Diseases

Infantile epilepsy.

Persons most commonly affected: About 25% of all cases of epilepsy develop before the age of five.
Organ or part of body involved: Nervous system.
Causes and risk factors: There are clusters of nerve cells in the brain called neurons. A person's thoughts, feelings, and actions are produced by the electrochemical impulses that the neurons generate. Usually, the neurons send signals, or fire, around 80 times a second. Various conditions and stimuli can cause the neurons to fire abnormally, which causes a seizure. During a seizure, neurons may fire as many as 500 times a second. In about 50 to 70% of all cases of epilepsy, the cause of the abnormal electrical impulses is unknown. Epilepsy without a known cause is called ideopathic.

Other forms of epilepsy occur because of brain injury at birth, which can be caused by insufficient oxygen to the brain, head injury, heavy bleeding; incompatible blood types between the mother and the child, and infection immediately before, after, or at the time of birth. One type of seizure disorder, called juvenile myoclonic epilepsy, is inherited at birth. Other causes include head trauma; birth defects; brain or spinal cord inflammation; diseases such as measles, mumps, and diphtheria; inhaling or ingesting poisonous substances such as lead, mercury, or carbon monoxide.