Rasmussen's encephalitis is a rare neurological disorder of uncertain etiology.

Mechanism: It appears to be mediated by T cells. Antineuronal autoantibodies have not been identified (Samanci et al).


Clinical features:

(1) It usually occurs in pediatric patients and young adults.

(2) There is unilateral inflammation of the cerebral cortex with eventual atrophy.

(3) The patient usually develops drug-resistant epilepsy, A few patients may be free of seizures.

(4) There is progressive cognitive and neurological deterioration with hemiparesis and hemianopia.


Diagnostic criteria - one or both of the following:

(1) all of the following:

(1a) focal seizures and unilateral cortical deficits

(1b) EEG shows unihemispheric slowing with or without epileptiform activity and unilateral seizure onset

(1c) unihemispheric focal cortical atrophy

(1d) grey or white matter T2/FLAIR hyperintense signal OR hyperintense signal of ipsilateral caudate head OR atrophy of the ipsilateral caudate head

(2) >= 2 of the following:

(2a) epilepsia partialis continua or progressive unilateral cortical deficits

(2b) progressive unihemispheric focal cortical atrophy

(2c) T-cell dominated encephalitis with activated microglial cells


The diagnosis is excluded if a biopsy shows:

(1) numerous parenchymal macrophages, B cells, or plasma cells

(2) viral inclusions

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