Telemedicine assessment of long-term cognitive and functional status in anti-leucine-rich, glioma-inactivated 1 encephalitis

Machine learning for the early prediction of long-term cognitive outcome in autoimmune encephalitis

BACKGROUND AND OBJECTIVE

Autoimmune encephalitis (AE) is an immune-mediated disease. Some patients experience persistent cognitive deficits despite receiving immunotherapy. We aimed to develop a prediction model for long-term cognitive outcomes in patients with AE.

METHOD

In this multicenter cohort study, a total of 341 patients with AE were enrolled from February 2014 to July 2023. Cognitive impairment was identified using the telephone Mini-Mental State Examination (t-MMSE). Six machine learning (ML) algorithms were used to assess the risk of developing cognitive impairment.

RESULTS

The median age of the patients with AE was 30.0 years (23.0-48.25), and 48.90 % (129/264) were female in the training cohort.77 (29.2 %) patients were identified with cognitive impairment after a median follow-up of 49 months. Among 16 features, the following six features were finally selected to develop the model: Cognitive Reserve Questionnaire (CRQ), Clinical Assessment Scale for Autoimmune Encephalitis (CASE), status epilepticus (SE), age, MRI abnormalities, and delayed immunotherapy. Compared to other ML models, the random forest (RF) model demonstrated superior performance with an AUC of 0.90. The accuracy, sensitivity, and specificity in the testing cohort were 0.87, 0.79, and 0.90, respectively.

CONCLUSION

The RF model based on CRQ, CASE scores, SE, age, MRI abnormalities and delayed immunotherapy demonstrates superior predictive performance and shows promise in predicting the risk of long-term cognitive outcomes in patients with AE in clinical settings.

Recent advances in autoimmune encephalitis

Since the description of autoimmune encephalitis (AE) associated with N-methyl-D-aspartate receptor antibodies (anti-NMDARE) in 2007, more than 12 other clinical syndromes and antibodies have been reported. In this article, we review recent advances in pathophysiology, genetics, diagnosis pitfalls, and clinical phenotypes of AE associated with cell surface antibodies and anti-GAD associated neurological syndromes. Genetic studies reported human leukocyte antigen (HLA) associations for anti-LGI1, anti-Caspr2, anti-IgLON5, and anti-GAD. Follow-up studies characterized cognitive dysfunction, psychiatric symptoms, sleep disorders, and adaptative behavior dysfunction, mainly for anti-NMDARE. Late-onset anti-NMDARE and anti- GABA-B receptor (GABA-BR) encephalitis patients were described to have worse prognoses and different tumor associations. Additionally, the clinical spectrum of anti-LGI1, anti-AMPAR, anti-CASPR2, and anti-IgLON5 was expanded, comprising new differential diagnoses. The diagnostic criteria for AE were adapted to the pediatric population, and a diagnostic algorithm was proposed, considering potential mimics and misdiagnosis. We also review the limitations of commercial assays for AE and treatment recommendations, as well as clinical scales for short and long-term assessment of AE patients, along with cognitive evaluation.

Clinical Features and Electroencephalogram Analysis of Brain Network Functional Connectivity in Anti-Leucine-Rich Glioma-Inactivated 1 Antibody Encephalitis

Purpose

To summarize the clinical manifestations, laboratory findings, and magnetic resonance imaging (MRI) characteristics of anti-leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis (anti-LGI1 antibody encephalitis) and explore the electroencephalogram (EEG) features.

Patients and Methods

We retrospectively analyzed the medical history of 16 patients diagnosed with anti-LGI1 antibody encephalitis at the First Hospital of Hebei Medical University from 2021 to 2023. EEGs of patients with anti-LGI1 antibody encephalitis and healthy individuals were analyzed. Based on Video-EEG signal analysis of EEG δ, θ, α, β frequency bands, weighted phase lag index values were calculated to form brain network matrices, studying differences in coherence between brain regions of patients with anti-LGI1 antibody encephalitis and healthy individuals.

Results

Patients with anti-LGI1 antibody encephalitis often presented with subacute onset seizures and cognitive decline. Routine test of cerebrospinal fluid was mostly normal. Serum testing revealed hyponatremia in 62.50% of patients, along with positive serum antinuclear antibodies, decreased vitamin B12, and abnormal cytokines such as interleukin-6. Head MRI revealed abnormal lesions related to the disease in seven cases (43.75%), mainly located in the unilateral or bilateral frontal and temporal lobes of the hippocampus. The EEG mainly showed generalized and focal slow waves, sometimes with focal discharges. Brain network functional connectivity analysis found a significant weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands. Intravenous pulse corticosteroids and intravenous immunoglobulin are first-line immunotherapies for anti-LGI1 antibody-related encephalitis. The disease recovery and cognitive decline improved in most patients.

