Ohtahara EEG

An EEG (electroencephalogram) in Ohtahara syndrome is very abnormal with a burst suppression pattern (high amplitude spikes followed by little brain activity or flattening of the brain waves).

What is Ohtahara syndrome?

Ohtahara syndrome is a rare epilepsy syndrome seen in infants. It is also known as early infantile epileptic encephalopathy (EIEE) or early infantile epileptic encephalopathy with burst suppression pattern.

  • Seizures begin before age 3 months.
  • Babies typically show severe developmental challenges and abnormal neurological examination, even before seizures start.
  • Motor and cognitive problems can get progressively worse as seizures increase.
  • Ohtahara syndrome can affect both boys and girls.

What types of seizures are seen in Ohtahara syndrome?

Many seizure types may occur, but tonic seizures (stiffening of the arms or legs) are seen most often.

  • These seizures last only seconds and can occur alone or in clusters.
  • They may affect one side of the body more prominantly.
  • They are seen both when the baby is awake and sleeping.
  • Other seizure types that may also occur in Ohtahara syndrome include focal (start in one area of the brain), atonic, myoclonic or generalized tonic-clonic seizures.
  • Infants with Ohtahara syndrome may also develop infantile spasms.

What causes Ohtahara syndrome?

Most cases of Ohtahara syndrome are due to brain malformation or certain gene mutations. Metabolic causes are less likely. In some cases, no clear cause is found.

Brain malformations may be diffuse (affecting both sides of the brain) or focal (affecting only one area or side).

Gene mutations refer to changes in a gene or group of genes that may affect how the gene affects brain development or function. Some genes that have been associated with Ohtahara syndrome include

  • ARX
  • CDKL5
  • SLC25A22
  • STXBP1
  • SPTAN1
  • KCNQ2
  • ARHGEF9
  • PCDH19
  • PNKP
  • SCN2A
  • PLCB1
  • SCN8A
  • ST3GAL3
  • TBC1D24
  • BRAT1

How is Ohtahara syndrome diagnosed?

Diagnosing a baby with Ohtahara syndrome is based on clinical features (what signs or symptoms the baby has) and EEG (electroencephalogram) findings.

The EEG is the most important test in making a diagnosis of Ohtahara syndrome.

  • The EEG is very abnormal with a burst suppression pattern (high amplitude spikes followed by little brain activity or flattening of the brain waves). (See test image at the top of the page.)
  • These changes can be seen during sleep and when the infant is awake.

An MRI (magnetic resonance imaging) scan is required to look for structural changes in the brain that could cause Ohtahara syndrome. If the MRI is initially normal, follow up MRIs can show atrophy (shrinkage) of the brain.

Genetic testing with chromosomal microarray followed by an epilepsy gene panel or whole exome sequencing should be done if no cause is found on MRI.

Blood and urine tests to evaluate for metabolic disorders should also be considered.

How is Ohtahara syndrome treated?

Anti-seizure medications are routinely used, but seizures with Ohtahara syndrome are usually drug resistant. Medications that are often tried include vigabatrin (Sabril), ACTH or prednisone, clobazam (Onfi), clonazepam (Klonopin), topiramate (Topamax), zonisamide (Zonegran), phenobarbital, valproate, or felbamate (Felbatol).

Epilepsy surgery may be an option in children with seizures starting in one area or involving one side of the brain. In these situations, a focal resection (removal of one area) or a hemispherectomy (removing most of one side of the brain) should be considered early. Successful surgery may be associated with improved developmental outcome.

Ketogenic diet may be considered if seizures are drug resistant and the child is not a candidate for epilepsy surgery.

When a child is in the early preschool years, a vagus nerve stimulator (VNS) could be considered.

Correcting Metabolic Problems

Sometimes a metabolic disorder that affects how the brain works may lead to Ohtahara syndrome. While these currently can’t be reversed, sometimes treating the underlying disorder can help.

What is the outlook for people with Ohtahara syndrome?

The outlook for children with Ohtahara syndrome may be grim. Many children progress to have infantile spasms (West Syndrome) or Lennox-Gastaut syndrome (LGS). Some children with Ohtahara syndrome may die within the first 2 years of life. Those who survive are typically left with severe physical and cognitive disabilities.

Children who are candidates for epilepsy surgery should be considered for that procedure early, as this may lead to improved developmental outcome.

Hope for children with Ohtahara syndrome relies on the medical and research community understanding more about the causes and what treatment may work best in Ohtahara syndrome.

The Rare Epilepsy Network (REN) helps connect families with research in these areas.

Resources

Authored By: 
Elaine Kiriakopoulos MD, MSc
Angel Hernandez MD
Elaine Wirrell MD
Authored Date: 
11/2019
Reviewed By: 
Elaine Wirrell MD
on: 
Sunday, November 24, 2019