Prevalence
The most common type of epileptic encephalopathy.

Incidence
3 to 5/10,000 live births.

Age at onset
3 to 7 months (77%); rarely before 3 months or after 12 months to 5 years.

Sex
Males (60%) predominate.

Neurological and mental state
Developmental delay, mild or severe, pre-exists in ~2/3.

Etiology
Severe causes predominate. Tuberous sclerosis is common.

Clinical manifestations
Epileptic (infantile) spasms are the defining seizure. A cry may follow the end of the attack. Spasms occur in 1 to 30 clusters/day of 20 to 100 spasms each.

Timing
On arousal and during alert states, less often during sleep.

Diagnostic procedures
Clinical neurodevelopment assessment. Screening for electrolyte, metabolic, or other disturbances are usually normal. Unless an alternative cause is clear, CSF examination, neurometabolic tests, and chromosome analysis may lead to a specific diagnosis.

Computed tomography (CT) and mainly magnetic resonance imaging (MRI) are mandated prior to steroid treatment.

Inter-ictal EEG
Hypsarrhythmia, the archetypal pattern, occurs in 2/3 of patients. Asymmetrical and modified hypsarrhythmia occur in 1/3.

Ictal EEG
11 different types lasting for 0.5 sec to 2 min. The most common pattern (72%) consists of a high-voltage generalized slow wave, episodic low-amplitude fast activity, and marked diffuse attenuation of EEG electrical activity.

Prognosis
5% die, 65% develop intractable epilepsy, half develop permanent motor disabilities, and 2/3 develop severe cognitive/psychological impairment. Only 5% to 12% have near normal development.

Differential diagnosis
Non-epileptic conditions: normal startle responses or ‘colic, abdominal pain’, benign non-epileptic infantile spasms, benign neonatal sleep myoclonus, Sandifer syndrome of gastro-esophageal reflux, torticollis, abnormal dystonic posturing of the body, and mainly opisthotonus.

Benign or other severe forms of epilepsies in this age group.

Management options*
Vigabatrin# or adrenocorticotropin hormone (ACTH) control the spasms in 2/3 patients within days. Final outcome may not be influenced by treatment.

Resective neurosurgery can be indicated for selected medically intractable cases with localized structural lesions.

*Expert opinion, please check FDA-approved indications and prescribing information
#Not approved by the FDA