EEG Findings May Serve as a Potential Biomarker for Anti-NMDA Receptor Encephalitis

Immune Mechanisms in Epileptogenesis: Update on Diagnosis and Treatment of Autoimmune Epilepsy Syndromes

Seizures and epilepsy can result from various aetiologies, yet the underlying cause of several epileptic syndromes remains unclear. In that regard, autoimmune-mediated pathophysiological mechanisms have been gaining attention in the past years and were included as one of the six aetiologies of seizures in the most recent classification of the International League Against Epilepsy. The increasing number of anti-neuronal antibodies identified in patients with encephalitic disorders has contributed to the establishment of an immune-mediated pathophysiology in many cases of unclear aetiology of epileptic syndromes. Yet only a small number of patients with autoimmune encephalitis develop epilepsy in the proper sense where the brain transforms into a state where it will acquire the enduring propensity to produce seizures if it is not hindered by interventions. Hence, the term autoimmune epilepsy is often wrongfully used in the context of autoimmune encephalitis since most of the seizures are acute encephalitis-associated and will abate as soon as the encephalitis is in remission. Given the overlapping clinical presentation of immune-mediated seizures originating from different aetiologies, a clear distinction among the aetiological entities is crucial when it comes to discussing pathophysiological mechanisms, therapeutic options, and long-term prognosis of patients. Moreover, a rapid and accurate identification of patients with immune-mediated epilepsy syndromes is required to ensure an early targeted treatment and, thereby, improve clinical outcome. In this article, we review our current understanding of pathogenesis and critically discuss current and potential novel treatment options for seizures and epilepsy syndromes of underlying or suspected immune-mediated origin. We further outline the challenges in proper terminology.

Quantitative EEG as a Prognostic Tool in Suspected Anti-N-Methyl- d -Aspartate Receptor Antibody Encephalitis

PURPOSE

Anti-N-methyl- d -aspartate receptor (anti-NMDAR) encephalitis is a form of autoimmune encephalitis associated with EEG abnormalities. In view of the potentially severe outcomes, there is a need to develop prognostic tools to inform clinical management. The authors explored whether quantitative EEG was able to predict outcomes in patients with suspected anti-NMDAR encephalitis.

METHODS

A retrospective, observational study was conducted of patients admitted to a tertiary clinical neuroscience center with suspected anti-NMDAR encephalitis. Peak power and peak frequency within delta (<4 Hz), theta (4-8 Hz), alpha (8 - 13 Hz), and beta (13-30 Hz) frequency bands were calculated for the first clinical EEG recording. Outcome was based on the modified Rankin Scale (mRS) score at 1 year after hospital discharge. Binomial logistic regression using backward elimination was performed with peak frequency and power, anti-NMDAR Encephalitis One-Year Functional Status score, age, and interval from symptom onset to EEG entered as predictors.

RESULTS

Twenty patients were included (mean age 48.6 years, 70% female), of which 7 (35%) had a poor clinical outcome (mRS 2-6) at 1 year. There was no association between reported EEG abnormalities and outcome. The final logistic regression model was significant (χ 2 (1) = 6.35, P < 0.012) with peak frequency in the delta range (<4 Hz) the only retained predictor. The model explained 38% of the variance (Nagelkerke R2 ) and correctly classified 85% of cases. Higher peak frequency in the delta range was significantly associated ( P = 0.04) with an increased likelihood of poor outcome.

CONCLUSIONS

In this exploratory study, it was found that quantitative EEG on routinely collected EEG recordings in patients with suspected anti-NMDAR encephalitis was feasible. A higher peak frequency within the delta range was associated with poorer clinical outcome and may indicate anti-NMDAR-mediated synaptic dysfunction. Quantitative EEG may have clinical utility in predicting outcomes in patients with suspected NMDAR antibody encephalitis, thereby serving as a useful adjunct to qualitative EEG assessment; however, given the small sample size, replication in a larger scale is indicated.

Novel qEEG Biomarker to Distinguish Anti-NMDAR Encephalitis From Other Types of Autoimmune Encephalitis

Objective

To establish the diagnostic biomarker of electroencephalogram (EEG) to distinguish between anti-N-methyl-d-aspartate receptor encephalitis (NMDARE) and other types of autoimmune encephalitis (other AEs).

Methods

We reviewed the clinical records of 90 patients with acute encephalitis who were treated in our institution between January 2014 and October 2020. We enrolled the patients who fulfilled the diagnostic criteria for possible AE (pAE) defined by Graus et al. (pAE criteria) and then classified into definite NMDARE and other AEs. We investigated the main syndrome and analyzed all admission EEGs using EEG power value (PV). Statistical significance was tested using the Mann–Whitney U test or Fisher’s exact test.

