps by increasing a person's susceptibility to seizures that are triggered by an environmental factor.
Several types of epilepsy have now been linked to defective genes for ion channels, the "gates" that control the flow of ions in and out of cells and regulate neuron signaling. Another gene, which is missing in people with progressive myoclonus epilepsy, codes for a protein called cystatin B. This protein regulates
enzymes that break down other
proteins. Another gene, which is altered in a severe form of epilepsy called LaFora's disease, has been linked to a gene that helps to break down
carbohydrates.
While abnormal genes sometimes cause epilepsy, they also may influence the disorder in subtler ways. For example, one study showed that many people with epilepsy have an abnormally active version of a gene that increases resistance to drugs. This may help explain why anticonvulsant drugs do not work for some people. Genes also may control other aspects of the body's response to medications and each person's susceptibility to seizures, or seizure threshold. Abnormalities in the genes that control neuronal migration -- a critical step in brain development -- can lead to areas of misplaced or abnormally formed neurons, or
dysplasia, in the brain that can cause epilepsy. In some cases, genes may contribute to development of epilepsy even in people with no family history of the disorder. These people may have a newly developed abnormality, or
mutation, in an epilepsy-related gene.
Other Disorders
In many cases, epilepsy develops as a result of brain damage from other disorders. For example,
brain tumors,
alcoholism, and Alzheimer's disease frequently lead to epilepsy because they alter the normal workings of the brain. Strokes,
heart attacks, and other conditions that deprive the brain of
oxygen also can cause epilepsy in some cases. About 32 percent of all cases of newly developed epilepsy in elderly people appears to be due to
cerebrovascular disease, which reduces the supply of oxygen to brain cells. Meningitis,
AIDS,
viral encephalitis, and other infectious diseases can lead to epilepsy, as can hydrocephalus -- a condition in which excess fluid builds up in the brain. Epilepsy also can result from intolerance to wheat gluten (also known as celiac disease), or from a
parasitic infection of the brain called
neurocysticercosis. Seizures may stop once these disorders are treated successfully. However, the odds of becoming seizure-free after the primary disorder is treated are uncertain and vary depending on the type of disorder, the brain region that is affected, and how much brain damage occurred prior to treatment.
In some cases, head injury can lead to seizures or epilepsy. Safety measures such as wearing seat belts in cars and using helmets when riding a motorcycle or playing competitive sports can protect people from epilepsy and other problems that result from head injury.
Prenatal Injury and Developmental Problems
The developing brain is susceptible to many kinds of injury. Maternal infections, poor nutrition, and oxygen deficiencies are just some of the conditions that may take a toll on the brain of a developing baby. These conditions may lead to cerebral palsy, which often is associated with epilepsy, or they may cause epilepsy that is unrelated to any other disorders. About 20 percent of seizures in children are due to cerebral palsy or other
neurological abnormalities. Abnormalities in genes that control development also may contribute to epilepsy. Advanced brain imaging has revealed that some cases of epilepsy that occur with no obvious cause may be associated with areas of dysplasia in the brain that probably develop before birth.
Poisoning
Seizures can result from exposure to lead, carbon monoxide, and many other
poisons. They also can result from exposure to street drugs and from overdoses of antidepressants and other medications.
Seizures are often triggered by factors such as lack of sleep, alcohol consumption, stress, or hormonal changes associated with the
menstrual cycle. These seizure triggers do not cause epilepsy but can provoke first seizures or cause breakthrough seizures in people who otherwise experience good seizure control with their medication. Sleep deprivation in particular is a universal and powerful
trigger of seizures. For this reason, people with epilepsy should make sure to get enough sleep and should try to stay on a regular sleep schedule as much as possible. For some people, light flashing at a certain speed or the flicker of a computer monitor can trigger a seizure; this problem is called photosensitive epilepsy.
Smoking cigarettes also can trigger seizures. The nicotine in cigarettes acts on receptors for the excitatory neurotransmitter
acetylcholine in the brain, which increases neuronal firing. Seizures are not triggered by sexual activity except in very rare instances.
A brain tumor can be either benign (non cancerous) or malignant (cancerous), primary, or secondary. Causes and risk factors include age, gender, family history, and exposure to chemicals. Symptoms range from headaches, leg and feet numbness to seizures. Treatment is dependant upon the type and location of the brain tumor.
