Pediatrics (System-Integrated)

Childhood absence epilepsy: diagnosis and treatment

Clinical Overview and When to Suspect Childhood Absence Epilepsy

— Accounts for ~10–17% of childhood epilepsies

— Peak onset age 4–10 years, girls > boys (~2:1)

— Normal development and intellect at baseline in classic CAE

— School-age child with "daydreaming spells," declining grades, or teacher reports of "tuning out"

— Episodes occur dozens to hundreds of times per day, each lasting 5–20 seconds

— Abrupt onset and offset, no aura, no postictal confusion

— Triggered or unmasked by hyperventilation (90%+ of untreated cases)

— Subtle automatisms: lip smacking, eyelid flutter, fumbling — may be mistaken for complex partial seizures

— Polygenic; associations with GABA-A receptor subunit genes (GABRG2, GABRA1), CACNA1H (T-type calcium channel), SLC2A1 (GLUT1)

— GLUT1 deficiency should be considered in atypical, early-onset, or treatment-refractory absence — screen with CSF/serum glucose ratio

Definition: Childhood absence epilepsy (CAE) is a generalized genetic (idiopathic) epilepsy syndrome characterized by brief, frequent absence seizures with abrupt behavioral arrest and a pathognomonic 3 Hz generalized spike-and-wave discharge on EEG.

Epidemiology:

When to suspect in clinic:

Genetic underpinning:

Step 3 management: A pediatric patient referred for "ADHD-like" inattention who has staring spells lasting seconds with no recall should get an outpatient EEG with hyperventilation provocation before any stimulant is prescribed — stimulants will not help, and a missed absence diagnosis delays appropriate antiseizure therapy and worsens academic outcomes.

Prognosis snapshot: ~65–70% remission by adolescence on first-line therapy; small subset evolves into juvenile myoclonic epilepsy (JME) or juvenile absence epilepsy (JAE), particularly if generalized tonic-clonic seizures appear later.

Differentiation principle: CAE is a clinical-electrographic diagnosis — neither clinical features nor EEG alone suffice; both must align with the ILAE syndrome criteria.

Presentation Patterns and Key History

— Sudden behavioral arrest mid-activity (mid-sentence, mid-bite, mid-step)

— Blank stare, unresponsive to voice or touch

— Duration typically 4–20 seconds; >30 seconds suggests atypical absence or non-absence event

— Immediate resumption of prior activity with no awareness of the lapse and no postictal phase

— Frequency: often >10–100/day untreated; may cluster

— Eyelid fluttering (3 Hz), upward eye deviation

— Oral automatisms (chewing, lip smacking)

— Hand fumbling or perseverative movements

— Mild loss of postural tone (head nod), but no falls in typical CAE

— Trigger by hyperventilation (running, blowing up balloons), photic stimulation in a minority

— Sleep deprivation, stress, illness as exacerbators

— Recent decline in school performance, "spacey" episodes during reading

— Absence of nocturnal events, tongue biting, incontinence, or focal features

— Developmental milestones — should be normal; regression suggests an alternative syndrome

— ~15–40% report a first-degree relative with a generalized epilepsy or febrile seizures

— Asking about JME (early-morning myoclonus) in older siblings/parents is high yield

— Onset <3 years or >12 years

— Episodes >30 seconds, gradual onset/offset

— Postictal confusion, focal automatisms confined to one side

— Myoclonic jerks on awakening, generalized tonic-clonic seizures at diagnosis, intellectual disability

— Episodes during sleep

Classic seizure semiology:

Associated subtle features:

History points to elicit:

Family history:

Red flags arguing AGAINST classic CAE:

Board pearl: A 7-year-old with hundreds of brief blank-stare episodes provoked when blowing on a pinwheel in clinic is a near-pathognomonic Step 3 vignette for CAE — order EEG with hyperventilation, do not order MRI first.

Differential framing on history alone: Daydreaming (responsive to touch, no automatisms) and focal impaired-awareness seizures (longer, postictal confusion, auras) are the two most commonly tested mimics.

Physical Exam Findings and In-Office Provocation

— Normal growth parameters and head circumference

— Normal neurologic exam: cranial nerves, motor tone/strength, deep tendon reflexes, coordination, gait

— Normal cognitive screen and age-appropriate language

— Neurocutaneous stigmata (ash-leaf spots, café-au-lait, port-wine stain) → suggests tuberous sclerosis, NF1, or Sturge-Weber with focal epilepsy

— Dysmorphic features → genetic/metabolic syndrome

— Focal neurologic deficit, hemiparesis, asymmetric reflexes → structural lesion, focal epilepsy

— Microcephaly, hypotonia, developmental delay → consider GLUT1 deficiency or other encephalopathic syndromes

— Have the child hyperventilate for 3–5 minutes (blow on a pinwheel or paper strip, count breaths)

— Observe for behavioral arrest, eyelid flutter, automatisms

— Provocation is positive in ~80–90% of untreated CAE patients and is essentially free

— Document duration, semiology, and recovery

— Less sensitive than HV for CAE but may unmask generalized photoparoxysmal response (more typical of JME)

— Baseline HR, BP, and a brief cardiac exam are reasonable before considering valproate or other AEDs that may have systemic effects; rule out long-QT mimics of "spells"

General exam: Typically completely normal in CAE — this is itself a diagnostic clue.