Results

Twenty-five patients fulfilled the pAE criteria and were classified into 9 with definite NMDARE (median age: 21 years; 8 women) and 12 with other AEs (median age: 37.5 years; 6 women). Four were eventually excluded. Speech dysfunction (9/9 vs. 4/12, p = 0.005) and movement disorders (6/9 vs. 1/12, p = 0.016) were more frequent in NMDARE than in other AEs. The PV analyses revealed the novel quantitative EEG (qEEG) index, namely, fast slow ratio (FSR) (PV of total beta/PV of total theta + delta). The median FSR (0.139 vs. 0.029, p = 0.004) was higher for NMDARE than other AEs, and the receiver operating characteristic curve area of FSR was 0.86 (95% CI 0.70–1.00). A cutoff value of 0.047 yielded a specificity of 0.75 and a sensitivity of 1.00. Focusing on patients who did not meet the “probable NMDARE criteria” in Graus 2016 (proNMDARE criteria) (n = 10), the pretest probability of NMDAR antibody test was 0.30 (3/10), which increased in patients with an FSR greater than the cutoff (n = 5) to 0.60 (3/5).

Conclusions

The NMDARE group highlighted speech dysfunction and movement disorders, and a novel qEEG index FSR accurately distinguished the NMDARE patients from other AEs. The FSR is a promising diagnostic marker for NMDARE that indicates the positive results of NMDAR antibodies in patients with AE when combined with the proNMDARE criteria.

Electroclinical biomarkers of autoimmune encephalitis

OBJECTIVE

To evaluate the utility of electroencephalography (EEG) changes as diagnostic and prognostic biomarkers in acute autoimmune encephalitis (AIE).

METHODS

One hundred and thirty-one patients with AIE were recruited retrospectively across 7 hospitals. Clinical data were collected during admission and at 12 months. EEGs were reviewed using a standard reporting proforma. Associations between EEG biomarkers, AIE subtypes, and clinical outcomes were assessed using logistic regression modeling.

RESULTS

Presence of superimposed fast activity (OR 34.33; 95% CI 3.90, 4527.27; p < 0.001), fluctuating EEG abnormality (OR 6.60; 95% CI 1.60, 37.59; p = 0.008), and hemispheric focality (OR 28.48; 95% CI 3.14, 3773.14; p < 0.001) were significantly more common in N-methyl-d-aspartate receptor (NMDAR) antibody-associated patients with AIE compared to other AIE subtypes. Abnormal background rhythm was associated with a poor mRS (modified Rankin score) at discharge (OR 0.29; 95% CI 0.10, 0.75; p = 0.01) and improvement in mRS at 12 months compared with admission mRS (3.72; 95% CI 1.14, 15.23; p = 0.04).

SIGNIFICANCE

We have identified EEG biomarkers that differentiate NMDAR AIE from other subtypes. We have also demonstrated EEG biomarkers that are associated with poor functional outcomes.

Seventeen-Year-Old Female With History of Depression Presented With Mania and Enuresis

A 17-year-old girl with a history of depression was referred by her psychologist to the emergency department (ED) because of concerning behavioral changes for the past 2 weeks. She was engaging in erratic behaviors, including excessive baking, handling broken glass, mixing chemicals, and swimming alone while clothed. She denied any intention to harm herself or others. She was feeling energized in the morning despite only sleeping a few hours at night. She also urinated on herself the day before her ED visit. Her examination and preliminary testing findings in the ED were largely normal. Her initial presentation was concerning for a psychiatric etiology, such as new-onset bipolar disorder given previous history of depression and recent impulsive symptoms suggestive of mania. As her clinical course evolved and urinary incontinence continued, her definitive diagnosis was made by an interdisciplinary team that included child psychiatry and pediatric neurology.

