Rasmussen encephalitis
Updates to Article Attributes
Rasmussen encephalitis (RE), aka also know as chronic focal encephalitis (and not to be confused with a Rasmussen aneurysm), is a chronic inflammatory disease of unknown origin, usually affecting one brain hemisphere.
Epidemiology
Children of ten years or younger age group are affected in 85% cases 1. However, disease detection rate in adults is increasing with routine MRI investigations in intractable seizure patients 5.
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 loss9,10.
Autoimmune mechanism has also been proposed decribingdescribing antibodies againsagainstt GluR3 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in a few patients.11.
Aetiology
Exact cause of the disease is unknown, however various viral (SSPE like, EBV or CMV), or inflammatory episodes have been implicated by different authors 3, 4, 6.
Clinical featurespresentation
Patients frequently have episodes of epilepsia partialis continua and, much less frequently, generalized status epilepticus. 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 younghood.
Radiographic features
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 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
Treatment
Treatment with high-dose methylprednisolone and intravenous immunoglobulin 12 has been successful further supporting the autoimmune nature of the disease.
Functional hemispherectomy is the only definitive treatment in refractory cases 12.
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
Treatment
Treatment with high-dose methylprednisolone and intravenous immunoglobulin 12 has been successful further supporting the autoimmune neature of the disease.
Functional hemispherectomy is the only definitive treatment in refractory cases.12
Etymology
It was first described by American neurologist Theodore Brown Rasmussen (1910-2002) in 1958 2
See also
-<p><strong>Rasmussen encephalitis (RE)</strong>, aka <strong>chronic focal encephalitis</strong> (and 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>Children of ten years or younger age group are affected in 85% cases <sup>1</sup>. However, disease detection rate in adults is increasing with routine MRI investigations in intractable seizure patients <sup>5</sup>.</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>Autoimmune mechanism has also been proposed decribing antibodies agains<sup>t </sup>GluR3 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in a few patients.<sup>11</sup></p><h5>Aetiology</h5><p>Exact cause of the disease is unknown, however various viral (<a href="/articles/sub-acute-sclerosing-panencephalitis">SSPE</a> like, EBV or CMV), or inflammatory episodes have been implicated by different authors <sup>3, 4, 6</sup>.</p><h4><strong>Clinical features</strong></h4><p>Patients frequently have episodes of epilepsia partialis continua and, much less frequently, generalized status epilepticus. 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>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><h5>MRI</h5><ul>- +<p><strong>Rasmussen encephalitis (RE)</strong>, also know as <strong>chronic focal encephalitis</strong> (and 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>Children of ten years or younger age group are affected in 85% cases <sup>1</sup>. However, disease detection rate in adults is increasing with routine MRI investigations in intractable seizure patients <sup>5</sup>.</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>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>Exact cause of the disease is unknown, however various viral (<a href="/articles/subacute-sclerosing-panencephalitis-1">SSPE</a> like, EBV or CMV), or inflammatory episodes have been implicated by different authors <sup>3, 4, 6</sup>.</p><h4><strong>Clinical presentation</strong></h4><p>Patients frequently have episodes of epilepsia partialis continua and, much less frequently, generalized status epilepticus. 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>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>
-</ul><h4> </h4><h4>Differential diagnosis</h4><p>General imaging differential considerations include</p><ul>- +</ul><h4>Treatment</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>
-</ul><h4>Treatment</h4><p>Treatment with high-dose methylprednisolone and intravenous immunoglobulin <sup>12 </sup>has been successful further supporting the autoimmune neature of the disease<sup>.</sup></p><p>Functional hemispherectomy is the only definitive treatment in refractory cases.<sup>12</sup></p><h4>Etymology</h4><p>It was first described by American neurologist <strong>Theodore Brown Rasmussen</strong> (1910-2002) in 1958 <sup>2</sup></p><h4>See also</h4><ul><li><a href="/articles/rasmussen-aneurysm">Rasmussen aneurysm</a></li></ul>- +</ul><h4>See also</h4><ul><li><a href="/articles/rasmussen-aneurysm">Rasmussen aneurysm</a></li></ul>
References changed:
- 2. Rasmussen T, Olszewski J, Lloyd-Smith D. Focal Seizures Due to Chronic Localized Encephalitis. Neurology. 1958;8(6):435. <a href="https://doi.org/10.1212/wnl.8.6.435">doi:10.1212/wnl.8.6.435</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/13566382">Pubmed</a>
- 7. Oguni H, Andermann F, Rasmussen TB. The syndrome of chronic encephalitis and epilepsy. A study based on the MNI series of 48 cases. Adv Neurol. 1992;57: 419-33. <a href="http://www.ncbi.nlm.nih.gov/pubmed/1543071">Pubmed citation</a><span class="auto"></span>
- 2. Rasmussen T, Olszewski J, Lloyd‐Smith D. Focal seizures due to chronic localized encephalitis. Neurology 1958; 8: 435–45.
- 7. Oguni H, Andermann F, Rasmussen TB. The natural history of the syndrome of chronic encephalitis and epilepsy: A study of the Montreal Neurological Institute series of forty-eight cases. In: Andermann F, editor. Chronic encephalitis and epilepsy:Rasmussen’s syndrome. Boston: Butterworth-Heinemann; 1991. pp. 7–35
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