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Detailed information of RASMUSSEN'S ENCEPHALITIS
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RASMUSSEN'S ENCEPHALITIS
DEFINITION:
A neurodegenerative disorder characterized by intractable focal
motor seizures and progressive neurologic deterioration (dementia,
hemiparesis).
EPIDEMIOLOGY:
- incidence: ?
- age of onset:
- risk factors:
PATHOGENESIS:
- also known as Chronic Focal Encephalitis or Chronic
Progressive Epilepsia Paritalis Continua of Childhood
- this may represent an etiologically diverse disorder inwhich
the common clinicopathologic features represent the terminal
stage of expression of various viral brain infections, i.e., CMV,
EBV (Farrell et al., 1991)
2. Pathogenesis
- there may be an abnormal immune attack against GluR3 as
antibodies directed against GluR3 have been identified in
patients
- this hypothesis suggests that a focal interruption of
the blood-brain barrier must occur for the GluR3 antibodies
to enter the brain and thus must look for a previous history
of head injury or vascular malformations in each patient
2. Viral
- a viral infection may produce an autoimmune reaction
resulting in an inflammatory response within the central
nervous system (CNS) and then a slowly progressive
destruction of the cortical and white matter
- the viral infection does not appear to produce the usual
systemic features of encephalitis nor an inflammatory
response in the cerebral spinal fluid (CSF)
PATHOLOGY:
- persistent inflammatory reaction in a localized area of
the brain (suggestive of a viral or bacterial agent)
- thought to represent seizure foci and not the consequence
of seizure activity
- perivascular lymphocytic infiltrates and astrogliosis
- microglial nodules throughout the grey and white matter
- neuronophagia with neuronal loss and gliosis
- immune complexes in affected brain tissue +/- evidence of
viral (CMV, EBV) genomic material
2. Degeneration
- ranging from laminar necrosis to spongy degeneration
CLINICAL FEATURES:
- normal development prior to onset of seizures
- simple partial seizures before the age of 10
- also may initially present with generalized seizures
2. Later
- in about 50% of cases
- severe, progressive and chronic focal motor seizures
- initially affect both limbs on one side then the limbs
on the other side
2. Others
- simple motor seizures
- complex partial seizures
- secondary generalized
- status epilepticus
2. Others
- neurologic deficit in affected limbs
- may slowly progress to a hemiparesis
- developmental arrest or regression
- homonymous hemianopia
- mental retardation
- neuropsychologic deficits or behavioural disturbances
- features initially progressive then eventually stabilize
INVESTIGATIONS:
- progressive focal cerebral or hemispheric atrophy
2. EEG
- nonspecific
- continuous partialis continuans
- continuous spike discharges originating in one part of the
cortex with spread to contiguous areas of the cortex and to a
mirror focus on the other side
3. CSF
- mild pleocytosis or elevated protein but not consistent with
a viral encephalitis
MANAGEMENT:
- no treatment for the disorder
- no evidence that steriods are of benefit
- ? role of antibiotics or antiviral agents
2. Seizures
- medically refractory focal epilepsy
- surgery indicated when illness is no longer progressive but
has stabilized and may result in a reduction in seizure
frequency, i.e., cortical excision, multilobar resection, hemi-spherectomy
3. Experimental
- used to remove GluR3
- initial studies show dramatic but short-lived improvement
INTERNET LINKS:
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Pediatric Database - RASMUSSEN'S ENCEPHALITIS
Pediatric Organization - Pedbase [at] Gmail.com