Seizure Disorder, Absence

Descriptive text is not available for this image BASICS

DESCRIPTION

A type of generalized nonmotor seizure characterized by a brief lapse of awareness; classified by the International League Against Epilepsy (ILAE) (1):

  • Typical has an abrupt onset, last 5 to 30 seconds and offset of behavioral arrest, loss of awareness, and blank staring, sometimes with eyelid movements, eye opening, or oral automatisms (e.g., lip smacking).
  • Atypical has a less abrupt onset, last 10 to 45 seconds and offset and often associated with loss of muscle tone or subtle myoclonic jerks. Brief postictal confusion can sometimes occur.
  • Myoclonic has an abrupt onset, last 10 to 60 seconds and offset of staring and loss of awareness with continuous rhythmic jerks of shoulders, arms, legs, head, or perioral muscles. They can have impairment of consciousness varying from complete loss of awareness to retained awareness.
  • Eyelid myoclonia has an abrupt onset, last <6 seconds and offset of repetitive, rhythmic jerks of the eyelids with simultaneous upward deviation of the eyeballs, and extension of the head. They can also have incomplete impairment of consciousness, often with awareness mostly retained.

EPIDEMIOLOGY

  • Predominant age of onset: between 4 and 10 years, with peak onset between 5 and 7 years
  • Predominant gender: female > male (2:1) with male predominance in myoclonic absence seizure

Incidence

6 to 8/100,000 per year in children up to 15 years of age

Prevalence

Prevalence: 5 to 50/10,000 children

ETIOLOGY AND PATHOPHYSIOLOGY

  • Mainly genetic with complex, multifactorial inheritance; however, may be secondary to a variety of congenital or acquired brain disorders such as hypoxia–ischemia, trauma, CNS infection, cortical malformations, or inborn errors of metabolism
  • Absences are triggered in the cortico-thalamocortical system when γ-aminobutyric acid (GABA)-mediated activity induces prolonged hyperpolarization and activates T-type (“low-threshold”) calcium channels, resulting in sustained-burst firing of these neurons, causing absence seizures.

Genetics

  • 75% concordance occurs in monozygotic twins; 84% share EEG features (2).
  • 15–44% of patients with childhood absence epilepsy (CAE) have a family history of epilepsy.
  • Mutations of GABA-A/B receptors—involved in spike wave discharges
  • Mutations in calcium channels (CACNA1A, CACNA1H, CACNA1I, CACNG3)—thalamocortical dysrhythmia
  • Mutations of SLC21A, which encodes GLUT1—associated with a worse prognosis

RISK FACTORS

  • Lack of medication compliance
  • Lack of sleep
  • Alcohol use
  • Medications that lower seizure threshold
  • Hyperventilation

GENERAL PREVENTION

  • Primary prevention can’t be studied and likely is not achievable because the causes are mostly, if not all genetic.
  • Secondary prevention is achievable by avoiding triggers including:
    • Adequate sleep per age based recommendations
    • Adherence to an individualized medication regimen
    • There is a growing body of evidence that suggests exercise may help reduce episode frequency in some forms of epilepsy, but the effect with regard to CAE/JAE is still undetermined.

COMMONLY ASSOCIATED CONDITIONS

Difficulties in visual attention and visuospatial skills, verbal learning and memory, fine motor skills, executive functions, reduced language abilities, ADHD, anxiety, depression, social isolation, and low esteem

Descriptive text is not available for this image DIAGNOSIS

HISTORY

  • Detailed description of episode, including activity at onset, any automatisms, duration of episode, frequency of episodes, aura or postictal state, age of onset, and birth and developmental history.
  • Teachers report that child seems to daydream or zone out frequently, and during episodes become unresponsive and unaware with a blank stare.
  • Pallor is frequently reported.
  • Child will forget portions of conversations.
  • Child with normal IQ underperforms in school.
ALERT

Seizures are often so brief that untrained observers are not aware of the occurrence.

PHYSICAL EXAM

  • Unless a child has another genetic or acquired abnormality, a neurologic exam usually is normal. Abnormal physical exam indicates the need for further diagnostic workup (e.g., MRI, metabolic, or genetic testing).
  • Seizures may be induced by hyperventilation:
    • Have the child blow on a pinwheel or similar exercise for 3 to 5 minutes to provoke seizure.
    • Alternatively, ask the patient to perform hyperventilation with eyes closed and count. Patient will open eyes at onset of seizure and stop counting.
ALERT
  • Absence seizures are not associated with sensitivity to light or other photic stimuli (e.g., strobe lights).
  • Voluntary hyperventilating (tantrums) may induce absences

