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Ohtahara Syndrome

Reviewed by: HU Medical Review Board

A rare type of epilepsy that affects infants, usually before they are 3 months old, is known as Ohtahara syndrome (OS). It is also called early infantile epileptic encephalopathy (EIEE) and EIEE with burst suppression pattern (EIEE-BS).1,2

Getting a rare disease diagnosis comes with many unanswered questions. For parents of children with Ohtahara syndrome, these questions can be difficult to cope with. Learning about the condition, what to expect, and where to find support can help ease the journey.1

What is Ohtahara syndrome?

Ohtahara syndrome is a type of epilepsy that impacts development at an early age. Boys and girls are affected equally. Most children who have Ohtahara syndrome start having seizures within the first weeks or months of life. These seizures can be hard to control. Children with Ohtahara syndrome also have developmental delays.1,2

What causes Ohtahara syndrome?

Ohtahara syndrome is most often caused by a problem with the brain or a gene change (mutation). Rarely, it is caused by a problem with the body's metabolism. In some cases, the cause is not clear.1,2

Brain structure problems

Most of the time, Ohtahara syndrome is caused by problems with how the brain develops and grows. Problems with brain structure can be either:1

  • Diffuse: Both sides of the brain are affected. Most babies with Ohtahara syndrome have this problem.
  • Focal: Only one area or side of the brain is affected. This is less common.

Genetic mutations

A genetic mutation is a change in a gene or group of genes. These changes might impact how the gene affects brain development or function. Some genetic mutations can cause Ohtahara syndrome. There are at least 15 different genes that are linked to Ohtahara syndrome.1,2

Metabolic problems

Metabolic disorders can cause Ohtahara syndrome. These disorders affect how the brain and body use energy. Problems with how the body uses energy can lead to seizures and abnormal brain function. Metabolic causes are less common in Ohtahara syndrome.1,2

Seizures and developmental delays

Types of seizures in Ohtahara syndrome

Children with Ohtahara syndrome have seizures during the first 3 months of life. Most often, the seizures happen in the first 2 weeks after birth.1

Many types of seizures can happen in Ohtahara syndrome, but tonic seizures are the most common. These seizures cause a child’s arms and legs to suddenly get stiff. Tonic seizures can:1,2

  • Last only a few seconds
  • Affect one or both sides of the body
  • Happen alone or in clusters (back to back)
  • Occur when the baby is asleep or awake

Other seizures can occur in Ohtahara syndrome, including:1,2

  • Atonic – Known as "drop attacks" because they cause the child to suddenly lose muscle tone and go limp.
  • MyoclonicQuick jerks like electrical shocks. These affect one muscle or a group of muscles.
  • Focal – Start in one part of the brain. These cause abnormal movements in one part of the body.
  • Generalized tonic-clonic – Also known as "grand mal" seizures. These cause muscle stiffening, sudden loss of alertness, and violent jerking.

Developmental delays

Infants with Ohtahara syndrome have slower development than other infants. They often reach developmental milestones later than other infants. These delays can be caused by the baby's seizures as well as by the original cause of their Ohtahara syndrome.1

How Ohtahara syndrome is diagnosed

Your child's doctor will ask you questions about your child's medical history. The doctor will also order tests such as an electroencephalogram (EEG). An EEG is a painless test that measures the electrical activity of your child's brain.1,2

Long-term video EEG monitoring (LTM) is a way to record and study seizures over time. LTM can help doctors find the type of seizure a person is having and how often the seizures happen. LTM can also help rule out other causes of seizures, such as sleep disorders.1

Burst suppression is a pattern seen on an EEG in children with Ohtahara syndrome. It is caused by electrical activity that starts and stops suddenly in the brain. This pattern can help doctors diagnose Ohtahara syndrome.1

What is the treatment?

There is no cure for Ohtahara syndrome. But treatment is available. Treatment in Ohtahara syndrome focuses on controlling seizures, including:1,2

  • Anti-seizure drugs (ASDs) – These are the first line of treatment for Ohtahara syndrome. Seizures from Ohtahara syndrome are hard to control and usually are resistant to drugs. Your child will likely need multiple drugs to help control their seizures.
  • Surgery – If your child has focal seizures (from one area of the brain), epilepsy surgery might help. A focal resection removes one part of the brain. Another option might be the removal of nearly one side of the brain (called a hemispherectomy).
  • Diet – A diet that is very low in carbohydrates and high in fat, called a ketogenic (keto) diet, might help. This diet helps some but not all people with seizures. A keto diet has risks. Talk to your doctor or nutritionist before starting a new diet.
  • Vagus nerve stimulation (VNS)VNS uses a device that is implanted under the skin and sends electrical impulses to the vagus nerve. The vagus nerve runs from the brainstem to the abdomen. The electrical impulses help prevent seizures.
  • Treating metabolism problems – Finding underlying metabolic problems and treating those might better help control seizures related to Ohtahara syndrome.

Is a good outcome possible?

Ohtahara syndrome is a very serious condition. Seizures are often frequent and hard to control. This can lead to developmental delays and difficulties with daily activities. Many children with Ohtahara syndrome require lifelong care. Some children with the condition do not survive. Early diagnosis and treatment is important for the best possible outcome.1,2

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