OBJECTIVE: To report a novel anatomical pattern of autoimmune encephalitis characterized by strictly unilateral cortical inflammation and a clinical picture overlapping with late-onset Rasmussen\'s encephalitis.
METHODS: We retrospectively gathered data of patients identified at two tertiary referral academic centers who met inclusion criteria.
RESULTS: We identified twelve cases (average age 65, +/- 19.8 years, 58% female). All patients had unilateral cortical inflammation manifesting with focal seizures, cognitive decline, hemicortical deficits, and unilateral MRI and/or EEG changes. Six cases were idiopathic, two paraneoplastic, two iatrogenic (in the setting of immune checkpoint inhibitors), and two post-COVID-19. Serologically, ten patients were seronegative, one had high titer anti-GAD65, and one had anti-NMDAR. Five patients met Rasmussen\'s encephalitis criteria, and six did not fully meet the criteria but had symptoms significantly overlapping with the condition. Most patients had significant improvement with immunotherapy.
CONCLUSIONS: Unilateral cortical AE seems to be more prevalent in the elderly and more frequently idiopathic and seronegative. Patients with this anatomical variant of autoimmune encephalitis have overlapping features with late-onset Rasmussen\'s encephalitis but are more responsive to immunotherapy. In cases refractory to immunotherapy, interventions used in refractory Rasmussen\'s encephalitis may be considered, such as functional hemispherectomy.

Hemispherectomy is a neurosurgical procedure that is frequently performed in pediatric patients diagnosed with Rasmussen\'s encephalitis. Postoperative complications include immediate complications such as hydrocephalus and hemorrhage and behavioral complications such as language impairments and contralateral weakness. However, there are limited studies or case reports that address the potential endocrinopathies associated with this and other pediatric epileptic surgeries. This case report describes the endocrinopathies following an anatomical hemispherectomy procedure. A four-year-old African-American female had a right anatomical hemispherectomy for the treatment of Rasmussen\'s encephalitis in 2020. The postoperative course was immediately complicated by central diabetes insipidus which was stabilized with desmopressin. The patient\'s labs in 2021 were consistent with central precocious puberty with elevated luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Additionally, the patient was found to have secondary adrenal insufficiency in which she failed a low-dose adrenocorticotropic hormone (ACTH) stimulation test. Oral hydrocortisone therapy was initiated for secondary adrenal insufficiency in addition to initiating leuprolide injections for central precocious puberty. Furthermore, at the age of seven years, the patient had her first menarche. This case report emphasizes the need for closer and long-term surveillance for endocrine issues in postepileptic surgical pediatric patients as well as a surveillance plan for the development of other potential endocrine abnormalities throughout the patient\'s life.

Epilepsia partialis continua (EPC) is a rare type of focal motor status epilepticus that causes continuous muscle jerking in a specific part of the body. Experiencing this type of seizure, along with other seizure types, such as focal motor seizures and focal to bilateral tonic-clonic seizures, can result in a disabling situation. Non-invasive brain stimulation methods like transcranial direct current stimulation (tDCS) show promise in reducing seizure frequency (SF) when medications are ineffective. However, research on tDCS for EPC and related seizures is limited. We evaluated personalized multichannel tDCS in drug-resistant EPC of diverse etiologies for long-term clinical efficacy We report three EPC patients undergoing a long-term protocol of multichannel tDCS. The patients received several cycles (11, 9, and 3) of five consecutive days of stimulation at 2 mA for 2 × 20 min, targeting the epileptogenic zone (EZ), including the central motor cortex with cathodal electrodes. The primary measurement was SF changes. In three cases, EPC was due to Rasmussen\'s Encephalitis (case 1), focal cortical dysplasia (case 2), or remained unknown (case 3). tDCS cycles were administered over 6 to 22 months. The outcomes comprised a reduction of at least 75% in seizure frequency for two patients, and in one case, a complete cessation of severe motor seizures. However, tDCS had no substantial impact on the continuous myoclonus characterizing EPC. No serious side effects were reported. Long-term application of tDCS cycles is well tolerated and can lead to a considerable reduction in disabling seizures in patients with various forms of epilepsy with EPC.

Rasmussen encephalitis is a rare and unexplained chronic brain hemispheric inflammatory disease. We report a case of epilepsy in which magnetoencephalography showed dipoles localized only in the operculum. Because the patient\'s clinical presentation and examination findings did not meet the diagnostic criteria for Rasmussen encephalitis, he underwent cortical electroencephalogram (ECoG) record and limited resection surgery. However, the seizures were not relieved after surgery, and imaging findings showed significant features of hemisphere atrophy. This young male patient was eventually diagnosed with Rasmussen encephalitis and the seizures was completely vanished following hemispherectomy. His data can provide a reference for the early identification of this devastating disease.

