Utility of an immunotherapy trial in evaluating patients with presumed autoimmune epilepsy

An Update on the Treatment of Pediatric Autoimmune Encephalitis

PURPOSE OF REVIEW

Autoimmune encephalitis (AE) is an increasingly recognized etiology for neuropsychiatric deficits that are highly responsive to immunotherapy. As a result, rheumatologists are often called upon to help with the diagnosis and treatment of these conditions. The purpose of this review is to provide an update on the pharmacologic treatment of AE.

RECENT FINDINGS

To date, there are no prospective randomized placebo-controlled trials to guide treatment recommendations for AE. First-line therapies include corticosteroids, intravenous immunoglobulin, and plasma exchange. Second-line therapies include rituximab and cyclophosphamide (CYC), as well as mycophenolate mofetil and azathioprine. For patients refractory to both first- and second-line therapy, there is emerging evidence for the interleukin-6 (IL-6) inhibitor tocilizumab, the proteasome inhibitor bortezomib, and low-dose IL-2. Early treatment initiation and treatment escalation in patients with refractory disease improve outcomes. Given the delayed time between dosing and treatment effects of second-line agents, continuing first-line treatment until the patients shows improvement is recommended.

SUMMARY

Although AE can present with dramatic, life-threatening neuropsychiatric deficits, the potential for recovery with prompt treatment is remarkable. First- and second-line therapies for AE lead to clinical improvement in the majority of patients, including full recoveries in many. Early treatment and escalation to second-line therapy in those with refractory disease improves patient outcomes. Novel treatments including IL-6 blockade and proteasome inhibitors have shown promising results in patients with refractory disease.

Seizure semiology: an important clinical clue to the diagnosis of autoimmune epilepsy

Objective

The purpose of this study is to analyze the seizure semiologic characteristics of patients with autoimmune epilepsy (AE) and describe the investigation characteristics of AE using a larger sample size.

Methods

This observational retrospective case series study was conducted from a tertiary epilepsy center between May 2014 and March 2017. Cases of new‐onset seizures were selected based on laboratory evidence of autoimmunity. At the same time, typical mesial temporal lobe epilepsy (MTLE) patients with hippocampal sclerosis (HS) were recruited as the control group from the subjects who underwent presurgical evaluation during the same period.

Results

A total of 61 patients with AE were identified. Specific autoimmune antibodies were detected in 39 patients (63.93%), including anti‐VGKC in 23 patients (37.70%), anti‐NMDA‐R in 9 patients (14.75%), anti‐GABA_B‐R in 6 patients (9.84%), and anti‐amphiphysin in 1 patient (1.64%). Regarding the seizure semiology, no significant differences were noted between AE patients with autoantibody and patients with suspected AE without antibody. Compared to typical MTLE patients with HS, both AE patients with autoantibody and patients with suspected AE without antibody had the same seizure semiologic characteristics, including more frequent SPS or CPS, shorter seizure duration, rare postictal confusion, and common sleeping SGTC seizures.

Significance

This study highlights important seizure semiologic characteristics of AE. Patients with autoimmune epilepsy had special seizure semiologic characteristics. For patients with autoimmune epilepsy presenting with new‐onset seizures in isolation or with a seizure‐predominant neurological disorder, the special seizure semiologic characteristics may remind us to test neuronal nuclear/cytoplasmic antibodies early and initiate immunomodulatory therapies as soon as possible. Furthermore, the absence of neural‐specific autoantibodies does not rule out AE.

Claustrum hyperintensities: A potential clue to autoimmune epilepsy

In a cohort of 34 patients with autoimmune limbic encephalitis and/or epilepsy, we identified 4 patients exhibiting claustrum fluid‐attenuated inversion recovery (FLAIR) hyperintensities. All 4 patients presented with explosive onset of seizures and developed medically intractable epilepsy, and 2 exhibited a marked response to immunotherapy. Associated features included cognitive and behavioral disturbances (4/4), cerebrospinal fluid (CSF) lymphocytic pleocytosis (3/4), and a neural autoantibody (2/4). Electroencephalogram (EEG) features consisted of slow wave activity and epileptiform discharges in frontal and parasagittal regions, where ictal patterns were captured in 1 patient. In 1 patient, magnetoencephalographic source imaging of interictal spikes revealed dipole sources in anterior insular or subinsular localizations, mirroring claustrum FLAIR hyperintensities, which developed after a short lag from presentation and resolved in all but 1 patient. These MRI abnormalities were isolated (2/4) or associated with mesial temporal hyperintensities (2/4). Claustrum FLAIR hyperintensities may be a useful MRI marker of autoimmune epilepsy.

Innate and adaptive immunity in human epilepsies

Inflammatory mechanisms have been increasingly implicated in the origin of seizures and epilepsy. These mechanisms are involved in the genesis of encephalitides in which seizures are a common complaint. Experimental and clinical evidence suggests different inflammatory responses in the brains of patients with epilepsy depending on the etiology. In general, activation of both innate and adaptive immunity plays a role in refractory forms of epilepsy. Epilepsies in which seizures develop after infiltration of cells of the adaptive immune system in the central nervous system (CNS) include a broad range of epileptic disorders with different (known or unknown) etiologies. Infiltration of lymphocytes is observed in autoimmune epilepsies, especially the classical paraneoplastic encephalitides with antibodies against intracellular tumor antigens. The presence of lymphocytes in the CNS also has been found in focal cerebral dysplasia type 2 and in cortical tubers. Various autoantibodies have been shown to be associated with temporal lobe epilepsy (TLE) and hippocampal sclerosis of unknown etiology, which may be due to the presence of viral DNA. During the last decade, an increasing number of antineuronal autoantibodies directed against membranous epitopes have been discovered and are associated with various neurologic syndromes, including limbic encephalitis. A major challenge in epilepsy is to define biomarkers, which would allow the recognition of patient populations who might benefit from immune-modulatory therapies. Some peripheral inflammatory markers appear to be differentially expressed in patients with medically controlled and medically refractory and, as such, could be used for diagnostic, prognostic, or therapeutic purposes. Establishing an autoimmune basis in patients with drug-resistant epilepsy allows for efficacious and targeted immunotherapy. Although current immunotherapies can give great benefit to the correctly identified patient, there are limitations to their efficacy and they may have considerable side effects. Thus the identification of new immunomodulatory compounds remains of utmost importance.