A stroke results from impaired oxygen delivery to brain cells via the bloodstream. A stroke is also referred to as a CVA, or cerebrovascular incident. Symptoms of stroke include: sudden numbness or weakness of the face, arm or leg. Sudden confusion, trouble speaking or understanding. Sudden trouble seeing in one or both eyes, sudden trouble walking, dizziness, or loss of balance, and/or sudden severe headache with no known cause. A TIA, or transient ischemic attack is a short-lived temporary impairment of the brain caused by loss of blood supply. Stroke is a medical emergency.
Systemic lupus erythematosus is a condition characterized by chronic inflammation of body tissues caused by autoimmune disease. Lupus can cause disease of the skin, heart, lungs, kidneys, joints, and nervous
system. When only the skin is involved, the condition is called discoid lupus.
When internal organs are involved, the condition is called systemic lupus
erythematosus (SLE).
Stress occurs when forces from the outside world impinge on the individual. Stress is a normal part of life. However, over-stress, can be harmful. There is now speculation, as well as some evidence, that points to the abnormal stress responses as being involved in causing various diseases or conditions.
Heart attack happens when a blood clot completely obstructs a coronary
artery supplying blood to the heart muscle. A heart attack can cause chest pain, heart failure, and electrical
instability of the heart.
Hypoglycemia is a syndrome caused by low blood sugar. Symptoms of hypoglycemia include palpitations, trembling, intense hunger, sweating, nervousness, and weakness. Consuming lifesavers, table sugar, soda, and juice are good treatment options for hypoglycemia.
Alcoholism is a disease that includes alcohol craving and continued drinking despite repeated alcohol-related problems, such as losing a job or getting into trouble with the law.
Group B strep are bacteria called Streptococcus agalactiae that may sometimes cause infections both in a pregnant woman and her newborn. Symptoms include fever, seizures, heart rate abnormalities, breathing problems, and fussiness. Intravenous antibiotics are used to treat group B strep infections.
Whooping cough (pertussis) is highly contagious respiratory infection that is caused by the bacteria Bordetella pertussis. There are an estimated 300,000 plus deaths annually from whooping cough (pertussis). Whopping cough commonly affects infants and young children, but can be prevented with immunization with the vaccine. First stage whooping cough symptoms are a runny nose, sneezing, low-grade fever, a mild cough with the cough gradually becoming more severe. After one to two weeks, the second stage of whooping cough begins.
Malaria is an infectious disease transmitted by the bite of an infected Anopheles mosquito. Symptoms of malaria include chills, pain, fever, and sweating. Though mild cases of malaria can be treated with oral medication, severe cases require intravenous drug treatment and fluids.
Rhabdomyolysis is a rapid deterioration and destruction of skeletal muscle. Some of the causes of rhabdomyolysis include severe burns, muscle trauma, coma, seizures, electrolyte imbalance, medications (statins), viruses, bacteria. Treatment of rhabdomyolysis depends on the cause.
Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain. Symptoms of hydrocephalus vary with age, progression of the disease, and individual tolerance to the condition. Hydrocephalus is most often treated by surgery in which a shunt system is inserted.
Huntington's disease is the result of degeneration of neurons in areas of the brain. Huntington's disease is an inherited disorder. Early symptoms include mood swings, apathy, depression, and anger uncharacteristic of the individual. Judgement, memory, and other cognitive functions may become impaired. Presymptomatic testing is available for individuals who have a family history of Huntington's disease. Treatment includes medication and therapy for symptoms.
Pulmonary edema (swelling or fluid in the lungs) can either be caused by cardiogenic causes (congestive heart failure, heart attacks, abnormal heart valves) or noncardiogenic causes such as ARDS, kidney failure, high altitude, pneumothorax, pleural effusion, aspirin overdose, pulmonary embolism, and infections. The treatment of pulmonary edema depends on the cause of the condition.
Encephalopathy means brain disease, damage, or malfunction. Causes of encephalopathy are varied and numerous. The main symptom of encephalopathy is an altered mental state. Other symptoms include lethargy, dementia, seizures, tremors, and coma. Treatment of encephalopathy depends on the type of encephalopathy (anoxia, diabetic, Hashimoto's, hepatic, hyper - hypotensive, infectious, metabolic, infections, uremic, or Wernicke's) are examples of types of encephalopathy.
A number of vital tasks carried out during sleep help maintain good health and enable people to function at their best. Sleep needs vary from individual to individual and change throughout your life. Not getting enough sleep can hurt memory performance, health, and your mood.
