Peripherally-derived LGI1-reactive monoclonal antibodies cause epileptic seizures in vivo.

One striking clinical hallmark in patients with autoantibodies to leucine-rich glioma inactivated 1 (LGI1) is the very frequent focal seizure semiologies, including faciobrachial dystonic seizures (FBDS), in addition to the amnesia. Polyclonal serum IgGs have successfully modelled the cognitive changes in vivo but not seizures. Hence, it remains unclear whether LGI1-autoantibodies are sufficient to cause seizures. We tested this with the molecularly precise monoclonal antibodies directed against LGI1 (LGI1-mAbs), derived from patient circulating B cells. These were directed towards both major domains of LGI1, LRR and EPTP and infused intracerebroventricularly over 7 days into juvenile male Wistar rats using osmotic pumps. Continuous wireless EEG was recorded from a depth electrode placed in hippocampal CA3 plus behavioural tests for memory and hyperexcitability were performed. Following infusion completion (Day 9), post-mortem brain slices were studied for antibody binding and effects on Kv1.1. The LGI1-mAbs bound most strongly in the hippocampal CA3 region and induced a significant reduction in Kv1.1 cluster number in this subfield. By comparison to control-Ab injected rats video-EEG analysis over 9 days revealed convulsive and non-convulsive seizure activity in rats infused with LGI1-mAbs, with a significant number of ictal events. Memory was not impaired in the novel object recognition test. Peripherally-derived human LGI1-mAbs infused into rodent CSF provide strong evidence of direct in vivo epileptogenesis with molecular correlations. These findings fulfill criteria for LGI1-antibodies in seizure causation.

Autoimmune and paraneoplastic seizures.

Seizures are a common feature of autoimmune encephalitis and are especially prevalent in patients with the commonest autoantibodies, against LGI1, CASPR2 and the NMDA, GABAB, and GABAA receptors. In this chapter, we discuss the classification, clinical, investigation, and treatment aspects of patients with these, and other autoantibody-mediated and -associated, illnesses. We highlight distinctive and common seizure semiologies which, often alongside other features we outline, can help the clinical diagnosis of an autoantibody-associated syndrome. Next, we classify these syndromes by either focusing on whether they represent underlying causative autoantibodies or T-cell-mediated syndromes and on the distinction between acute symptomatic seizures and a more enduring tendency to autoimmune-associated epilepsy, a practical and valuable distinction for both patients and clinicians which relates to the pathogenesis. We emphasize the more effective immunotherapy response in patients with causative autoantibodies, and discuss the emerging evidence for various first-, second-, and third-line immunotherapies. Finally, we highlight available clinical rating scales which can guide autoantibody testing and immunotherapy in patients with seizures of unknown etiology. Throughout, we relate the clinical and therapeutic observations to the immunobiology and neuroscience which drive these seizures.

What Is Different about Teratoma-Associated Anti-LGI1 Encephalitis? A Long-Term Clinical and Neuroimaging Case Series.

INTRODUCTION: Anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis is clinically heterogeneous, especially at presentation, and though it is sometimes found in association with tumor, this is by no means the rule. METHODS: Clinical data for 10 patients with anti-LGI1 encephalitis were collected including one case with teratoma and nine cases without and compared for clinical characteristics. Microscopic pathological examination and immunohistochemical assay of the LGI1 antibody were performed on teratoma tissue obtained by laparoscopic oophorocystectomy. RESULTS: In our teratoma-associated anti-LGI1 encephalitis case, teratoma pathology was characterized by mostly thyroid tissue and immunohistochemical assay confirmed positive nuclear staining of LGI1 in some tumor cells. The anti-LGl1 patient with teratoma was similar to the non-teratoma cases in many ways: age at onset (average 47.3 in non-teratoma cases); percent presenting with rapidly progressive dementia (67% of non-teratoma cases) and psychiatric symptoms (33%); hyponatremia (78%); normal cerebrospinal fluid results except for positive LGI1 antibody (78%); bilateral hippocampal hyperintensity on magnetic resonance imaging (44%); diffuse slow waves on electroencephalography (33%); good response to immunotherapy (67%); and mild residual cognitive deficit (22%). Her chronic anxiety and presentation with status epilepticus were the biggest differences compared with the non-teratoma cases. CONCLUSION: In our series, anti-LGI1 encephalitis included common clinical features in our series: rapidly progressive dementia, faciobrachial dystonic seizures, behavioral disorders, hyponatremia, hippocampal hyperintensity on magnetic resonance imaging, and residual cognitive deficit. We observed some differences (chronic anxiety and status epilepticus) in our case with teratoma, but a larger accumulation of cases is needed to improve our knowledge base.