Anti-Neuronal Autoantibodies in Both Drug Responsive and Resistant Focal Seizures with Unknown Cause

BACKGROUND

and Objective Autoimmunity is an emerging field of research in the etiology of different neurological disorders including epilepsy. We aimed to investigate the presence of neuronal autoantibodies in focal epilepsy with unknown cause and their clinical correlates in both drug-responsive and resistant patients.

METHOD

Between 2009 and 2010 94 patients were prospectively enrolled, had their antibodies tested and clinically followed." An additional 50 age- and gender-matched controls were also tested for antibodies. Age at examination, gender, age at onset, seizure frequency, risk factors, seizure precipitants, and type of seizures were noted. Plasma obtained from patients was frozen at -80°C and analysed for autoantibodies against VGKC-complex, VGCC, GAD, LGI1, CASPR2, NMDA, AMPA and GABAB receptors with immunocytochemistry and radioimmunoassay as required.

RESULTS

Thirteen (13.8%) patients, but none of the controls, had antibodies (p=0.003). Antibodies were directed against the uncharacterized components of VGKC-complex in 5 patients (5.3%), GAD in 4 patients (4.2%), NMDA-R in 1 patient (1%), AMPA-R in 1 patient (1%) and both GAD and VGKC-complex in 2 patients (2.1%). Prognosis of epilepsy, in subsequent follow-up, did not correlate to general presence of anti-neuronal antibodies with slightly more patients with antibodies epilepsy control than without (76.9% vs. 69.1%, not-statistically significant. Three patients with suspected active autoimmunity and epilepsy who were treated, showed a response to treatment with a reduction in the seizure frequency. Although most clinical features were identical between seropositive and seronegative patient groups, seropositive patients were more likely to have inflammatory/autoimmune disorders in their medical history.

DISCUSSION

In keeping with previous studies, we have shown anti-neuronal antibodies in a proportion of focal epilepsy patients. Although autoimmunity might merely occur as a bystander effect in many chronic neurological disorders, association of anti-neuronal antibodies with good response to immunotherapy and coexisting autoimmune disorders suggests that anti-neuronal autoimmunity might participate in seizure formation at least in a subgroup of focal epilepsy patients.

CONCLUSION

Immunity may play a role in some patients with unknown etiology regardless of prognosis and immunmodulatuar treatment may be helpful in seropositive group.

Seizures and risk of epilepsy in autoimmune and other inflammatory encephalitis

PURPOSE OF REVIEW

The aim of this study was to assess the seizure manifestations and risk of epilepsy in encephalitis associated with antibodies against neuronal cell-surface (autoimmune encephalitis) or myelin-associated antigens, and to review several chronic epileptic disorders, including Rasmussen's encephalitis, fever-induced refractory epileptic syndromes (FIRES) and new-onset refractory status epilepticus (NORSE).

RECENT FINDINGS

Seizures are a frequent manifestation of autoimmune encephalitis. Some autoimmune encephalitis may associate with characteristic features: faciobrachial dystonic seizures (anti-LGI1 encephalitis), electroencephalogram extreme delta brush (anti-NMDAR) or multifocal FLAIR-MRI abnormalities (anti-GABAAR). In anti-LGI1 encephalitis, cortical, limbic and basal ganglia dysfunction results in different types of seizures. Autoimmune encephalitis or myelin-antibody associated syndromes are often immunotherapy-responsive and appear to have a low risk for chronic epilepsy. In contrast patients with seizures related to GAD65-antibodies (an intracellular antigen) frequently develop epilepsy and have suboptimal response to treatment (including surgery). Rasmussen's encephalitis or FIRES may occur with autoantibodies of unclear significance and rarely respond to immunotherapy. A study of patients with NORSE showed that 30% developed chronic epilepsy.

SUMMARY

Although seizures are frequent in all types of autoimmune encephalitis, the risk for chronic epilepsy is dependent on the antigen: lower if located on the cell-surface, and higher if intracellular. For other disorders (Rasmussen's encephalitis, FIRES, NORSE), the prognosis remains poor.

LGI1-antibody encephalitis is characterised by frequent, multifocal clinical and subclinical seizures

PURPOSE

To describe clinical and electrographic characteristics of seizures LGI1-antibody encephalitis, and their correlations with two-year outcomes.

METHODS

Video-electroencephalography recordings were performed on a cohort of 16 consecutive patients with LGI1-antibodies from two UK neuroscience-centers over five-years.

RESULTS

From 14 of 16 patients (13 males; age-range 53-92years), 86 faciobrachial dystonic seizures were recorded at a median frequency of 0.4 per hour (range 0.1-9.8), and ictal EEG changes accompanied 5/86 events. In addition, 11/16 patients showed 53 other seizures - subclinical (n=18), motor (n=16), or sensory (n=19) - at a median of 0.1 per hour (range 0.1-2) associated with temporal and frontal discharges. The sensory events were most commonly thermal sensations or body-shuddering, and the motor events were frequently automatisms or vocalisations. Furthermore, multifocal interictal epileptiform discharges, from temporal, frontal and parietal regions, and interictal slow-wave activity were observed in 25% and 69% of patients, respectively. Higher observed seizure frequency correlated with poorer functional recovery at two-years (p=0.001).

