Childhood absence epilepsy occurs in children 4–8 years of age with peaks around 6 years. It is more frequent in girls. CAE is characterized by very frequent absence seizures (pyknolepsy). Hyperventilation induces the absence seizures. Based on clinical and electrographic features, absence seizures are classified as typical and atypical absence seizures.

Typical absence seizures are associated with transient impaired consciousness (behavioral arrest, staring) with or without eye fluttering and automatisms. Onset and cessation are abrupt. Ictal EEG shows >2.5 Hz generalized spike and wave lasting >3 s (average <10 s).

Atypical absence seizures tend to have less abrupt onset and cessation, greater change in tone, longer duration, and variable impairment of consciousness. Interictally, the EEG shows generalized irregular and asymmetric slow spike and waves (1.5–2.5 Hz). The ictal EEG is similar to the interictal discharges but may be associated with diffuse fast activity.

According to the cortical focus theory, spikes are generated at a cortical focus and propagate rapidly via cortico-cortical networks to both hemispheres resulting in rapid synchronization. Paroxysmal oscillation in the cortico-thalamic loops amplifies and sustains the spike-wave discharges.

Genetic mutations currently account for a small proportion of patients with absence epilepsy. Mutations in GABA receptor (GABRG2, GABRA1), calcium channels, and non-ion channel proteins have been identified in CAE. Glut-1 transporter deficiency is described in about 10% of children with early-onset (under the age of 4 years) absence epilepsy.

Several animal models are available for generalized epilepsy and absence epilepsy, which include acute pharmacologic models [pentylenetetrazole (PTZ), penicillin, THIP, GBL], chronic models [genetic absence epilepsy rats from Strasbourg (GAERS), Wistar Albino Glaxo/Rijswijk (WAG/Rij)] and other models [AY-9944, MAM-AY].

These include ethosuximide, lamotrigine, and valproate [1]. A double-blinded, randomized, comparative clinical trial compared the three medications in CAE and found that ethosuximide provided the best combination of seizure control and fewest attentional side effects, making it the optimal initial monotherapy in CAE. Ethosuximide provided better seizure control compared to lamotrigine and fewer attentional effects compared to valproic acid. Although CAE is often perceived as “benign”, many children with CAE have cognitive deficits and long-term psychosocial problems.

The majority (70%) of children with epilepsy with myoclonic absences are boys. The average age of onset is 7 years. In about one-third of patients a specific cause is identified. Family history of epilepsy is reported in 20%. Neuroimaging abnormalities, mainly some degree of diffuse atrophy, are seen in 17% of patients.

Patients have variable impairment of consciousness. Myoclonic jerks involving shoulders, arms, and legs are seen. Tonic contractions, particularly elevation of the arms, are often noted. At times, the tonic activity may be asymmetric. Arrest of respiration and urinary incontinence may occur. Seizures last 10–60 s and frequent seizures may occur on awakening. Other seizure types such as GTC, absence, and drop seizures may also occur. Some children may evolve to Lennox-Gastaut syndrome (LGS), and cognitive impairment may occur.

The ictal EEG shows 3 Hz rhythmic, bilateral, synchronous, and symmetric spike-wave discharges. Intermixed polyspikes may be seen. Bilateral myoclonias occur at same frequency as spike waves, i.e., 3/second. Treatment options include valproate and ethosuximide [2].

[Also known as Doose syndrome, or Epilepsy with myoclonic astatic epilepsy]

Age of onset is 1–5 years, and the child is normal at onset. There is strong family history of idiopathic epilepsy in 15–32%. Myoclonic and atonic seizures with falls suggest the diagnosis. A mix of generalized seizures occurs including myoclonic, atonic, absence, GTC, and tonic (less common). Non-convulsive status epilepticus may occur on awakening from sleep or nap. GTC is usually the first seizure and is seen in 75–95% of patients. Prognosis for seizure and cognitive outcome is variable.