Whole-brain metabolic pattern analysis in patients with anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis.

BACKGROUND AND PURPOSE: Faciobrachial dystonic seizures (FBDS) and hyponatremia are the distinct clinical features of autoimmune encephalitis (AE) caused by antibodies against leucine-rich glioma-inactivated 1 (LGI1). The present study aims to explore the pathophysiological patterns and neural mechanisms underlying these symptoms. METHODS: We included 30 patients with anti-LGI1 AE and 30 controls from a retrospective observational cohort. Whole-brain metabolic pattern analysis was performed to assess the pathological network of anti-LGI1 AE, as well as the symptom networks associated with FBDS. Logistic regression was applied to explore independent predictors of FBDS. Finally, we used a multiple regression model to investigate the hyponatremia-associated brain network and its effect on serum sodium levels. RESULTS: The pathological network of anti-LGI1 AE involved hypermetabolism in the cerebellum, subcortical structures and Rolandic area, as well as hypometabolism in the medial prefrontal cortex. The symptom network of FBDS included hypometabolism in the cerebellum and Rolandic area (pFDR <0.05). Hypometabolism in the cerebellum was an independent predictor of FBDS (p < 0.001). Hyponatremia-associated network highlighted a negative effect on the caudate nucleus, frontal and temporal white matter. The metabolism of the hypothalamus was negatively associated with (Pearson's R = -0.180, p = 0.342), while not the independent predictor for serum sodium level (path c' = -7.238, 95% confidence interval = -30.947 to 16.472). CONCLUSIONS: Our results provide insights into the whole-brain metabolic patterns of patients with anti-LGI1 AE, including the symptom network associated with FBDS and the hyponatremia-associated brain network. The findings help us to understand the neural mechanisms underlying anti-LGI1 AE and to evaluate the progress of this disease.

Great balls of fire! The basal ganglia on fire.

A 76-year-old man presented to the hospital with intermittent dizziness, memory impairment and jerky movements. Evaluation revealed them to be faciobrachial dystonic seizures and antibodies to voltage-gated potassium channel complexes were found. He was treated with intravenous methylprednisolone and rituximab, and made a remarkable recovery. Magnetic resonance imaging of the brain was normal, although positron emission tomography - computed tomography showed striking basal ganglia changes.

Long-term evolution and prognostic factors of epilepsy in limbic encephalitis with LGI1 antibodies.

