Epilepsy of infancy with migrating focal seizures

Epilepsy of infancy with migrating focal seizures (EIMFS) is a form of recurrent seizures (epilepsy) that begins early in life. Seizures typically start before the age of 6 months. Babies with this condition can reach early developmental milestones, such as the ability to follow movement with their eyes or control their head movement. However, as seizure activity develops, children with EIMFS typically stop developing new skills and may experience a gradual loss of existing skills (developmental regression).

Focal motor seizures are the most common type of seizure seen in children with EIMFS. Focal motor seizures start in one area of the brain and affect muscle (motor) activity on one side of the body. Affected individuals may have more than one focal seizure at a time, and seizure activity can spread (migrate) from one brain region to another during an episode.

Although the seizures that are associated with EIMFS may be relatively infrequent at first, the seizure frequency increases rapidly. Affected individuals often experience several seizures per day; in some cases, the seizures may seem almost continuous. Children with EIMFS may also have individual seizures that last for several minutes (status epilepticus). After a year or more of persistent seizures, the episodes may become less frequent.

In children with EIMFS, seizures can affect the growth of the brain, leading to a small head size (microcephaly). The problems with brain development can also cause significant developmental delays and intellectual disabilities. Many affected individuals do not learn to walk or talk. Additional signs and symptoms of EIMFS may include weak muscle tone (hypotonia), abnormal tensing of the muscles (spasticity), and abnormal involuntary muscle movements.

EIMFS is one of a group of severe epilepsies called developmental and epileptic encephalopathies (DEEs). These disorders are characterized by significant developmental delays and seizures that begin early in life and may be difficult to treat.

Though some people with EIMFS have had milder signs and symptoms, many affected individuals do not survive past early childhood because of the serious health problems that are associated with this condition.