What is Ohtahara Syndrome?
Ohtahara syndrome is a neurological disorder which shows a pattern of burst activity observed on an electroencephalogram. In Ohtahara syndrome, the babies suffer from epileptic seizures and also they are intellectually disabled. Ohtahara syndrome gets the name EIEE – Early Infantile Epileptic Encephalopathy with burst suppression because of this reason. The infants may usually have tonic seizures, but they may also have partial or myoclonic seizures. In Ohtahara syndrome, the patients have underdeveloped parts of brain particularly cerebral hemispheres.1 This syndrome is named after Shunsuke Ohtahara, a Japanese neurologist who found out this syndrome in 1976.
Ohtahara syndrome affects the new born babies and the children of 3 – 4 months of age, but most of the times, the babies of 10 days of age are the victims. Some study reports show that that boys are more affected than girls. It is a progressive epileptic encephalopathy.
Causes of Ohtahara Syndrome
In most of the cases the reason for Ohtahara syndrome cannot be determined. Also, there is no single cause of Ohtahara syndrome. It is suspected that the cause of Ohtahara syndrome might be any physiological damage to the brain or any metabolic disorder. The abnormalities in brain might be seen which are identified as hemimegaloencephaly, Olivary dentate dysplasia, agenesis of mamillary bodies, linear sebaceous nevus syndrome, porencephaly, focal cortical dysplasia, etc. New researches have shown that Ohtahara syndrome is associated with various kinds of genetic mutations in STXBP1, SCN2A, ARX, KCNQ2, CDKL5, SLC25A22, SPTAN1, ARHGEF9, PCDH19, PNKP, PLCB1, SCN8A and other genes. In case it is confirmed from EEG, that there is no such abnormalities in brain or its associated parts, it is suspected that the Ohtahara syndrome might be related to metabolism. In such cases, it is identified as mitochondrial respiratory chain complex I defect.
Epidemiology of Ohtahara Syndrome
It has been difficult to bring about the number and area of prevalence. Ohtahara syndrome is a very serious disease of the neonates. Many times the infants die so soon even before any clinical evaluations or EEG studies. Hence the rate of mortality and morbidity is more in Ohtahara syndrome. The seizures are seen in 1 to 5 per 1000 newborn babies.
Symptoms of Ohtahara Syndrome
Ohtahara syndrome is infant epilepsy which is very rare. Though the main symptom of Ohtahara syndrome is the epileptic seizures which is age related, there are some other symptoms-
Epileptic Seizures- Sudden stiffening of muscles of limbs which is called tonic seizures. These are typical pharmaco-resistant seizures.
Physical Disabilities- Rarely, this syndrome is associated with some other symptoms like diplegia (parts of either side of the body is paralyzed), hemiplegia (one side of the body is paralyzed), tetraplegia (all the four limbs having spasticity and weakness), ataxia (there might be lack of balance due to poor coordination of the parts of the body), or dystonia (increased tone causing abnormal movement).
Repeated seizures and other problems suggestive of brain damage can also reflect with some mental disabilities.
Diagnosis of Ohtahara Syndrome
Diagnosis of Ohtahara syndrome can be made on the basis of clinical presentation and by taking electroencephalograph (EEG). In the EEG, a typical pattern is exhibited. The pattern is called as ‘burst suppression’ which is characterized by high voltage spike wave discharge which is followed by little brain wave activity. The duration of the tonic seizures would be at the interval of 5 to 10 sec. The frequency also will be more, with higher amplitude. In case if there is no such abnormalities found in EEG studies, metabolic screening is done which would be identified as the main cause.
Treatment for Ohtahara Syndrome
The treatment for Ohtahara syndrome includes therapies for symptoms and day to day care. There are some drugs and supportive therapies which may be helpful but the effectiveness is very poor. The kind and duration of the treatment would be decided by the specialists depending upon the condition, severity and the cause of the syndrome.
The possible treatment of Ohtahara syndrome and therapies caused as a result of both brain abnormalities and metabolic changes are given here-
- Specialists try to address the seizures by prescribing antiseizure drugs, though in most of the cases are ineffective.
- Steroids like corticosteroids are prescribed in some cases of Ohtahara syndrome.
- To improve the health condition of Ohtahara syndrome patient, a special diet with high fat and low carbohydrate (ketogenic diet) is advised.
- In few cases surgery is performed where there are physiological abnormalities in brain such as damage or abnormal development. In focal cerebral dysplasia, a neurosurgery is sometimes helpful.
- There are special therapies for abnormal muscle tone.
- Stomach or lung problems are addressed with specific drugs and therapies.
- Most of the times, physical, speech and occupational therapies would be supportive.
- Palliative care would be helpful and supportive in Ohtahara syndrome.
- Vitamin and coenzyme therapies are helpful in many cases.
- For some patients of Ohtahara syndrome, antioxidant treatment is also advised.
In some cases of infantile epileptic encephalopathies, Vigabatrin treatment would be surely helpful to control the seizures. It is found out from some records that this treatment particularly used for infantile spasms, helped up to 50% of the patients. In spite of its great help towards controlling the spasms, the side effects of it like irreversible bilateral concentric constriction of visual fields should also be considered while deciding the duration and dosage.
Prognosis of Ohtahara Syndrome
Ohtahara is a progressive syndrome. Both the physical and cognitive development is hindered because of the seizures. While anti-convulsive treatment may help, many times epilepsy surgery is not helpful. The children in some cases will either die in infant stage itself or may have physical or mental abnormalities if survived.2
Ohtahara syndrome is progressive epilepsy of infants which would affect the newborns between the ages of 10 days to 3 months. Infant mortality rate is high and the reason for Ohtahara syndrome in many cases is unknown. It is found from records that it is not an inherited syndrome. Seizures in infants is the most identified symptom and as the children grow, they may have learning disabilities. Also in most survived individuals, they may also be physically handicaps. As such there are no effective drugs for Ohtahara syndrome. The research is going on in this way. Physiotherapies, medications, nutritional support and some other caring techniques specified for Ohtahara syndrome would be helpful for managing the condition of the children.