OBJECTIVE: To characterize the evolution of epilepsy in patients with leucine-rich glioma inactivated 1 antibody-associated (LGI1ab) limbic encephalitis, including factors associated with drug-resistant epilepsy (DRE). METHODS: Retrospective analysis of patients with LGI1 encephalitis managed at two tertiary epilepsy centers between 2005 and 2019 and whose samples were confirmed by the French Reference Center of Paraneoplastic Neurological Syndromes. Raw clinical, biological, EEG, and MRI data were reviewed. Two endpoints were defined: (i) Epilepsy remission: patients seizure free and in whom anti-seizure medications (ASM) have been stopped for at least 1 year at the last follow-up visit (ii) DRE: patients with persistent seizures at the last follow-up despite at least two ASM used at efficacious daily dose. RESULTS: 39 patients with LGI1 encephalitis were included with a median follow-up duration of 42 months (range 13-169). All of them reported seizures at the acute phase, with faciobrachial dystonic seizures (FBDS) in 23 (59%) and other focal seizures in 38 (97%), including 4 patients (10%) with de novo status epilepticus. At the last follow-up visit, 11 patients (28%) achieved epilepsy remission. Among the 28 patients with persistent epilepsy, eight (29%) fulfilled criteria of DRE. The only factor significantly associated with epilepsy remission was the time from clinical onset of the encephalitis to initiation of the first immunomodulatory treatment, with longer delay in patients with persistent epilepsy (7.5 ± 8.9 vs 2.4 ± 1.7 months, p = 0.006). Evolution to DRE was only driven by MRI evolution. Eight of the 15 patients (53%) who developed hippocampal atrophy (p = 0.007) also suffered from drug-resistant seizures at the last follow-up. SIGNIFICANCE: In patients with LGI1 encephalitis, rapid initiation of immunomodulatory treatment favors long-term epilepsy remission. Evolution to DRE might primarily reflect the anatomical lesion of limbic structures. Determining what modalities of immune treatment may alter these outcomes requires prospective studies with long-term follow-up.

Bi-Basal Ganglia Involvement with Signal Evolution in a Case of Anti-LGI1 Encephalitis.

Anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis is a rare type of non-paraneoplastic limbic encephalitis (LE) mainly characterized by seizures, cognitive disorder, faciobrachial dystonic seizures (FBDS), hyponatremia, insomnia, and autonomic dysfunction. Here, we report the case of an elderly female patient who tested positive for antibodies against LGI1 and was initially thought to have Hashimoto encephalopathy (HE) due to its similar clinical features and the patient's high titers of antithyroid antibody. Interestingly, during the course of the disease, the patient exhibited typical FBDS and brain magnetic resonance imaging (MRI) showed a hyperintense signal evolution from T2/Fluid attenuated inversion recovery (FLAIR) to T1-weighted image in the bilateral basal ganglia (BG), which have rarely been reported previously.

Faciobrachial Myoclonus as the Presenting Manifestation of Diabetic Keto-Acidosis.

Background: Chorea and ballism are well-recognized acute potentially reversible movement disorders as the presenting manifestation of non-ketotic hyperglycemic states among older type-2 diabetics. Myoclonus as the form of presentation of diabetic keto-acidosis (DKA) in previously undiagnosed type-1 diabetic has never been reported before. Case report: We herein report the case of a 36-year-old previously healthy patient who presented with acute onset incessant faciobrachial myoclonus for 10 days. The patient was found to be suffering from DKA and eventually diagnosed as type-1 diabetes mellitus. Myoclonus disappeared with achieving euglycemia and did not recur. Discussion: Apart from expanding the spectrum of acute movement disorder among diabetics, this case reiterates the importance of rapid bedside measurement of capillary blood glucose in all patients presenting with acute onset abnormal movements irrespective of their past glycemic status. This simple yet life-saving approach can clinch the diagnosis at the earliest and thus will avoid costly investigations and mismanagement.

Electroencephalographic findings in antileucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis: A systematic review.

BACKGROUND: Antileucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis is a distinct syndrome of early onset faciobrachial dystonic seizures (FBDS) and other focal seizures followed by neuropsychiatric symptoms. The electroclinical syndrome of this condition is yet to be fully understood. The main objective of this study was to determine the frequencies of electroencephalogram (EEG) findings in patients diagnosed with anti-LGI1 autoimmune encephalitis through a systematic review of published relevant articles. METHODS: Major electronic healthcare databases were searched for relevant published articles until July 2020. RESULTS: From 327 articles, 23 case reports and 14 case series were included in the review after satisfying the eligibility criteria. Data from a total of 151 cases of definite anti-LGI1 encephalitis were analyzed in this systematic review. Epileptiform discharges were the most frequent finding at 57.3%. Focal electroencephalographic abnormalities including slow wave (59.3%) and epileptiform activities (53.5%) most commonly arise from the temporal region. Faciobrachial dystonic seizures often have no ictal electroencephalographic correlate but would show electrodecremental events when seizure duration is prolonged. CONCLUSION: Electroencephalogram abnormalities are seen in anti-LGI1 autoimmune encephalitis with epileptiform discharges as the most common finding followed by focal slowing. These findings were most frequently seen arising in the temporal region. Further studies using a standardized protocol focusing on electroencephalographic findings in anti-LGI1 encephalitis with clinical correlation to disease stage and treatment outcomes in terms of seizure control and memory and cognitive function are needed. Particular attention on ictal electrodecremental activity during FBDS should be done in studies with a larger sample size.