CONCLUSIONS

Multiple frequent seizure semiologies, in addition to numerous subclinical seizures and interictal epileptiform discharges, are hallmarks of LGI1-antibody encephalitis. High overall seizure frequency may predict more limited long-term recovery. These observations should encourage closer monitoring and proactive treatment of seizure activity in these patients.

Antiepileptic drug therapy in patients with autoimmune epilepsy

Objective:

We aimed to report the pattern of usage and efficacy of antiepileptic drugs (AEDs) in patients with autoimmune epilepsy (AE).

Methods:

We retrospectively studied the Mayo Clinic's electronic medical record of patients with AE in which seizures were the main presenting feature. Clinical data, including demographics, seizure characteristics, type of AED and immunotherapy used, presence of neural antibody, and treatment outcomes, were reviewed.

Results:

The medical records of 252 adult patients diagnosed with autoimmune encephalitis and paraneoplastic disorders were reviewed. Seizure was the initial presentation in 50 patients (20%). Serum and/or CSF autoantibodies were detected in 41 (82%) patients, and 38 (76%) patients had neural autoantibodies. The majority (n = 43, 86%) received at least 1 form of immunotherapy in combination with AEDs, while the remainder received AEDs alone. Twenty-seven patients (54%) became seizure free: 18 (36%) with immunotherapy, 5 (10%) with AEDs alone, and 4 (8%) with AEDs after immunotherapy failure. Levetiracetam was the most commonly used (42/50); however, it was associated with 0% seizure-free response. AED seizure-free responses occurred with carbamazepine (n = 3) [3/16, 18.8%], lacosamide (n = 3) [3/18, 16.6%] with phenytoin (n = 1) [1/8, 12.5%], or oxcarbazepine (n = 2) [2/11, 18.1%]. Regardless of the type of therapy, voltage-gated potassium channel-complex antibody–positive patients were more likely to become seizure free compared with glutamic acid decarboxylase 65 antibody–positive cases (12/17 vs 2/10, p = 0.0183).

Conclusions:

In select patients, AEDs alone were effective in controlling seizures. AEDs with sodium channel blocking properties resulted in seizure freedom in a few cases. Prospective studies are needed to clarify AED selection and to elucidate their immunomodulatory properties in AE.

GAD65 neurological autoimmunity

The glutamic acid decarboxylase 65-kilodalton isoform (GAD65) antibody is a biomarker of autoimmune central nervous system (CNS) disorders and, more commonly, nonneurological autoimmune diseases. Type 1 diabetes, autoimmune thyroid disease, and pernicious anemia are the most frequent GAD65 autoimmune associations. One or more of these disorders coexists in approximately 70% of patients with GAD65 neurological autoimmunity. Neurological phenotypes have CNS localization and include limbic encephalitis, epilepsy, cerebellar ataxia, and stiff-person syndrome (SPS), among others. Classic SPS is a disorder on the spectrum of CNS hyperexcitability which also includes phenotypes that are either more restricted (stiff-limb syndrome) or more widespread (progressive encephalomyelitis with rigidity and myoclonus). GAD65 antibody is not highly predictive of a paraneoplastic cause for neurological disorders, but diverse cancer types have been occasionally reported. For all phenotypes, responses to immunotherapy are variable (approximately 50% improve). GAD65 autoimmunity is important to recognize for both coexisting nonneurological autoimmune associations and potential immunotherapy-response. Muscle Nerve 56: 15-27, 2017.

Intracellular and non-neuronal targets of voltage-gated potassium channel complex antibodies

OBJECTIVES

Autoantibodies against the extracellular domains of the voltage-gated potassium channel (VGKC) complex proteins, leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-2 (CASPR2), are found in patients with limbic encephalitis, faciobrachial dystonic seizures, Morvan's syndrome and neuromyotonia. However, in routine testing, VGKC complex antibodies without LGI1 or CASPR2 reactivities (double-negative) are more common than LGI1 or CASPR2 specificities. Therefore, the target(s) and clinical associations of double-negative antibodies need to be determined.

METHODS

Sera (n=1131) from several clinically defined cohorts were tested for IgG radioimmunoprecipitation of radioiodinated α-dendrotoxin (¹²⁵I-αDTX)-labelled VGKC complexes from mammalian brain extracts. Positive samples were systematically tested for live hippocampal neuron reactivity, IgG precipitation of ¹²⁵I-αDTX and ¹²⁵I-αDTX-labelled Kv1 subunits, and by cell-based assays which expressed Kv1 subunits, LGI1 and CASPR2.

RESULTS

VGKC complex antibodies were found in 162 of 1131 (14%) sera. 90 of these (56%) had antibodies targeting the extracellular domains of LGI1 or CASPR2. Of the remaining 72 double-negative sera, 10 (14%) immunoprecipitated ¹²⁵I-αDTX itself, and 27 (38%) bound to solubilised co-expressed Kv1.1/1.2/1.6 subunits and/or Kv1.2 subunits alone, at levels proportionate to VGKC complex antibody levels (r=0.57, p=0.0017). The sera with LGI1 and CASPR2 antibodies immunoprecipitated neither preparation. None of the 27 Kv1-precipitating samples bound live hippocampal neurons or Kv1 extracellular domains, but 16 (59%) bound to permeabilised Kv1-expressing human embryonic kidney 293T cells. These intracellular Kv1 antibodies mainly associated with non-immune disease aetiologies, poor longitudinal clinical-serological correlations and a limited immunotherapy response.

CONCLUSIONS

Double-negative VGKC complex antibodies are often directed against cytosolic epitopes of Kv1 subunits and occasionally against non-mammalian αDTX. These antibodies should no longer be classified as neuronal-surface antibodies. They consequently lack pathogenic potential and do not in themselves support the use of immunotherapies.

