Myoclonic Epilepsy Beginning in Infancy or Early Childhood Workup

Updated: Jul 26, 2022
  • Author: Michael C Kruer, MD; Chief Editor: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP, FANA  more...
  • Print

Approach Considerations

EEG is the centerpiece of the diagnostic evaluation. If neuroimaging is performed, magnetic resonance imaging is preferred. Results are often normal, reflecting a genetic rather than structural etiology, although congenital brain abnormalities sometimes are observed. In some forms of childhood myoclonic epilepsy, progressive cortical atrophy may be seen.



The ictal EEG correlate of myoclonic seizures consists of fast spike-wave discharges (>2.5 Hz), which, at times, are associated with slower 2- to 2.5-Hz discharges. [10] Interictal recordings may be normal or show slowing, depending on the etiology. Like other generalized epilepsies, abnormalities are frequently seen on routine EEG, even if myoclonus is not captured.

Brief (< 3 seconds) interictal bursts of irregular polyspike-waves may be seen either spontaneously or with photic stimulation. The occurrence of these discharges is increased during non–rapid eye movement (REM) sleep.

Also see EEG in Common Epilepsy Syndromes, EEG Video Monitoring, and Generalized Epilepsies on EEG.


Additional Testing

Genetic tests

In select cases, testing for SCN1A or other genetic etiologies suggested by clinical history and/or examination may be appropriate.

Lumbar puncture

Lumbar puncture may be helpful in identifying mitochondrial disorders (elevated cerebrospinal fluid [CSF] lactate) or nonketotic hyperglycinemia (elevated CSF glycine). Elevated protein may indicate a neurodegenerative disease.