|Classification and external resources|
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 encephalopathy, with seizure onset occurring within the first three months of life, and often in the first ten days. Many, but not all, cases of OS evolve into other seizure disorders, namely West syndrome and Lennox-Gastaut syndrome.
The primary outward manifestation of OS is seizures, usually presenting as tonic seizures (a generalized seizure involving a sudden stiffening of the limbs). 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.
It is named for the Japanese neurologist Shunsuke Ohtahara (1930–2013), who identified it in 1976.
Causes and treatment
No single cause of OS has been identified. In most cases, there is severe atrophy of both hemispheres of the brain. Less often, the root of the disorder is an underlying metabolic syndrome. Although it was initially published that no genetic connection had been established, several genes have since associated with Ohtahara syndrome. It can be associated with mutations in ARX, CDKL5, SLC25A22, STXBP1, SPTAN1, KCNQ2, ARHGEF9, PCDH19, PNKP, SCN2A, PLCB1, SCN8A, and likely others.
Treatment outlook is poor. Anticonvulsant drugs and glucocorticoid steroids may be used to try to control the seizures, but their effectiveness is limited. Most therapies are related to symptoms and day-to-day living.
When the cause of the seizures is a malformation of either the left or right hemisphere of the brain then a surgical procedure, a functional hemispherectomy, can significantly improve the developmental outcome of the child and even completely stop the seizures.
Ivan Cameron, son of David Cameron, leader of the British Conservative Party and Prime Minister of the UK, was born with the condition and that of Cerebral Palsy. He died aged six on 25 February 2009, while his father was still opposition leader.
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- National Institute of Neurological Disorders and Stroke (5 December 2008). "NINDS Ohtahara Syndrome Information Page". Retrieved 2009-03-10.
- Ohtahara S, Ishida T, Oka E et al. (1976). "[On the specific age dependent epileptic syndrome: the early-infantile epileptic encephalopathy with suppression-burst]". No to Hattatsu (in Japanese) 8: 270–9.
- Holmes, Gregory L. (January 2004). "Tonic". Epilepsy.com/Professionals. Retrieved 2007-11-26.
- Nabbout, Rima (July 2004). "Early infantile epileptic encephalopathy" (PDF).
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- Kato M, Saitoh S, Kamei A et al. (August 2007). "A Longer Polyalanine Expansion Mutation in the ARX Gene Causes Early Infantile Epileptic Encephalopathy with Suppression-Burst Pattern (Ohtahara Syndrome)". Am. J. Hum. Genet. 81 (2): 361–6. doi:10.1086/518903. PMC 1950814. PMID 17668384.
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- "Cameron's 'beautiful boy' dies". BBC News Online. 25 February 2009. Retrieved 2009-03-10.
- Ohtahara syndrome information from Epilepsy Action
- Aaron's Ohtahara, an organization dedicated to helping families with children diagnosed with Ohtahara Syndrome