BACKGROUND: Bilateral Rasmussen encephalitis is a rare variant of a debilitating, typically unihemispheric disease with limited treatment options. Few cases with bilateral histopathology have been reported, all with poor seizure control following surgery. Here we report a favorable outcome following hemispherotomy in a four-year-old male with biopsy-confirmed bilateral disease.
METHODS: The patient presented with right hemispheric focal seizures with behavioral arrest and over a year progressed to left lower extremity clonic seizures, epilepsia partialis continua, and loss of ambulation, with transient response to steroids and tacrolimus. Histopathology confirmed bilateral disease. The patient developed super-refractory status epilepticus and underwent right functional hemispherotomy 4.5 years after initial presentation. In a 2.5-year follow-up period, an Engel 1D outcome classification was observed with substantially improved quality of life.
CONCLUSIONS: Previous reports of bilateral Rasmussen encephalitis describe universally poor outcomes, and hemispherotomy is often considered contraindicated. However, hemispherotomy in a patient with bilateral Rasmussen encephalitis may have a good outcome if seizures are unihemispheric.

Relatively rare, Rasmussen encephalitis is a chronic inflammatory disease conditioning a single cerebral hemisphere. It is a progressive pathology with different stages clinically and on MRI. Therefore, imaging has an important role in evoking the diagnosis and also excluding other possible etiologies. We report a case of Rasmussen encephalitis with 2 different stages on MRI and also provide a review of the role of imaging in diagnostic criteria, differential diagnoses, and stages of this pathology.

BACKGROUND: Rasmussen encephalitis (RE) is characterized by pharmacoresistant epilepsy and progressive neurological deficits concurrent with unilateral hemispheric atrophy. Evidence of an inflammatory autoimmune process has been extensively described in the literature; however, the precise etiology of RE is still unknown. Despite data supporting a beneficial effect of early immunosuppressive and immunomodulatory interventions, surgical disconnection of the affected hemisphere is considered the treatment of choice for these patients. The aim of this study was to report a series of children and adolescents who underwent hemispheric surgery (HS) for the treatment of RE, analyzing their clinical, electrographic, and neuroimaging features pre-operatively, as well as their postoperative status, including seizure and functional outcomes.
METHODS: All patients with RE who underwent HS in the Epilepsy Surgery Center (CIREP) of the University Hospital of Ribeirão Preto Medical School, between 1995 and 2020 were retrospectively reviewed. Preoperative and postoperative analyses included gender; age at epilepsy onset; seizure semiology; seizure frequency; interictal and ictal electroencephalographic (EEG) findings; age at surgery; duration of epilepsy; surgical complications; duration of follow-up; histopathological findings; and postoperative seizure, cognitive, and functional outcomes.
RESULTS: Forty-four patients were evaluated. Mean age at seizure onset and epilepsy duration was 6 years and 2.5 years, respectively. Mean age at surgery was 9 years, with an average follow-up ranging from 3 months to 23 years. All patients presented with severe epilepsy and distinct neurological abnormalities on MRI. Before HS, different degrees of abnormal intellectual performance as well as hemiparesis were seen in 86% and 90%, respectively. Histopathology examination confirmed this diagnosis in 95% patients. At the last follow-up, 68% of patients were seizure free, and 70% were classified as Engel Class I or II. Postoperatively, the cognitive status remained unchanged in 64% of patients. Likewise, the gross motor function remained unchanged in 54% of patients and 74% had functional hand ability after HS.
CONCLUSIONS: Considering the progressive damage course of RE, hemispheric surgery should be offered to pediatric patients. It has manageable risks and results in good seizure outcome, and the preoperative functional status of these children is often preserved (even when the left hemisphere is involved), thus improving their quality of life.

