17.2 Epilepsy Syndromes & Status Epilepticus
Key Takeaways
- Childhood absence epilepsy presents with brief, frequent staring spells with abrupt onset and offset and no postictal confusion, confirmed by generalized 3 Hz spike-and-wave discharges on EEG.
- Ethosuximide is first-line for pure absence seizures; carbamazepine, oxcarbazepine, phenytoin, and vigabatrin can worsen absence seizures.
- Infantile spasms (West syndrome) present as a triad of epileptic spasms, hypsarrhythmia, and developmental regression around 3-12 months, and tuberous sclerosis complex is the most common identifiable cause.
- Status epilepticus treatment is time-based: a benzodiazepine at 5 minutes, a second-line agent (fosphenytoin, levetiracetam, or valproic acid) at 20 minutes, and anesthetic infusion with ICU-level care at 40 minutes.
- Bedside glucose must be checked and hypoglycemia treated during initial stabilization of any seizing child, since hypoglycemic seizures will not respond to antiepileptic drugs alone.
Epilepsy Syndromes & Status Epilepticus
Pediatric epilepsy syndromes are defined by a cluster of typical age of onset, seizure semiology, electroencephalogram (EEG) pattern, and prognosis; the exam rewards recognizing the overall pattern rather than memorizing every possible syndrome. This section covers the syndrome tested most often on Part 1 (childhood absence epilepsy), two other syndromes you must recognize on sight (benign rolandic epilepsy and infantile spasms/West syndrome), and the time-based management of status epilepticus, one of the highest-yield algorithms on the exam.
Childhood Absence Epilepsy
Childhood absence epilepsy (CAE) typically begins between 4 and 10 years of age (peak 5-7 years) and is more common in girls. The hallmark presentation is brief, frequent staring spells:
- Sudden onset and offset, with no aura and no warning
- Duration of roughly 5-10 seconds
- Behavioral arrest with a blank stare; may include subtle automatisms such as eyelid fluttering or lip smacking
- No postictal confusion; the child resumes the prior activity immediately
- Can occur dozens to hundreds of times per day, often mistaken for daydreaming or inattention and misdiagnosed as attention-deficit/hyperactivity disorder
- Reliably provoked by 3 minutes of hyperventilation in clinic, a classic bedside diagnostic maneuver and a favorite exam stem
The EEG is diagnostic: generalized, bilaterally synchronous 3 Hz spike-and-wave discharges on an otherwise normal background, activated by hyperventilation.
Treatment: ethosuximide is first-line for pure absence seizures with no generalized tonic-clonic component; valproic acid is preferred if the child also has generalized tonic-clonic seizures; lamotrigine is an alternative. A classic exam trap is selecting carbamazepine, oxcarbazepine, phenytoin, gabapentin, or vigabatrin; these agents can worsen absence seizures and should be avoided.
Prognosis is generally favorable; most children outgrow CAE by adolescence, although a minority go on to develop juvenile myoclonic epilepsy or other generalized epilepsies.
Other High-Yield Pediatric Epilepsy Syndromes
| Syndrome | Typical age | Seizure pattern | EEG | Prognosis |
|---|---|---|---|---|
| Benign rolandic epilepsy (benign epilepsy with centrotemporal spikes) | 3-13 years, peak 7-10 | Nocturnal focal seizures: unilateral facial or oral twitching, drooling, speech arrest; may secondarily generalize | Centrotemporal spikes, activated by sleep | Excellent; remits by adolescence, often needs no daily medication if seizures are infrequent |
| Infantile spasms (West syndrome) | 3-12 months, peak about 6 months | Clusters of flexor, extensor, or mixed spasms, often on waking | Hypsarrhythmia: chaotic, high-voltage, disorganized background | Often poor; high rate of evolution to Lennox-Gastaut syndrome and intellectual disability |
Benign rolandic epilepsy is reassuring: seizures are typically brief, nocturnal, and infrequent, and the EEG abnormality dramatically out-paces the mild clinical picture, so this syndrome should not be over-treated.
Infantile spasms/West syndrome is the opposite: it is a neurologic emergency for development. The classic triad is epileptic spasms, hypsarrhythmia, and developmental regression or arrest. Any infant who stops meeting milestones or loses previously acquired skills around 6 months of age with new spasm-like movements needs an urgent EEG. Tuberous sclerosis complex is the most common identifiable structural or genetic cause and should be actively screened for on exam (hypopigmented ash-leaf macules on skin exam, cardiac rhabdomyoma on echocardiogram). Other causes include hypoxic-ischemic encephalopathy and other structural brain malformations, and many cases remain cryptogenic. First-line treatment is adrenocorticotropic hormone (ACTH) or high-dose oral corticosteroids; vigabatrin is preferred first-line specifically when tuberous sclerosis is the underlying cause, and is also used more broadly.
Status Epilepticus: The Time-Based Algorithm
Status epilepticus (SE) is operationally defined for treatment purposes as a single seizure lasting 5 minutes or longer, or recurrent seizures without return to baseline consciousness between them; the older strict definition of 30 minutes describes established status rather than the point at which treatment should begin. Every additional minute of ongoing seizure activity increases the risk of neuronal injury and treatment resistance, so the exam rewards knowing exactly which therapy belongs at which time point.
| Time / line of therapy | Action |
|---|---|
| 0-5 minutes | Stabilize: airway, breathing, and circulation; give oxygen; check bedside glucose and treat hypoglycemia; obtain intravenous (IV) access |
| 5 minutes, first-line | Benzodiazepine: IV lorazepam (0.1 mg/kg), or intramuscular (IM) midazolam (0.2 mg/kg, preferred if IV access is not yet available), or rectal diazepam. May repeat one dose if the seizure continues after about 5 minutes |
| 20 minutes, second-line | IV fosphenytoin (20 mg/kg phenytoin-equivalents), or levetiracetam (about 60 mg/kg, up to 4500 mg), or valproic acid (about 40 mg/kg) |
| 40 minutes, third-line/refractory | Repeat or combine second-line agents, or proceed to continuous anesthetic infusion (midazolam, pentobarbital, or propofol) with intubation, continuous EEG monitoring, and intensive care unit (ICU) admission |
Exam traps: first, treatment should not wait for a true 30-minute mark before starting benzodiazepines; treatment starts at the 5-minute mark. Second, IM midazolam is the preferred first-line route when IV access is not immediately available, rather than delaying treatment to secure a line. Third, bedside glucose must always be checked and hypoglycemia treated as part of initial stabilization, since hypoglycemic seizures will not respond to antiepileptic drugs alone. Fourth, seizures refractory to an adequate benzodiazepine dose plus one second-line agent are termed refractory status epilepticus, and status persisting beyond 24 hours despite anesthetic-level therapy is termed super-refractory status epilepticus.
A 6-year-old girl is brought in for episodes her teacher describes as daydreaming: brief 5-10 second blank stares occurring many times a day, with no confusion afterward. In clinic, 3 minutes of hyperventilation reproduces a typical episode. Which EEG finding would confirm the diagnosis?
A child recently diagnosed with childhood absence epilepsy is started on a new antiepileptic drug, after which her staring spells become more frequent. Which medication most likely explains this worsening?
A 7-month-old who previously smiled, tracked, and rolled over now has clusters of sudden flexor spasms on waking and has stopped smiling or tracking objects. What is the most likely diagnosis and the most appropriate next step?
A 4-year-old has had continuous generalized tonic-clonic seizure activity for 22 minutes. IV lorazepam was given at 5 minutes with no sustained response, and a second appropriately dosed benzodiazepine was given at 10 minutes. Bedside glucose is normal. What is the most appropriate next step?