Findings that should prompt reconsideration:

In-office provocation — the highest-yield maneuver:

Photic stimulation:

Cardiovascular/respiratory check:

Step 3 management: If hyperventilation in the office reproduces a typical episode and the child has no focal findings, the appropriate next step is outpatient EEG with HV and photic stimulation — not emergent neuroimaging. Reserve MRI for atypical features, focal findings, or refractory seizures.

Counsel parents at the exam visit: Until diagnosis is confirmed, instruct no swimming alone, no bathing unsupervised, and bike helmet use; episodes during these activities can cause drowning or head injury even though typical CAE rarely causes falls.

Diagnostic Workup — EEG as the Cornerstone

— Generalized, bilaterally synchronous, symmetric 3 Hz (2.5–4 Hz) spike-and-wave discharges

— Abrupt onset and offset, normal background activity between bursts

— Clinically evident absence corresponds to discharges lasting >3 seconds; shorter bursts may be subclinical

— Hyperventilation for 3–5 minutes provokes typical bursts in the vast majority of untreated patients — highest single-test yield

— Photic stimulation — generalized photoparoxysmal response present in a minority

— Sleep recording — useful if routine EEG is non-diagnostic; consider sleep-deprived EEG before declaring it negative

— Slow spike-and-wave (<2.5 Hz) → think Lennox-Gastaut syndrome

— Polyspike-and-wave or 4–6 Hz discharges → think JME or JAE

— Focal or asymmetric discharges → focal epilepsy with bilateral propagation

— Abnormal background (slowing, encephalopathic pattern) → symptomatic generalized epilepsy

— CBC, CMP, magnesium, glucose — baseline before starting AEDs

— Pregnancy test in post-menarchal adolescents before valproate

— CSF and serum glucose (ratio <0.45) if GLUT1 deficiency suspected (early onset, movement disorder, paroxysmal exercise-induced dyskinesia, microcephaly, refractory absences)

EEG is the diagnostic test of choice and should be obtained in any child with suspected absence seizures.

Hallmark finding — typical CAE:

Activation procedures (mandatory):

Atypical features that should reclassify the diagnosis:

Adjunct labs (selective, not routine):

ECG: Reasonable to obtain to rule out long-QT or arrhythmogenic "spells" mimicking absence — particularly if episodes are precipitated by exertion, startle, or have any syncopal quality.

Board pearl: The single most specific finding for CAE is a normal EEG background with 3 Hz generalized spike-and-wave provoked by hyperventilation — committing this image to memory pays off across Step 2/3 question banks.

Diagnostic Workup — Neuroimaging and Confirmatory Studies

— MRI is NOT routinely indicated in classic CAE with typical semiology, normal exam, normal development, and characteristic EEG.

— This is a frequently tested point: ordering MRI in a textbook CAE child wastes resources and exposes the patient to sedation risk without changing management.

— Focal seizure features or focal EEG findings

— Abnormal neurologic exam, developmental regression, or focal deficit

— Onset <3 or >10 years (atypical age)

— Refractoriness to two appropriate first-line AEDs

— Episodes that evolve in character (e.g., new generalized tonic-clonic, myoclonus)

— SLC2A1 sequencing (GLUT1 deficiency) in early-onset, refractory, or atypical absence — especially with paroxysmal exercise-induced dyskinesia or low CSF glucose; highly actionable because ketogenic diet is the definitive treatment

— Epilepsy gene panel if family history is strong or features overlap with developmental and epileptic encephalopathies

— Karyotype/microarray if dysmorphism or intellectual disability

— Indicated when routine EEG is non-diagnostic but clinical suspicion remains high

— Useful to distinguish absence from focal impaired-awareness seizures, non-epileptic events, and stereotypies

— Consider at baseline and follow-up because CAE is associated with attention and executive function deficits even when seizures are controlled — informs IEP/504 plan discussions

Neuroimaging — when NOT to order:

Neuroimaging — when TO order MRI brain (with and without contrast, epilepsy protocol):

Genetic and metabolic testing — targeted use:

Video-EEG monitoring:

Neuropsychological testing:

Step 3 management: A child with classic CAE confirmed by EEG should proceed directly to pharmacotherapy initiation and school accommodations counseling — no MRI, no lumbar puncture, no admission. Adding low-value imaging is a commonly tested wrong answer.

Key distinction: Atypical absence (slow spike-wave, mixed seizure types, intellectual disability) is part of Lennox-Gastaut spectrum — these patients do require MRI and broader workup.

Risk Stratification and Treatment Decision Framework

— Complete seizure freedom (achievable in the majority)

— Preservation of cognition, attention, and academic performance

— Minimize AED adverse effects, especially behavioral and cognitive

— Plan for eventual taper after a seizure-free interval

— Virtually all confirmed CAE patients warrant treatment because of seizure frequency, injury risk (drowning, traffic), and academic impairment.