Pilomotor Seizures in a Patient With LGI1 Encephalitis.

Limbic encephalitis (LE) with antibodies against leucine-rich glioma inactivated protein 1 (LGI1) is an autoimmune disease with variable clinical features, including seizures, cognitive disorders, psychiatric disturbances, and hyponatremia. The majority of these patients present faciobrachial dystonic seizures (FBDS), which are regarded as a characteristic symptom. A few cases have reported pilomotor seizures as the main manifestation of anti-LGI1 encephalitis. Here, we described a Chinese woman with frequent pilomotor seizures who was finally diagnosed as having anti-LGI1 encephalitis. Our report emphasizes the possible significance of pilomotor seizures in anti-LGI1 encephalitis.

Anti-leucine-rich Glioma Inactivated-1 Encephalitis Associated with Essential Thrombocythemia.

Anti-leucine-rich glioma inactivated-1 (anti-LGI1) encephalitis is a subgroup of autoimmune encephalitis. We herein report the case of a 60-year-old man who presented with typical symptoms, including short-term memory loss, mental abnormalities, hyponatremia and seizures characterized by faciobrachial dystonic seizures and who was diagnosed with anti-LGI1 encephalitis. At the same time, he was diagnosed with essential thrombocythemia. A significant improvement was obtained by treatment with corticosteroid, immunoglobulin, mycophenolate mofetil, and hydroxyurea. Autoimmune diseases are associated with a significantly increased risk of developing myeloproliferative neoplasms, which may explain the coexistence of anti-LGI1 encephalitis and essential thrombocythema in this patient; however, but more cases and studies are needed to determine whether there is any correlation between these conditions.

The exploration of the spectrum of motor manifestations of anti-LGI1 encephalitis beyond FBDS.

PURPOSE: The purpose of this study was to characterize the spectrum of motor events in patients with acute anti-leucine-rich glioma-inactivated protein 1 (anti-LGI1) encephalitis through video-electroencephalogram (VEEG) recordings. METHOD: We collected data retrospectively from 16 patients diagnosed with anti-LGI1 encephalitis who had completed VEEG recording during hospitalization. RESULTS: VEEG monitoring lasted a median of 11.0 h (range 4.5∼20). Fourteen types of seizures were recorded in 9 patients (56.3 %). Eight of the 14 types of seizures demonstrated typical ictal EEG evolution (including 2 subclinical seizures), 3/14 demonstrated EEG electrodecremental events (EDE) at onset but without further evolution, and 3/14 could be only judged by analyzing semiology. FBDS was recorded in 6 patients (37.5 %), and all these attacks were followed by epileptic seizures. Simple hyperkinetic movements (HMs), such as jerk-like or twisting movements, were found in 8 (50 %) patients, and 6 of them had complex HMs, such as manipulating movements or mimics of daily activities, during sleep. CONCLUSIONS: 1. Atypical seizures, for instance, seizures without EEG evolution, are not rare but likely to be overlooked. 2. FBDS is closely linked with epileptic seizures, revealing FBDS to be a part of epileptic attacks. 3. HMs could expand the spectrum of motor manifestations, overlapping with sleep disorders. 4. The high prevalence of these motor events might be due to the disrupted cortical-subcortical network, which is critical in motor control and sleep.

Three cases of antibody-LGI1 limbic encephalitis and review of literature.

