The primary diagnostic test for<unk> s is electroencephalography (EEG). However, brain scans such as by an MRI can help rule out other diseases, such as a stroke or a brain tumor. During EEG, hyperventilation can be used to provoke these seizures. Ambulatory EEG monitoring over 24 hours can quantify the number of seizures per day and their most likely times of occurrence.<unk> s are brief (usually less than 20 seconds) generalized epileptic seizures of sudden onset and termination. When someone experiences an<unk>  they are often unaware of their episode. Those most susceptible to this are children, and the first episode usually occurs between 4–12 years old. It is very rare that someone older will experience their first<unk> . Episodes of<unk> s can often be mistaken for inattentiveness when misdiagnosed, and can occur 50–100 times a day. They can be so difficult to detect that some people may go months or years before being given a proper diagnosis. There are no known before or after effects of<unk> s.<unk> s have two essential components: * Clinical - the impairment of consciousness<unk>  * EEG - the EEG shows generalized spike-and-slow wave discharges<unk> s are broadly divided into typical and atypical types: * Typical<unk> s usually occur in the context of idiopathic generalised epilepsies and an EEG shows fast >2.5 Hz generalised spike-wave discharges. The prefix "typical" is to differentiate them from atypical<unk> s rather than to characterise them as "classical" or characteristic of any particular syndrome. * Atypical<unk> s: * Occur only in the context of mainly severe symptomatic or cryptogenic epilepsies of children with learning difficulties who also suffer from frequent seizures of other types, such as atonic, tonic and myoclonic. * Have slower onset and termination and changes in tone are more pronounced. * Have particular ictal characteristics: EEG is of slow (less than 2.5 Hz) spike and slow wave. The discharge is heterogeneous, often asymmetrical and may include irregular spike and slow wave complexes, fast and other paroxysmal activity. Background interictal EEG is usually abnormal. Syndromes<unk>  syndromes are childhood<unk>  epilepsy, epilepsy with myoclonic<unk> s, juvenile<unk>  epilepsy and juvenile myoclonic epilepsy. Other proposed syndromes are Jeavons syndrome (eyelid myoclonia with<unk> s), and genetic generalised epilepsy with phantom<unk> s.<unk> s are also known to occur to patients suffering with porphyria and can be triggered by stress or other porphyrin-inducing factors.
Absence seizure
Focal seizure
Intercalated seizure
Reflex seizure
Atonic seizure
Musicogenic seizure
Status epilepticus
Gelastic seizure