Epileptic seizures can occur because the brain has wired itself incorrectly during development, or as the result of damage after head injury or stroke. In some cases, epileptic seizures happen for no medically defined reason. The U.S. National Institute of Neurological Disorders and Stroke (NINDS) estimates that about 1 percent of the population suffers from unprovoked seizures or is diagnosed with an epilepsy syndrome. The kind of seizure a person experiences depends on the location and extent of brain tissue involved.
Simple and Complex Partial Seizures
Seizures break down into two broader categories: partial and generalized. People who suffer from partial seizures exhibit heightened electrical activity in a distinct area of the brain for 1 to 2 minutes before the episode naturally ends.
During one type of partial seizure termed "simple," individuals retain consciousness but show sudden, jerky movements in the extremities or have sensory hallucinations in which they smell, hear or see things that are not really there.
During a different type of partial seizure termed "complex," individuals lose awareness of their surroundings and can exhibit odd, robotic-like movements such as lip smacking. The Epilepsy Foundation points out that people about to undergo a complex partial seizure sometimes feel a warning sign or "aura" before the episode begins.
Generalized Tonic-Clonic Seizures
Generalized seizures affect the brain widely. Tonic-clonic or grand mal seizures--the most common variety--occur in 1 to 3 min bursts, and cause stiffening of the trunk, leg and arm muscles followed by violent bodily convulsions. According to Epilepsy.com, children and adults who experience tonic-clonic seizures will typically lose consciousness and collapse to the floor with waning muscle control. Their face might appear blue because of poor blood oxygenation. After a slight period of rigidity and shaking, their bodies will then relax back to normal as they regain consciousness. Although disturbing to watch, tonic-clonic seizures often manage well with anti-epileptic medication.
Generalized Absence Seizures
Absence seizures (pronounced ab-SAWNTZ) comprise another class of generalized seizures in which children experience brief, 10-second lapses of awareness accompanied by blank staring or repetitive eye blinking. Unlike other seizures, absence episodes are passive; they might go undetected even when occurring dozens of times a day. A significant majority of patients with absence epilepsy outgrow the attacks by age 18. Stanford University Hospital indicates that these seizures do not readily distinguish themselves from complex partial ones.
