Limbic encephalitis in Taiwanese children and adolescence: a single center study

A systematic review and quantitative synthesis of the long-term psychiatric sequelae of pediatric autoimmune encephalitis

BACKGROUND

Long-term neuropsychiatric sequelae of autoimmune encephalitis (AE) remain understudied, particularly in pediatric-onset AE. We aimed to synthesize the published data on ongoing psychiatric symptoms in pediatric-onset AE.

METHODS

The Pubmed, PyscINFO, Web of Science databases were searched from their inception years to August 23, 2021, and 29 studies were identified and analyzed. We also performed a quantitative synthesis of available patient data from the 29 studies combined with a cohort of anti-NMDA receptor (NMDAR) AE from our institution to examine the associations between acute treatment course and long-term psychiatric outcome.

RESULTS

At long-term follow up, 52.4% of the cases with pediatric-onset AE had any persistent symptom and 36.0% had at least one psychiatric symptom. Pooled data found that 36.3% of pediatric-onset anti-NMDAR AE had ongoing psychiatric symptoms. Using a univariate logistic regression analysis, we found that abnormal initial EEG, use of certain immunotherapies, and persistent cognitive impairments were associated with ongoing psychiatric symptoms.

LIMITATIONS

Limitations of the existing literature included a significant paucity of outcomes measured using consistent, objective methods. Limitations of the systematic review included the wide variability among the studies reviewed, which rendered a meta-analysis impossible and beyond the scope of the paper.

CONCLUSION

Chronic psychiatric and behavioral problems remain present in one-third of children months to years after onset of AE. Larger scaled prospective observational studies with a consistent standardized battery of testing are needed to examine impact of specific clinical features and immunotherapies on long-term mental health outcomes.

Pediatric GAD-65 Autoimmune Encephalitis: Assessing Clinical Characteristics and Response to Therapy With a Novel Assessment Scale

BACKGROUND

Glutamic acid decarboxylase (GAD) encephalitis is a neuroinflammatory disease characterized by a broad range of symptoms including cognitive deficits, behavioral changes, and seizures. Children with this disorder have heterogeneous presentations, and little is known about symptom progression over time and response to immunotherapy.

METHODS

This study reports 10 pediatric GAD encephalitis cases and symptoms found at presentation and follow-up. In addition, symptom severity was reported utilizing a novel scale evaluating functional outcomes across the domains affected by autoimmune encephalitis including cognition, language, seizures, psychiatric symptoms, sleep, and movement. Retrospective chart review was conducted for 10 patients aged <18 years, diagnosed with GAD encephalitis, and followed for one year or more. Chart review included clinical, imaging, and laboratory findings at time of diagnosis and at six- and 12-month follow-ups.

RESULTS

At presentation, cognitive deficits were found in all patients, seizures in six of 10, and language decline in seven of 10. Psychiatric symptoms were prominent for all but one patient with three of nine patients presenting with psychosis. Fatigue, sleep disruption, and movement disorders were less prominent symptoms, occurring in approximately half of the cohort. Cognition and fatigue improved significantly over time when compared with symptom severity, whereas seizures, psychiatric symptoms, and sleep did not. Language and sleep showed improvement only in early stages. Analysis of seizure frequency and type noted variability mirroring trends noted in adult studies of GAD encephalitis.

CONCLUSIONS

This study demonstrated the variability of symptom profiles of pediatric GAD encephalitis and benefits of symptom severity scales. Symptom profiles and progression vary in this population.

OUP accepted manuscript

Objective

Autoimmune limbic encephalitis (ALE) is characterized by memory impairment, psychiatric symptoms, and epileptic seizures. Though, the neuropsychological profile of ALE is not yet well defined. However, there is some evidence that neuropsychological impairments might exceed those related to the limbic system and that different autoantibodies (AABs) are associated with distinguishable pattern of neuropsychological impairments. We provide a comprehensive presentation of neuropsychological performance of ALE in an immune therapy-naïve sample.

