Absence seizures are a type of generalized seizure characterized by brief episodes of staring with impairment of consciousness (absence). They usually last no more than 20 to 30 sec. The onset and the end of the seizures are sudden. Patients are typically unaware of the seizure and resume the activity they were performing before the seizure. The electroencephalogram signature of absence seizures consists of a generalized 3-Hz spike and slow wave discharges.

Childhood absence epilepsy

Seizures, absence

• Patients with absence seizures usually have normal physical and neurologic examinations.
• During the seizures, the patients are unresponsive and can have motor phenomena (automatisms, eye blinks, mouth and hand movements).
• Absence seizures are not associated with post-ictal confusion.
• They may be triggered by hyperventilation associated with activity.
• Tonic clonic seizures are not usually a feature of this syndrome. If the patient also experiences tonic clonic seizures, other etiologies should be investigated, such as juvenile absence epilepsy, juvenile myoclonic epilepsy, complex partial seizures, etc.

Genetic

It is important to distinguish between focal onset impaired awareness seizures (previously called complex partial seizures) and absence seizures (Tables E1 and E2).

• Juvenile absence epilepsy
• Juvenile myoclonic epilepsy
• Complex partial seizures
• Focal seizures with altered consciousness
• Nonepileptic spells comprised of staring

• EEG with hyperventilation and photic stimulation is crucial in the diagnosis. (Fig. E1)
• Ambulatory EEG and video EEG are recommended for patients with diagnostic uncertainty.

No specific studies needed

• MRI of the brain with and without contrast should be performed in all epilepsy patients, especially if the EEG does not show the typical characteristic of absence seizures (3-Hz spike and slow wave discharges).
• Computed tomography scans of the head should be avoided in children due to unnecessary exposure to radiation and low yield of the test except when MRI cannot be obtained.

Not applicable

• Ethosuximide: Initial dose: 10 mg/kg/day; then after 7 days, 20 mg/kg
• Divalproex sodium (Depakote): Initial dose: 5 to 10 mg/kg/day (divided bid), maximum dose: 60 mg/kg/day
• Lamotrigine (Lamictal): Dose for patients on no other antiepileptic drugs. Wk 1 and 2: 0.3 mg/kg/day. Wk 3 and 4: 0.6 mg/kg/day. Wk 5 onward: Increase every 1 to 2 wk by 0.6 mg/kg/day. Maintenance: 4.5 to 7.5 mg/kg/day. Warning: Should be used with caution due to the potential for toxicity and Stevens-Johnson syndrome. Patients on other antiepileptic drugs can also have severe adverse reactions (e.g., valproate can cause increased levels of lamotrigine, and lamotrigine must be titrated much more slowly in patients on valproate therapy)

• Children with recurrent seizures require chronic treatment.
• If children are seizure-free for a period of 1 to 2 yr, a trial on no medications should be considered; children typically outgrow childhood absence seizures.

• Response to treatment is excellent.
• Absence seizures tend to remit in teenage yr.
• Epilepsy can be considered as resolved once 10 yr have elapsed since the last event, including 5 yr free from medications.

Not applicable

Patients with epilepsy should be referred for a consultation by a child neurologist, preferably one specializing in epilepsy.

• Absence seizures can be present in other epilepsy syndromes.
• Valproate should be avoided in girls and women with childbearing potential due to the risk of teratogenicity.
• Carbamazepine and phenytoin should be avoided in the treatment of absence seizures since these medications may worsen seizures and provoke absence status epilepticus.
• All women of childbearing age taking antiepileptic drugs should take folic acid supplementation (1 to 4 mg/day) for the prevention of neural tube defects.

Sleep deprivation and alcohol consumption should be avoided.

Patients with ongoing seizures are forbidden to drive; check state regulations and laws regarding driving and epilepsy.

Absence Seizures (Patient Information)