Rasmussen encephalitis
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Rasmussen encephalitis (RE), also known as chronic focal encephalitis (not to be confused with a Rasmussen aneurysm), is a chronic inflammatory disease of unknown origin, usually affecting one brain hemisphere.
Epidemiology
Most cases (85% cases) occur in children under the age of 10 years 1. However, detection in adults is increasing with routine MRI investigations for intractable seizures 5.
Clinical presentation
Patients frequently have episodes of epilepsia partialis continua or generalized status epilepticus, although this is less common. The seizures are intractable despite aggressive medical management 1.
Apart from seizures, patient may have hemiparesis and speech disturbances, as well as hemianopia (pertaining to unilateral cerebral involvement). Mental deterioration over time may also be seen, especially in patient presenting later in younghoodadolescence.
Pathology
Pathologic features are similar to viral encephalitis, with lymphocytes around round cells and diffuse proliferation of microglia. However, later spongiform degeneration and cortical atrophy sets in.
The observed inflammatory changes in RE include perivascular cuffing, microglial nodules, T-lymphocytic infiltration gliosis, meningeal inflammation, and neuronal injury or loss 9,10.
An autoimmune mechanism has also been proposed describing antibodies againstGluR3 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in a few patients 11.
The exact cause of the disease is unknown. However, various viral (SSPE-like, EBV or CMV), or or inflammatory episodes have been implicated by different authors 3,4,6.
Radiographic features
Radiographic features are usually isolated to a single hemisphere, however bilateral Rasmussen encephalitis has also been rarely described in numerous case reports 12-14.
CT
CT may not show any specific feature in early imaging; however, patchy hypodense attenuation areas (similar to viral encephalitis) may be seen. Late stage disease may show unilateral cortical atrophy. CT perfusion may show decreased cerebral blood flow (CBF) 1.
MRI
- T1: unilateral cortical atrophy with ex-vacuo ventricular dilatation15
- T2: hyperintense signal areas in the affected hemisphere15
- DWI/ADC: restricted diffusion may be seen in altered signal areas15
- T1 C+ (Gd): no significant post-contrast enhancement15
Treatment and prognosis
Treatment with high-dose methylprednisolone and intravenous immunoglobulin 1216 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 1216.
History and etymology
It was first described by American neurologist Theodore Brown Rasmussen (1910-2002) in 1958 2.
Differential diagnosis
General imaging differential considerations include:
- Dyke-Davidoff-Masson syndrome
- Sturge Weber syndrome
- unilateral megalencephaly
-
hemiconvulsion-hemiplegia epilepsy syndrome (HHE)
- HHE syndrome usually shows a seizure free interval of months to years from initial presentation 7-8
-<p><strong>Rasmussen encephalitis (RE)</strong>, also known as <strong>chronic focal encephalitis</strong> (not to be confused with a <a href="/articles/rasmussen-aneurysm">Rasmussen aneurysm</a>), is a chronic inflammatory disease of unknown origin, usually affecting one brain hemisphere.</p><h4>Epidemiology</h4><p>Most cases (85% cases) occur in children under the age of 10 years <sup>1</sup>. However, detection in adults is increasing with routine MRI investigations for intractable seizures <sup>5</sup>.</p><h4>Clinical presentation</h4><p>Patients frequently have episodes of epilepsia partialis continua or generalized <a href="/articles/status-epilepticus">status epilepticus</a>, although this is less common. The seizures are intractable despite aggressive medical management <sup>1</sup>.</p><p>Apart from seizures, patient may have hemiparesis and speech disturbances, as well as hemianopia (pertaining to unilateral cerebral involvement). Mental deterioration over time may also be seen, especially in patient presenting later in younghood.</p><h4>Pathology</h4><p>Pathologic features are similar to viral encephalitis, with lymphocytes around round cells and diffuse proliferation of microglia. However, later spongiform degeneration and cortical atrophy sets in.