Pediatric Autoimmune Epileptic Encephalopathies

Pediatric autoimmune epileptic encephalopathies are predominantly characterized by the presence of autoantibodies to the surface of neuronal proteins, for example, N-methyl-d-aspartate (NMDA) receptor antibodies, but also include diseases with non-cell surface antibodies (eg, anti-Hu, glutamic-acid decarboxylase antibodies). In some cases with distinct clinical and para-clinical features, an autoimmune epileptic encephalopathy can be diagnosed without the presence of an antibody and will also respond favorably to immunotherapy. In this review, we summarize the common presentations of pediatric autoimmune epileptic encephalopathies, treatments, and outcomes, and report recent findings in the field of epilepsy, encephalopathy, and the immune system.

Autoimmune epilepsy

Seizures are a common manifestation of autoimmune limbic encephalitis and multifocal paraneoplastic disorders. Accumulating evidence supports an autoimmune basis for seizures in the absence of syndromic manifestations of encephalitis. The autoimmune epilepsies are immunologically mediated disorders in which recurrent seizures are a primary and persistent clinical feature. When other etiologies have been excluded, an autoimmune etiology is suggested in a patient with epilepsy upon detection of neural autoantibodies and/or the presence of inflammatory changes on cerebrospinal fluid (CSF) or magnetic resonance imaging. In such patients, immunotherapy may be highly effective, depending on the particular autoimmune epilepsy syndrome present. In this chapter, several autoimmune epilepsy syndromes are discussed. First, epilepsies secondary to other primary autoimmune disorders will be discussed, and then those associated with antibodies that are likely to be pathogenic, such as voltage-gated potassium channel-complex and N-methyl-d-aspartate receptor, gamma-aminobutyric acid A and B receptor antibodies. For each syndrome, the typical clinical, imaging, electroencephaloram, CSF, and serologic features, and pathophysiology and treatment are described. Finally, suggested guidelines for the recognition, evaluation, and treatment of autoimmune epilepsy syndromes are provided.

Management of status epilepticus

Status epilepticus is a neurologic and medical emergency manifested by prolonged seizure activity or multiple seizures without return to baseline. It is associated with substantial medical cost, morbidity, and mortality. There is a spectrum of severity dependent on the type of seizure, underlying pathology, comorbidities, and appropriate and timely medical management. This chapter discusses the evolving definitions of status epilepticus and multiple patient and clinical factors which influence outcome. The pathophysiology of status epilepticus is reviewed to provide a better understanding of the mechanisms which contribute to status epilepticus, as well as the potential long-term effects. The clinical presentations of different types of status epilepticus in adults are discussed, with emphasis on the hospital course and management of the most dangerous type, generalized convulsive status epilepticus. Strategies for the evaluation and management of status epilepticus are provided based on available evidence from clinical trials and recommendations from the Neurocritical Care Society and the European Federation of Neurological Societies.

Suspected antibody negative autoimmune limbic encephalitis: outcome of immunotherapy

OBJECTIVES

Whether and when to immunologically treat epilepsy patients with suggested autoantibody (AB)-negative limbic encephalitis (LE) is clinically challenging. Therefore, we evaluated the clinical outcome and eventual outcome predictors of immunotherapy in a group of AB-negative patients with recent-onset temporal lobe epilepsy (TLE), magnetic resonance imaging (MRI) indicators of LE, subjective cognitive decline, and/or psychiatric symptoms.

METHODS

This retrospective, observational, uncontrolled study monitored 28 TLE patients with suggested AB-negative LE along with methylprednisolone immunotherapy.

RESULTS

All patients had seizures, amygdala and/or -hippocampal enlargement, subjective cognitive decline and/or behavioral problems. Eighty-six percent (24/28) were impaired in executive or memory functions, 39% (10/25) depressed, 81% were on antiepileptic drugs when pulse therapy started. After a median follow-up of 18 months, 46% (13/28) of the patients were seizure free (>2 months), 48% (13/27) showed MRI improvements (amygdala and/or hippocampal volume reduction), cognition improved in 57% (16/28), worsened in 32% (9/28), mood improved in 14% (4/25), and deteriorated in 11% (3/25). Immunotherapy was discontinued in 75% (21/28). Clinical changes did not correlate to each other. Outcomes could not be predicted.

CONCLUSION

Immunological treatment of suggested AB-negative LE showed reasonable seizure control, MRI and cognitive improvements. Treatment success was not predictable from clinical features, nor definitely attributable to immunological treatment. Lacking biomarkers for the reliable diagnosis of AB-negative LE, we suggest that in presence of mild manifestations, and after initiating antiepileptic drug therapy, negative dynamics in MRI, seizures, cognition, and behavior should be documented before immunosuppressive treatment is initiated.

A case of neurosyphilis presenting with limbic encephalitis

A 46-year-old man presented with a history of personality change and memory disturbance for 5 months. He gradually became difficult in doing a daily job. Brain MRI showed abnormal hyperintensity within bilateral mesial temporal lobes on T₂ weighted image. Therefore, viral and autoimmune limbic encephalitis was initially suspected. However, because treponemal and non-treponemal specific antibodies were positive in serum and cerebrospinal fluid (CSF), the diagnosis of neurosyphilis was made. Patients of neurosyphilis with mesiotemporal T₂ weighted hyperintensity reportedly showed common features such as relatively young age, HIV-negative, subacute cognitive impairment and seizure, as seen in our patient. Neurosyphilis should be included in the differential diagnosis for mesiotemporal abnormality in patients with these features. In addition, in our patient, anti-glutamate receptor ε2 antibody (ELISA) was strongly positive in CSF that suggested additional autoimmune pathophysiological mechanism.

