Unifying Concepts

Common Types of Seizures in Adolescents and Adults

The clinical diagnosis of an epileptic seizure requires a detailed history taking and, ideally, an eyewitness account of the seizure. Evaluation with 12-lead electrocardiography is essential in a patient who has had a first seizure or an unexplained blackout spell.
Patients who have had an epileptic seizure should be informed about factors that may provoke seizures (e.g., sleep deprivation and alcohol use), the risk of a seizure occurring while driving or engaging in solitary activities, and the risks of harm from further seizures.

Common Types of Seizures in Adolescents and Adults

Seizure Type Description and Common Examples
Generalized onset The patient’s symptoms or description of the seizure by a witness do not indicate an anatomical localization of the seizure. It is thought to start within and rapidly engage bilaterally distributed cerebral networks.
  • Motor
Myoclonic seizures manifest as involuntary “jumps” of the arms, legs, or head, especially shortly after waking and with sleep deprivation; generalized tonic–clonic seizures typically occur without warning, although they may follow myoclonic or absence seizures and are most likely to occur within 1 hr after waking and with sleep deprivation.
  • Nonmotor
Typical absences manifest as a brief loss of awareness, with an abrupt onset and offset, provoked by hyperventilation, often with eyelid flickering, and ictal 3-Hz generalized spike-and-wave activity on EEG; atypical absences have a less abrupt onset and offset, with an atypical, generalized spike-and-wave activity on EEG that is slower (<2.5 Hz) than that in typical seizures.
Focal onset Most new-onset seizures in adults, including tonic–clonic seizures, are of focal onset. There is clinical evidence of seizure onset localized to one part of the brain, regardless of whether it subsequently involves the remainder of the brain. The site of onset determines the features: temporal lobe (epigastric “rising” sensation, déjà vu, and smell or taste), frontal lobe (features are often sleep-related, with adversive head turn, arm and leg jerking, and speech arrest), occipital lobe (elementary visual hallucinations in the contralateral visual field), parietal lobe (lateralized sensory symptoms, including pain), or insular cortex (laryngeal constriction, dyspnea, and contralateral somatosensory symptoms).
  • Awareness
In focal-onset aware (formerly called simple partial) seizures, awareness of the self or environment is retained; in focal-onset impaired awareness (formerly called complex partial) seizures, awareness of the self or environment is impaired.
  • Motor features
Motor seizures include automatisms (e.g., lip smacking and picking at clothes) and atonic, tonic, clonic, and myoclonic features; nonmotor seizures include autonomic, behavior arrest, cognitive, emotional, and sensory features.
  • Secondary generalization
In focal to bilateral tonic–clonic (formerly called secondarily generalized) seizures, the focal seizure develops into a tonic–clonic seizure. Such seizures often first occur during sleep.
Unknown onset The origin of a seizure is often uncertain, especially after only one seizure



  1. Smith PEM. Initial Management of Seizure in Adults. N Engl J Med. 2021 Jul 15;385(3):251-263. [Medline]
  2. Gesche J, Hjalgrim H, Rubboli G, Beier CP. Patterns and prognostic markers for treatment response in generalized epilepsies. Neurology. 2020 Nov 3;95(18):e2519-e2528. [Medline]


Created Dec 28, 2021.

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