RARE DISEASE
Rasmussen subacute encephalitis
Rasmussen subacute encephalitis
Rasmussen subacute encephalitis
Synonyms: Rasmussen syndrome
Synonyms: Rasmussen syndrome
Synonyms: Rasmussen syndrome
Drug discovery
1
drug
With orphan designation
Overview
Rasmussen Subacute Encephalitis
A rare, immune-mediated chronic encephalitis characterized by progressive unihemispheric inflammation, drug-resistant focal epilepsy (often epilepsia partialis continua), hemiparesis, and cognitive decline. Pathophysiology involves T-cell-driven neuronal damage and microglial activation, leading to cortical atrophy. Diagnosis relies on clinical triad, MRI showing unilateral atrophy, and EEG demonstrating focal epileptiform activity [1][2][4][16].
Burden
Functional: 80–90% develop permanent hemiparesis, cognitive deficits, and refractory epilepsy [1][5][20].
Socioeconomic: High care needs due to progressive disability; surgery costs and rehabilitation burdens [13][20].
Mortality: Low direct mortality but profound morbidity; 50% require lifelong assistance [1][4][8].
Therapies
Immunomodulation: Early steroids, IVIG, or tacrolimus may slow progression; rituximab/natalizumab under investigation [4][6][8].
Surgery: Hemispherectomy/hemispherotomy remains definitive treatment for seizure control but causes permanent deficits (hemiplegia, aphasia) [8][13][19].
Symptomatic care: AEDs for non-EPC seizures; botulinum toxin for focal motor symptoms [2][4][7].
Categories: rare neurological diseases
Research Papers
74 drug discovery papers about Rasmussen subacute encephalitis, with 2 first-in-class and 2 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
74 drug discovery papers about Rasmussen subacute encephalitis, with 2 first-in-class and 2 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-06-03 | Centroparietal periodic sharp-wave discharges and biphasic complexes: Novel EEG biomarkers for early diagnosis of Rasmussen encephalitis.
Rasmussen encephalitis (RE) is a rare, chronic inflammatory brain disorder that predominantly affects one hemisphere in children. It is characterized by progressive neurological deterioration and refractory seizures. Early diagnosis remains challenging due to nonspecific initial symptoms and diagnostic features that overlap with other neurological conditions. To identify early and specific EEG patterns that may support timely initiation of immunomodulatory therapies. Continuous long-term video-EEG monitoring was repeatedly conducted in a female patient who experienced her first seizures at age 16, soon after a febrile illness. Identification of two distinctive EEG patterns-focal periodic sharp-wave discharges and biphasic complexes-allowed early diagnosis prior to the onset of severe deficits or epilepsia partialis continua. The biphasic complexes occurred alongside unilateral slow-wave activity, whereas focal periodic sharp-wave discharges were initially observed on an otherwise normal background. The biphasic complexes appear to herald evolution to the acute phase of the disease. Prompt immunomodulatory therapy (intravenous immunoglobulin followed by adalimumab) successfully halted disease progression, nearly normalized EEG background activity, and reduced seizure frequency. This case underscores the prognostic value of recurrent focal periodic sharp-wave discharges and biphasic complexes as prodromal EEG biomarkers for RE, aligning with one prior study linking these biphasic complexes to early-stage disease (Beaumanoir et al., 1997). Early recognition of these patterns is essential. Early initiation of immunotherapy may prevent irreversible neurological damage, highlighting the critical role of recognizing these electrographic patterns for timely diagnosis and intervention.