Current Status of Biomarkers in Anti-N-Methyl-D-Aspartate Receptor Encephalitis

The discovery of biomarkers in rare diseases is of paramount importance to allow a better diagnosis, improve predictions of outcomes, and prompt the development of new treatments. Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a rare autoimmune disorder associated with the presence of antibodies targeting the GluN1 subunit of the NMDAR. Since it was discovered in 2007, large efforts have been made towards the identification of clinical, paraclinical, and molecular biomarkers to better understand the immune mechanisms that govern the course of the disease as well as to define predictors of treatment response and long-term outcomes. However, most of these biomarkers are still in an exploratory phase, with only a few candidates reaching the final phases of the always-complex process of biomarker development, mainly due to the low incidence of the disease and its recent description. Clinical and paraclinical markers are probably the most widely explored in anti-NMDAR encephalitis, five of them combined in a clinical score to predict 1 year outcome. On the contrary, soluble molecules, such as persistent antibody positivity, antibody titers, cytokines, and other inflammatory mediators, have been proposed as biomarkers of clinical activity, inflammation, prognosis, and treatment response, but further studies are required for their clinical validation including larger and more homogenous cohorts of patients. Similarly, genetic susceptibility biomarkers are still in the exploratory phase and, therefore, weak conclusions can for now only be achieved. Thus, further studies are warranted to define biomarkers and unravel the underlying mechanisms driving rare diseases such as anti-NMDAR encephalitis. Future international collaborative studies with prospective designs that enable the enrollment of large cohorts will allow for the identification and validation of novel biomarkers for clinical decision-making.

Spectrum and Evolution of EEG Changes in Anti-NMDAR Encephalitis

Background:

NMDA receptor encephalitis (NMDARE) is the most prevalent autoimmune encephalitis and it encompasses a spectrum of clinical features. It is most commonly associated with alteration in consciousness, seizures, neuro-psychiatric symptoms, and movement disorders. Electroencephalography (EEG) plays a vital role and can give clues to diagnosis in a subset of patients.

Methods:

We retrospectively characterized the clinical and EEG findings in our NMDARE patients (n = 48). A total of 131 EEGs were analyzed.

Results:

We observed that patients with seizures had a younger age of onset (p < 0.001). The most common EEG pattern that was noted was diffuse slowing (n = 20) followed by generalized rhythmic delta activity (n = 9), focal spikes and slowing (n = 8 each). Delta brush pattern was seen in only 3 EEGs. Focal ictal rhythms were seen in 3 EEGs. There was no significant difference in outcomes such as seizure recurrence, modified Rankin score (mRS) at follow up/discharge or relapse between groups of patients who had EEG abnormalities in the first EEG and with those who did not.

Conclusions:

NMDARE has varied EEG findings, most of them being non-specific. When combined with clinical presentation, EEG is a useful tool in the diagnosis and management of NMDARE.

Using EEG and MEG to characterize extreme delta brush in a patient with anti-NMDA receptor encephalitis

Background

Extreme delta brush (EDB) is considered a potential marker for anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. The brain regions involved in EDB are unclear.

Case presentation

A 16-year-old woman with anti-NMDAR encephalitis who was experiencing psychosis was admitted. Electroencephalography (EEG) and magnetoencephalography (MEG) were used to analyze EDB in the patient. EDB on EEG could be disturbed by opening and closing the eyes, by occipital alpha rhythms and by sleep-wake cycles. The MEG results showed beta activity originating from bilateral superior parietal lobes. However, the delta wave originated from bilateral superior temporal gyri, the right middle temporal gyrus, the right inferior frontal gyrus, and the left inferior parietal lobe.

Conclusions

Delta wave and beta activity might originate from different brain regions. Beta activity might be transmitted forward to the frontotemporal lobe and superimposed with delta activity to form EDB on EEG.

EEG Findings and Releases From Hospital for Patients With Anti-NMDA Receptor Encephalitis

PURPOSE

Anti-N-methyl-D-aspartate receptor encephalitis is produced by an autoimmune reaction against macromolecular structures that form ionotropic receptors for glutamic acid NR2A and NR2B subunits. Other important findings are the multiple clinical and paraclinical manifestations, among which the EEG stands out. We characterized EEG patterns and their association with functional disability and hospitalization time in patients with anti-N-methyl-D-aspartate receptor encephalitis admitted in our center.

METHODS

We performed a retrospective cohort study that included patients with anti-N-methyl-D-aspartate receptor encephalitis. We recorded the clinical and sociodemographic characteristics and initial scalp EEG data. Functional disability was evaluated at admission and follow-up using the modified Rankin scale.

RESULTS

Forty-five patients aged 15 to 80 years were included. An abnormal EEG was reported in 92.5% of patients. We identified six EEG patterns. The mean hospitalization time was 3.2 (±2.4) months. The higher modified Rankin scale at admission and the absence of parietal or temporal epileptiform activity were associated with more prolonged hospitalization, hazard ratio of 0.338 for each modified Rankin scale level (95% confidence interval 0.174-0.658, P = 0.001), 14.5, P = 0.017, and hazard ratio of 5.6, P = 0.009, respectively.

CONCLUSIONS

EEGs are frequently abnormal in patients with anti-N-methyl-D-aspartate receptor encephalitis. The lower modified Rankin scale at admission and the absence of some focal epileptiform activity may be associated with shorter hospitalizations.

