Rasmussen encephalitis in the eye of a Radiologist

Rasmussen encephalitis a rare entity of neurodegenerative disorder found in a 6 year old girl during my residency pleriod.

1. Rasmussen Encephalitis Dr. Santosh Atreya Phase B Resident Department of Radiology & Imaging BSMMU

2. History and Etymology It was first described by American neurologist  Theodore Brown Rasmussen  (1910-2002) in 1958 

3. Introduction Rasmussen encephalitis (RE), also known as chronic focal encephalitis  is an extremely rare chronic inflammatory neurodegenerative disease of unknown origin.

4. History A 6 year-old girl, daughter of a rickshaw puller presented to pediatric OPD with a history of febrile illness with clonic movements of the left hand and leg since 5 years, she was developing normally till the age of 1 year with no significant illness, gradually she developed difficulty in walking. With these complain she was taken to local doctor where they were counselled to be better as time goes by.

5. Contd… For the past one year, she was having mild frontal headache. Her perinatal period and developmental milestones had been normal. On examination ,her hearing, vision & speech were intact. Other systemic examination was apparently normal. Routine blood and cerebrospinal fluid investigations were within normal range.

6. Epidemiology Most cases (85% cases) occur in children under the age of 10 years  .

7. Clinical presentation Patients frequently have generalised   status epilepticus .  The seizures are intractable despite aggressive medical management  .

8. Apart from seizures, patient may have hemiparesis and speech disturbances, as well as hemianopia (pertaining to unilateral cerebral involvement). Mental deterioration-in adolescence.

9. Radiographic features

10. Radiographic features are usually isolated to a single hemisphere, however bilateral Rasmussen encephalitis has also been rarely described in numerous case reports.   Radiological study is an important tool for early diagnosis and excluding differential diagnoses

11. CT SCAN CT may not show any specific feature in early imaging; however, patchy hypo dense attenuation areas may be seen. Late stage disease may show unilateral cortical atrophy

12. MRI T1:  unilateral cortical atrophy with ex-vacuo ventricular dilatation  T2:   hyperintense signal areas in the affected hemisphere  DWI:  restricted diffusion may be seen in altered signal areas  T1 C+ ( Gd ):  no significant post-contrast enhancement 

13. PET studies

14. Differentials Differential Diagnosis: Differential diagnostic considerations usually need to cover: 1.Dyke-Davidoff-Masson syndrome 2.Sturge-Weber syndrome 3.hemi-megalencephaly.

15. Dyke-Davidoff-Masson syndrome Cerebral hemiatrophy characterised by : Thickening of skull vault(compensatory) Enlargement of PNS & mastoid air cells Ipsilateral falcine displacement Capillary malformations

16. Sturge-Weber syndrome Tram-track sign  of cortical and sub cortical calcification, with or without ipsilateral prominence of choroid plexus- hall mark radiological sign.

17. H emi- megalencephaly .

18. Often Cortex appears thickened “lumpy-bumpy” on T1 scans I/L ventricle is usually enlarged and deformed In severe cases almost no normal hemispheric architecture can be discerned

19. T2WI – shows areas of patchy & polymicrogyria with indistinct borders between gray & white matter White matter signal intensity on T2/FLAIR is often heterogenous with cysts and gliosis -like hyperintensity

20. Treatment and prognosis Treatment with high-dose methylprednisolone and intravenous immunoglobulin  has been successful, further supporting the autoimmune nature of the disease. Functional hemispherectomy is the only definitive treatment in refractory cases, with most patients having either no or less frequent seizures  .

21. Reference : Binoj Varghese , MK Aneesh ,  Navdeep Singh ,and   Percival Gilwaz . A Case of Rasmussen Encephalitis: The Differential Diagnoses and Role of Diagnostic Imaging. Oman Med J. 2014 Jan; 29(1): 67–70. Rimzim Gupta, Rashi Bhargava , Rajesh Kumar Gupta, Prem Prakash Gupta Rasmussen encephalitis: A case report Indian J Child Health Vol 2 | Issue 2 | Apr - Jun 2015 Joseph Vimal ,   Ramesh Nagarajan , and  Deepika Sriram Rasmussen’s encephalitis: A case report Australas Med J . 2015; 8(3): 80–84. Sadhanandham Shrinuvasan ,  Ranganathan Chidambaram Rasmussen's encephalitis: A rare case report CHRISMED J Health Res 16-Mar-2015 Lei Chen, M.D. Peimin Feng , M.D. Dong Zhou, M.D. Case Reports of Rasmussen’s Syndrome and Literature Review J Neuropsychiatry Clin Neurosci 24:3, Summer 2012 Yvonne Hart Radcliffe Infirmary, Oxford, UK Rasmussen’s encephalitis Epileptic Disorders Vol. 6, No. 3, September 2004 C. G. Bien,1 T. Granata,2 C. Antozzi,2 J. H. Cross,3 O. Dulac,4 M. Kurthen,1 H. Lassmann,5 R. Mantegazza,2 J.-G. Villemure,6 R. Spreafico2 and C. E. Elger Pathogenesis, diagnosis and treatment of Rasmussen encephalitis A European consensus statement Brain (2005), 128, 454–471 Deepak Jain , 1   Hari Krishan Aggarwal , 1   Shivraj Goyal , 1  and  Ansul Mittal 1 Dyke–Davidoff–Masson syndrome: A rare case report ran J Neurol . 2014 Oct 6; 13(4): 255–256 Siddarth Ragupathi 1 ,  Ajit Kumar Reddy 2 ,  Annitha Elavarasi Jayamohan 2 , Prakash Manikka Lakshmanan 3 Sturge-Weber syndrome: CT and MRI illustrations BMJ Case Reports  2014; doi:10.1136/bcr-2014-205743 Greg James & Mano Shanmuganathan & William Harkness Hemimegalencephaly without epilepsy: case report Childs Nerv Syst Springer- Verlag Berlin Heidelberg 2014