2026-04-24 | International consensus recommendations for the diagnosis and treatment of Rasmussen syndrome: A modified Delphi procedure
Rasmussen syndrome (RS) includes a well-described constellation of refractory focal seizures, often including epilepsia partialis continua, hemiplegia with progressive unilateral cortical atrophy, and cognitive/language decline. However, the precise early pathogenesis and reliable biomarkers remain elusive. In addition, we lack operational management guidelines, including diagnostic evaluation, disease-monitoring assessments, and medical and surgical treatment approaches. We aimed to create an expert consensus statement to guide and standardize the treatment of RS, with the goal of providing recommendations applicable to a global population. An expert panel was convened to complete three rounds of a modified Delphi procedure given the lack of high-level evidence, with a focus on workup to exclude mimicking diagnoses, disease-activity metrics, and treatment. Consensus was defined as ≥75% of responses being agree/strongly agree in either two subsequent rounds or in the third and final round. A total of 122 of 143 statements met consensus. Proposed diagnostic evaluation in patients with possible RS is outlined, including physical examination, blood/cerebrospinal fluid analyses, neuroimaging, electroencephalography (EEG), and biopsy. Suggested disease-monitoring assessments include neuropsychological testing and serial magnetic resonance imaging (MRI). Intravenous corticosteroids are recommended as first-line, acute immunotherapy for seizure exacerbations and status epilepticus, with or without the addition of intravenous immunoglobulin. Options for maintenance immunotherapy are outlined, with lack of evidence noted for comparing efficacy of these treatments. Hemispheric disconnection remains the most effective seizure treatment, with parameters including age, function, seizure burden, and patient values influencing candidacy for surgery. This consensus statement offers a guideline to standardize management, as well as suggests future directions to further elucidate underlying pathophysiology and target more-effective, better-tolerated treatments.
2025-08-31 | Immune-mediated inflammatory conditions in epilepsy: role of autoimmunity.
Several studies have demonstrated the relationship between epilepsy and neuroinflammation; syndromes such as Rasmussen syndrome and paraneoplastic limbic encephalitis associated with epilepsy and some cases with refractory status epilepticus are prominent examples of this relationship. However, seizures are one of the symptoms that patients with autoimmune encephalitis frequently present with or are at increased risk for epilepsy, hence the confusion with associated autoimmune epilepsy. Moreover, the etiology of one-third of all epilepsies remains unknown, and it is estimated that approximately 5% of focal epilepsies of unknown cause without clinical suspicion of encephalopathy may be immune-mediated. Autoimmune pathophysiologic mechanisms have been included as one of the etiologies of seizures in the most recent classification by the International League Against Epilepsy. The antigens most associated with epilepsy of autoimmune origin are mainly intracellular antigens such as glutamic acid decarboxylase 65 (GAD65) and neuronal surface antigens such as inactivated glioma leucine-rich protein-1 (LGI1), GABAb receptor, and it has recently been shown that more than one autoantibody can be present in patients with drug-resistant epilepsy. This could cause an overlap of clinical features, thus complicating clinical symptoms and treatment; therefore, early identification of more than one autoantibody, in addition to rigorous clinical diagnosis, imaging studies, and assessment of the response to immunotherapy, is of utmost importance. Thus, new immunomodulatory therapies are emerging that show promising effects, as anticonvulsants (ASM) usually do not stop immune-mediated seizures and are often used for symptomatic control. This manuscript will review the most recent advances in inflammation in developing autoimmune-associated epilepsy, its pathophysiology, diagnosis, and recent treatments.
2026-06-03 | Centroparietal periodic sharp-wave discharges and biphasic complexes: Novel EEG biomarkers for early diagnosis of Rasmussen encephalitis.
Rasmussen encephalitis (RE) is a rare, chronic inflammatory brain disorder that predominantly affects one hemisphere in children. It is characterized by progressive neurological deterioration and refractory seizures. Early diagnosis remains challenging due to nonspecific initial symptoms and diagnostic features that overlap with other neurological conditions. To identify early and specific EEG patterns that may support timely initiation of immunomodulatory therapies. Continuous long-term video-EEG monitoring was repeatedly conducted in a female patient who experienced her first seizures at age 16, soon after a febrile illness. Identification of two distinctive EEG patterns-focal periodic sharp-wave discharges and biphasic complexes-allowed early diagnosis prior to the onset of severe deficits or epilepsia partialis continua. The biphasic complexes occurred alongside unilateral slow-wave activity, whereas focal periodic sharp-wave discharges were initially observed on an otherwise normal background. The biphasic complexes appear to herald evolution to the acute phase of the disease. Prompt immunomodulatory therapy (intravenous immunoglobulin followed by adalimumab) successfully halted disease progression, nearly normalized EEG background activity, and reduced seizure frequency. This case underscores the prognostic value of recurrent focal periodic sharp-wave discharges and biphasic complexes as prodromal EEG biomarkers for RE, aligning with one prior study linking these biphasic complexes to early-stage disease (Beaumanoir et al., 1997). Early recognition of these patterns is essential. Early initiation of immunotherapy may prevent irreversible neurological damage, highlighting the critical role of recognizing these electrographic patterns for timely diagnosis and intervention.
