Seizures--a symptom of epilepsy--are characterized by behavioral and physical changes (such as blackouts) caused by abnormal electrical activity in the brain. The presentation of symptoms varies depending upon the type of seizure and part of the brain that is affected. While some types of seizures affect one side of the brain (partial seizures), others simultaneously affect both brain hemispheres (generalized seizures).
Generalized Seizures
Generalized seizures typically affect both sides (hemispheres) of the brain from the onset of the seizure. They may cause a brief or extended loss of consciousness. According to the Epilepsy Foundation, generalized seizures are subdivided into four different types.
Tonic clonic seizures are the most common type of generalized seizure, causing a stiffening of the limbs (tonic phase), followed by a jerking movement of the arms, legs and face (clonic phase). Some people may experience only the tonic or only the clonic phases of this type of seizure, while others may develop a tonic-clonic-tonic pattern. During the tonic phase, breathing often stops or diminishes significantly, causing the lips, face and nail beds to become cyanotic (turning bluish in color due to lack of sufficient oxygen). During the clonic phase--which usually lasts less than one minute--breathing typically resumes.
Myoclonic seizures cause rapid, brief jerking movements caused by muscle contractions that often occur simultaneously on both sides of the body in an arm or foot. According to the Neurology Channel, these seizures usually occur in children up to 5 years in age.
Atonic seizures (also called drop attacks or astatic or akinetic seizures) cause a sudden loss of muscle tone that may cause a loss of posture, a drop of the head or complete collapse. Because these seizures occur without warning and often involve hard falls to the ground, the risk of associated injury is relatively high.
Absence (petit mal) seizures cause a brief loss of consciousness with no associated movement. Individuals having an absence seizure may suddenly stop without warning and stare blankly in an altered and unresponsive level of consciousness. After 5 to 10 seconds, they may then resume normal activity with no recollection of the seizure.
Partial Seizures
Partial seizures--the most common type of seizure affecting those with epilepsy--begin in a discrete spot limited to one side of the brain. In some cases, the underlying electrical disturbance may spread to another location in the brain, causing a generalized seizure (known as a partial seizure secondarily generalized). Partial seizures are subcategorized into simple and complex partial seizures. Simple partial seizures cause weakness, numbness and unusual smells or tastes, but no changes in consciousness. Muscle or limb twitching, paralysis, vision changes, movement of the head from side-to-side or vertigo may also occur, according to the Neurology Channel. Complex partial seizures affect the temporal lobe and cause altered consciousness. People having a complex partial seizure may appear to be conscious and may even speak to others; however, their words are unlikely to make sense, and they are not in control of their actions. In a trance-like state, they may wander aimlessly, uncontrollably flail their arms and legs or engage in repetitive behavior like walking in circles or smacking their lips.
Status Epilepticus
Status epilepticus is a life-threatening continuous state of seizure that occurs when seizures are prolonged or occur in a series. Status epilepticus is a medical emergency that can cause brain damage or death. The Epilepsy Foundation advises the public to call 9-1-1 in the event a seizure lasts longer than five minutes.