Influencing electroclinical features and prognostic factors in patients with anti-NMDAR encephalitis: a cohort follow-up study in Chinese patients

The clinical manifestations of patients with anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis in East China and factors associated with prognosis were analyzed. A retrospective study of 106 patients (58 females; 48 males) with anti-NMDAR encephalitis in East China was carried out from June 2015 to February 2019. Clinical features and factors influencing outcomes were reviewed. Behavioral changes were observed in 74.5% (79/106) of patients, and comprised the initial symptoms in 61.3% (65/106). Seizures were observed in 67% (71/106) of patients, and served as initial symptoms in 31.1% (33/106). A total of 54.9% (39/71) of seizures were focal seizures. More clinical symptoms were observed in female patients than in male patients (P = 0.000). Similarly, background activity (BA) with high cerebrospinal fluid (CSF) antibody titers at the peak stage was more severe in female patients than in male patients (P = 0.000). The Binary logistic regression and receiver operating characteristic (ROC) curve analyses revealed the factors associated with poor outcomes included consciousness disturbance (OR 4.907, 95% CI 1.653-14.562, P = 0.004; area: 65.4%, sensitivity: 44.2%, specificity: 86.5%, P = 0.014), EEG BA (OR 3.743, 95% CI 1.766-7.932, P = 0.001; area: 76.6%, sensitivity: 73%, specificity: 75%, P = 0.000), number of symptoms (OR 2.911, 95% CI 1.811-4.679, P = 0.000; area: 77.1%, sensitivity: 59.5%, specificity: 78.6%, P = 0.000) and CSF antibody titer (OR 31.778, 95% CI 8.891-113.57, P = 0.000; area: 83.9%, sensitivity: 89.2%, specificity: 78.6%, P = 0.000). EEG BA and number of symptoms were associated with CSF antibody titers. Consciousness disturbances, EEG BA, number of symptoms and CSF antibody titers served as predictors of poor outcomes.

Current Progress on Assessing the Prognosis for Anti-N-Methyl-D-Aspartate Receptor (NMDAR) Encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most common antineuronal antibody encephalitis in autoimmune encephalitis found at present. It has complex clinical manifestations such as psychiatric and behavioral abnormalities, seizures, movement disorders, consciousness, and autonomic dysfunction. The relationship between those manifestations and prognosis is unclear. Electroencephalography (EEG) is gradually becoming useful in the evaluation of the prognosis of anti-NMDAR encephalitis patients, while imaging and antibody testing have a limited prognostic value. Starting the patients on adequate treatments (such as immunotherapy) in a timely fashion has a positive impact on their prognosis. Nevertheless, research on the prognosis of anti-NMDAR encephalitis remains scarce. Here, we review the current advances of prognosis-related research from the clinical manifestations of the disease and auxiliary examinations such as EEG, magnetic resonance imaging (MRI), 18F fluorodeoxyglucose positron emission tomography (FDG-PET), and antibody measurement. In addition, we also discuss the impact of different treatment options on prognosis. In-depth research on the prognosis of patients with anti-NMDAR encephalitis will contribute to a better understanding of this disease, leading to better treatments options and, ultimately, a better prognosis.

Altered cerebral blood flow in patients with anti-NMDAR encephalitis

OBJECTIVE

This study aimed to identify to resting-state cerebral blood flow (CBF) connectivity alterations in patients with anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis.

METHODS

Three-dimensional pseudo-continuous arterial spin labeling (pcASL) imaging was performed to measure the resting-state CBF in 23 patients with anti-NMDAR encephalitis at the peak stage of the disease and 32 healthy subjects. CBF was normalized to reduce variations among subjects. CBF was compared between the groups, and the correlations between the CBF alterations and clinical parameters were assessed. Differences in CBF connectivity in specific brain regions were also compared between groups.

RESULTS

Compared with the healthy subjects, the patients with anti-NMDAR encephalitis exhibited increased CBF in the left insula (L_insula), left superior temporal lobe (L_STL), L_hippocampus, L_pallidum, bilateral putamen (Bi_putamen), and Bi_caudate, and decreased CBF in the bilateral precuneus (Bi_Pc) and bilateral occipital lobe (Bi_OL) (P < 0.05, FEW corrected). Compared with healthy subjects, the patients with anti-NMDAR encephalitis exhibited increased negative CBF connectivity between the Bi_Pc, Bi_OL and L_TL, L_insula (P < 0.05, FEW corrected). Anti-NMDAR encephalitis patients with behavioral changes exhibited higher CBF in the L_insula and lower CBF in the R_Pc, Bi_calcarine, Bi_cuneus, and Bi_lingual than patients without behavioral changes and health controls. The ROC curve shows changed CBF in the L_insula, and R_Pc, Bi_calcarine, Bi_cuneus, and Bi_lingual served as a predictor of behavioral changes in patients with anti-NMDAR encephalitis.