Concussion is a short-lived loss of brain function that is due to head trauma. There are two types of concussion, simple and complex. Symptoms of concussion include headache, nausea, dizziness, dazed feeling, irritability, visual symptoms. Physical signs include poor concentration, emotional changes, slurred speech, and personality changes. Concussion is diagnosed with physical examination and testing. Treatment for concussion in general are treatment for control of the symptoms, and time.
Smoking is an addiction. More than 430,000 deaths occur each year in the U.S. from smoking related illnesses. Secondhand smoke or "passive smoke" also harm family members, coworkers, and others around smokers. There are a number of techniques available to assist people who want to quit smoking.
Listeria is a type of bacteria that can cause food poisoning. Listeriosis symptoms include diarrhea, nausea and fever. Pregnant women are 20 times more likely than other healthy adults to get listeriosis. Listeria infection is treated with antibiotics.
Cancers that form from brain tissue are called primary brain tumors. Brain tumors may be malignant (brain cancer) or benign. Certain risk factors, such as working in an oil refinery, as a chemist, or embalmer, increase the likelihood of developing brain cancer. Symptoms include headaches, weakness, seizures, difficulty walking, blurry vision, nausea and vomiting, and changes in speech, memory, or personality. Treatment may involve surgery, radiation therapy, or chemotherapy.
Toxoplasmosis (toxo) is a parasitic infection that causes flulike symptoms, swollen lymph nodes, and muscle aches and pains that may last from a few days to several weeks. Toxoplasmosis can be contracted by touching the hands to the mouth after gardening, cleaning a cat's litter box, or anything that came into contact with cat feces. Toxoplasmosis can also be contracted by eating raw or partly cooked meat, especially pork or lamb, or touching the hands to the mouth after contact with raw or undercooked meat.
Cerebral palsy (CP) is an abnormality of motor function and postural tone acquired at an early age (even before birth). Cerebral palsy is generally caused by brain trauma. Types of cerebral palsy include: spastic, choreoathetoid, and hypotonic. There is no cure for cerebral palsy, and treatment is generally managing the symptoms of the condition.
Encephalitis is a brain inflammation that causes sudden fever, vomiting, headache, light sensitivity, stiff neck and back, drowsiness, and irritability. Meningitis is an infection that causes inflammation of the meninges that surround the brain and spinal cord. Symptoms of meningitis include high fever, headache, nausea, vomiting, and stiff neck.
Coma is the inability to waken or react to the surrounding environment. The Glasgow Coma Scale is frequently used to measure the depth of coma. Causes of coma include trauma, bleeding, edema, lack of oxygen, poisoning, or hypoglycemia. Prognosis for a patient in a coma depends on the cause of the coma.
Autism in children and adults is a developmental disorder, characterized by impaired development in communication, social interaction, and behavior. Autism is classified as a pervasive developmental disorder (PDD), which is part of a broad spectrum of developmental disorders affecting young children and adults. There are numerous theories and studies about the cause of autism. The treatment model for autism is an educational program that is suitable to an individual's developmental level of performance. There is no "cure" for autism.
A brain hemorrhage is a type of stroke caused when an artery bursts in the brain, causing localized bleeding in the surrounding tissue. Causes of brain hemorrhage include aneurysm, liver disease, brain tumor, head trauma, high blood pressure, and blood vessel abnormalities. Symptoms include sudden severe headache, nausea, vomiting, loss of balance, tingling, numbness, vision changes, loss of consciousness, and loss of fine motor skills. Treatment depends upon the cause, location, and size of the brain hemorrhage.
In the United States, head injuries are one of the most common causes of death and disability. Head injuries due to bleeding are generally classified by the location of the blood within the scull, these include: epidural hematoma, subdural hematoma, subarachnoid bleed, intracranial bleed, sheer injury, edema, and skull fracture. Some common symptoms of a head injury include: vomiting, bleeding from the ear, speech difficulties, paralysis, difficulty swallowing, and body numbness. Treatment of a head injury depends on the type and severity of the injury.
Novel H1N1 influenza A virus infection (swine flu) is an infection that generally is transferred from an infected pig to a human, however there have been reported cases where infection has occured with no contact with infected pigs. Symptoms of swine flu are "flu-like" and include fever, cough, and sore throat. Treatment is generally with the antibiotics oseltamivir (Tamiflu) or zanamivir (Relenza).
Trichinosis is a food-borne disease caused by ingesting parasites (roundworms) in undercooked pork or wild-game meat. Symptoms of trichinosis include diarrhea, nausea, muscle aches, itching, fever, chills, and joint pains. Trichinosis usually resolves without treatment, but more severe cases are treated with thiabendazole, albendazole, or mebendazole.
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