</p><p>The observed inflammatory changes in RE include perivascular cuffing, microglial nodules, T-lymphocytic infiltration gliosis, meningeal inflammation, and neuronal injury or loss <sup>9,10</sup>.</p><p>An autoimmune mechanism has also been proposed describing antibodies against<sup> </sup>GluR3 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in a few patients <sup>11</sup>.</p><p>The exact cause of the disease is unknown. However, various viral (SSPE-like, EBV or CMV), or inflammatory episodes have been implicated by different authors <sup>3,4,6</sup>.</p><h4>Radiographic features</h4><h6>CT</h6><p>CT may not show any specific feature in early imaging; however, patchy hypodense attenuation areas (similar to viral encephalitis) may be seen. Late stage disease may show unilateral cortical atrophy. CT perfusion may show decreased cerebral blood flow (CBF) <sup>1</sup>.</p><h6>MRI</h6><ul>- +<p><strong>Rasmussen encephalitis (RE)</strong>, also known as <strong>chronic focal encephalitis</strong> (not to be confused with a <a href="/articles/rasmussen-aneurysm">Rasmussen aneurysm</a>), is a chronic inflammatory disease of unknown origin, usually affecting one brain hemisphere.</p><h4>Epidemiology</h4><p>Most cases (85% cases) occur in children under the age of 10 years <sup>1</sup>. However, detection in adults is increasing with routine MRI investigations for intractable seizures <sup>5</sup>.</p><h4>Clinical presentation</h4><p>Patients frequently have episodes of epilepsia partialis continua or generalized <a href="/articles/status-epilepticus">status epilepticus</a>, although this is less common. The seizures are intractable despite aggressive medical management <sup>1</sup>.</p><p>Apart from seizures, patient may have hemiparesis and speech disturbances, as well as hemianopia (pertaining to unilateral cerebral involvement). Mental deterioration over time may also be seen, especially in patient presenting later in adolescence.</p><h4>Pathology</h4><p>Pathologic features are similar to viral encephalitis, with lymphocytes around round cells and diffuse proliferation of microglia. However, later spongiform degeneration and cortical atrophy sets in.</p><p>The observed inflammatory changes in RE include perivascular cuffing, microglial nodules, T-lymphocytic infiltration gliosis, meningeal inflammation, and neuronal injury or loss <sup>9,10</sup>.</p><p>An autoimmune mechanism has also been proposed describing antibodies against<sup> </sup>GluR3 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in a few patients <sup>11</sup>.</p><p>The exact cause of the disease is unknown. However, various viral (SSPE-like, EBV or CMV) or inflammatory episodes have been implicated by different authors <sup>3,4,6</sup>.</p><h4>Radiographic features</h4><p>Radiographic features are usually isolated to a single hemisphere, however bilateral Rasmussen encephalitis has also been rarely described in numerous case reports <sup>12-14</sup>. </p><h5>CT</h5><p>CT may not show any specific feature in early imaging; however, patchy hypodense attenuation areas (similar to viral encephalitis) may be seen. Late stage disease may show unilateral cortical atrophy. CT perfusion may show decreased cerebral blood flow (CBF) <sup>1</sup>.</p><h5>MRI</h5><ul>
-<strong>T1:</strong> unilateral cortical atrophy with ex-vacuo ventricular dilatation</li>- +<strong>T1:</strong> unilateral cortical atrophy with ex-vacuo ventricular dilatation <sup>15</sup>
- +</li>
-<strong>T2:</strong> hyperintense signal areas in the affected hemisphere</li>- +<strong>T2:</strong> hyperintense signal areas in the affected hemisphere <sup>15</sup>
- +</li>
-<strong>DWI/ADC:</strong> restricted diffusion may be seen in altered signal areas</li>- +<strong>DWI/ADC:</strong> restricted diffusion may be seen in altered signal areas <sup>15</sup>
- +</li>
-<strong>T1 C+ (Gd):</strong> no significant post-contrast enhancement</li>-</ul><h4>Treatment and prognosis</h4><p>Treatment with high-dose methylprednisolone and intravenous immunoglobulin <sup>12 </sup>has been successful further supporting the autoimmune nature of the disease.</p><p>Functional hemispherectomy is the only definitive treatment in refractory cases <sup>12</sup>.</p><h4>History and etymology</h4><p>It was first described by American neurologist <strong>Theodore Brown Rasmussen</strong> (1910-2002) in 1958 <sup>2</sup>.</p><h4>Differential diagnosis</h4><p>General imaging differential considerations include:</p><ul>- +<strong>T1 C+ (Gd):</strong> no significant post-contrast enhancement <sup>15</sup>