CONCLUSIONS

Our results suggest that patients with anti-NMDAR encephalitis may exhibit both regional CBF abnormalities and deficits in CBF connectivity, which may underlie the clinical symptoms of anti-NMDAR encephalitis.

Electroencephalogram and Clinical Characteristics and Correlations in Patients With Anti-N-Methyl-d-Aspartate Receptor Encephalitis

Objective. Electroencephalogram (EEG) is a sensitive method for evaluation of anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. The aim was to investigate the EEG and clinical features and correlations in patients with anti-NMDAR encephalitis. Methods. Anti-NMDAR encephalitis patients (n = 98) with at least 1 EEG recording in our hospital were recruited between January 2012 and October 2017. We reviewed and analyzed the EEG and clinical data. Results. In our cohorts, 79 patients underwent EEG in the disease acute stage, and 39 in the recovery stage. Of the 79 patients, 70 (88.6%) EEG recordings in acute period were abnormal. Symptoms, including consciousness, movement disorder, coma, were correlated to the degree of EEG abnormalities (P < .05). The patients with more severe EEG abnormalities also had longer hospitalized and intensive care unit stay time (P < .05). We found that the EEG pattern of abnormal occipital alpha rhythm had a correlation with the clinical severity, and the Spearman coefficient was 0.448 (P = .000). Neither delta activities distribution nor prevalence showed correlations with clinical severity in acute stage. However, delta activities significantly decreased in the disease recovery stage. The other findings of EEG records were extreme delta brush (7cases, 8.9%), excess delta activities (diffuse slowing 30 cases, 38.0%), and epileptiform discharge (10 cases, 14.3%). Conclusion. This is the largest study of EEG recording in patients with anti-NMDAR encephalitis patients in China. EEG abnormalities, particularly occipital alpha rhythm, are correlated with clinical severity. EEG is useful for diagnosis and monitoring of treatment response in conjunction with clinical improvement.

Anti-N-methyl-D-aspartate receptor encephalitis: A review of pathogenic mechanisms, treatment, prognosis

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a treatable autoimmune disorder characterized by prominent neuropsychiatric symptoms that predominantly affects children and young adults. In this review, we discuss the pathogenic mechanisms and immunologic triggers of anti-NMDAR encephalitis, and provide an overview of treatment and prognosis of this disorder, with specific focus on the management of common symptoms, complications, and patients during pregnancy. Most patients respond well to first-line treatment and surgical resection of tumors. When first-line immunotherapy fails, second-line immunotherapy can often improve outcomes. In addition, treatment with immunomodulators and tumor resection are effective treatment strategies for pregnant patients. Benzodiazepines are the preferred treatment for patients with catatonia, and electroconvulsive therapy (ECT) may be considered when pharmacological treatment is ineffective. Age, antibody titer, cerebellar atrophy, levels of biomarkers such as C-X-C motif chemokine 13 (CXCL13), cell-free mitochondrial (mt)DNA in cerebral serum fluid (CSF), and timing from symptom onset to treatment are the main prognostic factors. Patients without tumors or those who receive insufficient immunotherapy during the first episode are more likely to relapse.

A review of EEG in anti-NMDA receptor encephalitis

Anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) is common among autoimmune encephalitides (AE) and can present with protean features and nonspecific laboratory and neuroimaging results. Antibody testing is specific, but results are often delayed, and prompt diagnosis and treatment is vital given associated morbidity and mortality. Electroencephalography (EEG) may be a useful tool given ease of performance and short turn-around time for results. As such, we performed a systematic review of the literature on anti-NMDARE and EEG characteristics. We found that EEG is often pathologic in anti-NMDAR encephalitis, though at times nonspecific. A stronger focus on common EEG features in patient with this type of encephalitis and an effort to identify when these features are present in the course of the disease may allow for improved diagnosis, description and differentiation of anti-NMDARE.

Analysis of Relation Between Electroclinical Features and Cerebrospinal Fluid Antibody Titers in Patients With anti-NMDAR Encephalitis

PURPOSE

This study aimed to determine the relation between electroclinical features and cerebrospinal fluid (CSF) antibody titers in patients with anti- N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis.

METHOD

Clinical symptoms and electroencephalography (EEG) at different stages were analyzed in 51 hospitalized patients with anti-NMDAR encephalitis.