2026-04-24 | International consensus recommendations for the diagnosis and treatment of Rasmussen syndrome: A modified Delphi procedure
Rasmussen syndrome (RS) includes a well-described constellation of refractory focal seizures, often including epilepsia partialis continua, hemiplegia with progressive unilateral cortical atrophy, and cognitive/language decline. However, the precise early pathogenesis and reliable biomarkers remain elusive. In addition, we lack operational management guidelines, including diagnostic evaluation, disease-monitoring assessments, and medical and surgical treatment approaches. We aimed to create an expert consensus statement to guide and standardize the treatment of RS, with the goal of providing recommendations applicable to a global population. An expert panel was convened to complete three rounds of a modified Delphi procedure given the lack of high-level evidence, with a focus on workup to exclude mimicking diagnoses, disease-activity metrics, and treatment. Consensus was defined as ≥75% of responses being agree/strongly agree in either two subsequent rounds or in the third and final round. A total of 122 of 143 statements met consensus. Proposed diagnostic evaluation in patients with possible RS is outlined, including physical examination, blood/cerebrospinal fluid analyses, neuroimaging, electroencephalography (EEG), and biopsy. Suggested disease-monitoring assessments include neuropsychological testing and serial magnetic resonance imaging (MRI). Intravenous corticosteroids are recommended as first-line, acute immunotherapy for seizure exacerbations and status epilepticus, with or without the addition of intravenous immunoglobulin. Options for maintenance immunotherapy are outlined, with lack of evidence noted for comparing efficacy of these treatments. Hemispheric disconnection remains the most effective seizure treatment, with parameters including age, function, seizure burden, and patient values influencing candidacy for surgery. This consensus statement offers a guideline to standardize management, as well as suggests future directions to further elucidate underlying pathophysiology and target more-effective, better-tolerated treatments.
2025-08-31 | Immune-mediated inflammatory conditions in epilepsy: role of autoimmunity.
Several studies have demonstrated the relationship between epilepsy and neuroinflammation; syndromes such as Rasmussen syndrome and paraneoplastic limbic encephalitis associated with epilepsy and some cases with refractory status epilepticus are prominent examples of this relationship. However, seizures are one of the symptoms that patients with autoimmune encephalitis frequently present with or are at increased risk for epilepsy, hence the confusion with associated autoimmune epilepsy. Moreover, the etiology of one-third of all epilepsies remains unknown, and it is estimated that approximately 5% of focal epilepsies of unknown cause without clinical suspicion of encephalopathy may be immune-mediated. Autoimmune pathophysiologic mechanisms have been included as one of the etiologies of seizures in the most recent classification by the International League Against Epilepsy. The antigens most associated with epilepsy of autoimmune origin are mainly intracellular antigens such as glutamic acid decarboxylase 65 (GAD65) and neuronal surface antigens such as inactivated glioma leucine-rich protein-1 (LGI1), GABAb receptor, and it has recently been shown that more than one autoantibody can be present in patients with drug-resistant epilepsy. This could cause an overlap of clinical features, thus complicating clinical symptoms and treatment; therefore, early identification of more than one autoantibody, in addition to rigorous clinical diagnosis, imaging studies, and assessment of the response to immunotherapy, is of utmost importance. Thus, new immunomodulatory therapies are emerging that show promising effects, as anticonvulsants (ASM) usually do not stop immune-mediated seizures and are often used for symptomatic control. This manuscript will review the most recent advances in inflammation in developing autoimmune-associated epilepsy, its pathophysiology, diagnosis, and recent treatments.
Access all drug discovery articles and probability of success in trials forecasts:
Access all drug discovery articles and probability of success in trials forecasts:
Drug Discovery Landscape
1 orphan drug designation for Rasmussen subacute encephalitis.
1 orphan drug designation for Rasmussen subacute encephalitis.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
rituximab | antibodies | FDA | 2016-11-09 | — | Keck Graduate Institute of Applied Life Sciences |
Let's accelerate rare disease drug discovery
Let's accelerate drug discovery
Get access to Explority AI's forecasts to outperform average preclinical success rates. Whether you're expanding your R&D pipeline, evaluating a partnership, or simply have a question — we'd love to hear from you.