— Untreated CAE rarely remits spontaneously in early childhood

— Ethosuximide and valproic acid were both more effective than lamotrigine for seizure freedom

— Ethosuximide had significantly fewer attentional adverse effects than valproate

— Therefore ethosuximide is the preferred first-line agent for typical CAE without generalized tonic-clonic seizures

— Coexisting generalized tonic-clonic seizures or myoclonic seizures (ethosuximide does NOT cover GTCs)

— Suspected evolution toward JME/JAE

— Caveat: avoid in female adolescents of childbearing potential when alternatives exist — teratogenicity (neural tube defects, lower IQ in offspring)

— Patient/family preference for a better cognitive-behavioral profile

— Adolescent females where valproate is contraindicated and ethosuximide insufficient

— Slower titration accepted (rash risk, including Stevens-Johnson)

Treatment goals in CAE:

Treat or observe?

First-line choice — guided by landmark RCT (Glauser et al., NEJM 2010; long-term follow-up 2013):

When to choose valproate over ethosuximide:

When lamotrigine is reasonable:

Board pearl: The single most testable CAE fact: ethosuximide is first-line for absence-only CAE; valproate is first-line if GTCs coexist; lamotrigine is third because it was less effective in the head-to-head trial.

Counseling at decision point: Discuss expected timeline (assess response in ~4–6 weeks), driving permits (delayed until seizure-free per state law), swimming/bathing precautions, and school accommodations under IDEA/504.

Pharmacotherapy — First-Line Regimens and Titration

— Mechanism: blocks T-type calcium channels in thalamocortical neurons — the circuit generating 3 Hz spike-wave

— Dosing: start 10–15 mg/kg/day divided BID; titrate every 1–2 weeks to 20–40 mg/kg/day (max ~1500 mg/day in older children)

— Therapeutic level: 40–100 mcg/mL (useful for adherence or breakthrough seizures)

— Adverse effects: GI upset (most common — give with food), hiccups, headache, drowsiness; rare SLE-like syndrome, aplastic anemia, Stevens-Johnson syndrome

— Monitoring: baseline CBC and LFTs; repeat if symptomatic

— Mechanism: broad — enhances GABA, blocks Na+ and T-type Ca++ channels

— Dosing: start 10–15 mg/kg/day; titrate to 20–40 mg/kg/day divided BID-TID

— Therapeutic level: 50–100 mcg/mL

— Adverse effects: weight gain, tremor, alopecia, thrombocytopenia, hyperammonemia, pancreatitis, hepatotoxicity (especially <2 yrs or polytherapy); PCOS-like features; teratogenic — neural tube defects, decreased IQ

— Monitoring: baseline + periodic CBC, LFTs, ammonia if symptomatic; pregnancy test in adolescents

— Mechanism: Na+ channel blockade, modulates glutamate release

— Slow titration over 6–8 weeks to reduce Stevens-Johnson/TEN risk; titration even slower if combined with valproate (which doubles lamotrigine levels)

— Target: ~5–15 mg/kg/day divided BID; therapeutic level 4–18 mcg/mL

— Better cognitive-behavioral profile; risk: rash

Ethosuximide (first-line for absence-only CAE):

Valproic acid (first-line if GTCs coexist):

Lamotrigine (second/third-line):

Step 3 management: If first-line therapy fails after adequate dose and adherence verification, switch monotherapy to the alternative first-line agent (ethosuximide ↔ valproate) before adding combination therapy. Sequential monotherapy is preferred to minimize toxicity.

Drugs to AVOID in absence seizures (can worsen them): carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin, tiagabine, vigabatrin — a high-yield "wrong answer" trap on exams.

Refractory Disease and Non-Pharmacologic Options

— Ethosuximide + valproate (synergistic for absence, additive toxicity — monitor LFTs, CBC, ammonia)

— Valproate + lamotrigine (synergy demonstrated; titrate lamotrigine very slowly due to interaction)

— Add-on clobazam, zonisamide, levetiracetam, or topiramate in selected cases

— Levetiracetam: behavioral side effects (irritability) common in children

— Topiramate: cognitive slowing, weight loss, kidney stones, oligohidrosis

— Zonisamide: weight loss, kidney stones, sulfa allergy caution

— Repeat prolonged or video-EEG to confirm typical features

— Screen for GLUT1 deficiency (SLC2A1) — ketogenic diet is dramatically effective

— Reassess for atypical absence, JAE, or non-epileptic events

— Review adherence, drug interactions, sleep, and substance use in adolescents

— Strongly indicated for GLUT1 deficiency (treatment of choice, mimics ketone substrate for brain)

— Reasonable adjunct for refractory CAE; requires dietitian and family commitment

— Monitor growth, lipids, renal stones, carnitine, vitamin D

— Resective surgery is not appropriate for generalized epilepsy

— Vagus nerve stimulation (VNS) can be considered in highly refractory generalized epilepsy as palliative therapy

Defining refractoriness: Failure of two appropriately chosen, adequately dosed, tolerated AEDs (monotherapy trials) → drug-resistant epilepsy. Refer to pediatric epileptologist.