Methods

We retrospectively analyzed 69 immunotherapy-naïve ALE-patients (26 seropositive—[8 LGI1-, 4 CASPR2-, 2 GABA_B-R-, 3 Hu-, 4 GAD65-, 2 Ma2-, 2 unknown antigen, and 1 Yo-AABs] and 43 seronegative patients, mean age 56.0 years [21.9–78.2], mean disease duration 88 weeks [0–572]). Neuropsychological evaluations comprised of the domains memory, attention, praxis, executive functions, language, social cognition, and psychological symptoms. We compared these functions between seronegative −, seropositive patients with AABs against intracellular neural antigens and seropositive patients with AABs against surface membrane neural antigens.

Results

No effect of AAB group on neuropsychological performance could be detected. Overall, ALE predominantly presents with deficits in long-term memory and memory recognition, autobiographical-episodic memory loss, impairment of emotion recognition, and depressed mood. Furthermore, deficits in praxis of pantomimes and imitations, visuo-construction, and flexibility may occur.

Conclusion

ALE shows a wide spectrum of neuropsychological impairments, which might exceed the limbic system, with no evidence of differences between AAB groups. Neuropsychological assessment for diagnosing ALE should include long-term memory, memory recognition, autobiographical-episodic memory, emotion recognition, and a detailed investigation of depression.

Autoimmune Encephalitis and Other Neurological Syndromes With Rare Neuronal Surface Antibodies in Children: A Systematic Literature Review

Neuronal surface antibody syndromes (NSAS) are an expanding group of autoimmune neurological diseases, whose most frequent clinical manifestation is autoimmune encephalitis (AE). Anti-NMDAR, anti-LGI1, and anti-CASPR2 autoimmunity represent the most described forms, while other NSAS are rarer and less well-characterized, especially in children. We carried out a systematic literature review of children with rare NSAS (with antibodies targeting D2R, GABAAR, GlyR, GABABR, AMPAR, amphiphysin, mGluR5, mGluR1, DPPX, IgLON5, and neurexin-3alpha) and available individual data, to contribute to improve their clinical characterization and identification of age-specific features. Ninety-four children were included in the review (47/94 female, age range 0.2-18 years). The most frequent NSAS were anti-D2R (28/94, 30%), anti-GABAAR (23/94, 24%), and anti-GlyR (22/94, 23%) autoimmunity. The most frequent clinical syndromes were AE, including limbic and basal ganglia encephalitis (57/94, 61%; GABAAR, D2R, GABABR, AMPAR, amphiphysin, and mGluR5), and isolated epileptic syndromes (15/94, 16%; GlyR, GABAAR). With the limitations imposed by the low number of cases, the main distinctive features of our pediatric literature cohort compared to the respective NSAS in adults included: absent/lower tumor association (exception made for anti-mGluR5 autoimmunity, and most evident in anti-amphiphysin autoimmunity); loss of female preponderance (AMPAR); relatively frequent association with preceding viral encephalitis (GABAAR, D2R). Moreover, while SPS and PERM are the most frequent syndromes in adult anti-GlyR and anti-amphiphysin autoimmunity, in children isolated epileptic syndromes and limbic encephalitis appear predominant, respectively. To our knowledge, this is the first systematic review on rare pediatric NSAS. An improved characterization may aid their recognition in children.

Autoimmune encephalitis in children and adolescents

Background

Autoimmune encephalitides with neural and glial antibodies have become an attractive field in neurology because the antibodies are syndrome-specific, explain the pathogenesis, indicate the likelihood of an underlying tumor, and often predict a good response to immunotherapy. The relevance and the management of antibody-associated encephalitides in the pediatric age group are to be discussed.

Main body

Subacutely evolving, complex neuropsychiatric conditions that are otherwise unexplained should raise the suspicion of autoimmune encephalitis. Determination of autoantibodies is the key diagnostic step. It is recommended to study cerebrospinal fluid and serum in parallel to yield highest diagnostic sensitivity and specificity. The most frequently found antibodies are those against the N-methyl-D-asparate receptor, an antigen on the neural cell surface. The second most frequent antibody is directed against glutamic acid decarboxylase 65 kDa, an intracellular protein, often found in chronic conditions with questionable inflammatory activity. Immunotherapy is the mainstay of treatment in autoimmune encephalitides. Steroids, apheresis and intravenous immunoglobulin are first-line interventions. Rituximab or cyclophosphamide are given as second-line treatments. Patients with surface antibodies usually respond well to immunotherapy whereas cases with antibodies against intracellular antigens most often do not.

