A generalized seizure occurs when the abnormal electrical activity causing a seizure begins in both halves (hemispheres) of the brain at the same time.
Generalized Seizures: What You Need to Know
Generalized seizures include absence, atonic, tonic, clonic, tonic-clonic, myoclonic, and febrile seizures.
Loss of consciousness may be accompanied by spasms, stiffening, shaking, muscle contractions or loss of muscle tone.
Diagnosis begins with a doctor taking a careful medical history and may include tests such as EEG, MRI and blood tests.
As is the case with all seizures and epilepsies, treatment calls for an individualized approach to each patient, and may include medication or other therapy if medicines do not work.
Different Types of Generalized Seizures
Once known as “petit mal” seizures, these are staring spells that start suddenly and may be mistaken for simple daydreaming. The person having an absence seizure will typically stop moving and stare in one direction for 15 seconds or less.
The episode resolves on its own, and though the person may not remember what happened during the seizure, their normal state of alertness returns immediately afterward.
Atonic Seizures (Drop Attacks)
A seizure of this type involves a sudden decrease in muscle tone, causing a person’s body to go limp, slump or collapse, possibly causing injury. Atonic seizures characterize certain epilepsy syndromes such as Lennox-Gastaut syndrome.
Myoclonic seizures are characterized by a sudden body “jolts” or increases in muscle tone as if the person had been jolted with electricity. A myoclonic seizure is similar to the single or multiple sudden jerks people sometimes experience as they are falling asleep. “Sleep myoclonic” jerks are benign whereas myoclonic seizures can be harmful, since the “jolts” occur in bouts.
Infantile spasms is a subtype type of myoclonic epilepsy that typically begins between the ages of 3 and 12 months of age and may persist for several years. Infantile spasms typically consist of a sudden jerk followed by stiffening. Often the child’s arms fling outward as the knees pull up and the body bends forward. Each spasm lasts only a second or two but they usually occur close together in a series. Sometimes the spasms are mistaken for colic, but the cramps of colic do not typically occur in a series.
Infantile spasms are most common just after waking up or falling asleep. This particularly severe form of epilepsy can have lasting effects on a child and should be evaluated and treated promptly.
Tonic and Clonic Seizures
In a tonic seizure, the person’s muscles stiffen, and they lose consciousness. The eyes roll back in their head, and muscles of the chest, arms and legs stiffen, causing the back to arch. The contracting muscles in the chest make it hard to breathe, and the person’s lips and face may turn gray or blue. The person may make gurgling sounds while struggling to breathe.
Clonic seizures cause a person’s muscles to spasm and jerk. Muscles in the elbows, legs and neck flex and then relax in rapid succession. The jerking motion slows down as the seizure subsides, and finally stops altogether. As the jerking stops, it is common for the person to let out a deep sigh before resuming normal breathing.
Tonic-clonic seizures, once known as “grand mal” or “convulsive” seizures, occur when tonic and clonic movements happen at the same time.
Though witnessing a seizure can be frightening, it is a myth that a person having a seizure is in danger of swallowing their tongue, which is not anatomically possible. NEVER put anything in the mouth or forcefully open a tightly clenched jaw while the seizure is happening as this could harm the person.
A seizure typically lasts a few minutes or less, after which the person is likely to remain unconscious for a few minutes more, depending on the intensity of the seizure. This is the post-seizure or post-ictal period, and during this phase the person’s brain is extremely active as it tries to contain the abnormal electrical impulses and bring the seizure under control.
People regaining consciousness after a seizure are likely to be sore, confused or frightened and very tired. Providing assurance and support is the best help an observer can offer.
More Information About Seizures and Epilepsy in the Health Library