Combination therapy options:

Reconsider the diagnosis in any "refractory" CAE:

Ketogenic or modified Atkins diet:

Surgical/neuromodulation:

CCS pearl: On a CCS-style case of "refractory absence in a 5-year-old," the highest-yield next orders are video-EEG, SLC2A1 genetic testing, and pediatric neurology consult — before escalating to polypharmacy. Document re-counseling on safety precautions at every visit and advance the clock by 2–4 weeks to evaluate response.

Board pearl: Refractory absence with paroxysmal exercise-induced dyskinesia or a low CSF/serum glucose ratio = GLUT1 deficiency → start the ketogenic diet, not another AED.

Special Populations — Hepatic, Renal, and Drug Interactions

— Valproate is contraindicated or used with extreme caution in significant hepatic disease, mitochondrial disorders (especially POLG mutations), and children <2 years on polytherapy — risk of fatal hepatotoxicity and pancreatitis

— Ethosuximide is hepatically metabolized (CYP3A4) but is generally safer; monitor LFTs

— Lamotrigine undergoes hepatic glucuronidation; reduce dose in moderate-severe hepatic impairment

— Ethosuximide is partially renally excreted — reduce dose if significant CKD

— Levetiracetam, topiramate, zonisamide — all require renal dose adjustment

— Lamotrigine — minimal renal adjustment

— HLA-B*1502 screening recommended before carbamazepine/oxcarbazepine in Asian ancestry — though these drugs are not used in CAE, this is a high-yield generalizable AED-safety point

— Valproate inhibits lamotrigine glucuronidation → roughly doubles lamotrigine level → half the lamotrigine starting dose and titrate slower when co-administered

— Enzyme inducers (phenytoin, carbamazepine, phenobarbital, rifampin) lower ethosuximide and lamotrigine levels

— Valproate can raise phenobarbital levels and free fraction of highly protein-bound drugs

— Lamotrigine levels are reduced ~50% by combined oral contraceptives (estrogen induces glucuronidation) — counsel on cyclic breakthrough seizures; adjust dose

— Topiramate and oxcarbazepine reduce OCP efficacy at higher doses

Hepatic impairment:

Renal impairment:

Pharmacogenomic and ethnicity considerations:

Key drug-drug interactions to know:

Oral contraceptive interactions in adolescents:

Step 3 management: Before starting valproate in any child, document baseline CBC, LFTs, and weight; for adolescent females, document a pregnancy test, contraception plan, and folic acid 0.4–4 mg daily counseling. Pre-emptive risk discussion and documentation are tested under both pharmacology and safety stems.

Key distinction: In any child with developmental regression, hypotonia, or lactic acidosis suspected of having a mitochondrial disorder — avoid valproate entirely; choose ethosuximide or lamotrigine.

Special Populations — Adolescents, Pregnancy, and Transitions

— Avoid valproate if alternatives are reasonable — risk of neural tube defects (~10×), cleft palate, cardiac malformations, and lower offspring IQ (~7–10 points)

— Prefer ethosuximide or lamotrigine; document discussion in chart

— Folic acid 0.4–4 mg daily for all adolescent females on AEDs

— Contraception counseling and pregnancy planning — multidisciplinary approach

— Switch to lowest effective dose of safest AED before conception if possible

— Lamotrigine and levetiracetam have the most favorable pregnancy data among AEDs

— Monitor lamotrigine levels (clearance increases up to 3-fold by third trimester)

— Enroll in the North American AED Pregnancy Registry

— Vitamin K is no longer routinely recommended for enzyme-inducing AEDs late in pregnancy per current guidance, but check local practice

— Atypical age — reconsider diagnosis (think GLUT1, structural lesion, or developmental epileptic encephalopathy)

— Valproate carries higher hepatotoxicity risk in toddlers, especially with polytherapy

— Up to 15% develop JME (myoclonic jerks on awakening + GTCs) — warn families about morning jerks and sleep deprivation

— A subset develops JAE with fewer but longer absences and GTCs

— Lifelong AED therapy may be required for those who evolve

— Adolescents should transition from pediatric to adult neurology with a structured handoff (seizure history, AED trials, EEG history, comorbidities, contraception plan)

— Address driving laws (state-specific seizure-free interval, often 3–12 months), employment, alcohol, and sleep hygiene

Adolescent females of childbearing potential:

Pregnancy management (when CAE persists or evolves into JAE/JME):

Younger children (<4 yrs):

Evolution to other syndromes:

Transition of care:

CCS pearl: For an adolescent female with CAE planning sexual activity, the highest-yield orders are: switch valproate to ethosuximide or lamotrigine, start folic acid, document contraception (note lamotrigine-OCP interaction), and arrange neurology follow-up. Missing any one is commonly the "best next step" trap.