RESULTS

Behavioral changes were the initial symptoms in 90.9% (20/22) of female patients with high (1:10 or 1:32) CSF antibody titers. A greater number of clinical symptoms were observed in the patients with high CSF antibody titers than in those with low (1:1 or 1:3.2) CSF antibody titers (mean 3.11 ± 1.06 vs 1.62 ± 0.65, P = .000). The number of clinical symptoms was greater in the female patients than in the male patients (mean 3.52 ± 0.98 vs 2.69 ± 1.09, P = .000). At the peak stage, worse background activity (BA) in EEG recordings was observed in patients with high CSF antibody titers than in those with low CSF antibody titers (Mann-Whitney U test, P = .001). The peak-stage BA in EEG was worse in female patients than in male patients (Mann-Whitney U test, P = .000). Modified Rankin scale scores were higher in patients with high CSF antibody titers than in those with low CSF antibody titers (mean 2.62 ± 1.42 vs 0.75 ± 0.97, P = .000). Brush patterns and constant chewing were observed primarily in female patients with high CSF antibody titers. Epileptic discharges were located predominately in the frontal regions and were noted to vary.

CONCLUSION

The electroclinical features of patients with anti-NMDAR encephalitis were associated with gender and CSF antibody titers.

Mycophenolate mofetil, azathioprine and methotrexate usage in paediatric anti-NMDAR encephalitis: A systematic literature review

BACKGROUND

Available data on mycophenolate mofetil (MMF), azathioprine (AZA) and methotrexate (MTX) for paediatric-onset anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) is limited.

METHODS

Systematic literature review on patients treated with MMF/AZA/MTX for paediatric-onset anti-NMDARE, with focus on modes of use, efficacy and safety.

RESULTS

87 patients were included (age at onset median 11 years, range 0.8-18 years; 69% females). 46% had a relapsing course. 52% received MMF, 27% AZA, 15% MTX, and 6% a combination of MMF/AZA/MTX (7 patients received intrathecal MTX). Before MMF/AZA/MTX, 100% patients received steroids, 83% intravenous immunoglobulin and 45% plasma exchange, and 50% received second-line treatments (rituximab/cyclophosphamide). MMF/AZA/MTX were administered >6 months from onset in 51%, and only after relapse in 40%. Worst mRS before MMF/AZA/MTX was median 4.5 (range 3-5). At last follow-up (median 2 years, range 0.2-8.6), median mRS was 1 (range 0-6). Median annualised relapse rate was 0.4 (range 0-6.7) pre-MMF/AZA/MTX (excluding first events), and 0 on MMF/AZA/MTX (mean 0.03, range 0-0.8). 7% patients relapsed on MMF/AZA/MTX. These relapsing patients had low rate of second-line treatments before MMF/AZA/MTX (25%), long median time between onset and MMF/AZA/MTX usage (18 months), and frequently they were started on MMF/AZA/MTX only after relapse (75%). Relapse rate was lower among patients who received first immune therapy ≤30 days (25%) than later (64%), who received second-line treatments at first event (14%) rather than not (64%), who were started on MMF/AZA/MTX after the first (12%) rather than subsequent events (17%), and who were started on MMF/AZA/MTX ≤3 months from onset (33%) rather than later (53%). Adverse reactions to MMF/AZA/MTX occurred in 2 cases (cytomegalovirus colitis and respiratory infection), of grade 3 Common Terminology Criteria for Adverse Events v4.0.

DISCUSSION

Our literature review disclosed heterogeneity in the use of MMF/AZA/MTX in paediatric-onset anti-NMDARE. MMF/AZA/MTX usage is mostly restricted to retrospective cohort descriptions. These agents may reduce risk of relapse, and have a reasonable safety profile, however data on larger cohorts are required to definitively determine effect.

Features and Prognostic Value of Quantitative Electroencephalogram Changes in Critically Ill and Non-critically Ill Anti-NMDAR Encephalitis Patients: A Pilot Study