Conclusion

Anti-LGI1 antibody encephalitis is characterized by seizures and cognitive dysfunction. Serum may show abnormalities in immune indicators such as cytokines. Head MRI mainly reveals abnormal signals in the frontal-temporal lobes and the hippocampus. EEG brain network connectivity analysis reveals characteristic weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands.

Origin and significance of leucine-rich glioma-inactivated 1 antibodies in cerebrospinal fluid

BACKGROUND

Whether antibodies against leucine-rich glioma-inactivated 1 (LGI1-Abs) in cerebrospinal fluid (CSF) are partially transferred from serum and the impact of CSF-LGI1-Ab positivity on clinical features and prognosis are unclear. Therefore, we aim to investigate the differences in serum titers, clinical features, and outcomes between LGI1-Ab CSF-positive and LGI1-Ab CSF-negative patients.

METHODS

Retrospective analysis of serum titers and clinical features according to CSF LGI1-Ab status. In addition, univariate and multivariate logistic regression were performed to identify predictors of worse outcomes.

RESULTS

A total of 60 patients with anti-LGI1 encephalitis and positive serum LGI1-Abs were identified, of whom 8 (13.3%) patients were excluded due to the absence of CSF LGI1-Ab testing. Among the remaining 52 patients, 33 (63.5%) were positive for LGI1-Abs in CSF. CSF-positive patients were more likely to have high serum titers (≥ 1:100) than CSF-negative patients (p = 0.003), and Spearman's correlation analysis showed a positive correlation between CSF and serum titers in CSF-positive patients (r2 = 0.405, p = 0.019). Psychiatric symptoms and hyponatremia were more frequent in CSF-positive patients (p < 0.05). Both univariate and multivariate logistic regression analyses showed that CSF LGI1-Ab positivity and delayed immunotherapy are independent risk factors for incomplete recovery (modified Rankin Scale (mRS) > 0 at last follow-up).

CONCLUSIONS

LGI1-Ab CSF-positive patients have higher serum titers, and their CSF titers are positively correlated with serum titers, indicating a possible peripheral origin of CSF LGI1-Abs. CSF-positive patients more often present with psychiatric symptoms, hyponatremia, and worse outcomes, suggesting more severe neuronal damage.

MR Imaging Findings in Anti-Leucine-Rich Glioma Inactivated Protein 1 Encephalitis: A Systematic Review and Meta-analysis

BACKGROUND

Antibodies against leucine-rich glioma inactivated protein 1 (LGI1) constitute a common form of autoimmune encephalitis. On MR imaging, it may show T2 FLAIR hyperintensities of the medial temporal lobe (T2 FLAIR-MTL), involve the basal ganglia, or be unremarkable.

PURPOSE

We performed a systematic review and meta-analysis to obtain prevalence estimates of abnormal findings on MR imaging in anti-LGI1 encephalitis. A human brain map of the LGI1 microarray gene expression was derived from the Allen Human Brain Atlas.

DATA SOURCES

PubMed and Web of Science were searched with the terms "LGI1" and "encephalitis" from inception to April 7, 2022.

STUDY SELECTION

Thirty-one research publications, encompassing case series and retrospective cohort and case-control studies, with >10 patients with anti-LGI1 encephalitis and MR imaging data were included.

DATA ANALYSIS

Pooled prevalence estimates were calculated using Freeman-Tukey double-arcsine transformation. Meta-analysis used DerSimonian and Laird random effects models.

DATA SYNTHESIS

Of 1318 patients in 30 studies, T2 FLAIR-MTL hyperintensities were present in 54% (95% CI, 0.48-0.60; I2 = 76%). Of 394 patients in 13 studies, 27% showed bilateral (95% CI, 0.19-0.36; I2 = 71%) and 24% unilateral T2 FLAIR-MTL abnormalities (95% CI, 0.17-0.32; I2 = 61%). Of 612 patients in 15 studies, basal ganglia abnormalities were present in 10% (95% CI, 0.06-0.15; I2 = 67%). LGI1 expression was highest in the amygdala, hippocampus, and caudate nucleus.

LIMITATIONS

Only part of the spectrum of MR imaging abnormalities in anti-LGI1 encephalitis could be included in a meta-analysis. MR imaging findings were not the main outcomes in most studies, limiting available information. I2 values ranged from 62% to 76%, representing moderate-to-large heterogeneity.

CONCLUSIONS

T2 FLAIR-MTL hyperintensities were present in around one-half of patients with anti-LGI1. The prevalence of unilateral and bilateral presentations was similar, suggesting unilaterality should raise the suspicion of this disease in the appropriate clinical context. Around 10% of patients showed basal ganglia abnormalities, indicating that special attention should be given to this region. LGI1 regional expression coincided with the most frequently reported abnormal findings on MR imaging. Regional specificity might be partially determined by expression levels of the target protein.