Complications and Adverse Outcomes

— Absence status epilepticus — prolonged confusion, decreased responsiveness lasting minutes to hours; rare in CAE but more common in JAE; treat with IV benzodiazepine (lorazepam) and optimize maintenance AED

— Injury during seizures: drowning (highest mortality risk in pediatric epilepsy), motor vehicle/bicycle accidents, burns, falls from heights

— Generalized tonic-clonic seizures developing later — signals possible evolution to JME/JAE

— Attention deficits, executive dysfunction, and academic underachievement — present even with good seizure control

— Higher rates of ADHD, anxiety, depression, and social difficulties than in healthy peers

— Screen at every visit; consider neuropsychological evaluation

— Ethosuximide: GI upset, hiccups, headache; rare blood dyscrasias (aplastic anemia, agranulocytosis), SLE-like syndrome, Stevens-Johnson syndrome, psychosis (rare)

— Valproate: hepatotoxicity, pancreatitis, hyperammonemic encephalopathy, thrombocytopenia, weight gain, alopecia, tremor, PCOS, teratogenicity

— Lamotrigine: rash (including SJS/TEN, more likely with rapid titration or valproate combo), hypersensitivity syndrome

— Rare in CAE but families should be aware (especially if GTCs develop)

— Risk factors: uncontrolled GTCs, nocturnal seizures, non-adherence

— Stigma, bullying, restricted activities (swimming alone, driving, contact sports under certain conditions)

— IEP/504 plan to address attention and seizure-frequency-related learning gaps

Seizure-related complications:

Cognitive and behavioral complications:

Medication-related complications:

Sudden Unexpected Death in Epilepsy (SUDEP):

Psychosocial impact:

Board pearl: The most common long-term morbidity of CAE is not the seizures themselves but attention and executive-function deficits — a frequently missed answer choice. Treat the seizures AND screen for/manage neurocognitive comorbidity.

Key distinction: Brief absence-related lapses are not "status epilepticus"; absence status requires prolonged altered awareness with continuous or near-continuous spike-wave on EEG.

When to Escalate Care and Consult

— Initial diagnosis confirmation and treatment plan

— Annual or biannual follow-up while on AEDs

— Earlier referral if any atypical features

— Failure of 2 appropriately dosed first-line AEDs (drug-resistant epilepsy)

— Atypical features: focal seizures, developmental regression, abnormal exam, abnormal MRI

— Suspected GLUT1 deficiency or other genetic syndromes

— Need for video-EEG monitoring, ketogenic diet, or genetic testing

— Absence status epilepticus — prolonged confusion or altered mentation suggestive of ongoing spike-wave; requires EEG and IV benzodiazepine

— First generalized tonic-clonic seizure in a child with established CAE — evaluate for evolution to JME/JAE; usually outpatient workup unless prolonged

— Suspected AED toxicity: ataxia, encephalopathy, hepatotoxicity (valproate), severe rash (lamotrigine SJS/TEN), pancytopenia (ethosuximide)

— Trauma from a seizure-related fall, drowning event, or motor vehicle event

— Refractory status epilepticus requiring continuous EEG and IV infusion (midazolam, pentobarbital)

— Severe AED-related organ toxicity (hepatic failure from valproate, SJS/TEN from lamotrigine)

— Genetics if GLUT1 or other syndromic features suspected

— Psychology/neuropsychology for ADHD comorbidity and academic accommodations

— Dietitian for ketogenic diet

— School nurse and educators — IEP/504 coordination

Outpatient neurology referral (routine, all CAE patients):

Urgent pediatric epileptology referral:

Emergency department / inpatient escalation:

ICU criteria (rare in CAE):

Other consults:

CCS pearl: In a CCS case with an adolescent female on valproate presenting with confusion and tremor, the right early orders are ammonia level, valproate level, LFTs, CBC, and lactate — don't just escalate AEDs. Hyperammonemic encephalopathy is reversible if recognized; missing it is a tested patient-safety failure.

Step 3 management: Document a written seizure action plan at every visit — to be shared with school, caregivers, and after-school programs.

Key Differentials — Other Seizure Types

— Slower onset/offset, longer duration (often >30 sec)

— EEG: slow spike-and-wave <2.5 Hz, abnormal background

— Associated with intellectual disability, multiple seizure types (tonic, atonic, GTC)

— Requires MRI and broader workup; treated with valproate, lamotrigine, rufinamide, clobazam, cannabidiol

— Onset ~age 10–17

— Fewer, longer absences (often >10 sec)

— Frequent generalized tonic-clonic seizures (~80%)

— EEG: faster spike-wave (3.5–4.5 Hz)

— Treatment: valproate (or lamotrigine/levetiracetam in females) — ethosuximide insufficient because of GTCs

— Onset adolescence; triad of myoclonic jerks (especially on awakening), GTCs, and absences

— EEG: 4–6 Hz polyspike-and-wave

— Treatment: valproate (lamotrigine, levetiracetam alternatives); usually lifelong

— May evolve from CAE

— Longer duration (1–2 minutes), aura, postictal confusion

— Prominent automatisms typically unilateral

— Often temporal lobe origin → MRI shows mesial temporal sclerosis or other lesion

— Treatment: carbamazepine, oxcarbazepine, lacosamide, levetiracetam

— Eyelid jerks with upward eye deviation, photosensitivity, brief absences

— Triggered by eye closure and photic stimulation

— Treatment: valproate, levetiracetam

Atypical absence seizures (Lennox-Gastaut syndrome):

Juvenile absence epilepsy (JAE):

Juvenile myoclonic epilepsy (JME):

Focal impaired-awareness seizures (formerly complex partial):

Eyelid myoclonia with absences (Jeavons syndrome):

Key distinction: Absence seizures have abrupt onset/offset and NO postictal phase; focal impaired-awareness seizures have gradual evolution, longer duration, and postictal confusion. This single feature separates the two on most exam vignettes.