OBJECTIVE: Rasmussen Encephalitis (RE) is a rare inflammatory neurodegenerative disease associated with refractory seizures, hemiparesis, and cognitive deterioration, due to lateralized cortical atrophy. Hemispheric surgery (hemispherotomy) is the mainstay of treatment, but its unavoidable motor deficits and lack of long-term data regarding seizure outcomes can make patients and families apprehensive to undergo this procedure. The present study aimed at analyzing the results of surgical treatment for RE from a motor and epilepsy standpoint, and mitigate such concerns.
METHODS: Clinical and operative data were retrospectively collected from medical records of pharmacoresistant patients treated with functional hemispherectomy at a tertiary reference center for epilepsy surgery, during a 24-year period (1996-2020). Variables such as age of epilepsy onset, seizure semiology, seizure frequency, immunomodulatory therapy, age at surgery, duration of epilepsy, surgical procedures and complications, number of medications used preoperatively and postoperatively were described and statistically analyzed.
RESULTS: Forty-three (43) patients were included in this study. Mean age of epilepsy onset was 6.14 years, the average interval between epilepsy onset and hemispherotomy was 2.21 years. and the mean age at surgery was 8.28 years. Thirty patients (69.7%) were Engel I at their last follow-up, of whom 23 (56.4%) were Engel Ia, within a mean follow-up of 11.3 years. Duration of epilepsy, seizure frequency, and age at surgery, among others, did not correlate with seizure outcome, except the use of immunotherapy which led to worse outcomes (p < .05). Also, after surgery, motor functionality was significantly recovered (i.e., most patients returned to their previous status) with time.
CONCLUSIONS: This study tackled some issues regarding the surgical treatment of this disease, particularly showing that hemispherotomy is safe and leads to potentially recoverable disability of motor functions while providing high rates of effective and long-lasting seizure control; therefore, early surgical indication should be warranted once medical refractoriness has been established.

BACKGROUND: Rasmussen encephalitis (RE) is a rare progressive presumed autoimmune disorder characterized by pharmacoresistant epilepsy and progressive motor and cognitive deterioration. Despite immunomodulation, more than half of the patients with RE ultimately require functional hemispherotomy. In this study, we evaluated the potential beneficial effects of early initiation of immunomodulation in slowing disease progression and preventing the need for surgical interventions.
METHODS: A retrospective chart review over a 10-year period was conducted at the American University of Beirut Medical Center to identify patients with RE. Data were collected on seizure characteristics, neurological deficits, electroencephalography, brain magnetic resonance imaging results (including volumetric analyses for an objective assessment of radiographic progression), and treatment modalities.
RESULTS: Seven patients met the inclusion criteria for RE. All patients received intravenous immunoglobulins (IVIGs) as soon as the diagnosis was entertained. Five patients with only monthly to weekly seizures at the time of IVIG initiation had favorable outcomes without resorting to surgery, along with a relative preservation of the gray matter volumes in the affected cerebral hemispheres. Motor strength was preserved in those patients, and three were seizure free at their last follow-up visit. The two patients who required hemispherotomy were already severely hemiparetic and experiencing daily seizures at the time of IVIG initiation.
CONCLUSIONS: Our data suggest that the early initiation of IVIG as soon as a diagnosis of RE is suspected, and particularly before the appearance of motor deficits and intractable seizures, can maximize the beneficial effects of immunomodulation in terms of controlling seizures and reducing the rate of cerebral atrophy.

OBJECTIVE: Rasmussen encephalitis (RE) is a focal encephalitis, characterized by epilepsia partialis continua (EPC) with or without seizures and progressive unilateral deficits. Imaging characteristics of RE have been rarely described in detail in relation to EPC. So, the study aimed to explore if any relationship exists between the imaging characteristics and the presence or evolution of EPC in patients with RE.
METHODS: This retrospective study included 11 patients with RE fulfilling the European consensus statement on RE followed between 2015 and 2020.
RESULTS: The mean age for onset of seizures was 12 years (range 2.5-24 years). Seven patients had limb EPCs, two had face EPCs, face, and limb EPC in one, and lingual EPC in one patient. The first MRI was done within 1 day to 1 month of the onset of seizures. It was normal in two patients and showed only cortical atrophy, focal or hemispheric in four patients, caudate atrophy in two, and cortical or subcortical hyperintensity (HI) in six patients. Follow-up MRI, within 3 weeks to 6 months of the onset of EPC (mean 1.6 months) showed paramedian frontal HI with limb EPC in six patients. Insular HI in four patients; two had facial EPCs while lingual EPC and limb EPC with facial EPC was observed in one patient each.
CONCLUSIONS: Fluid-attenuated inversion recovery (FLAIR) HI and focal cortical atrophy on MRI is the most common finding in the early course of RE. T2 and FLAIR hyperintensity in the paramedian frontal or insular cortex may antedate the onset of EPC or may occur simultaneously with EPC.