Myoclonic-Astatic Epilepsy usually occurs in children with an uneventful history; there is likely to be no pre-existing neurological disorder.

It clearly affects more boys than girls at a ratio of about 3:1.

In 24% of the cases, the epilepsy starts during the first year of life (at 2, 4 or 5 months of age).

In 94% of the cases, the epilepsy starts within the first five years of life.

In 100% of cases, the child develops myoclonic and/or myoclonic-astatic (or drop) seizures. The -astatic (loss of muscle tone) feature of the myoclonic-astatic seizure is rare and unique to MAE, and is the most important and distinct feature which helps differentiate it from other syndromes.

In addition to myoclonic seizures, children may also have a combination other generalised seizures including tonic-clonic, absence and non-convulsive status epilepticus and, rarely, tonic seizures. See Seizure types.

Hallmark features on an EEG help define MAE and, in almost all cases, rhythmic parietally accentuated 4-7 Hz background seizure activity develops early in the course.¨