NEURORADIOLOGY
Case 27 :
An 8-year-old male with epilepsy. CSF shows mild pleocytosis with elevated protein count that is not consistent with a viral encephalitis. What is the diagnosis on MRI?
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Findings reveal hyperintensity of bilateral perisylvian temporal and frontal grey and subcortial grey mater with evidence of focal atropy. Rest of the neuro parenchyma is normal.

Diagnosis
Rasmussen encephalitis

 

Discussion

It is a neurodegenerative disorder characterized by intractable focal motor seizures and progressive neurologic deterioration (dementia, hemiparesis). It is 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. Etiolopathogenesis is believed to be autoimmune:

IGlutamate Receptor R3 (GluR3):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

Net References

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.

Until very recently, the ultimately customary treatment has been hemispherectomy (excising the affected area of the brain). Since the victims are mostly young children, the remaining areas of the brain can often learn to perform some tasks that the removed section performed, and often the young patients resume a normal lifestyle with little or no restrictions or handicaps. An adult brain usually cannot learn new tasks in this manner. Where this procedure was contra-indicated, and sometimes even when performed, the prognosis for Rasmussen's patients has been poor. Several alternative treatment courses include plasmapheresis (removal, reconstitution and re-infusion of patient's plasma), ketogenic diet (high fat, low/no carbohydrates), and steroids. The latter is used especially cautiously. Steroid treatment has produced results similar to IVIG, and like IVIG, long-term effectiveness is not known. However, the negative effects of long-term steroid use is well-documented.

http://www.medhelp.org/www/rasm.htm
www.pedianet.com/news/illness/disease/files

Dr. Deepak Patkar, MRI Centre, Nanavati Hospital, Mumbai