Early myoclonic encephalopathy, or neonatal myoclonic encephalopathy, is a seizure disorder that begins in the neonatal period.67 Seizures consist of:

• partial or fragmentary erratic myoclonic seizures
• massive myoclonia
• partial motor seizures (jerking movements of one side)
• tonic seizures.

The EEG demonstrates bursts of spikes, sharp waves, and slow waves separated by suppression of the background activity.

Early myoclonic encephalopathy is associated with a variety of different etiologies, including nonketotic hyperglycinemia.

The seizures are very difficult to treat and affected infants are usually severely impaired neurologically. More than half of them die before 1 year of age.

Adapted from: Holmes GL. Classification of seizures and the epilepsies. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 1-36.
With permission from Elsevier (www.elsevier.com)
Reviewed and revised January 2004 by Gregory L. Holmes, MD, Dartmouth Medical School