Predictors and Clinical Characteristics of Relapses in LGI1-Antibody Encephalitis

BACKGROUND AND OBJECTIVES

Relapses occur in 15%-25% of patients with leucine-rich glioma-inactivated 1 antibody (LGI1-Ab) autoimmune encephalitis and may cause additional disability. In this study, we clinically characterized the relapses and identified factors predicting their occurrence.

METHODS

This is a retrospective chart review of patients with LGI1-Ab encephalitis diagnosed at our center between 2005 and 2022. Relapse was defined as worsening of previous or appearance of new symptoms after at least 3 months of clinical stabilization.

RESULTS

Among 210 patients, 30 (14%) experienced a total of 33 relapses. The median time to first relapse was 23.9 months (range: 4.9-110.1, interquartile range [IQR]: 17.8). The CSF was inflammatory in 11/25 (44%) relapses, while LGI1-Abs were found in the serum in 16/24 (67%) and in the CSF in 12/26 (46%); brain MRI was abnormal in 16/26 (62%) relapses. Compared with the initial episode, relapses manifested less frequently with 3 or more symptoms (4/30 patients, 13% vs 28/30, 93%; p < 0.001) and had lower maximal modified Rankin scale (mRS) score (median 3, range: 2-5, IQR: 1 vs 3, range: 2-5, IQR: 0; p = 0.001). The median mRS at last follow-up after relapse (2, range: 0-4, IQR: 2) was significantly higher than after the initial episode (1, range: 0-4, IQR: 1; p = 0.005). Relapsing patients did not differ in their initial clinical and diagnostic features from 85 patients without relapse. Nevertheless, residual cognitive dysfunction after the initial episode (hazard ratio:13.8, 95% confidence interval [1.5; 129.5]; p = 0.022) and no administration of corticosteroids at the initial episode (hazard ratio: 4.8, 95% confidence interval [1.1; 21.1]; p = 0.036) were significantly associated with an increased risk of relapse.

DISCUSSION

Relapses may occur years after the initial encephalitis episode and are usually milder but cause additional disability. Corticosteroid treatment reduces the risk of future relapses, while patients with residual cognitive dysfunction after the initial episode have an increased relapse risk.

Neurological, psychiatric, and sleep investigations after treatment of anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis in Spain: a prospective cohort study

BACKGROUND

Anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis is an autoimmune disorder that can be treated with immunotherapy, but the symptoms that remain after treatment have not been well described. We aimed to characterise the clinical features of patients with anti-LGI1 encephalitis for 1 year starting within the first year after initial immunotherapy.

METHODS

For this prospective cohort study, we recruited patients with anti-LGI1 encephalitis as soon as possible after they had received conventional immunotherapy for initial symptoms; patients were recruited from 21 hospitals in Spain. Patients were excluded if they had an interval of more than 1 year since initial immunotherapy, had pre-existing neurodegenerative or psychiatric disorders, or were unable to travel to Hospital Clínic de Barcelona (Barcelona, Spain). Patients visited Hospital Clínic de Barcelona on three occasions-the first at study entry (visit 1), the second 6 months later (visit 2), and the third 12 months after the initial visit (visit 3). They underwent neuropsychiatric and videopolysomnography assessments at each visit. Healthy participants who were matched for age and sex and recruited from Hospital Clínic de Barcelona underwent the same investigations at study entry and at 12 months. Cross-sectional comparisons of clinical features between groups were done with conditional logistic regression, and binary logistic regression was used to assess associations between cognitive outcomes at 12 months and clinical features before initial immunotherapy and at study entry.

FINDINGS

Between May 1, 2019, and Sept 30, 2022, 42 participants agreed to be included in this study. 24 (57%) participants had anti-LGI1 encephalitis (mean age 63 years [SD 12]; 13 [54%] were female and 11 [46%] were male) and 18 (43%) were healthy individuals (mean age 62 years [10]; 11 [61%] were female and seven [39%] were male). At visit 1 (median 88 days [IQR 67-155] from initiation of immunotherapy), all 24 patients had one or more symptoms; 20 (83%) patients had cognitive deficits, 20 (83%) had psychiatric symptoms, 14 (58%) had insomnia, 12 (50%) had rapid eye movement (REM)-sleep behaviour disorder, nine (38%) had faciobrachial dystonic seizures, and seven (29%) had focal onset seizures. Faciobrachial dystonic seizures were unnoticed in four (17%) of 24 patients and focal onset seizures were unnoticed in five (21%) patients. At visit 1, videopolysomnography showed that 19 (79%) patients, but no healthy participants, had disrupted sleep structure (p=0·013); 15 (63%) patients and four (22%) healthy participants had excessive fragmentary myoclonus (p=0·039), and nine (38%) patients, but no healthy participants, had myokymic discharges (p=0·0051). These clinical and videopolysomnographic features led to additional immunotherapy in 15 (63%) of 24 patients, which resulted in improvement of these features in all 15 individuals. However, at visit 3, 13 (65%) of 20 patients continued to have cognitive deficits. Persistent cognitive deficits at visit 3 were associated with no use of rituximab before visit 1 (odds ratio [OR] 4·0, 95% CI 1·5-10·7; p=0·0015), REM sleep without atonia at visit 1 (2·2, 1·2-4·2; p=0·043), and presence of LGI1 antibodies in serum at visit 1 (11·0, 1·1-106·4; p=0·038).

