Epilepsy/Seizures

Causes and Risk Factors

Many abnormalities of the nervous system can result in seizure activity. Seizures can also occur in the normal nervous system when its metabolic balance is disturbed. The cause (etiology) of epilepsy may be not clearly known (idiopathic) or related to a particular disease state. About 35% of all cases of epilepsy have no clearly definable cause.

Genetic Factors
Some persons may have a genetic predisposition to the development of seizures. There is also an increased incidence of epilepsy in relatives of those with a seizure disorder.

Head Injury
Seizures may develop at or around the time of injury or years after (usually not more than 2 years later).

Stroke
Seizures can occur at the time of a stroke or many years later. They may occur with strokes that result in lack of blood flow to the brain, but are more common with those that involve bleeding (hemorrhage) into or around the brain.

Metabolic Disturbances
Disorders that change levels of various metabolic substances in the body sometimes result in seizures.

• Altered levels of sodium, calcium, or magnesium (electrolyte imbalance)
• Kidney failure with increased urea in the blood (uremia) or changes that occur with kidney dialysis
• Low blood sugar (hypoglycemia) or elevated blood sugar (hyperglycemia)
• Lowered oxygen level in the brain (hypoxia)
• Severe liver disease (hepatic failure) and elevation of associated toxins

Toxins
Overdose of and abrupt withdrawal from some prescription drugs can result in seizure activity. Substances that may induce seizures in some people include the following:

• Antidepressants (e.g., bupropion [Wellbutrin®])
• Antipsychotic medications (e.g., chlorpromazine, haloperidol, clozapine)
• Aminophylline (bronchodilator; Phyllocontin®, Truphylline®)
• High doses of penicillin
• Lithium (Eskalith®)
• Pain relievers (e.g., tramadol [Ultram®])
• Tricyclic antidepressants (Elavil®, Limbitrol®, Tofranil®)

Chronic illicit drug use also may cause seizures, particularly cocaine, heroine, amphetamines, and PCP. Alcohol withdrawal can produce seizures, which usually occur 12-24 hours after the last drink but can occur up to 48 hours or more after binge drinking. Poisoning from carbon monoxide, lead, and other heavy metals also may cause seizures.

Infections
Infections of the nervous system may result in seizure activity. These include infection of the covering of the brain and the spinal fluid (meningitis), infection of the brain (encephalitis), and human immunodeficiency virus (HIV) and related infections.

Tumors
Cancerous (malignant) and benign brain tumors may be associated with seizures. The location of the lesion influences the risk.

Degenerative Disorders
Several neurodegenerative disorders produce seizure activity, including the following:

• Alzheimer's disease
• Creutzfeld-Jakob disease
• Neurofibromatosis
• Phenylketonuria (PKU)
• Tuberous sclerosis
• Sturge-Weber syndrome
• Tay-Sachs disease

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Cerebral Palsy
Epilepsy is often a symptom of cerebral palsy, which results from lack of oxygen, infection, or trauma during birth or infancy.

Febrile Seizures
Febrile seizures occur in small children and are caused by high fever. From birth up to the age of 5, about 2% to 4% of children in the United States experience a febrile seizure. Approximately one-third of these children may experience another febrile seizure, but only a few develop epilepsy.

Triggers
Triggers do not cause seizures but provoke the onset of a seizure or cause a seizure in a patient whose epilepsy is under control. Alcohol consumption, hormonal changes of the menstrual cycle, sleep deprivation, flickering or flashing light, and stress can trigger a seizure in a susceptible person.

« Types of Seizures

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Epilepsy/Seizures, Causes and Risk Factors, Triggers reprinted with permission from neurologychannel.com
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