Board pearl: 3 Hz spike-wave = CAE; 4–6 Hz polyspike-wave = JME; <2.5 Hz slow spike-wave = Lennox-Gastaut. Memorize the EEG frequencies — they are repeatedly tested.

Key Differentials — Non-Epileptic Mimics

— Common in school-age children, especially with ADHD

— Episodes interruptible by calling the child's name or touching them — absence seizures are NOT interruptible

— No automatisms, no eyelid flutter, no EEG abnormality

— Hyperventilation does not provoke the episodes

— Pervasive across settings, gradual onset, no abrupt arrest

— May coexist with CAE — screen for both

— Stimulants treat ADHD but do not cause or worsen absence seizures at typical doses (older concern; current evidence supportive of safe use once seizures controlled)

— Stereotyped, repetitive movements without loss of awareness

— Suppressible voluntarily (tics) or interruptible (stereotypies)

— Triggered by upright posture, pain, prolonged standing; preceded by lightheadedness, pallor, nausea

— Long QT syndrome, CPVT — spells with exertion, swimming, startle; family history of sudden death

— Always obtain ECG in any child with paroxysmal loss of awareness

— Toddlers; triggered by emotional upset or pain; cyanotic or pallid type; brief loss of consciousness

— Often adolescents; longer duration, atypical features, normal EEG during typical event

— Requires video-EEG confirmation; managed with psychotherapy, not AEDs

— Longer duration, headache component, family history of migraine

— Occur from sleep, not while alert and engaged in activity

Daydreaming / inattention:

ADHD inattentive type:

Tics and stereotypies:

Syncope / cardiogenic spells:

Breath-holding spells:

Non-epileptic psychogenic events:

Migraine variants and confusional migraine:

Sleep-related events (parasomnias):

Step 3 management: A 6-year-old with "staring spells" who is fully interruptible by tapping on the shoulder and has normal HV-EEG most likely has inattention/daydreaming, not CAE — reassure, screen for ADHD, and avoid empiric AEDs. Starting valproate "just in case" is a tested wrong answer.

Key distinction: Interruptibility, postictal state, EEG, and HV-provocation distinguish CAE from its mimics — apply this checklist to every staring-spell vignette.

Long-Term Plan, Discharge Planning, and Taper

— Continue AED until child is seizure-free for ~2 years AND has a normalized EEG (no spike-wave even with HV)

— Then taper over 3–6 months under neurology guidance

— Remission rate ~65–70% with proper treatment

— Predictors of remission: typical EEG, normal cognition, no GTCs, response to first AED, normal MRI

— Predictors of evolution to JME/JAE or persistence: family history, GTCs at onset, photosensitivity, abnormal cognition

— Counsel families that some patients relapse during taper or later; restart prior effective AED at previously effective dose

— Sleep deprivation, alcohol (adolescents), missed doses, and intercurrent illness can precipitate breakthrough

— Adequate sleep, regular meals, hydration, stress management

— Swimming with adult supervision and life jacket while on AEDs and during taper

— Helmet use for biking, skating, skateboarding

— Avoid alcohol, recreational drugs in adolescents — lower seizure threshold and interact with AEDs

— Driving: per state law (typically 6–12 months seizure-free); document discussion

— Continue standard pediatric vaccinations (no AED-related contraindications)

— Annual influenza vaccination

— Dental care (gingival hyperplasia concerns mostly with phenytoin, not first-line CAE drugs)

— Bone health: consider vitamin D and calcium intake, especially with enzyme-inducing AEDs

Duration of therapy:

Prognosis:

Relapse considerations:

Lifestyle and secondary prevention counseling:

Routine health maintenance:

CCS pearl: Schedule EEG before AED taper — a persistent abnormal EEG predicts higher relapse risk and may warrant continued therapy. Ordering the EEG, then advancing the clock to review with the family before taper, is the high-yield move.

Step 3 management: A clear written seizure action plan, a medication reconciliation at each visit, and transition planning to adult neurology as the patient approaches age 18 are essential discharge/longitudinal items.