DIFFERENTIAL DIAGNOSIS

  • Juvenile absence epilepsy (JAE)
  • Juvenile myoclonic epilepsy (JME)
  • Focal seizures with or without awareness
  • Psychogenic nonepileptic seizures
  • ADHD
  • Confusional states and acute memory disorders
  • Migraine variants
  • Panic/anxiety attacks
  • Breath-holding spells
  • Nonepileptic staring spells/behavioral
  • Febrile seizures
  • Status epilepticus

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

  • Video-EEg monitoring, including sleep and awake with hyperventilation resulting in spike-wave complexes from <2.5 to 6 Hz, depending on type of absence seizure, is standard for diagnosis.
  • Imaging is not routinely indicated in children with typical absence and normal neurologic exam and cognition. If imaging is performed, MRI is preferable to CT scan due to higher sensitivity for anatomic abnormalities.
  • Presently, no laboratory values can definitively prove or rule out the diagnosis of an absence seizure. However, labs such as electrolytes, creatinine, liver and renal function tests, TSH, CBC, and toxicology screen can rule out endocrine, metabolic, toxic, or infectious etiologies (3)[C].

Follow-Up Tests & Special Considerations

  • Drug levels are useful in evaluating symptoms of toxicity or for breakthrough seizures.
  • Follow blood chemistry, hepatic function, blood counts, etc., specific to drug regimen.

Diagnostic Procedures/Other

Uncommonly, there may be a need for an lumbar puncture (LP) to rule out causes of treatment resistant absences

Test Interpretation

  • CSF glucose levels
  • Variations in GLUT1 expression or SLC2A1 gene, etc.

Descriptive text is not available for this image TREATMENT

GENERAL MEASURES

ALERT

Patients should refrain from activities that would put them at risk if a seizure occurred (e.g., climbing heights, swimming unsupervised, cycling on busy roads, driving, operating heavy machinery, cooking with stoves unsupervised). Providers should be familiar with state laws concerning driving with epilepsy.

MEDICATION

ALERT
  • Certain common anticonvulsants may exacerbate absence including carbamazepine, oxcarbazepine, phenytoin, phenobarbital, tiagabine, vigabatrin, pregabalin, and gabapentin.
  • 20–25% of children with CAE, and probably also with JAE, are pharmacoresistant (2).

First Line

  • Ethosuximide (ETX) blocks T-type calcium channels:
    • High efficacy (4)[A], fastest onset of efficacy (5)[B], and fewer adverse attentional effects compared to valproic acid (4)[A]; however, it is only effective against absence seizures.
    • Possible disease-modifying effects—remission is achieved more frequently when ETX is introduced as a first drug (2).
    • Side effects: vomiting, diarrhea, abdominal discomfort, hiccups, headache, sedation
    • Adverse effects: aplastic anemia, skin reactions, and renal/hepatic impairment; monitor CBC and CMP (6)[C].
  • Valproic acid (alternative first line)
    • Attention deficits persist more frequently with valproic acid monotherapy compared to ETX or lamotrigine.
    • Adverse effects: teratogenicity, behavior/cognitive abnormalities, hepatotoxicity, pancreatitis; monitor CMP, amylase, and lipase (6)[C]; reduced bone mineral density and increased risk of osteoporosis and fractures
    • Side effects: tremor, drowsiness, dizziness, weight gain, alopecia, sedation, vomiting

Second Line

Lamotrigine affects sodium channels:

  • Controls seizures but may be less efficacious than ethosuximide or valproic acid (4)[A]
  • Side effects: rash, diplopia, headache, insomnia, dizziness, nausea, vomiting, diarrhea
  • Adverse effects: rare Stevens-Johnson rash, more often when coadministered with valproic acid

ISSUES FOR REFERRAL

  • Failure to gain seizure control for at least 1 year with two AEDs (whether as monotherapy or in combination) should prompt referral to neurologist for confirmation of the diagnosis for seizure, search for a pathogenic genetic variant (i.e. GLUT1 deficiency) and/or syndrome classification and, if appropriate, for consideration of epilepsy surgery (5)[B].

Pediatric Considerations

  • Neuropsychological testing, such as the Wechsler Intelligence Scale for Children (WISC) and the NEPSY-II, along with assessing developmental milestones, behavior, teacher and parent reports can help diagnose comorbid conditions caused by or associated with CAE.
  • Prescribe vitamin D supplementation (usual dose 400 to 1,000 IU/day for children without deficiency and 1,000 to 2,000 IU or more daily for children with deficiency) in children taking valproic acid due to AE of reduced bone mineral density (7).
  • Fatal hepatotoxicity with valproic acid risk is greatest in <2 years old (6)[C].

Pregnancy Considerations
Anticonvulsants, especially valproic acid, are associated with an increase in fetal malformations. Use of valproic acid in women of childbearing age, who are not using adequate birth control, is contraindicated.

