Editing Absence seizure (section)

==Risk factors==
Typical absences are easily induced by [[hyperventilation]] in more than 90% of people with typical absences. This is a reliable test for the diagnosis of absence seizures: a patient suspected of typical absences should be asked to hyperventilate for three minutes, counting breaths. During hyperventilation, the oxygen and carbon dioxide level will become abnormal. This results in weakening of electrical signal which leads to a reduction in the seizure threshold.<ref>{{cite web |last1=Rakhimov |first1=Artour |title=Seizure Threshold Is Controlled by Brain CO2 and O2 |url=https://www.normalbreathing.com/seizure-threshold/ |date=1 June 2019 }}{{self-published inline|date=November 2024}}</ref> [[Intermittent photic stimulation]] may precipitate or facilitate absence seizures; eyelid [[Myoclonus|myoclonia]] is a common clinical feature. {{Citation needed | date = October 2014}}

A specific mechanism difference exists in absence seizures in that [[T-type calcium channel|T-type Ca<sup>++</sup> channels]] are believed to be involved. [[Ethosuximide]] is specific for these channels and thus it is not effective for treating other types of seizures. [[Valproate]] and [[gabapentin]] (among others) have multiple mechanisms of action including blockade of T-type Ca<sup>++</sup> channels, and are useful in treating multiple seizure types.{{Citation needed | date = October 2014}} Gabapentin can aggravate absence seizures.<ref>{{cite journal |last1=Perucca |first1=E. |last2=Gram |first2=L. |last3=Avanzini |first3=G. |last4=Dulac |first4=O. |title=Antiepileptic Drugs as a Cause of Worsening Seizures |journal=Epilepsia |date=January 1998 |volume=39 |issue=1 |pages=5–17 |doi=10.1111/j.1528-1157.1998.tb01268.x |pmid=9578007 }}</ref>