Paraneoplastic epilepsy

Epilepsy can be a manifestation of paraneoplastic syndromes which are the consequence of an immune reaction to neuronal elements driven by an underlying malignancy affecting other organs and tissues. The antibodies commonly found in paraneoplastic encephalitis can be divided into two main groups depending on the target antigen: 1) antibodies against neuronal cell surface antigens, such as against neurotransmitter (N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), gamma-aminobutyric acid (GABA)) receptors, ion channels (voltage-gated potassium channel (VGKC)), and channel-complex proteins (leucine rich, glioma inactivated-1 glycoprotein (LGI1) and contactin-associated protein-2 (CASPR2)) and 2) antibodies against intracellular neuronal antigens (Hu/antineuronal nuclear antibody-1 (ANNA-1), Ma2/Ta, glutamate decarboxylase 65 (GAD65), less frequently to CV2/collapsin response mediator protein 5 (CRMP5)). In this review, we provide a comprehensive survey of the current literature on paraneoplastic epilepsy indexed by the associated onconeuronal antibodies. While a range of seizure types can be seen with paraneoplastic syndromes, temporal lobe epilepsy is the most common because of the association with limbic encephalitis. Early treatment of the paraneoplastic syndrome with immune modulation/suppression may prevent the more serious potential consequences of paraneoplastic epilepsy.

Antibody-associated epilepsies: Clinical features, evidence for immunotherapies and future research questions

PURPOSE

The growing recognition of epilepsies and encephalopathies associated with autoantibodies against surface neuronal proteins (LGI1, NMDAR, CASPR2, GABABR, and AMPAR) means that epileptologists are increasingly asking questions about mechanisms of antibody-mediated epileptogenesis, and about the use of immunotherapies. This review summarizes clinical and paraclinical observations related to autoimmune epilepsies, examines the current evidence for the effectiveness of immunotherapy, and makes epilepsy-specific recommendations for future research.

METHOD

Systematic literature search with summary and review of the identified publications. Studies describing the clinical characteristics of autoantibody-associated epilepsies and treatments are detailed in tables.

RESULTS

Literature describing the clinical manifestations and treatment of autoimmune epilepsies associated with neuronal cell-surface autoantibodies (NSAbs) is largely limited to retrospective case series. We systematically summarize the features of particular interest to epileptologists dividing patients into those with acute or subacute encephalopathies associated with epilepsy, and those with chronic epilepsy without encephalopathy. Available observational studies suggest that immunotherapies are effective in some clinical circumstances but outcome data collection methods require greater standardization.

CONCLUSIONS

The clinical experience captured suggests that clusters of clinical features associate well with specific NSAbs. Intensive and early immunotherapy is indicated when patients present with autoantibody-associated encephalopathies. It remains unclear how patients with chronic epilepsy and the same autoantibodies should be assessed and treated. Tables in this paper provide a comprehensive resource for systematic descriptions of both clinical features and treatments, and highlight limitations of current studies.

Evaluation of positive and negative predictors of seizure outcomes among patients with immune-mediated epilepsy: a meta-analysis

BACKGROUND

The objective of this study was to analyze published literature on autoimmune epilepsy and assess predictors of seizure outcome.

METHODS

From PubMed and EMBASE databases, two reviewers independently identified publications reporting clinical presentations, management and outcomes of patients with autoimmune epilepsy. A meta-analysis of 46 selected studies was performed. Demographic/clinical variables (sex, age, clinical presentation, epilepsy focus, magnetic resonance imaging [MRI] characteristics, time to diagnosis and initiation of immunomodulatory therapy, and type of immunomodulatory therapy) were compared between two outcome groups (responders and nonresponders). Clinical response was defined as >50% reduction in seizure frequency. Unstandardized effect sizes were collected for the studies for responder and nonresponder groups. Sample size was used as the weight in the meta-analysis. The random effects model was used to account for heterogeneity in the studies.

RESULTS

The 46 reports included 186 and 96 patients in responder and nonresponder groups respectively. Mean age of the responders and nonresponders was 43 and 31 years (p < 0.01). Responders were more likely to have cell-surface antibodies (68% versus 39%, p < 0.05), particularly voltage-gated potassium channel complex antibodies (p < 0.01). Mean duration from symptom onset to diagnosis, and symptom onset to initiation of immunomodulation was significantly lower among the responders (75 versus 431 days, p < 0.05, and 80 versus 554, p < 0.01, respectively). There was no outcome difference based on gender, MRI characteristics, seizure type, type of acute immunomodulatory therapy, or use of chronic immunomodulation.

CONCLUSIONS

Among published cases to date, older age, presence of cell-surface antibodies, early diagnosis and immunomodulatory treatment are associated with better seizure outcomes among patients with autoimmune epilepsy.

Antibody-Mediated Autoimmune Encephalitis in Childhood

BACKGROUND

The differential diagnosis of encephalitis in childhood is vast, and evaluation for an etiology is often unrevealing. Encephalitis by way of autoimmunity has long been suspected, as in cases of acute disseminated encephalomyelitis; however, researchers have only recently reported evidence of antibody-mediated immune dysregulation resulting in clinical encephalitis.

MAIN FINDINGS

These pathologic autoantibodies, aimed at specific neuronal targets, can result in a broad spectrum of symptoms including psychosis, catatonia, behavioral changes, memory loss, autonomic dysregulation, seizures, and abnormal movements. Autoimmune encephalitis in childhood is often quite different from adult-onset autoimmune encephalitis in clinical presentation, frequency of tumor association, and ultimate prognosis. As many of the autoimmune encephalitides are sensitive to immunotherapy, prompt diagnosis and initiation of appropriate treatment are paramount.

CONCLUSIONS

Here we review the currently recognized antibody-mediated encephalitides of childhood and will provide a framework for diagnosis and treatment considerations.

Neuronal autoantibodies in mesial temporal lobe epilepsy with hippocampal sclerosis

OBJECTIVE

Our aim was to investigate the prevalence of neuronal autoantibodies (NAbs) in a large consecutive series with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and to elucidate the clinical and laboratory clues for detection of NAbs in this prototype of frequent, drug-resistant epilepsy syndrome.

