Feature | CAE | JAE |
Age at onset | | |
Usual | 4–10 years | 9-13 yrs |
Range | 2–13; caution if diagnosing at <4yrs of age | 8–20 years; exceptional cases may present in adulthood |
Development | Typically normal, but may have learning difficulties or ADHD | Typically normal, but may have learning difficulties or ADHD |
Absences | | |
Frequency | At least daily to multiple per day but may be underrecognized by family | less than daily |
Duration | Typical duration = 3–20 s | Typical duration = 5–30 s |
Impaired awareness | Severe loss of awareness | Less complete impairment of awareness |
Other seizure types | | |
Febrile | Occasional | Occasional |
Generalized tonic-clonic seizures | Rarely precede or occur during period of frequent absences but may occur later with evolution to other IGE syndrome | May precede and commonly occur during the period of frequent absences |
Myoclonic | Prominent myoclonus exclusionary | Prominent myoclonus exclusionary |
EEG background | OIRDA in 21% | Normal |
Interictal epileptiform
discharge | | |
Awake | 2.5–4-Hz generalized spike-wave | 3–5.5-Hz generalized spike-wave |
Asleep | Polyspike and wave may be seen in drowsiness and sleep only | |
Irregular generalized spike-wave | Uncommon | More common than CAE |
Photoparoxysmal response | Rare
IPS triggers generalized spike-wave in 15%–21% but does
not induce seizures | Rare IPS triggers generalized spike-wave in 25% but does not induce seizures |
Hyperventilation induction | 87% | 87% |
ICTAL EEG | Regular 3-Hz (range = 2.5–4 Hz) generalized spikewave; 21% may have absences starting at 2.5-Hz spike-wave, and 43% may have absences starting at 4 Hz; if no generalized spike-wave is seen with hyperventilation for 3 min in an untreated patient, CAE can be excluded Disorganized dischargesa less frequent | Regular 3–5.5-Hz generalized spike-wave If no generalized spike-wave is seen with hyperventilation for 3 min in an untreated patient, JAE can be excluded Disorganized dischargesa 8 times more frequent than CAE |
Abbreviations: ADHD, attention-deficit/hyperactivity disorder; CAE, childhood absence epilepsy; EEG, electroencephalogram; IGE, idiopathic generalized epilepsy; IPS, intermittent photic stimulation; JAE, juvenile absence epilepsy; OIRDA, occipital intermittent rhythmic delta activity. a Disorganized discharges are defined as either brief (less than 1 sec and and transient interruptions in ictal rhythm or waveforms of different frequency or morphology during the ictal rhythm. |