Follow-Up, Monitoring, and Family Counseling

— 2–4 weeks after AED initiation to assess response, adverse effects, adherence

— 3 months to confirm seizure freedom and tolerability

— Then every 6 months while on therapy

— Repeat EEG: at 6–12 months if seizures controlled; before taper; sooner if breakthrough

— Seizure diary: number, type, triggers, duration

— School performance, attention, behavior, mood

— Growth and weight (valproate weight gain; topiramate weight loss)

— AED adverse effects review (rash, GI, mood, alopecia, tremor, somnolence)

— Adherence — common cause of "breakthrough"

— Medication levels if breakthrough or toxicity suspected (not routine for steady-state ethosuximide/valproate)

— Valproate: baseline CBC, LFTs, ammonia (if symptomatic); repeat at 1 and 3 months, then every 6–12 months

— Ethosuximide: baseline CBC; repeat if symptomatic (rash, fever, infection, fatigue)

— Lamotrigine: mainly clinical monitoring for rash; level if breakthrough on OCPs or pregnancy

— Driving laws (when applicable), swimming/bathing precautions, sports participation

— Sleep hygiene — sleep deprivation is a major trigger

— Adolescents: alcohol, recreational drugs, contraception, planning for pregnancy

— Folic acid in adolescent females

— School accommodations: 504 plan for attention, breaks, untimed assessments after seizures

— Breakthrough seizures, change in semiology, before AED taper, new GTCs (rule out JME evolution)

Follow-up cadence:

What to monitor at each visit:

Laboratory monitoring:

Counseling topics each visit:

When to obtain repeat EEG:

Step 3 management: Use a shared electronic seizure diary (app or paper) and ensure the family brings it to each visit — pattern recognition guides taper decisions and identifies non-adherence early. Document the next planned EEG date in the chart at every visit.

Board pearl: A child with CAE on ethosuximide whose seizures are controlled but who has worsening grades should be screened for ADHD/executive dysfunction — refer for neuropsych evaluation, not necessarily medication escalation.

Ethics, Legal, and Patient Safety Considerations

— Parents/guardians provide informed consent; obtain age-appropriate assent from school-age children for AED therapy and EEG

— Document specific discussion of teratogenicity, cognitive effects, rash, and behavioral side effects — particularly with valproate in adolescent females

— Most US states require a seizure-free interval (commonly 3–12 months) before driving licensure

— Some states have mandatory physician reporting of seizure disorders (e.g., California, Pennsylvania); know your state's law

— Document each driving counseling discussion in the chart — failure to counsel is a recurring malpractice scenario

— Drowning is the leading cause of death in pediatric epilepsy; counsel no unsupervised bathing or swimming, shower preferred over tub, lifeguard supervision

— Document this at diagnosis and at follow-ups

— Provide a written seizure action plan for the school nurse and teachers

— Coordinate 504 plan for academic accommodations

— Address bullying/stigma proactively

— Counsel confidentially on contraception in adolescents on AEDs (especially lamotrigine-OCP interaction)

— Pre-conception planning for adolescent females on valproate — switch to safer agent

— Hand-off from pediatric to adult neurology at ~age 18 is a high-risk transition for medication errors and follow-up loss

— Provide a written transition summary (seizure history, EEG history, AED trials, levels, allergies, action plan, contraception, social context)

— Verify the patient has an adult neurologist appointment scheduled before transferring care

— If seizures occur in unsafe contexts suggesting neglect (e.g., medication not given, repeated burns/drownings), assess for child abuse/neglect and report to CPS per state law

Informed consent and assent in pediatric epilepsy:

Driving safety and reporting:

Water safety:

School-based safety:

Reproductive ethics and adolescent autonomy:

Transitions of care — a Step 3 priority:

Mandatory reporting:

Step 3 management: At every CAE visit, document four safety items: driving (age-appropriate), swimming/bathing, school plan, and AED adherence + adverse effects review. Missing transitions and missing teratogenicity counseling in adolescent females are the two most-tested ethics/safety failures.

High-Yield Associations and Rapid-Fire Facts

— CAE: 3 Hz spike-and-wave

— JAE: 3.5–4.5 Hz

— JME: 4–6 Hz polyspike-and-wave

— Lennox-Gastaut: <2.5 Hz slow spike-and-wave

— West syndrome: hypsarrhythmia

— CAE (no GTCs): ethosuximide

— CAE with GTCs / JAE / JME: valproate (or lamotrigine/levetiracetam in females)

— Lennox-Gastaut: valproate, lamotrigine, rufinamide, clobazam, cannabidiol

— Infantile spasms: ACTH or vigabatrin (vigabatrin first-line in tuberous sclerosis)

— Carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin, tiagabine, vigabatrin

— GABRG2, GABRA1, CACNA1H, SLC2A1 (GLUT1)

— GLUT1 deficiency: low CSF/serum glucose ratio (<0.45), paroxysmal exercise-induced dyskinesia, microcephaly → ketogenic diet

— Remission ~65–70%

— Evolution to JME ~15%

— Onset 4–10 years; F:M ≈ 2:1

— Valproate: hepatotoxicity, pancreatitis, teratogenicity

— Lamotrigine: SJS/TEN

— Ethosuximide: rare aplastic anemia, SJS

EEG frequencies — memorize cold:

First-line drugs by syndrome:

Drugs that WORSEN absence (and other generalized) seizures:

Genetic and metabolic associations:

Provocation test: Hyperventilation for 3–5 minutes — provokes absence in 80–90% of untreated patients (free, in-clinic, high-yield)

Trial that defined first-line therapy: Glauser et al., NEJM 2010 — ethosuximide > lamotrigine; ethosuximide ≈ valproate for efficacy; ethosuximide had fewer attentional adverse effects than valproate

Prognosis numbers:

Comorbidities to screen for: ADHD, anxiety, depression, learning difficulties

Therapeutic levels: ethosuximide 40–100 mcg/mL; valproate 50–100 mcg/mL; lamotrigine 4–18 mcg/mL

Black box / serious AED adverse effects:

Board pearl: When you see "3 Hz spike-and-wave + 7-year-old + staring spells + normal exam + provoked by blowing on a pinwheel," the answer is ethosuximide unless the stem mentions a generalized tonic-clonic seizure — then it is valproate. This single algorithm covers most CAE Step 2/3 questions.

Board Question Stem Patterns

— 7-year-old girl, declining grades, teacher reports "daydreaming" 20+ times/day

— In clinic, blowing on a pinwheel triggers a 10-second staring spell with eyelid flutter

— Normal exam → EEG with HV → 3 Hz spike-wave → ethosuximide

— Same child but now has a generalized tonic-clonic seizure → valproate (not ethosuximide, which doesn't cover GTCs)

— 14-year-old with absence seizures and GTCs, sexually active or considering OCPs

— Best first-line: lamotrigine or levetiracetam, NOT valproate (teratogenicity)

— Bonus: lamotrigine + OCP → reduced lamotrigine level; adjust dose

— Toddler with absences, paroxysmal exercise-induced dyskinesia, microcephaly, low CSF/serum glucose ratio → GLUT1 deficiency (SLC2A1) → ketogenic diet

— Child started on carbamazepine for "staring spells" misdiagnosed as focal seizures → absences worsened → recognize wrong drug, switch to ethosuximide

— 3 Hz spike-wave → CAE; <2.5 Hz slow spike-wave → Lennox-Gastaut; 4–6 Hz polyspike → JME

— Spells interruptible by touch + normal HV-EEG → inattention/ADHD, not CAE

— Spells with postictal confusion, aura, oral automatisms 1–2 min → focal impaired-awareness seizure → MRI brain

— Exertion-triggered spells with family history of sudden death → long QT → ECG

— Adolescent on valproate, new pregnancy → switch AED, fetal anatomic survey, folic acid, AED registry

— Counseling missed → drowning event → malpractice/safety failure

— Order EEG with HV, baseline CBC/LFTs, ethosuximide; advance clock 2 weeks; review adherence, side effects; advance to 3 months; consider taper after 2 years seizure-free with normal EEG

Classic CAE vignette:

CAE with GTC — switch the drug:

Adolescent female trap:

"Refractory" CAE:

Wrong-drug worsening seizures:

EEG frequency identification:

Mimic stems:

Safety/ethics stems:

CCS-style cases:

Board pearl: The drug "trap" is the most common CAE Step 3 question — they will offer carbamazepine, phenytoin, or gabapentin as plausible-sounding distractors. Never pick a Na+-channel blocker or GABA-reuptake inhibitor for generalized epilepsy with absences.

One-Line Recap

Childhood absence epilepsy is a genetic generalized epilepsy of school-age children diagnosed by typical brief staring spells with abrupt onset/offset, no postictal phase, and pathognomonic 3 Hz generalized spike-and-wave on EEG provoked by hyperventilation, and treated first-line with ethosuximide — switched to valproate (or lamotrigine/levetiracetam in adolescent females) if generalized tonic-clonic seizures coexist.

— Diagnosis: 3 Hz generalized spike-and-wave on EEG with HV provocation in a developmentally normal 4–10-year-old with brief, abrupt staring spells; MRI is NOT routinely needed in classic cases

— First-line therapy: ethosuximide for absence-only CAE (NEJM 2010 — equal efficacy to valproate with fewer attentional side effects); valproate if GTCs coexist; lamotrigine as alternative, especially in adolescent females

— Avoid in absence/generalized epilepsy: carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin, tiagabine, vigabatrin — they worsen seizures

— Refractory absence red flag: consider GLUT1 deficiency (SLC2A1) — confirm with low CSF/serum glucose ratio and treat with the ketogenic diet

— Long-term plan: taper AED after ~2 years seizure-free with normalized EEG; remission ~65–70%; ~15% evolve to JME

— Safety essentials: drowning prevention, driving counseling, school 504 plan, folic acid and contraception counseling in adolescent females, structured transition to adult neurology

High-yield bullet recaps:

Step 3 management: Confirm the diagnosis with EEG before treating, start ethosuximide for absence-only CAE, counsel on safety at every visit, monitor for cognitive/behavioral comorbidity even with seizure control, and re-evaluate the diagnosis before escalating to polytherapy — these five moves answer the majority of CAE board questions.