Abstracts

Rationale: Rasmussen Encephalitis is a rare devastating childhood disease characterized by intractable epilepsy, frequently with continuous partial epilepsy, progressive hemiparesis and unilateral hemispheric atrophy. The progression of the symptoms to significant neurological impairment usually occurs in months to few years. Rasmussen Encephalitis causes are unknown although evidence of autoimmune process has been extensively describe in the literature. Antiepileptic drugs are not effective controlling seizures and cerebral atrophy, and surgery with hemispheric disconnection is the treatment of choice to avoid mental retardation, dementia and death. Electrencephalographic abnormalities includes in early stages focal or lateralized intermittent or continuous slowing. With the progression of the disease continuous spikes, especially over the central motor area are observed and a pattern of recurrent seizures starts. Neuropathology characteristically shows cortical abnormalities that consisted mainly of microglial nodules, perivascular lymphocytic cuffing and neuronophagy. Methods: 23 patients with Rasmussen Encephalitis were evaluated between January 1995 and March 2008. The following variables were analyzed: age at surgery, age at epilepsy onset, antecedent of an initial precipitating injury, etiology, seizure semiology, interictal and ictal EEG findings, surgical considerations and post-surgical seizure outcome Results: Twelve patients (52.2%) were female. The youngest child in the entire group had two years of age, the oldest 14 years (mean: 7.8 ± 3.5 years). The mean age at epilepsy onset was 5.6 ± 2.5 years. Duration of epilepsy had a mean of 2.7 ± 2.6. All patients had daily focal motor seizure at the time of evaluation. Twenty two patients were operated on: 16 patients were submitted to hemispheric disconnection, three patients had anatomical resections, one patient was submitted to peri-sylvian resection, one patient to temporal lobectomy and one patient to frontal lobectomy (for diagnosis purpose only, parents refused hemispheric surgery). The surgical specimens revealed Rasmussen Encephalitis typical findings that consisted of microglial nodules, perivascular lymphocytic infiltrate, neuronophagia and gliosis. Mean follow-up was 65 months. Ten patients had total seizure control and 12 persisted with seizures that were mild facial jerks in four, occasionally hemigeneralized tonic-clonic seizures in three and frequently tonic-clonic seizures in five. Considering the five patients with worst outcome, one patient had seizure recurrence four years after surgery and another one after antiepileptic drugs were dropped out by parents and two patients died in follow-up. Patients operated on dominant hemisphere had moderate language impairment even when operated before seven years old Conclusions: Seizure control in patients with Rasmussen encephalitis may be achieved with hemispheric surgery. Language impairment may be severe and persistent in long term follow-up