Conclusion

With few exceptions, the experience in adult patients with autoimmune encephalitides can be applied to patients in the pediatric age range.

Pediatric autoimmune encephalitis in Denmark during 2011-17: A nationwide multicenter population-based cohort study

BACKGROUND

The incidence of pediatric autoimmune encephalitis (AIE) is unknown. Our aim was to assess the incidence of pediatric AIE in Denmark 2011-17.

METHODS

In a nationwide population-based setting, we retrieved data on all children tested for AIE before age 18 years. We reviewed medical records in a) children with AIE antibodies (n = 18) to assess whether children fulfilled the AIE consensus criteria, b) children tested negative for AIE antibodies who were registered with an AIE diagnostic code to estimate the incidence of "antibody negative but probable AIE", and c) a reference cohort (n = 596) to determine the positive predictive value of International Classification of Diseases (ICD) codes used for anti-NMDAR encephalitis.

RESULTS

375 children were tested for AIE 2011-17 (median age 11.1 years; 54% girls); 18 children (5%) had AIE antibodies (percentage tested positive): CSF GAD₆₅-IgG (3.1%), plasma NMDAR-IgG (2.8%), CSF NMDAR-IgG (1.8%), plasma GAD₆₅-IgG (1.0%), and plasma CASPR2-IgG (0.4%). Five children fulfilled the criteria for probably/definite anti-NMDAR encephalitis (incidence: 0.07/100,000 person-years; 95% CI = 0.03-0.17), and 4 children with anti-GAD₆₅ associated AIE (incidence = 0.055/100,000 person-years, 95% CI = 0.021-0.15). The incidence of "antibody negative but probable AIE" was 0.055/100,000 person-years (95% CI = 0.021-0.15). The positive predictive value of ICD diagnostic codes used for anti-NMDAR encephalitis was 8%.

CONCLUSIONS

We diagnosed only children with anti-NMDAR, anti-GAD₆₅, and "antibody negative but probable AIE". Before examining AIE antibodies, clinical presentation, paraclinical studies (CSF, EEG, and MRI), and incidence of pediatric AIEs should be considered. Updating the ICD to include AIE codes is warranted.

Investigation of neuronal auto-antibodies in children diagnosed with epileptic encephalopathy of unknown cause

AIM

Cryptogenic forms of epileptic encephalopathies (EE) with their well-known features of drug-resistance, mental deterioration and partial response to immunotherapies are ideal candidates for screening for neuronal autoantibodies (NAA).

METHOD

Fifty consecutive pediatric patients with a diagnosis of EE of unknown cause were included. Nine NAAs were tested by ELISA, RIA or cell-based assays. Clinical features of seronegative and seropositive patients were compared.

RESULTS

NAAs were found in 7/50 (14%) patients. They were N-methyl-d-aspartate receptor in two (4%), glycine receptor in two (4%), contactin-associated protein-like 2 in one (2%), glutamic acid decarboxylase in one (2%) and type A gamma aminobutyric acid receptor in one patient (2%). Furthermore, serum IgGs of two patients negative for well-characterized NAAs, showed strong reactivity with the uncharacterized membrane antigens of live hippocampal neurons. There were no significant differences between seropositive and seronegative patients by means of epilepsy duration, anti-epileptic drug resistance, EE type, types of seizures, seizure frequencies, EEG features or coexisting autoimmune diseases. Some seropositive patients gave good-moderate response to immunotherapy.

DISCUSSION

Potential clues for the possible role of autoimmunity in seropositive patients with EE were atypical prognosis of the classical EE type, atypical progression and unusual neurological findings like dyskinesia.

