Partial (focal) seizure

Alternative names:

Jacksonian seizure; seizure - partial (focal); simple seizure

Definition:

A brief, temporary change in movement, sensation, or autonomic function caused by abnormal electrical activity in a discrete area of the brain, often without changes in alertness or awareness.

Causes, incidence, and risk factors:

A partial (focal) seizure affects approximately 8 out of 100,000 people. This type of seizure may occur at any age, as a single episode or as a repeated, chronic condition (seizure disorder, epilepsy). It is seen less frequently in children than in adults, but still accounts for about 45% of pediatric seizure disorders.

Transmission of information from nerve cell to nerve cell occurs by an electrochemical process. This process can be detected as electrical activity by an electroencephalograph (EEG). Abnormal patterns of electrical activity are associated with seizures. Given sufficient circumstances, any person will have a seizure. Simple focal seizures are commonly the result of abnormal electrical activity in the motor (movement) and sensory (sensation) areas of the cerebral cortex. There are motor or sensory symptoms without loss of consciousness.

Seizures are commonly associated with epilepsy (seizure disorders). Spontaneous seizures may occur because of unknown causes. In some people, they can be triggered by menstruation; trauma; hypoxia; sensory stimuli such as lights, sounds, touch, reading; or other stimuli.

Specific causes of partial (focal) seizures most commonly include localized areas where tissue has been damaged by lack of oxygen, or tissue damage caused by brain tumors or discrete brain lesions of any sort. The most common location for the lesion is in the temporal lobe of the brain (temporal lobe seizures), but the lesion may occur in any location. In children, focal seizures are less likely to be caused by a definable lesion when compared to adults. More commonly, partial seizures arise from static lesions acquired during intra-uterine life.