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a common cause of encephalitis in intensive care units. Until now, no reliable method has existed for predicting the outcome of anti-NMDAR encephalitis. In this study, we used quantitative electroencephalography (qEEG) to examine the brain function of anti-NMDAR encephalitis patients and assessed its predictive value. Twenty-six patients diagnosed with anti-NMDAR encephalitis were included and grouped according to whether they were treated in intensive care units (14 critically ill vs. 12 non-critically ill). All patients underwent 2-h 10-channel qEEG recordings at the acute stage. Parameters, including amplitude-integrated electroencephalogram (aEEG), spectral edge frequency 95%, total power, power within different frequency bands (δ, θ, α, and β), and percentages of power in specific frequency bands from frontal and parietal areas were calculated with NicoletOne Software and compared between groups. The short-term outcome was death or moderate/severe disability at 3 months after onset, measured with a modified Rankin Scale, and the long-term outcome was death, disability or relapse at 12 months. No differences in qEEG parameters were observed between the critically ill and non-critically ill patients. However, differential anterior-to-posterior alterations in δ and β absolute band power were observed. Logistic regression analysis revealed that a narrower parietal aEEG bandwidth was associated with favorable long-term outcomes (odds ratio, 37.9; P = 0.044), with an optimal cutoff value of 1.7 μV and corresponding sensitivity and specificity of 90.00 and 56.25%, respectively. In a receiver operating characteristic analysis, the area under the curve was 0.7312. In conclusion, the qEEG parameters failed to reflect the clinical severity of anti-NMDAR encephalitis. However, the parietal aEEG bandwidth may separate patients with favorable and poor long-term outcomes in early stages. The underlying mechanisms require further investigation.

Predictive value of electroencephalography in anti-NMDA receptor encephalitis

OBJECTIVES

Anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) is a severe, but treatable disease. This study aims to give a detailed description of electroencephalogram (EEG) results in paediatric and adult patients to improve disease recognition, and analyses the predictive value of the first EEG for the final clinical outcome.

METHODS

This nationwide cohort study includes patients with N-methyl-D-aspartate receptor antibodies confirmed with cell-based assay and immunohistochemistry in serum and cerebrospinal fluid. EEG recordings were re-evaluated by two experienced neurophysiologists, mixed with control EEGs for blinding. Initial EEG as well as follow-up registrations were analysed.

RESULTS

35 adults and 18 children were included. Only two patients (4%) had a normal EEG. During the first recording, the majority of the patients had normal posterior rhythm (71%), which was associated with better modified Rankin Scale at final outcome (OR 4.74; 95% CI 1.56 to 14.47; p=0.006). In addition, EEGs showed focal (73%) or diffuse (67%) slowing. The first EEG was severely abnormal in 26%. However, 8 of 14 patients with a severely abnormal first EEG still had a favourable outcome. During the course of the disease, extreme delta brushes (EDBs) were present in 6 of 53(11%)patients.

CONCLUSIONS

The first EEG commonly shows normal posterior rhythm with focal or diffuse slowing. Although the sensitivity of an abnormal EEG is high (96%), normal EEG does not exclude anti-NMDARE. EDBs are only present in severely affected patients. The first EEG recording is predictive of the final clinical outcome.

Generalized and Lateralized Rhythmic Patterns

The relationship between generalized and lateralized rhythmic delta activity (RDA) and seizures is more ambiguous than the relationship between periodic discharges and seizures. Although frontally predominant generalized RDA is not associated with seizures, occipitally predominant RDA may be associated with the absence of seizures. Lateralized RDA seems to be more strongly associated with the presence of seizure activity. Appropriate recognition of generalized RDA and lateralized rhythmic delta activity may be confounded by benign etiologies of RDA, such as phi rhythm, slow alpha variant, subclinical rhythmic electrographic discharges of adults, or hyperventilation-induced high-amplitude rhythmic slowing. Angelman syndrome and NMDA-receptor antibody encephalitis can also produce morphologically distinct patterns of RDA.

Ictal Rhythmic Alpha Sinusoidal Waves in 3 Cases of Anti-NMDAR Encephalitis

Previous studies have shown that extreme delta brush and high beta/delta power ratio on electroencephalogram are suggestive of anti- N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. Here we report 3 anti-NMDAR encephalitis patients with ictal rhythmic alpha sinusoidal waves in temporal regions, which suggested electrographic seizures in anti-NMDAR encephalitis and indicated potential for seizure occurrence in the future. Rhythmic alpha sinusoidal waves may be an electrographic feature and helpful in distinguishing anti-NMDAR encephalitis. In addition, extreme delta brush was also observed at 47-50 days after morbidity in 2 of 3 patients.

Predictive values and specificity of electroencephalographic findings in autoimmune encephalitis diagnosis

OBJECTIVE

Early diagnosis of autoimmune encephalitis (AE) to not delay treatment is challenging but needed in practice. Most previous evidences of electroencephalographic (EEG) findings in AE were derived from descriptive studies. Given paucity of evidence of specific EEG findings to help with early diagnosis of AE, this study aimed to ascertain specific EEG findings and assess their predictive values in diagnosis of AE.

METHODS

We included all cases with AE in our institution from January 2013 to June 2017. Cases were matched with controls by age and level of consciousness (1:2 ratio). Potential confounders for EEG findings collected as baseline characteristics were compared. Two epileptologists independently reviewed EEGs. Standardized terminology, definitions, and scoring system of EEG findings were employed. Logistic regression analysis was performed, and diagnostic performance of significant EEG features was assessed.

