The symptoms may start appearing as early as a few hours after birth and up to three months of age. Around three-fourths of affected children present with neonatal seizure. Other seizure types such as focal or generalized tonic seizures, epileptic  spasms or other epileptic manifestations may occur at the course of the disease. The distinctive feature of the phenotype is severe progressive encephalopathy with delay in development and abnormal neurological examination delay (hypotonia, lethargy, poor eye contact, difficulties in feeding) usually being present even before the onset of other symptoms. Head circumference is usually normal at onset but microcephaly may develop over time. Family history is usually normal. Causes
There are varied etiologies related to EME that are mainly genetic abnormalities (mutations), brain structure abnormalities, or inborn metabolic defects. Another common reason rather than structural brain abnormality is inborn metabolic defects. Sometimes a metabolic disorder that affects how the brain works may lead to EME. While most of these metabolic disorders cannot be reversed, sometimes treating the underlying disorder can help. Vitamin-responsive epileptic encephalopathies are rare but significant reasons. Genetics
A growing number of genetic aetiologies have been linked to the phenotype of EME and Otahara syndrome and diagnosis by genetic testing can nowadays be achieved in around 50 percent of cases. Some examples of well described genetic aetiologies include: KCNQ2- DEE. • SCN2A-DEE • STXBP1-DEE. • CDKL5-DEE• KCNT1-DEE and UBA5-DEE. Acquired
No acquired aetiologies are known for EME although etiology remains unknown for a small percentage of patients after genetic, metabolic, and imaging workup.
Surgery is also a treatment option. In epilepsy surgery (focal resection or hemispherectomy) the part of the brain which creates the abnormal electrical current through the brain must be resected, but the surgery is very complicated and needs to be performed by expert surgeons in epilepsy reference centers. None of these treatments, with the exception of some metabolic disorders with specific treatments available, have shown any efficacy at avoid long-term consequences of the disease. Prognosis
The prognosis is usually poor. Mortality rate is high during early infancy and almost half of the children die by 2 years of age. In the patient with severe phenotype, even when optimal treatment is initiated promptly, the prognosis remains poor. Most of the survivors suffer from psychomotor impairment and develop electroclinical features of other epilepsy syndromes (i.e Lennox- Gastaut syndrome). In patients with reduced phenotype, if there is early treatment initiated the better developmental outcome can be observed. Epidemiology
The prevalence estimates among EME are of <1 / 1 000 000. References


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