| Clinical features | Presentation in young children | Presentation in older, previously undiagnosed children or adults |
| Age of onset | | - Early childhood or unknown
|
| Seizures | - Recurrent generalized tonic-clonic or hemiconvulsive seizures (all patients), often prolonged
- Myoclonic seizures, commonly seen by age 2 years
- Obtundation status, focal dyscognitive seizures, and atypical absences, commonly seen after age 2 years
- Typical absences and epileptic spasms are atypical
| - Persisting seizures*, which include:
- Focal and/or generalized convulsive seizures
- Myoclonic, atypical, absence, and tonic seizures (less common)
- Recurrent status epilepticus becomes less frequent with age, may not be seen in adolescence or young adulthood
|
| Seizure triggers | - Hyperthermia, which may be associated with vaccination (most patients)
- Flashing lights, visual patterns, bathing, eating, overexertion
- Sodium channel blocking antiseizure medications
| - Hyperthermia (may become less problematic in adolescence and adulthood)
- Sodium channel blocking antiseizure medications
|
| Development and neurologic examination | - Normal development and neurologic examination at baseline
| - Intellectual disability (typically evident by 18 to 60 months of age)
- Crouched gait, hypotonia, incoordination, impaired dexterity (typically evident by 3 to 4 years of age)
|
| MRI | | - Typically normal, may show mild generalized atrophy and/or hippocampal sclerosis
|
| EEG | - Nonspecific findings at onset
| - Diffuse background slowing, often with multifocal and/or generalized interictal discharges; photoparoxysmal response may be seen
|
