Ohtahara Syndrome

Ohtahara syndrome (OS), also known as Early Infantile Epileptic Encephalopathy with Burst-Suppression (EIEE), is a progressive epileptic encephalopathy.
The syndrome is outwardly characterized by tonic spasms and partial
seizures, and receives its more elaborate name from the pattern of burst
activity on an electroencephalogram (EEG). It is an extremely debilitating progressive neurological disorder, involving intractable seizures and severe mental retardation. No single cause has been identified, although in many cases structural brain damage is present.



Ohtahara syndrome is rare and the earliest-appearing age-related epileptic encephalophy, with seizure onset occurring within the first three months of life, and often in the first ten days.[3] Many, but not all, cases of OS evolve into other seizure disorders, namely West syndrome and Lennox-Gastaut syndrome.[2]

The primary outward manifestation of OS is seizures, usually presenting as tonic seizures (a generalized seizure involving a sudden stiffening of the limbs).[4] Other seizure types that may occur include partial seizures, clusters of infantile spasms, and, rarely, myoclonic seizures. In addition to seizures, children with OS exhibit profound mental and physical retardation.

Clinically, OS is characterized by a “burst suppression” pattern on an EEG. This pattern involves high voltage spike wave discharge followed by little brain wave activity.[2]

It is named for the Japanese neurologist Shunsuke Ohtahara (1930– ), who identified it in 1976.