SURGERY/OTHER PROCEDURES

  • Epilepsy surgery including ablation and resection for medically refractive absence epilepsy
  • Vagal nerve stimulator (VNS) may be considered as an option for medically refractory absence epilepsy.

COMPLEMENTARY & ALTERNATIVE MEDICINE

A ketogenic diet can reduce seizure frequency by 50% in children with drug-resistant epilepsy (8).

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

Status epilepticus requires inpatient care.

Descriptive text is not available for this image ONGOING CARE

PATIENT EDUCATION

  • Caregivers should be informed that tonic-clonic seizures are rare in absence seizures, but should be taught how to manage a generalized tonic-clonic seizure.
  • Sarah Jayne Has Staring Moments: a fictional children’s book for child absence seizure epilepsy by Kate Lambert

PROGNOSIS

  • Prognosis for CAE is excellent with 56–84% remission rate.
  • Remission is less common in JAE, JME, and those who progress to generalized tonic-clonic seizures or myoclonic seizures.
  • Patients whose shortest pretreatment EEG seizures are >20 seconds in duration are more likely to achieve seizure freedom, regardless of treatment.
  • Typical absence seizures generally cease spontaneously by age 12 years or sooner. However, a subset may develop other forms of epilepsy or experience cognitive and behavioral difficulties.

COMPLICATIONS

  • Reported frequencies of typical absence status epilepticus range from 5.8% to 9.4%.
  • <10% develop generalized tonic-clonic seizures.

Authors

Matthew J. Vargas, DO
Benjamin T. Rud, DO

REFERENCES

  1. Fisher RS, Cross JH, D’Souza C, et al. Instruction manual for the ILAE 2017 operational classification of seizure types. Epilepsia. 2017;58(4):531–542.  [PMID:28276064]
  2. Le Roux M, Benallegue N, Gueden S, et al. Care of pharmaco-resistant absence seizures in childhood. Rev Neurol (Paris). 2024;180(4):251–255.  [PMID:38388226]
  3. Nass RD, Sassen R, Elger CE, et al. The role of postictal laboratory blood analyses in the diagnosis and prognosis of seizures. Seizure. 2017;47:51–65.  [PMID:28288363]
  4. Glauser TA, Cnaan A, Shinnar S, et al; for Childhood Absence Epilepsy Study Team. Ethosuximide, valproic acid, and lamotrigine in childhood absence epilepsy: initial monotherapy outcomes at 12 months. Epilepsia. 2013;54(1):141–155.  [PMID:23167925]
  5. Mohanraj R, Brodie MJ. Early predictors of outcome in newly diagnosed epilepsy. Seizure. 2013;22(5):333–344.  [PMID:23583115]
  6. Posner E. Absence seizures in children. Am Fam Physician. 2015;91(2):114–115.
  7. Min L, Chunyan W, Biaoxue R. Effects of valproic acid on skeletal metabolism in children with epilepsy: a systematic evaluation and meta-analysis based on 14 studies. BMC Pediatr. 2020;20(1):97.  [PMID:32122313]
  8. Martin-McGill KJ, Bresnahan R, Levy RG, et al. Ketogenic diets for drug-resistant epilepsy. Cochrane Database Syst Rev. 2020;6(6):CD001903. doi:10.1002/14651858.CD001903.pub5.  [PMID:32588435]

Descriptive text is not available for this image CODES

ICD10

  • G40.409 Other generalized epilepsy and epileptic syndromes, not intractable, without status epilepticus
  • G40.419 Oth generalized epilepsy, intractable, w/o stat epi
  • G40.401 Oth generalized epilepsy, not intractable, w stat epi
  • G40.411 Oth generalized epilepsy, intractable, w status epilepticus
  • G40.A19 Absence epileptic syndrome, intractable, w/o stat epi
  • G40.A09 Absence epileptic syndrome, not intractable, w/o stat epi

SNOMED

  • 79631006 Absence seizure (disorder)
  • 23374007 Atypical absence seizure (disorder)

CLINICAL PEARLS

  • Children with CAE can exhibit cognitive, behavioral, and psychosocial comorbidities. For these children, attentional deficits are the most important marker of cognitive dysfunction and often associated with reduced academic performance, anxiety, depression, and behavioral disorders.
  • If parents are unable to determine the cause of a staring spell, try suggesting that parents mention something exciting or unexpected like “ice cream” during a spell to get the child’s attention rather than calling his or her name.
  • ETX and valproic acid are first-line agents in treatment of absence seizures.
  • Maintain a seizure diary to help identify type and cause of seizures: https://diary.epilepsy.com/login.
  • Review seizure precautions and create a seizure response plan: https://www.epilepsy.com/sites/core/files/atoms/files/GENERAL%20Seizure%20....

Last Updated: 2026

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