Intravenous immunoglobulin for the treatment of autoimmune encephalopathy in children with autism

The identification of brain-targeted autoantibodies in children with autism spectrum disorder (ASD) raises the possibility of autoimmune encephalopathy (AIE). Intravenous immunoglobulin (IVIG) is effective for AIE and for some children with ASD. Here, we present the largest case series of children with ASD treated with IVIG. Through an ASD clinic, we screened 82 children for AIE, 80 of them with ASD. IVIG was recommended for 49 (60%) with 31 (38%) receiving the treatment under our care team. The majority of parents (90%) reported some improvement with 71% reporting improvements in two or more symptoms. In a subset of patients, Aberrant Behavior Checklist (ABC) and/or Social Responsiveness Scale (SRS) were completed before and during IVIG treatment. Statistically significant improvement occurred in the SRS and ABC. The antidopamine D2L receptor antibody, the anti-tubulin antibody and the ratio of the antidopamine D2L to D1 receptor antibodies were related to changes in the ABC. The Cunningham Panel predicted SRS, ABC, parent-based treatment responses with good accuracy. Adverse effects were common (62%) but mostly limited to the infusion period. Only two (6%) patients discontinued IVIG because of adverse effects. Overall, our open-label case series provides support for the possibility that some children with ASD may benefit from IVIG. Given that adverse effects are not uncommon, IVIG treatment needs to be considered cautiously. We identified immune biomarkers in select IVIG responders but larger cohorts are needed to study immune biomarkers in more detail. Our small open-label exploratory trial provides evidence supporting a neuroimmune subgroup in patients with ASD.

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.

Systematic review of immunoglobulin use in paediatric neurological and neurodevelopmental disorders

AIM

A systematic literature review of intravenous immunoglobulin (IVIG) treatment of paediatric neurological conditions was performed to summarize the evidence, provide recommendations, and suggest future research.

METHOD

A MEDLINE search for articles reporting on IVIG treatment of paediatric neuroinflammatory, neurodevelopmental, and neurodegenerative conditions published before September 2015, excluding single case reports and those not in English. Owing to heterogeneous outcome measures, meta-analysis was not possible. Findings were combined and evidence graded.

RESULTS

Sixty-five studies were analysed. IVIG reduces recovery time in Guillain-Barré syndrome (grade B). IVIG is as effective as corticosteroids in chronic inflammatory demyelinating polyradiculoneuropathy (grade C), and as effective as tacrolimus in Rasmussen syndrome (grade C). IVIG improves recovery in acute disseminated encephalomyelitis (grade C), reduces mortality in acute encephalitis syndrome with myocarditis (grade C), and improves function and stabilizes disease in myasthenia gravis (grade C). IVIG improves outcome in N-methyl-d-aspartate receptor encephalitis (grade C) and opsoclonus-myoclonus syndrome (grade C), reduces cataplexy symptoms in narcolepsy (grade C), speeds recovery in Sydenham chorea (grade C), reduces tics in selected cases of Tourette syndrome (grade D), and improves symptoms in paediatric autoimmune neuropsychiatric disorder associated with streptococcal infection (grade B).

INTERPRETATION

IVIG is a useful therapy in selected neurological conditions. Well-designed, prospective, multi-centre studies with standardized outcome measures are required to compare treatments.

Type 1 diabetes and GAD65 limbic encephalitis: a case report of a 10-year-old girl

Limbic encephalitis is a rare neurological disorder that may be difficult to recognize. Clinical features include memory impairment, temporal lobe seizures and affective disturbance. We report the case of a 10-year-old girl with type 1 diabetes mellitus that presented with seizures, depressed mood and memory changes. The diagnosis of glutamic acid decarboxylase 65 (GAD65) mediated limbic encephalitis relied on cerebral magnetic resonance imaging lesions and high serological and cerebrospinal fluid GAD65-antibodies titers. High-dose steroidal therapy was started with clinical improvement. Relapse led to a second high-dose steroid treatment followed by rituximab with remission. A correlation between serum GAD65-antibodies levels and symptoms was found, demonstrating GAD65-antibodies titers may be useful for clinical follow-up and immunotherapy guidance. This report raises awareness of this serious neurological condition that may be associated with type 1 diabetes, underlining the importance of an early diagnosis and prompt treatment for a better prognosis.

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.