RESULTS

Twenty cases and 40 controls were included in this study. Poorly sustained posterior dominant rhythm (PDR) was significantly associated with AE (p = 0.007) and even more predictive in anti-N-methyl-d-aspartate (NMDA) encephalitis. Inter-rater agreement (kappa) was 0.714. None of the cases had normal EEG nor Grand Total EEG (GTE) score < 4 (negative predictive value (NPV) of 100%). Specificity of well sustained PDR to exclude the diagnosis of anti-NMDA encephalitis was high (91.67%).

CONCLUSIONS

Simple EEG assessment can be used to help exclude AE. When AE is suspected, careful assessment of the sustainment of the PDR is warranted. The NPV of GTE score < 4 and specificity of well sustained PDR can be simply used to differentiate many conditions from AE.

Electroencephalographic findings in anti-N-methyl-d-aspartate receptor encephalitis in children: A series of 12 patients

OBJECTIVE

Anti-N-methyl-d-aspartate receptor encephalitis (a-NMDARe) is an acute or subacute encephalopathy where electroencephalogram (EEG) is frequently obtained as part of the workup. Although no diagnostic EEG finding has been described so far, the definition of specific or typical patterns might help to distinguish this group among various encephalopathies of childhood. We examined EEG recordings of our patients with a-NMDARe in order to describe the most frequent findings.

METHODS

Clinical and laboratory data and digital EEG recordings of 12 pediatric patients diagnosed with a-NMDARe in two major child neurology centers are evaluated.

RESULTS

We reviewed 43 EEG recordings from 12 children with a-NMDARe and followed their evolution for a median of 6 (range: 1-60) months. Initial EEG was abnormal in 11/12 patients. The most frequent finding was focal or diffuse slowing of the background rhythm. Generalized rhythmic delta activity, brief rhythmic discharges (BRDs), and occipital intermittent rhythmic delta activity (OIRDA) were seen in two patients each. Diffuse excess beta frequency activity was seen in three patients. Extreme delta brushes were observed in 5/12 (41.7%) patients, disappeared in 4-6months (two patients), or persisted at 10-17months (two patients). Epileptic activity was seen in seven patients (58%) and lateralized periodic discharges in one. On follow-up EEGs, most epileptic activity disappeared in a median of 8months.

CONCLUSIONS

A normal EEG is rare in a-NMDARe. Focal or diffuse slowing, epileptic activity, and extreme delta brush are common findings. Epileptic activity in early EEGs do not persists in most patients. Severe diffuse slowing may predict neurological impairment if confirmed in larger series.

Unilateral predominance of abnormal movements: A characteristic feature of the pediatric anti-NMDA receptor encephalitis?

Anti-NMDA receptor encephalitis is a treatable autoimmune disease characterized by cognitive, motor and psychiatric features that primarily affects young adults and children. We present a case of a 7-year-old boy with asymmetrical (mainly right hemibody) and abnormal polymorphic movements without concomitant scalpictal EEG changes but had background slowing predominating over the left hemisphere. This report illustrates previous descriptions of asymmetric presentation of abnormal movements in pediatric anti-NMDA receptor encephalitis and emphasizes the importance of video-EEG interpreted within the overall clinical context, to differentiate epileptic from non-epileptic abnormal movements in patients with autoimmune encephalitis.

Clinical characteristics and outcomes between children and adults with anti-N-Methyl-D-Aspartate receptor encephalitis

Anti-N-Methyl-D-Aspartate receptor (NMDAR) encephalitis is an acute neurological disorder affecting children and adults. We aimed to compare the clinical characteristics, treatments, and outcomes between children and adults with anti-NMDAR encephalitis and to assess the probable risk factors. In this observational study, patients who tested positive for anti-NMDAR antibody in the cerebrospinal fluid were enrolled. The patients were divided into children and adults group on the basis of age (whether <16 or not). Clinical outcomes were assessed at onset, 1, 3, 6, 9, and 12 months after the patients received treatment and were scored based on whether they required hospitalization and intensive care. A total of 15 children and 14 adults were examined. The adults more likely manifested status epilepticus, central hypoventilation, and pneumonia but less likely exhibited movement disorder than the children did. All of the patients were subjected to corticosteroid treatment, 11 children and 9 adults were treated with intravenous immunoglobulin, and only the adults received plasma exchange or cyclophosphamide. The children recovered faster than the adults, especially in the first 6 months. Risk factors included age, status epilepticus, changes in consciousness, central hypoventilation, and pneumonia. Adults exhibit worse outcomes than children mostly because of status epilepticus.