This syndrome is characterized by onset of refractory focal seizures in the first year of life, with associated severe encephalopathy. Focal seizures arise independently in both hemispheres and can migrate from one cortical region to another randomly but consecutively in the same seizure. Seizures are often prolonged with episodes of status epilepticus. Prognosis is poor with severe neurological disability and reduced life expectancy, although a milder evolution has been reported in a few children. The cause is unknown in most cases, but a few genes have been recently linked with this syndrome.
NOTE Epilepsy of infancy with migrating focal seizures is considered an 'epileptic encephalopathy'. This term denotes the concept that the epileptic activity itself might directly contribute additional cognitive and behavioral impairments over those expected from the underlying etiology alone, and that suppression of epileptic activity might minimize this additional impairment.
This syndrome typically has onset in the first six months of life (mean 3 months), but later onset in the first year of life has been reported. Both sexes are equally affected. Antecedent and birth history is typically normal. Head size and neurological examination are usually normal at onset; neurological examination findings later are consistent with severe neurological impairment. Most patients develop microcephaly by 1 year of age. Development may be normal at onset, however regression and subsequent severe delay is typical. Prognosis is poor with ongoing intractable seizures, severe neurological disability and reduced life expectancy, although a milder evolution has been reported in a few children.