METHODS

Consecutive patients diagnosed with MTLE fulfilling the MRI criteria for HS were enrolled. The sera of patients and various control groups (80 subjects) were tested for eight NAbs after ethical approval and signed consents. Brain tissues obtained from surgical specimens were also investigated by immunohistochemical analysis for the presence of inflammatory infiltrates. The features of seropositive versus seronegative groups were compared and binary logistic regression analysis was performed to explore the differentiating variables.

RESULTS

We found antibodies against antigens, contactin-associated protein-like 2 in 11 patients, uncharacterised voltage-gated potassium channel (VGKC)-complex antigens in four patients, glycine receptor (GLY-R) in 5 patients, N-methyl-d-aspartate receptor in 4 patients and γ-aminobutyric acid receptor A in 1 patient of 111 patients with MTLE-HS and none of the control subjects. The history of status epilepticus, diagnosis of psychosis and positron emission tomography or single-photon emission CT findings in temporal plus extratemporal regions were found significantly more frequently in the seropositive group. Binary logistic regression analysis disclosed that status epilepticus, psychosis and cognitive dysfunction were statistically significant variables to differentiate between the VGKC-complex subgroup versus seronegative group.

CONCLUSIONS

This first systematic screening study of various NAbs showed 22.5% seropositivity belonging mostly to VGKC-complex antibodies in a large consecutive series of patients with MTLE-HS. Our results indicated a VGKC-complex autoimmunity-related subgroup in the syndrome of MTLE-HS.

Progress in autoimmune epileptic encephalitis

PURPOSE OF REVIEW

Autoimmune epileptic encephalopathy is a potentially treatable neurological syndrome characterized by the coexistence of a neuronal antibody in serum and, often, cerebrospinal fluid. Patients present with combinations of seizures, neuropsychiatric features, movement disorder, and cognitive decline, but some patients have isolated seizures either at first presentation or during their illness. This review summarizes our current understanding of the roles of specific neuronal antibodies in epilepsy-related syndromes and aims to aid the clinician in diagnosis and treatment.

RECENT FINDINGS

Antigen discovery methods in three neuroimmunology centres independently identified antibodies to different subunits of the γ amino butyric acid-A receptor; high levels of these antibodies were found mainly in patients with severe refractory seizures. These and other antibodies were also found in a proportion (<10%) of children and adults with epilepsy. A clinical study comparing immunotherapy in patients with autoantibodies or without an identified target antigen found neuroinflammatory features were predictive of a therapeutic response. New in-vitro and in-vivo studies, and spontaneous animal models, have confirmed the pathogenicity and epileptogenicity of neuronal antibodies and their relevance to other mammals.

SUMMARY

Neuronal antibodies are an important cause of autoimmune epileptic encephalopathy, early recognition is important as there may be an underlying tumour, and early treatment is associated with a better outcome. In the absence of an antibody, the clinician should adopt a pragmatic approach and consider a trial of immunotherapy when other causes have been excluded.

Effect of Immunotherapy on Seizure Outcome in Patients with Autoimmune Encephalitis: A Prospective Observational Registry Study

Objective

To evaluate the seizure characteristics and outcome after immunotherapy in adult patients with autoimmune encephalitis (AE) and new-onset seizure.

Methods

Adult (age ≥18 years) patients with AE and new-onset seizure who underwent immunotherapy and were followed-up for at least 6 months were included. Seizure frequency was evaluated at 2–4 weeks and 6 months after the onset of the initial immunotherapy and was categorized as “seizure remission”, “> 50% seizure reduction”, or “no change” based on the degree of its decrease.

Results

Forty-one AE patients who presented with new-onset seizure were analysed. At 2–4 weeks after the initial immunotherapy, 51.2% of the patients were seizure free, and 24.4% had significant seizure reduction. At 6 months, seizure remission was observed in 73.2% of the patients, although four patients died during hospitalization. Rituximab was used as a second-line immunotherapy in 12 patients who continued to have seizures despite the initial immunotherapy, and additional seizure remission was achieved in 66.6% of them. In particular, those who exhibited partial response to the initial immunotherapy had a better seizure outcome after rituximab, with low adverse events.

Conclusion

AE frequently presented as seizure, but only 18.9% of the living patients suffered from seizure at 6 months after immunotherapy. Aggressive immunotherapy can improve seizure outcome in patients with AE.

Autoimmune neurologic disorders in children

Autoimmune neurologic diseases are of major clinical importance in children. Antibody-mediated diseases of the central nervous system are now increasingly recognized in childhood, where the antibodies bind to cell surface epitopes on neuronal or glial proteins, and the patients demonstrate either focal or more generalized clinical signs depending on the extent of brain regions targeted by the antibodies. The antibodies are directed towards ion channels, receptors, and membrane proteins; and the diseases include limbic encephalitis and N-methyl-d-aspartate receptor-antibody encephalitis, among many others. Additionally there are conditions where the wider immune system is implicated. Neurologic features like seizures, movement disorders, autonomic dysfunction, and sleep disorders, with neuroimaging and electrophysiologic features, may indicate a specific antibody-mediated or immune disorder. Often, phenotypic overlap is observed between these conditions, and phenotypic variation seen in children with the same condition. Nevertheless, many patients benefit from immunotherapy with substantial improvement, although huge efforts are still required to optimize the outcome for many patients. In many patients no antibodies have yet been identified, even though they respond to immunotherapies. Here we describe the known antibodies and associated diseases, discuss conditions that are thought to be immune-mediated but have no known immunologic biomarker, and provide guidelines for the investigation and classification of these disorders.