PURPOSE: Antibody-LGI1 limbic encephalitis (LGI1-Ab LE) is an anti-neuronal surface antigen-related autoimmune encephalitis. we report three cases of LGI1-Ab LE, describe the characteristics of clinical manifestation, course of evolution, imaging manifestation and treatment outcomes. METHODS: Data from patients diagnosed with LGI1-Ab LE in the Second Hospital, Hebei Medical University, from June 2016 to July 2017, were retrospectively collected and analyzed. We followed up the patients for 90 days. RESULTS: Two of the three patients were females, the average age of onset is 53 years old. Epilepsy is the most common clinical manifestations, and one of patients developed faciobrachial dystonic seizures (FBDS), which was recently described as a characteristic feature of LGI1-Ab LE. All patients had cognitive impairment in different degrees and abnormal signal of hippocampus in cranial MRI. All serum LGI1 antibodies were positive, whereas one LGI1 antibodies of CSF were negative. All patients accepted first-line immune therapy and had a good outcome. CONCLUSION: LGI1-Ab LE, which is an autoimmune disease, is rare clinically and mostly nonparaneoplastic. We suggest that LGI1-Ab LE be considered in any patient with acute or subacute onset, cognitive dysfunction , various types of seizures, accompanied by mental disorders and hyponatremia, MR showed the involvement of the limbic system. It is necessary to have LE-related antibodies tested. Early immunotherapy can significantly improve the patient's overall prognosis. At the same time, we should also pay attention to the possibility of potential tumors.

Antiepileptic drug therapy in autoimmune epilepsy associated with antibodies targeting the leucine-rich glioma-inactivated protein 1.

OBJECTIVE: To characterize seizure semiology and the utility of antiepileptic drug (AED) therapy in leucine-rich glioma inactivated-1 ( LGI1-Ab) autoimmune epilepsy (AE). METHODS: Patients with voltage-gated potassium channel complex (VGKCc) titers higher than 0.02 nmol/L who were evaluated between May 2008 and June 2016 at the 3 Mayo Clinic sites (Arizona, Florida, or Minnesota) were identified. We then performed a retrospective review of those who were LGI1-Ab positive and were treated for seizures. RESULTS: A total of 1,095 patients with VGKCc titers higher than 0.02 nmol/L were identified, in which 77 were LGI1 positive. Of these, 56 patients with seizures were included in the analysis. Mean age at symptom onset was 62.9 years; 66% (n = 37) were male. The most common seizure semiology was focal faciobrachial dystonic seizures with preserved awareness (FBDS) (n = 35, 63%), followed by focal with impaired awareness (FIA) (n = 29, 52%), generalized tonic-clonic (GTCs) (n = 28, 50%), and focal non-motor seizures with preserved awareness (n = 28, 50%). The majority had more than one seizure type (n = 49, 88%; median = 2.5). Thirty-eight patients (68%) became seizure free: 29 (76%) with immunotherapy, 3 (5%) with AEDs alone, 2 (3%) with AEDs before any immunotherapy, and 4 (7%) with AEDs after immunotherapy. Levetiracetam (n = 47, 84%) and valproic acid (n = 21, 38%) were the most commonly used AEDs, but neither were associated with seizure freedom. Sodium channel blocking (NCB) AEDs were associated with seizure freedom in 4 patients compared to none treated with non-NCB AEDs. Regardless of class, AEDs prior to or apart from immunotherapy were associated with seizure freedom in only five patients (9%). In patients with FBDS, seizure freedom was more often associated with immunotherapy than AEDs (20/30 vs. 3/34, p = 0.001). SIGNIFICANCE: Although FBDS are the most characteristic seizure type seen in LGI1-Ab AE, other seizure types including FIA and GTCs also occur. Immunotherapy was the treatment most frequently associated with seizure freedom in LGI1-Ab AE. In general, AEDs seemed to confer a very low chance for seizure freedom, although AEDs with NCB-blocking properties were associated with seizure freedom in a limited number. Levetiracetam in particular appears to be ineffective in this patient population.

