EARLY-INFANTILE DEE (EIDEE)

Overview

Early-infantile developmental and epileptic encephalopathy syndrome (EIDEE) is characterized by frequent drug-resistant seizures that begin ≤3 months of age, with abnormal interictal EEG and neurological examination. This syndrome encompasses the previous syndromes of Ohtahara syndrome and early myoclonic encephalopathy. Treatable metabolic etiologies (especially pyridoxine and pyridoxal-5-phosphate disorders) should be excluded early.

Clinical context

This syndrome begins in the early infant period (0-3 months). Both sexes are affected equally. Family, pregnancy, and birth history are usually normal. Head size varies, depending on etiology, but may be normal at birth. Abnormalities of tone (most frequently central hypotonia) and posture are present. Abnormal neurodevelopment can precede seizure onset but may not have been recognised due to young age. Movement disorders are common and can be present at seizure onset, or appear with age. Most children will have moderate to profound developmental impairment. Cortical visual impairment, orthopaedic problems and feeding difficulties are also seen. Life-expectancy can be reduced. Seizures are usually drug-resistant unless a treatable structural, genetic or metabolic cause is found. Children with this syndrome may evolve to have infantile epileptic spasms syndrome or Lennox-Gastaut syndrome.

Causes:

• Structural brain abnormality, is the most common cause
• Genetic etiologies including chromosomal disorders, copy number variations, and pathogenic gene variations
• Metabolic etiologies (mitochondrial disorders, non-ketotic hyperglyinemia, pyridoxine/pyridoxal-5-phosphate disorders, carnitine palmitoyl transferase deficiency and others)

NOTE A cause can be found in ~80% of cases.