- +</li>
- +</ul><h4>Treatment and prognosis</h4><p>Treatment with high-dose methylprednisolone and intravenous immunoglobulin <sup>16 </sup>has been successful, further supporting the autoimmune nature of the disease.</p><p>Functional hemispherectomy is the only definitive treatment in refractory cases, with most patients having either no or less frequent seizures <sup>16</sup>.</p><h4>History and etymology</h4><p>It was first described by American neurologist <strong>Theodore Brown Rasmussen</strong> (1910-2002) in 1958 <sup>2</sup>.</p><h4>Differential diagnosis</h4><p>General imaging differential considerations include:</p><ul>
References changed:
- 12. Guan Y, Luan G, Zhou J, Liu X. Bilateral Rasmussen encephalitis. Epilepsy & behavior : E&B. 20 (2): 398-403. <a href="https://doi.org/10.1016/j.yebeh.2010.12.004">doi:10.1016/j.yebeh.2010.12.004</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/21216675">Pubmed</a> <span class="ref_v4"></span>
- 13. Tobias S, Robitaille Y, Hickey W, Rhodes C, Nordgren R, Andermann F. Bilateral Rasmussen Encephalitis: Postmortem Documentation in A Five‐year‐old. Epilepsia. 2003;44(1):127-30. <a href="https://doi.org/10.1046/j.1528-1157.2003.36602.x">doi:10.1046/j.1528-1157.2003.36602.x</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/12581240">Pubmed</a>
- 14. Peariso K, Standridge SM, Hallinan BE, Leach JL, Miles L, Mangano FT, Greiner HM. Presentation, diagnosis and treatment of bilateral Rasmussen's encephalitis in a 12-year-old female. Epileptic disorders : international epilepsy journal with videotape. 15 (3): 324-32. <a href="https://doi.org/10.1684/epd.2013.0594">doi:10.1684/epd.2013.0594</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/23917753">Pubmed</a> <span class="ref_v4"></span>
- 14. Peariso K, Standridge SM, Hallinan BE, Leach JL, Miles L, Mangano FT, Greiner HM. Presentation, diagnosis and treatment of bilateral Rasmussen's encephalitis in a 12-year-old female. Epileptic disorders : international epilepsy journal with videotape. 15 (3): 324-32. <a href="https://doi.org/10.1684/epd.2013.0594">doi:10.1684/epd.2013.0594</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/23917753">Pubmed</a> <span class="ref_v4"></span>
- 17. Varadkar S, Bien C, Kruse C et al. Rasmussen's Encephalitis: Clinical Features, Pathobiology, and Treatment Advances. Lancet Neurol. 2014;13(2):195-205. <a href="https://doi.org/10.1016/S1474-4422(13)70260-6">doi:10.1016/S1474-4422(13)70260-6</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/24457189">Pubmed</a>
- 15. Faria A, Reis F, Dabus G, Zanardi V, Guerreiro M, Cendes F. MRI Findings in the Diagnosis and Monitoring of Rasmussen's Encephalitis. Arq Neuro-Psiquiatr. 2009;67(3b):792-7. <a href="https://doi.org/10.1590/s0004-282x2009000500002">doi:10.1590/s0004-282x2009000500002</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/19838505">Pubmed</a>
- 12. Bien CG, Granata T, Antozzi C et-al. Pathogenesis, diagnosis and treatment of Rasmussen encephalitis: a European consensus statement. Brain. 2005;128 (3): 454-71. <a href="http://dx.doi.org/10.1093/brain/awh415">doi:10.1093/brain/awh415</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/15689357">Pubmed citation</a><span class="auto"></span>
- Peariso K, Standridge SM, Hallinan BE, Leach JL, Miles L, Mangano FT, Greiner HM. Presentation, diagnosis and treatment of bilateral Rasmussen's encephalitis in a 12-year-old female. Epileptic disorders : international epilepsy journal with videotape. 15 (3): 324-32. <a href="https://doi.org/10.1684/epd.2013.0594">doi:10.1684/epd.2013.0594</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/23917753">Pubmed</a> <span class="ref_v4"></span>
Images Changes:
Image 4 MRI (FLAIR) ( create )
Image 5 CT (non-contrast) ( create )
Image 6 MRI (T2) ( create )
Image 7 MRI (T1) ( create )
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