Rasmussen syndrome (commonly referred to as Rasmussen encephalitis) is a rare disorder of the central nervous system (CNS) [1] [2] [3] [4]. The exact pathogenesis remains unclear, but it is assumed that T-cell mediated reactions play a key role in inflammation and subsequent atrophy of one of the brain hemispheres [1]. The clinical presentation typically starts around the age of 6, and is divided into three distinct stages [1] [2] [3]:

• Prodromal phase - The initial phase of the illness is characterized by the infrequent onset of seizures or hemiparesis that usually last up to several months, but reports show that years may pass before the next stage of illness ensues [1] [2].
• Acute phase - All patients enter the acute stage of illness, whereas around 30% of individuals skip the prodromal phase [2]. Seizures appear in the form of epilepsia partialis continua - a type of simple partial, focal, and recurrent epilepsy that becomes quite frequent [1] [2] [5]. Additional findings include progressive hemiparesis, movement disorders, cognitive decline, as well as hemianopia and aphasia if the dominant hemisphere is affected by the disorder [1] [2] [6]. A growing number of studies have recognized that other types of focal seizures may emerge in the acute phase, all originating within the same hemisphere [1] [2].
• Residual stage - After a relatively intense acute phase, the rate of neurological decline stabilizes, as do seizures, and a somewhat stable clinical course is observed [1] [2] [3].

• Epilepsy

  In RE, the additional release gets lost over epilepsy duration. [doi.org]

  Yukitoshi Takahashi, Infections as causative factors of epilepsy, Future Neurology, 1, 3, (291), (2006). [oadoi.org]

• Osteoporosis

  Not unexpectedly, serious side effects partly necessitating steroid withdrawal have been noticed; fluid retention/Cushing's syndrome in all patients and, in single cases, psychosis, behavioural abnormalities, septicaemia, osteoporosis, hypertension and [dx.doi.org]

• Hemianopsia

  Later, it progresses to paralysis of one side of the body (hemiparesis), blindness in one eye ( hemianopsia ), and loss of mental function. [encyclopedia.com]

  Hemianopia or Hemianopsia which refers to a condition in which the person loses vision of one side of the visual field. Intellectual and cognitive difficulties such as of learning and memory etc. [epainassist.com]

  This usually results in further weakness, hemianopsia and cognitive problems, but the other side of the brain may be able to take over some of the function, particularly in young children. [en.wikipedia.org]

• Seizure

  Permanent opening of Na + channels by veratridine resembles maximal frequency of action potentials corresponding to epileptic seizures. These are preceded by a fall in [Ca 2+ ] e. [doi.org]

  The authors recommend testing for porphyria in cases of Rasmussen encephalitis and other intractable seizures. [ncbi.nlm.nih.gov]

• Aphasia

  The acute phase is characterized by rapidly progressive seizures, hemiparesis, hemianopia, aphasia (if the dominant hemisphere is involved), and cognitive decline over the first year. [visualdx.com]

  Language problems (aphasia) often occur if the disorder affects the side of the brain that controls most language functions, which is usually the left side. Who gets it? Rasmussen's syndrome usually begins between 14 months and 14 years of age. [epilepsy.com]

  Additional findings include progressive hemiparesis, movement disorders, cognitive decline, as well as hemianopia and aphasia if the dominant hemisphere is affected by the disorder. [symptoma.com]

  The first was after an upper respiratory tract infection, the second was a post-complicated meningo-encephalitis and the third episode was associated with receptive aphasia, hemiparesis and intellectual impairment. [njcponline.com]

  Presently, she has a dense right hemiparesis and severe global aphasia. Case 2 In 2001, a 44-year-old woman began having focal aware seizures characterized by episodic expressive aphasia. [frontiersin.org]

• Cognitive Impairment

  The disease is characterized by focal drug-resistant epilepsy, contralateral progressive hemiparesis, and cognitive impairment. [smjournals.com]

  Cognitive impairment is also apparent. Hemispherectomy or hemispheric disconnection remains the only cure for progressive epilepsy and should be considered early in the course to prevent comorbidity. [neuroscienceandgenetics.it]

  It causes drug resistant seizures, cognitive impairment, and eventual paralysis of half the body within a year or two of the first seizure. Sometimes, Ramussen’s encephalitis can also include cortical dysplasia. [brainrecoveryproject.org]

  impairments linked to the transient events that often go unnoticed. [books.google.com]

  Progressive cognitive impairment may also develop. On imaging, progressive hemiatrophy (of the side contralateral to the hemiparesis) occurs over time. [epilepsydiagnosis.org]

