Ohtahara syndrome (also known as early infantile epileptic encephalopathy, EIEE) is a syndrome characterized by frequent intractable seizures and severe early encephalopathy resulting in limited development and reduced life expectancy. Tonic seizures predominate, myoclonic seizures are uncommon, distinguishing this syndrome from early myoclonic encephalopathy. Treatable metabolic etiologies (especially pyridoxine and pyridoxal-5-phosphate disorders) should be excluded early.
NOTE Ohtahara syndrome is considered an 'epileptic encephalopathy'. This term denotes the concept that the epileptic activity itself might directly contribute additional cognitive and behavioral impairments over those expected from the underlying etiology alone, and that suppression of epileptic activity might minimize this additional impairment.
This syndrome has onset in the first month of life (range 1-3 months). Both sexes are affected equally. Antecedent and birth history is typically normal. Head size is typically normal, however microcephaly may occur. Neurological examination is abnormal in keeping with underlying structural brain abnormalities (if any) and the presence of severe neurological impairment. Abnormal neurological behavior may be present prior to onset of seizures. Severe developmental delay is seen, with or without regression. Children with this syndrome may evolve to have West or Lennox Gastaut syndrome.
There is overlap in the etiologies that cause Ohtahara syndrome and early myoclonic encephalopathy.