The importance of early immunotherapy in patients with faciobrachial dystonic seizures.

Faciobrachial dystonic seizures and limbic encephalitis closely associate with antibodies to leucine-rich glioma-inactivated 1 (LGI1). Here, we describe 103 consecutive patients with faciobrachial dystonic seizures and LGI1 antibodies to understand clinical, therapeutic and serological differences between those with and without cognitive impairment, and to determine whether cessation of faciobrachial dystonic seizures can prevent cognitive impairment. The 22/103 patients without cognitive impairment typically had normal brain MRI, EEGs and serum sodium levels (P < 0.0001). Overall, cessation of faciobrachial dystonic seizures with antiepileptic drugs alone occurred in only 9/89 (10%) patients. By contrast, 51% showed cessation of faciobrachial dystonic seizures 30 days after addition of immunotherapy (P < 0.0001), with earlier cessation in cognitively normal patients (P = 0.038). Indeed, expedited immunotherapy (P = 0.031) and normal cognition (P = 0.0014) also predicted reduced disability at 24 months. Furthermore, of 80 patients with faciobrachial dystonic seizures as their initial feature, 56% developed cognitive impairment after 90 days of active faciobrachial dystonic seizures. Whereas only one patient developed cognitive impairment after cessation of faciobrachial dystonic seizures (P < 0.0001). All patients had IgG4-LGI1 antibodies, but those with cognitive impairment had higher proportions of complement-fixing IgG1 antibodies (P = 0.03). Both subclasses caused LGI1-ADAM22 complex internalization, a potential non-inflammatory epileptogenic mechanism. In summary, faciobrachial dystonic seizures show striking time-sensitive responses to immunotherapy, and their cessation can prevent the development of cognitive impairment.awx323media15681705685001.

Frontal infraslow activity marks the motor spasms of anti-LGI1 encephalitis.

OBJECTIVE: The clinical and electrographic features of seizures in anti-LGI1 encephalitis are distinct from those seen in other autoimmune encephalitides or non-encephalitic epilepsies. One electroclinical phenomenon specific to the condition consists of lateralized motor spasms, known as faciobrachial dystonic seizures (FBDS). An electrodecremental pattern overriding a "DC shift" has been described as the EEG correlate of these spasms. We sought to further characterize this pre-spasm infraslow activity (ISA). METHODS: Continuous video-EEG recordings were acquired in four patients with anti-LGI1 encephalitis: each had frequent motor spasms/FBDS as well as frequent subclinical temporal lobe seizures (an independent indicator of anti-LGI1 encephalitis). RESULTS: In artifact-free recordings obtained using clinical amplifiers equipped with a low frequency analog filter of 0.07 Hz, ISA reliably preceded clinical onset of the motor spasms by ∼1.2 s and preceded the electrodecremental pattern by ∼700 ms. Pre-spasm ISA was invariably recorded contralateral to FBDS, with a voltage topographic maximum over the mid frontal region. The pre-movement ISA differed from the Bereitschaftspotential in timing and topography and was an order of magnitude higher in amplitude. Sporadic FBDS that occurred in association with temporal lobe seizures were preceded by identical ISA. CONCLUSIONS: The motor spasms of anti-LGI1 encephalitis are preceded by frontal ISA. A paucity of data at the microscale level precludes mechanistic explanations at the macroscale level, or even determination of the relative contributions of neurons and glia in the generation of the ISA. SIGNIFICANCE: Although fundamental cellular mechanisms await elucidation, the pre-spasm ISA represents a singular and readily identifiable EEG response to this autoimmune brain disorder.

Faciobrachial dystonic seizures result from fronto-temporo-basalganglial network involvement.

