Types of Generalized Seizures

Generalized Seizures

Generalized seizures begin with widespread manifestations, caused by widespread electrical dysfunction of the entire cortex. Types of generalized seizures include:
  • Absence seizures (as seen in Absence Epilepsy) Absence seizures appear as a sudden impairment in consciousness, often associated with eye blinking, staring, and other minor facial movements. There is abrupt interruption of preceding activities like talking, eating, or walking, but the child does not fall down or have a convulsion. Absence seizures may last from a few seconds to a minute and typically occur multiple times per day with abrupt onset/termination and minimal, if any, post-ictal manifestations.
  • Atypical absence seizures are most common in Lennox Gastaut syndrome and other epilepsy syndromes. Atypical absence seizures have gradual onset and termination, cyclic frequency, and are more prolonged or pronounced than typical absence seizures.
  • Myoclonic seizures are lightning-quick limb or body jerks, either unilateral or bilateral, usually without impairment of consciousness.
  • Tonic seizures are episodes of increased muscle tone (spasm) of truncal and facial muscles, associated with flexion of upper extremities and extension of lower extremities. They are most common in childhood and may result in falls.
  • Clonic seizures are common in children and may resemble myoclonus, except that there is a loss of consciousness, the repetition rate is slower, and the seizures are usually longer.
  • Tonic-clonic seizures generally involve tonic posturing followed by clonic activity, typically with sudden onset of increased truncal tone that causes the patient to cry out with forced expiration. They are usually accompanied by a marked increase in heart rate and blood pressure. Incontinence after the spells, as sphincter muscles relax, and post-ictal impairment of consciousness are common.
  • Atonic seizures (also called "drop attacks") result in a sudden loss of all muscle tone, causing the patient to fall to the ground, often with injury.


Authors: Lynne M Kerr, MD, PhD - 4/2013
Matthew Sweney, MD - 4/2013