Anti-NMDAR encephalitis and other glutamate and GABA receptor antibody encephalopathies

Over the last few year, antibodies to various central nervous system receptors, particularly the glutamate and γ-aminobutyric acid (GABA) receptors, have been found to be associated with autoimmune neurologic disorders. The receptors include the N-methyl-d-aspartate receptor (NMDAR), the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), the metabotropic glutamate receptors (mGluRs), and GABA type A and B receptors (respectively GABAAR and GABABR). Compared to the previously described paraneoplastic antibodies directed at intracellular targets, the patients with receptor antibodies are often younger, they less frequently have malignancies, and they respond better to immunotherapy. Many of the patients have limbic encephalitis with amnesia, disorientation, seizures, and psychological or psychiatric symptoms, but those with NMDAR antibodies usually develop a more widespread form of encephalitis, often leading to a decrease in consciousness and requirement for long-term intensive care treatment. The autoantibodies bind directly to the synaptic or extrasynaptic receptors on the membrane surface, and have direct effects on signal transduction in central synapses. These conditions are very important to recognize as the symptoms and complications can be fatal when not treated in time, whereas with immunotherapy many patients recover considerably.

Autoimmune epilepsy

Despite the fact that epilepsy is the third most common chronic brain disorder, relatively little is known about the processes leading to the generation of seizures. Accumulating data support an autoimmune basis in patients with antiepileptic drug-resistant seizures. Besides, recent studies show that epilepsy and autoimmune disease frequently co-occur. Autoimmune epilepsy is increasingly recognized in the spectrum of neurological disorders characterized by detection of neural autoantibodies in serum or spinal fluid and responsiveness to immunotherapy. An autoimmune cause is suspected based on frequent or medically intractable seizures and the presence of at least one neural antibody, inflammatory changes indicated in serum or spinal fluid or on MRI, or a personal or family history of autoimmunity. It is essential that an autoimmune etiology be considered in the initial differential diagnosis of new onset epilepsy, because early immunotherapy assures an optimal outcome for the patient.

Basal ganglia T1 hyperintensity in LGI1-autoantibody faciobrachial dystonic seizures

Objective:

To characterize the clinical features and MRI abnormalities of leucine-rich glioma-inactivated 1 (LGI1)-autoantibody (Ab) faciobrachial dystonic seizures (FBDS).

Methods:

Forty-eight patients with LGI1-Ab encephalopathy were retrospectively identified by searching our clinical and serologic database from January 1, 2002, to June 1, 2015. Of these, 26 met inclusion criteria for this case series: LGI1-Ab seropositivity and FBDS. In a separate analysis of all 48 patients initially identified, the MRIs of patients with (n = 26) and without (n = 22) FBDS were compared by 2 neuroradiologists blinded to the clinical details.

Results:

The median age of the 26 included patients was 62.5 years (range 37–78); 65% were men. FBDS involved arm (26), face (22), and leg (12). Ten were previously diagnosed as psychogenic. Ictal EEGs were normal in 20 of 23 assessed. Basal ganglia T1 and T2 signal abnormalities were detected in 11 patients (42%), with excellent agreement between neuroradiologists (κ scores of 0.86 and 0.93, respectively), and included T1 hyperintensity alone (2), T2 hyperintensity alone (1), or both (8). The T1 hyperintensities persisted longer than the T2 hyperintensities (median 11 weeks vs 1 week, p = 0.02). Improvement with immunotherapy (18/18) was more frequent than with antiepileptic medications (10/24). A separate analysis of all 48 patients initially identified with LGI1-Ab encephalopathy showed that basal ganglia MRI abnormalities were present in 11 of 26 with FBDS but not present in those without FBDS (0/22) (p < 0.001). In contrast, mesial temporal MRI abnormalities were less common among those with FBDS (42%) than those without (91%) (p < 0.001).

Conclusions:

Basal ganglia T1 hyperintensity is a clinically useful MRI biomarker of LGI1-Ab FBDS and suggests a basal ganglia localization.

A case of autoimmune epilepsy associated with anti-leucine-rich glioma inactivated subunit 1 antibodies manifesting electrical shock-like sensations and transparent sadness

Autoimmune epilepsy is an isolated phenotype of autoimmune encephalitis, which may be suspected in patients with unexplained adult-onset seizure disorders or resistance to antiepileptic drugs (AEDs). Antibodies against leucine-rich glioma inactivated subunit 1 of the voltage-gated potassium channel (VGKC) complex, recently termed anti-LGI-1 antibodies, are one of the causes of autoimmune epilepsies. Bizarre symptoms with extremely short duration and high frequency are clues to the possible presence of autoimmune epilepsy with anti-LGI-1 antibodies. Precise diagnosis is important because autoimmune epilepsy is treatable and the prognosis can be predicted.

New-onset refractory status epilepticus (NORSE)--The potential role for immunotherapy

New-onset refractory status epilepticus (NORSE) is defined as a state of persistent seizures with no identifiable etiology in patients without preexisting epilepsy that lasts longer than 24h despite optimal therapy. Management of NORSE is challenging, and the role of immunotherapy (IT) is unclear. We identified patients fulfilling the criteria for NORSE at a single institution. These patients were described, analyzed, and compared with NORSE cases available from the literature. Finally, a pooled analysis of available case series was conducted to compare the outcomes in patients who received IT with those not treated with IT during the course of NORSE in order to generate hypotheses for further research. In our case series, NORSE was diagnosed in 11 patients (9 females) with a mean age of 48 years and a mean duration of 54.4 days. Autoantibodies were identified in 7 patients, of which anti-GAD (glutamic acid decarboxylase) and anti-NMDAR (N-methyl-D-aspartate receptor) were most frequent. Of the 11 patients, 8 were treated with IT (intravenous steroids, immunoglobulins, plasmapheresis, or a combination), and 4 received chemotherapy. Of the 8 patients treated with IT, 6 had favorable outcomes (defined as any outcome other than death, vegetative state, or inability to take care of oneself) compared with 0 out of 3 patients who did not receive IT. Difference in outcomes was significant (p=0.026). Pooled analysis of all identified case series, including ours, showed a statistically significant effect (p=0.022), with favorable outcomes in 42% of the patients who received any IT compared with 20% in those who did not. In all patients with refractory SE and negative comprehensive investigations, a diagnosis of NORSE should be considered. This would aid planning for early immunotherapy. Currently, only Class IV evidence for the use of immunotherapy in NORSE is available. Prospective multicenter studies are necessary to assess the true efficacy of IT in NORSE.

