|Year : 2015 | Volume
| Issue : 2 | Page : 178-180
Rasmussen's encephalitis: A rare case report
Sadhanandham Shrinuvasan, Ranganathan Chidambaram
Department of Radiology, Sri Lakshmi Narayana Institute of Medical Sciences, (Affiliated to Bharath University), Puducherry, India
|Date of Web Publication||16-Mar-2015|
SLIMS, (Affiliated to Bharath University), Osudu, Agaram Village, Puducherry
Source of Support: None, Conflict of Interest: None
Rasmussen's encephalitis (RE) is a chronic neurological disorder, characterised by unilateral inflammation of the cerebral cortex leading to progressive neurological and cognitive deterioration. Advances in neuroimaging suggest that progression of the inflammatory process seen with magnetic resonance imaging (MRI) might be a good biomarker in RE. We present here a case of 8-year-old male child presented with repeated episodes of drug resistant seizures leading to intellectual impairment and cognitive deterioration. Further MRI was done which shows diffuse left cerebral atrophy.
Keywords: Epilepsy, Rasmussen encephalitis, unilateral cerebral atrophy
|How to cite this article:|
Shrinuvasan S, Chidambaram R. Rasmussen's encephalitis: A rare case report. CHRISMED J Health Res 2015;2:178-80
| Introduction|| |
Rasmussen's encephalitis (RE) is a chronic inflammatory disease of unknown origin, usually affecting one brain hemisphere, described by Rasmussen et al. in 1958.  It has been reported in adolescents, adults and more in children <10 years of age. , It is an uncommon unilateral hemispheric disease. Both clinical history and characteristic imaging features are necessary to make the diagnosis of RE. The most commonly encountered imaging feature is progressive unilateral cerebral cortical atrophy. 
| Case report|| |
A 8-year-old male child born of 2° consanguineous marriage residing at Pondicherry (Union Territory, India), presented with history of repeated episodes of tonic clonic seizures involving right upper and lower limbs and each episode lasting for 10-15 min with prolonged postictal state. The first episode started at the age of 3 years with rapid increase in seizure activity followed by decrease in frequency 1-2 episodes/day with slurring of speech and abnormal gait. He was born as a second twin and cried immediately after birth with normal APGAR score. No history of neonatal siezures. He had no history of blood transfusions, neurosurgery, traumatic head injury, proven allergies and family history of epilepsy. On examination, he was conscious not oriented to time, place and person. His vitals were stable. Central nervous system examination shows right sided hemiplegia with upper motor neuron type of facial palsy, exaggerated tendon reflexes (Biceps, Triceps, Supinator, Knee and Ankle) on left side. Bilateral extensor type of plantar reflexes seen. There were no signs of meningeal irritation. Other cranial nerves were intact. Clinically this case comes under Montreal Neurological Institute (MNI) stage 3. Noncontrast computed tomography (CT) brain [Figure 1] and [Figure 2] shows diffuse left cerebral subcortical and periventricular hypodensities with volume loss as evidenced by widening of interhemispheric fissure, cerebral sulci in frontal, insular cortex and temporal region. MRI Brain [Figure 3] shows diffuse left hemispherical cerebral volume loss with diffuse altered signal intensity changes appearing hyperintense in T2-weighted (T2W)/fluid attenuated inversion recovery (FLAIR) sequences and hypointense in T1W sequences involving cortical and subcortical regions. Right cerebral hemisphere and cerebellum appears normal [Figure 4].
|Figure 1: (a,b) Non Contrast Axial Sections of CT Brain shows unilateral left cerebral atrophy as evidenced by volume loss, widening of interhemispheric fi ssure, cerebral sulci in frontal, insular cortex and temporal region|
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|Figure 2: (a,b) Non Contrast Axial Sections of CT Brain shows diffuse left cerebral subcortical and periventricular hypodensities with dilatation of ipsilateral frontal and occipital horns|
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|Figure 3: (a,c) Brain MRI T2W and FLAIR transverse images shows diffuse increased signal intensity in the left cerebral cortical and subcortical white matter; (b) which are of decreased signal on T1W images|
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|Figure 4: (a,b) Brain MRI T2W coronal and (c) T1W sagital sections shows left sided cerebral atrophy with ipsilateral dilatation of the lateral ventricle and widening of the cerebral sulci. The right cerebral hemisphere, brainstem and|
cerebellum are all within normal limits
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| Discussion|| |
Etiologically, there are different theories for pathogenesis of RE.
A school of thought supports an autoimmune pathology.  Supporting this theory was presence of antibodies that bind to type-3 glutamate receptor.  Decades back; it was postulated to be an infective process. 
Diagnosis of RE is generally based on the characteristic clinical, radiological and pathological features. Clinical presentation is dependent on anatomical site and age at presentation. This includes the following: Epilepsy, focal or continuous, neurological deficits, aphasia and cognitive deficits. There is a clinical staging called the MNI. 
Stage 1 is the period from the first epileptic seizure until the beginning of stage 2.
Stage 2 is defined as the acute phase of the disease, with a rapid increase in seizure frequency (to >10/day) accompanied by the development or deterioration of a hemiparesis until the completion of neurological deterioration.
Stage 3 is defined as a relatively stable state, with a permanent hemiparesis and a seizure frequency lower than that during stage 2.
This child had first episode at the age of 3 years with rapid increase in seizure activity followed by decrease in frequency with 1-2 episodes/day which was drug resistant and now presented with permanent right sided hemiplegia indicating that this case is presently in advanced clinical stage.
The characteristic MRI features in RE are areas of cortical hyperintense T2/FLAIR signal. , Serial MRI studies  have demonstrated a spectrum of changes ranging from an apparently normal image at onset, to focal or hemispheric cortical atrophy of the affected lobes, in the late stage. CT and MRI studies in this case showed evidence of diffuse left cerebral atrophy suggesting advanced disease process.
Pathological appearances of RE, both macroscopic and microscopic, vary according to the severity of the disease. Macroscopic features in cases operated within 1-2 years of onset show subtle change in the form of slight discoloration and granularity, along with focal thinning of the cortex, while severe cases may show gyral atrophy with widespread hemiatrophy and ventricular dilatation.  Biopsy may not be useful in this case as the disease appears to be in advanced stage and may show only nonspecific findings.
This case is presented with classic clinical features suggestive of RE and MRI showed diffuse left hemispherical cerebral volume loss with diffuse altered signal intensity changes appearing hyperintense in T2W/FLAIR sequences and hypointense in T1W sequences involving cortical and subcortical regions. Although advanced neuroimaging studies and histopathological examination will confirm and quantify hemispherical volume loss; in a case with classic imaging findings MR imaging data alone are sufficient to suggest a diagnosis of RE. This case is presently in clinical MNI stage 3 with diffuse left cerebral atrophy.
| Conclusion|| |
Rasmussen's encephalitis is a rare chronic inflammatory progressive neurological disorder. In cases with classical clinical history, neuroimaging data alone can play a critical role in establishing a diagnosis and follow up of RE and in selecting patients for brain biopsy.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]