Absence seizure

Absence seizures are one of several kinds of generalized seizures. These seizures are sometimes referred to as petit mal seizures (from the French for "little illness", a term dated in the late 18th century). Absence seizures are characterized by a brief loss and return of consciousness, generally not followed by a period of lethargy (i.e. without a notable postictal state). Absence seizures are most common in children. They affect both sides of the brain. Absence seizures affect between 0.7 and 4.6 per 100,000 in the general population and 6 to 8 per 100,000 in children younger than 15 years. Childhood absence seizures account for 10% to 17% of all absence seizures. Onset is between 4 and 10 years and peaks at 5 to 7 years. It is more common in girls than in boys. An absence seizure is specifically caused by multifactorial inheritance. The voltage-gated T-type calcium channel is regulated by Gamma-aminobutyric acid receptor subunit gamma-2 (GABRG2), GABRG3, and CACNA1A2 genes. Inheritance of these genes is involved in the etiology (cause) of absence seizure. The clinical manifestations of absence seizures vary significantly among patients. Impairment of consciousness is the essential symptom, and may be the only clinical symptom, but this can be combined with other manifestations. The hallmark of the absence seizures is abrupt and sudden-onset impairment of consciousness, interruption of ongoing activities, a blank stare, possibly a brief upward rotation of the eyes. If the patient is speaking, speech is slowed or interrupted; if walking, they stand transfixed; if eating, the food will stop on its way to the mouth. Usually, the patient will be unresponsive when addressed. In some cases, attacks are aborted when the patient is called. The attack lasts from a few seconds to half a minute and evaporates as rapidly as it commenced. Absence seizures generally are not followed by a period of disorientation or lethargy (postictal state), in contrast to the majority of seizure disorders.