UNKNOWN ETIOLOGY

'Unknown' is meant to be viewed neutrally and to designate that the nature of the underlying cause of the epilepsy is as yet unknown; this may be because it has not been investigated, or because all current investigation has failed to identify the etiology.

Epilepsy syndromes with unknown etiology

• Rasmussen syndrome
• Febrile infection-related epilepsy syndrome

NOTEThough the etiology of the progressive acquired hemispheric injury in Rasmussen syndrome is unknown, it is still considered an 'etiology-specific epilepsy syndrome' as the final acquired hemispheric injury is itself the cause of the electroclinical syndrome.