• Mental Deterioration

  We describe a case of Rasmussen syndrome in a 7-year-old boy, presenting with epilepsia partialis continua, hemiplegia, and progressive mental deterioration. [ncbi.nlm.nih.gov]

  RE is characterized by frequent and severe seizures, progressive loss of neurological functions including motor skills, speech, and eventual paralysis on one side of the body (hemiparesis), inflammation of the brain (encephalitis), and mental deterioration [ninds.nih.gov]

  After 2 years, the patient was aphasic, hemiplegic, and mentally deteriorated, and seizures were refractory to antiepileptic drugs, corticosteroids, and alpha globulins. Plasmapheresis was of little benefit. [ 1 ] COMMENT. [pediatricneurologybriefs.com]

  To be more precise, there are frequent and severe seizures (convulsions), progressive loss of motor skills and speech, hemiparesis (paralysis on one side of the body), encephalitis (inflammation of the brain), dementia, and mental deterioration. [medicinenet.com]

• Confusion

  Recognition of the syndrome, especially in pediatric populations, is difficult and often undiagnosed and/or confused with neurological disorders with similar clinical features. [ncbi.nlm.nih.gov]

  After a seizure, your child may be confused, foggy or tired. If they want to lie down, let them. [childrens.com]

  Symptoms Symptoms of RE may include: Severe partial seizures Loss of motor skills Loss of speech Paralysis on one side of the body Learning disabilities Physical disabilities Confusion The partial seizures may progress to seizures that happen nearly all [cedars-sinai.edu]

  It is not to be confused with a Rasmussen aneurysm. 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. [radiopaedia.org]

  He was sleeping more, experience more confusion, and starting showing signs of a blood clot which was confirmed by a ct scan. He was moved to a step up unit so he could be more closely monitored. Again, Michael started to progress for a couple days. [gofundme.com]

Given the rare occurrence of Rasmussen syndrome in practice (a prevalence of approximately 0.18 per 100,000 individuals, and an incidence of 2.4 per 10 million individuals younger than 18 years of age), the diagnosis may be difficult to attain [1] [4], which is why physicians must obtain a detailed patient history and perform a thorough physical examination. The parents of the patient (especially if younger children are affected) could provide key information regarding the onset of symptoms and their severity. An additional challenge can be the highly variable course of Rasmussen syndrome, ranging from insidious and slowly progressive to rapidly ensuing and severely debilitating [6]. After an extensive neurological exam, electroencephalography (EEG) and magnetic resonance imaging (MRI) of the endocranium are recommended. EEG will show a unilateral pattern of slowed activity, whereas focal cortical atrophy, accompanied either by hyperintense signaling on T2-weighed or FLAIR images of the gray or white matter, or atrophy of the ipsilateral caudate head are main findings on MRI [1] [2] [7]. Unilateral ventriculomegaly is another hallmark of Rasmussen syndrome in the acute stage [1].

• Lymphocytic Infiltrate

  The observed inflammatory changes in Rasmussen encephalitis include perivascular cuffing, microglial nodules, T-lymphocytic infiltration gliosis, meningeal inflammation, and neuronal injury or loss 9,10. [radiopaedia.org]

  It was interesting to note that all the cases in the present study displayed CD3-immunopositive lymphocyte infiltrates, while CD20 (B cells) were largely absent. [neurologyindia.com]

  Early in the disease, signs of immunopathology in resected brain tissue include perivascular cuffing, lymphocyte infiltration, and activated microglia in the setting of neuronal loss [1]. [cureus.com]

  The degree of microglial activation follows the progression pattern of RE, parallels the degree of T lymphocyte infiltration, and is observed in the early stages of cortical involvement (Pardo et al., 2004; Troscher et al., 2019). [frontiersin.org]

  A viral etiology was already suggested by Rasmussen based on the constituents of the immune reaction in the brains such as lymphocyte infiltration and microglial nodules [ 4 ]. [clinmedjournals.org]

Medical treatment remains disappointing while results of surgical treatment are mixed. There are emerging insights into the disease, which are reviewed and a case study of a patient with Rasmussen syndrome is presented. [ncbi.nlm.nih.gov]

As in other inflammatory diseases, steroids may be used first of all, either as a short course of high-dose treatment, or in a lower dose for long-term treatment. [en.wikipedia.org]

We confirm the unsatisfactory seizure control and the guarded neurological and intellectual prognosis that has been associated with Rasmussen syndrome. [ncbi.nlm.nih.gov]