•Faciobrachial dystonic seizures (FBDS) are caused by autoantibodies to leucine-rich glioma-inactivated1 proteins, a component of the voltage-gated potassium channel complex (VGKC-complex) and precede the clinical presentation of limbic encephalitis.•The exact pathophysiology of FBDS is not known and whether they are seizures or movement disorder is still debated.•We suggest the fronto-temporo-basal ganglia network involving the medial frontal and temporal regions along with the corpus striatum and substantia nigra being responsible for the clinical phenomenon of FBDS.•The varied clinical, electrical and imaging features of FBDS in our cases and in the literature are best explained by involvement of this network.•Entrainment from any part of this network will result in similar clinical expression of FBDS, whereas other electro-clinical associations and duration depends on the extent of involvement of the network.

The importance of recognizing faciobrachial dystonic seizures in rapidly progressive dementias / A importância do reconhecimento das crises distônicas faciobraquiais nas demências rapidamente progressivas

ABSTRACT Background: Creutzfeldt-Jakob Disease (CJD) is the prototypical cause of rapidly progressive dementia (RPD). Nonetheless, efforts to exclude reversible causes of RPD that mimic prion disease are imperative. The recent expanding characterization of neurological syndromes associated with antibodies directed against neuronal cell surface or sympathic antigens, namely autoimmune encephalitis is shifting paradigms in neurology. Such antigens are well known proteins and receptors involved in synaptic transmission. Their dysfunction results in neuropsychiatric symptoms, psychosis, seizures, movement disorders and RPD. Faciobrachial dystonic seizure (FBDS) is a novel characterized type of seizure, specific for anti-LGI1 encephalitis. Objective: In order to improve clinical recognition we report the cases of two Brazilian patients who presented with characteristic FDBS (illustrated by videos) and anti-LGI1 encephalitis. Methods: We have included all patients with FBDS and confirmed anti-LGI1 encephalitis and video records of FDBS in two tertiary Brazilian centers: Department of Neurology of Hospital das Clínicas, Sao Paulo University, Sao Paulo, Brazil and Hospital Geral de Fortaleza, Fortaleza, Brazil between January 1, 2011 and December 31, 2015. Results: Both patients presented with clinical features of limbic encephalitis associated with FBDS, hyponatremia and normal CSF. None of them presented with tumor and both showed a good response after immunotherapy. Conclusion: FBDSs may be confounded with myoclonus and occurs simultaneously with rapid cognitive decline. Unawareness of FDBS may induce to misdiagnosing a treatable cause of RPD as CJD.

RESUMO Embasamento: A doença de Creutzfeldt-Jakob (DCJ) é o protótipo de demência rapidamente progressiva (DRP). No entanto, é imperativo que sejam excluídas causas reversíveis de DRPs que possam simular doença priônica. A recente caracterização de síndromes neurológicas associadas a anticorpos direcionados contra antígenos de superfície neuronal ou sinapse, assim denominadas de encefalites autoimunes, está mudando paradigmas em neurologia. Esses antígenos estão envolvidos na transmissão sináptica, sendo que as disfunções destes podem resultar em sintomas neuropsiquiátricos, psicose, crises epilépticas, distúrbios do movimento e DRP. A crise distônica faciobraquial (CDFB) é um tipo de crise recentemente caracterizada e específica da encefalite anti-LGI1. Objetivo: Para promover um melhor reconhecimento da doença relatamos os casos de 2 pacientes brasileiros que apresentaram CDFBs (ilustradas com vídeos) associadas à encefalite anti-LGI1. Métodos: Foram incluídos todos os pacientes com CDFBs e encefalite anti-LGI1 confirmados em 2 centros brasileiros terciários: Departamento de Neurologia do Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brasil e o Hospital Geral de Fortaleza entre 01 de janeiro de 2011 e 31 de dezembro de 2015. Resultados: Ambos os casos apresentaram quadro clinico típico de encefalite límbica associada a CDFBs e exame do LCR sem alterações. Nenhum caso associou-se à presença de neoplasia e ambos apresentaram boa resposta à imunoterapia. Conclusão: A CDFB podem ser confundidas com mioclonias e ocorrer simultaneamente com rápido declínio cognitivo, o seu não reconhecimento pode induzir ao diagnóstico errôneo de uma causa potencialmente tratável de DRP como sendo DCJ.