A partial seizure is an episode of abnormal electrical activity in one specific part of the brain.

Simple seizure; Jacksonian seizure; Seizure - partial (focal)

All seizures are caused by abnormal electrical disturbances in the brain. Partial (focal) seizures occur when this electrical activity remains confined to a limited area of the brain; they may sometimes progress to generalized seizures, which affect the whole brain.

Partial seizures can be further characterized as simple (not affecting awareness and memory) or complex (affecting awareness and memory of events before, during, and immediately after the seizure, and affecting behavior).

The abnormal electrical activity results from localized areas of abnormal brain tissue. These areas may have been present since birth or earlier (congenital), or they may develop following head trauma, infections, stroke, and certain other conditions. In many patients, no obvious cause can be determined. Partial seizures are more likely to be caused by a definable lesion in adults than in children.

A partial (focal) seizure may occur at any age, as a single episode or as a repeated, chronic seizure disorder (epilepsy). They are seen less frequently in children than in adults, but still account for about 45% of pediatric seizure disorders.

Risk factors include any injury to the brain. This includes trauma, stroke, brain tumors, infections (such as meningitis), or prior brain surgery.

Patients with focal seizures can have any of the symptoms below. Patients with simple focal seizures do not lose consciousness and will be aware and remember the events that occur at the time. Patients with complex partial seizures will have abnormal consciousness and may or may not remember any or all of the symptoms or events surrounding the seizure.

• Abnormal motor control
  • Muscle contraction /relaxation (clonic activity) -- common
  • Affecting one side of the body (leg, part of the face, or other isolated area)
  • Abnormal head movements
  • Forced turning of the head
• Automatisms -- purposeless, complex movement (such as picking at clothes)
  • Abnormal mouth behaviors
  • Lip smacking
  • Chewing/swallowing without cause
• Forced turning of the eyes
• Abnormal sensations
  • Numbness, tingling, crawling sensation, etc.
  • May occur in only one part of the body or may spread
  • May occur with or without motor symptoms
• Hallucinations (visual, hearing, touch, smells, etc.)
• Abdominal pain or discomfort
• Nausea
• Sweating
• Flushed face
• Dilated pupils
• Rapid heart rate/pulse

• Black out spells -- periods of time lost from memory
• Changes in vision
• Sensation of deja vu
• Changes in mood or emotion

The diagnosis is based on the symptoms, taking into consideration the patient's other history. It is extremely difficult to diagnose a single focal seizure. However, the diagnosis is easier to make in patients who have recurrent, stereotyped episodes --especially if there are risk factors such as a history of head injury.

Some of the tests that may be performed include:

• EEG -- this can show characteristic changes confirming partial (focal) seizures, and may show the focus (the location of the cause). A normal EEG does not rule out seizures.
• EEG monitoring over several days may be necessary in order to record an event while it is occurring.
• Head CT or head MRI scan -- these may show the location and extent of the lesion causing the symptom.