In some very rare cases, the disease can progress to involve the opposite brain hemisphere. x Prognosis The prognosis for individuals with Rasmussen’s encephalitis varies. [ninds.nih.gov]

The prognosis (outlook) for individuals with Rasmussen's encephalitis varies. Untreated, the disorder may lead to severe neurological deficits including mental retardation and paralysis. In some patients the surgery decreases the seizures. [medicinenet.com]

Prognosis The prognosis for children below the age of 10 who are treated early in the course of the syndrome is good. This group can often achieve normal psychosocial and intellectual functioning. [encyclopedia.com]

Magnetic resonance (MR) findings, associated with clinical data and electroencephalogram (EEG), may indicate the diagnosis and could be an indicative of prognosis. [scielo.br]

An etiology was not determined, but the disease was thought to be virally mediated. Many years later, the etiology remains elusive. [medlink.com]

Several etiologic hypotheses are presented. Double insults, porphyria, and an autoimmune process are suggested for the development of Rasmussen encephalitis in this patient. [ncbi.nlm.nih.gov]

Epidemiology and clinical characteristics of seizures in patients with acute intermittent porphyria. Epilepsia. 1996 ;37: 230 - 235. Google Scholar | Crossref | Medline | ISI Winkler AS, Peters TJ, Elwes Rdc. [doi.org]

An epidemiological study from Germany estimated that the annual incidence of RE was 2.4 cases/107 persons aged ≤ 8 years (Bien et al., 2013). [frontiersin.org]

DISCUSSION: The present findings suggest that complex pathophysiologic mechanisms involving CD4(+) T cells and CD8(+) T cells change evolutionally during the progression of RS. [ncbi.nlm.nih.gov]

We speculate that cellular autoimmunity and the subsequent humoral autoimmunity against GluRɛ2 may contribute to the pathophysiological processes in Rasmussen's encephalitis. [oadoi.org]

Pathology of brain tissue shows changes of chronic encephalitis; the exact pathophysiology of this is unknown (previous studies implicating certain viruses have not been replicated), however there is sufficient evidence to support an autoimmune basis. [epilepsydiagnosis.org]

[…] in Rasmussen encephalitis (RE) may be promoted by insufficient γ-aminobutyric acid (GABA) release. (3) H-GABA was released from neocortical synaptosomes through transporter reversal following intrasynaptosomal Na(+) accumulation by veratridine that prevents [ncbi.nlm.nih.gov]

Hemispherectomy or hemispheric disconnection remains the only cure for progressive epilepsy and should be considered early in the course to prevent comorbidity. [neuroscienceandgenetics.it]

[…] seizures in Rasmussen encephalitis (RE) may be promoted by insufficient γ‐aminobutyric acid (GABA) release. 3 H‐GABA was released from neocortical synaptosomes through transporter reversal following intrasynaptosomal Na + accumulation by veratridine that prevents [doi.org]

Early diagnosis and treatment with immunoactive agents or hemispherectomy are sought to prevent the cognitive decline. A hypothesis of the pathogenesis is glutamate receptor autoimmunity associated with persistent viral infection (24). [asnr.org]

1. Varadkar S, Bien CG, Kruse CA, et al. Rasmussen’s encephalitis: clinical features, pathobiology, and treatment advances. Lancet Neurol.. 2014;13(2):195-205.
2. Bien CG, Granata T, Antozzi C, et al. Pathogenesis, diagnosis and treatment of Rasmussen encephalitis: a European consensus statement. Brain. 2005;128:454–471.
3. Olson HE, Lechpammer M, Prabhu SP, et al. Clinical application and evaluation of the Bien diagnostic criteria for Rasmussen encephalitis. Epilepsia. 2013;54:1753–760.
4. Bien CG, Tiemeier H, Sassen R, et al. Rasmussen encephalitis: Incidence and course under randomized therapy with tacrolimus or intravenous immunoglobulins. Epilepsia. 2013;54:543–545.
5. Longaretti F, Dunkley C, Varadkar S, et al. Evolution of the EEG in children with Rasmussen’s syndrome. Epilepsia. 2012;53:1539–1545.
6. Vining EP. Struggling with Rasmussen’s Syndrome. Epilepsy Curr. 2006;6(1):20-21.
7. Yamazaki E, Takahashi Y, Akasaka N, Fujiwara T, Inoue Y. Temporal changes in brain MRI findings in Rasmussen syndrome. Epileptic Disord. 2011;13:229–239.