Efficacy of intravenous immunoglobulin in a cohort of children with drug-resistant epilepsy

OBJECTIVES

We describe the experience of a pediatric epilepsy center regarding the efficacy of intravenous immunoglobulin for drug-resistant seizures in children.

METHODS

A retrospective chart review of all children in a community-based, children's hospital neurology clinic from 2006 to 2012, inclusive, with intractable epilepsy who were treated with intravenous immunoglobulin for a minimum of six cycles was performed. Data collected included patient demographics, seizure and epilepsy syndrome type, presumed etiology for the seizures, and seizure frequency. Response to intravenous immunoglobulin was defined as "positive" if either seizure freedom or ≥50% reduction of seizures was achieved.

RESULTS

Twenty-seven children (3-17 years old) were identified and included in the analysis. Following treatment with intravenous immunoglobulin, the following outcomes were noted: four were seizure-free, eight had 90% reduction, five had 75% reduction, and five had 50% reduction. A total of 22 (81%) patients had a positive clinical response to treatment from baseline. Five patients (19%) were not responsive. No clear relationship of responsiveness to intravenous immunoglobulin with regard to age, gender, or epilepsy syndrome was apparent; however, the small numbers in each category precluded meaningful statistical analysis.

SIGNIFICANCE

Our findings and those of others suggest that intravenous immunoglobulin is a potentially high efficacy, low side effect profile therapy in the treatment of children with drug-resistant epilepsies. Intravenous immunoglobulin was able to reduce multiple seizure types in a variety of epilepsy etiologies, including those of unknown cause.

The recognition and treatment of autoimmune epilepsy in children

There is emerging interest in autoimmune epilepsy, which represents a small but potentially treatable form of epilepsy. Most insights into autoimmune epilepsy derive from the recent descriptions of autoimmune encephalitis that takes two general forms: a focal encephalitis (such as limbic) or a diffuse encephalitis (such as anti-N-methyl-D-aspartate receptor [NMDAR] encephalitis). The features of autoimmune epilepsy include acute or subacute onset of seizures, usually in the context of encephalopathy, and inflammation of the central nervous system on testing cerebrospinal fluid or magnetic resonance imaging. Neuronal antibodies associated with autoimmune encephalitis and seizures in children include NMDAR, voltage-gated potassium channel complex, glycine receptor, γ-Aminobutyric acid type A receptor (GABA(A)R), γ-Aminobutyric acid type B receptor (GABA(B)R), and glutamic acid decarboxylase antibodies. These antibodies support the diagnosis of autoimmune epilepsy, but are not essential for diagnosis. When autoimmune epilepsy is suspected, first-line immune therapy with corticosteroids in addition to intravenous immunoglobulin or plasma exchange should be considered. Second-line therapy with rituximab or cyclophosphamide can be considered if the syndrome is severe. A response to immune therapy supports the diagnosis of autoimmune epilepsy. Neuronal antibodies are increasingly found in patients with focal epilepsy of unknown cause who do not have 'encephalitis'. Recent epidemiological studies support the link between epilepsy and autoimmune diseases. Future studies need to define the spectrum of autoimmune epilepsy and focus on early identification and treatment.

Clinical manifestations of patients with CASPR2 antibodies

Contactin-associated protein-like 2 (CASPR2) is one of the target antigens of voltage-gated potassium channels (VGKC) complex antibodies. There has been relatively little information in the literature regarding CASPR2 autoimmunity, especially in Asian population. We investigated the presence of CASPR2 antibodies in patients with presumed autoimmune neurological disorders and described the clinical features, laboratory findings, and responses to immunotherapy. Five patients were identified to be positive for CASPR2 antibodies. The results obtained here suggested that CASPR2 antibodies might be the possible cause of epilepsy even in the absence of typical features of limbic encephalitis and that immunotherapy could provide a favorable outcome.

Autoimmunity and inflammation in status epilepticus: from concepts to therapies

The understanding of immunological mechanisms underlying some forms of epilepsy and encephalitis has rapidly increased for the last 10 years leading to the concept of status epilepticus of autoimmune origin. Actual treatment recommendations regarding autoimmune status epilepticus are based on retrospective case studies, pathophysiological considerations and experts' opinion. In addition, there are no clear indicators to predict outcome. In situations where autoimmune mechanisms are suspected in patients with status epilepticus, there is evidence that earlier treatment is related to better outcome. Increased awareness is mandatory to decrease the number of patients with major neurological problems or fatal outcome, which is overall about 50%. We here summarize findings of all pediatric and adult patients reported to date, and review the current state of knowledge in the field of immune therapeutic approaches of status epilepticus.

Immunomodulatory treatments in epilepsy

The role of immunity and inflammation appears to be an integral part of the pathogenic processes associated with some seizures, particularly with refractory epilepsy. Prompt treatment with immunotherapy may lead to better outcomes. Immune treatment options for treatment of epilepsy include therapies such as corticosteroids, immunoglobulins, plasmapheresis, or steroid-sparing drugs such as azathioprine. Recent alternatives have included even more aggressive treatment with cyclophosphamide, anti-pre-B-lymphocyte monoclonal antibody rituximab, and monoclonal antibodies such as efalizumab or natalizumab, which are presently used for other inflammatory disorders. Randomized controlled trials of immunotherapy in presumed autoimmune epilepsy are needed to provide further support for the rapid use of immunotherapy in patients with immune mediated epilepsy.