This is a very rare epilepsy syndrome. Seizures start before 3 months of age. Many babies have an underlying structural brain abnormality or a metabolic (biochemical) disorder. This may be genetic in origin (passed on through the genes), or happen because of brain damage before or around the time of birth. A number of gene abnormalities, called mutations, may also cause Ohtahara syndrome. These include STXBP1, ARX, CDKL5 and PNKP. Other mutations will almost certainly be found in the future. However, no cause will be found in some infants.
It is one of the group of severe epilepsy syndromes that start in the first year of life and are called the ‘Developmental and epileptic encephalopathies’.
This syndrome is quite similar to another developmental and epileptic encephalopathy called ‘Early myoclonic encephalopathy’.
Other names for Ohtahara syndrome
• Early infantile epileptic encephalopathy (EIEE) with burst-suppression
Seizures usually start in the first 7 to 10 days of life. Sometimes the mother may realise her baby was having seizures during the last couple of months of her pregnancy, when she sees her baby having seizures after birth.
Different types of seizures happen in this syndrome. The most common type is a tonic spasm where the baby suddenly has stiffening of the limbs, which last between 2 and 6 or more seconds. These tonic spasms may be quite subtle or quite severe. They are not the same as the epileptic spasms (infantile spasms) that occur in West syndrome. Children with Ohtahara syndrome also have focal (partial) motor seizures and myoclonic seizures with jerking of one limb, or one side of the body. These may last a few seconds to several minutes. Generalised seizures may happen later. After between 2 and 7 months, the seizure type may change to infantile spasms and the child may then develop West syndrome.
A full account and description of what happens during the seizures is important for the doctors to make the diagnosis. It is always helpful if you can record a video of some of the seizures and show these to the hospital doctor.
The EEG test, which records the electrical activity in the brain, is always abnormal, showing evidence of abnormal discharges, or spikes and waves (the ‘burst’) alternating with periods of looking flat and featureless (‘suppression’). This type of record is referred to as ‘burst-suppression’ pattern.
Epilepsy Action has more information on diagnosis.
The seizures are often resistant to epilepsy medicines. The choice of medicine is difficult, but often some of the older medicines, such as phenobarbital, are tried first. Other medicines that may be effective include levetiracetam (Keppra), clobazam (Frisium), clonazepam (Rivotril), vigabatrin (Sabril) and zonisamide (zonegran). Other medicines such as pyridoxine and pyridoxal phosphate and a course of steroids called prednisolone may also be effective in a small number of children. Some babies with a focal (in one area only) structural brain abnormality seen on a magnetic resonance imaging (MRI) scan may be able to have epilepsy surgery to remove the abnormal area of brain. It may be possible to reduce the numbers of seizures if the baby is found to have a treatable metabolic (biochemical) disorder.
If your child has this syndrome it is very likely they will have prolonged or repeated seizures that continue over many minutes or even hours. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.
There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.
Information about treatments for children can be found on the Medicines for Children website.
Affected babies do not behave normally. They are very floppy and excessively sleepy (described as an encephalopathy) and often have difficulty with feeding. With time they may develop stiffness (spasticity) in the limbs. They also make very little developmental progress and remain totally dependent. They often feed poorly. Sadly, they often die within the first two years of life, because of complications, including repeated chest infections. Those who do survive are usually severely disabled and will continue to have seizures despite treatment. Many babies go on to develop West syndrome, usually between 3 and 9 months of age.
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What is a syndrome?
A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.
If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact the Epilepsy Action Helpline.