RASMUSSEN SYNDROME (RS)

OVERVIEW

This syndrome, previously known as Rasmussen encephalitis, is characterized by the onset of intractable focal hemispheric seizures (mainly focal motor seizures) with progressive neurological deterioration and hemispheric atrophy on imaging. The cause is unknown.

Clinical context

Seizures begin between 1-10 years of age (median 6 years), around 10% of cases begin in adolescence or adulthood. Both sexes are affected equally. Antecedent and birth history is usually normal, however a history of pregnancy or perinatal complications has been reported. Head size and neurological examination are usually normal prior to the epilepsy. With time, pprogressive neurological deterioration related to the affected hemisphere develops. Hemiparesis, hemianopia or language dysfunction (if dominant hemisphere) may develop. Some children may present first with a unilateral movement disorder (hemidystonia, hemiathetosis). CSF may show non-specific findings including the presence of oligo- or monoclonal bands. Brain biopsy is not required, but if done may show multifocal cortical inflammation, neuronal loss and gliosis in the affected hemisphere.

There are three stages to the illness i) an initial prodromal phase with infrequent seizures and mild hemiparesis ii) an acute phase with frequent seizures and progressive neurological deterioration and iii) a chronic stage with permanent stable impairments and ongoing seizures.