A seizure is a sudden, abnormal discharge of electrical activity in the brain. During a tonic clonic seizure, the electrical impulses spread throughout the brain. This stimulates the brain to send uncontrolled signals to the rest of the body.

There are many conditions that either increase the risk of having seizures or directly cause them.

Common causes of seizures include:

• Alzheimer's disease
• Brain tumor
• Cancer
• Encephalitis
• Family history of epilepsy
• Head injury
• Kidney failure
• Low blood oxygen
• Low blood sugar
• Meningitis
• Stroke
• Subarachnoid hemorrhage

Less common causes of seizures include:

• AIDS
• Alcohol withdrawal
• Brain abscess
• Depression:
• Older adults with major depression have six times the risk for seizures
• Drug side effect
• Drug toxicity or side effect
• Drug withdrawal
• Eclampsia
• Encephalitis
• Febrile seizures:
• Occurs secondary to fever in children
• Hepatic failure
• Hydrocephalus
• Hypoglycemia
• Hypotension or shock
• Intracerebral hemorrhage
• Multiple sclerosis
• Neurosyphilis
• Parkinson's disease
• Phenylketonuria
• Poisoning:
• Drugs
• Chemicals and solvents
• Insecticides (organophosphates)
• Reye's syndrome
• Thiamin deficiency
• Tourette's syndrome