INTERPRETATION

Unsuspected but ongoing clinical and videopolysomnography alterations are common in patients with anti-LGI1 encephalitis during the first year or more after initial immunotherapy. Recognising these alterations is important as they are treatable, can be used as outcome measures in clinical trials, and might influence cognitive outcome.

FUNDING

Fundació La Caixa.

Longitudinal Disability, Cognitive Impairment, and Mood Symptoms in Patients With Anti-NMDA Receptor Encephalitis

BACKGROUND AND OBJECTIVES

Longitudinal outcomes in anti-NMDA receptor encephalitis (anti-NMDARe) are still not fully understood and may not be adequately captured with the modified Rankin Scale (mRS), often the sole reported outcome. We aim to characterize longitudinal outcomes in anti-NMDARe using multiple outcome measures.

METHODS

This single-center, retrospective, observational study examined outcome measures (mRS and Clinical Assessment Scale in Autoimmune Encephalitis [CASE]) in adults with NMDA receptor-IgG in CSF at short- and long-term follow-ups using linear and logistic regression modeling. Patients with evaluations for cognitive impairment (Montreal Cognitive Assessment/Mini-Mental State Examination), depression (Patient Health Questionnaire-9), and anxiety (General Anxiety Disorder-7) >6 months from symptom onset were correlated with final CASE scores.

RESULTS

Thirty-eight patients (76% female, median disease onset age = 28 years, range = 1-75 years) were included. The majority received first-line immunosuppressants (97%) at a median of 3.9 weeks (interquartile range [IQR] = 2.1-9.7) from symptom onset and 68% received second-line therapies. At baseline, median/mean mRS and CASE were 4 (IQR = 3-5) and 12.9 (SD = 7.2), respectively. At short-term follow-up (median = 10 weeks, IQR = 6-17), factors associated with higher CASE and mRS included dysautonomia, coma/lethargy, seizures/status epilepticus, and intensive care unit admission (p < 0.05). At long-term follow-up (median = 70 weeks, IQR = 51-174), median/mean mRS and CASE were 2 (IQR = 1-3) and 4.4 (SD = 4.2), respectively. Only weakness at symptom onset predicted higher mRS scores (odds ratio = 5.6, 95% confidence interval 1.02-30.9, p = 0.047). Despite both mRS and CASE improving from baseline (p < 0.001), only 9 patients (31%) returned to their premorbid function. Among patients with cognitive and mood evaluations >6 months from onset, moderate-severe cognitive impairment (42%), depression (28%), and anxiety (30%) were frequent. Cognitive and depression measures were associated with final CASE subscores (including memory, language, weakness, and psychiatric).

DISCUSSION

Multiple clinical factors influenced short-term outcomes, but only onset weakness influenced long-term mRS, highlighting that mRS is predominantly affected by global motor function. Although mRS and CASE improved over time for most patients, these outcome measures did not capture the full extent of long-term functional impairment in terms of mood, cognition, and the ability to return to premorbid function. This emphasizes the need for increased utilization of more nuanced cognitive and mood outcome measures.

Outcome and Sequelae of Autoimmune Encephalitis

Autoimmune etiologies are a common cause for encephalitis. The clinical syndromes consistent with autoimmune encephalitis are both distinct and increasingly recognized, but less is known about persisting sequelae or outcomes. We searched PubMed for reports on outcomes after autoimmune encephalitis. Studies assessing validated, quantitative outcomes were included. We performed a narrative review of the published literature of outcomes after autoimmune encephalitis. We found 146 studies that produced outcomes data. The mortality rates were 6%-19% and the relapse risks were 10%-62%. Most patients achieved a good outcome based on a score on the modified Rankin Scale (mRS) of ≤2. Forty-nine studies evaluated outcomes beyond mRS; these studies investigated cognitive outcome, psychiatric sequelae, neurological deficits, global function, and quality-of-life/patient-reported outcomes using various tools at varying time points after the index hospital discharge. These more-detailed assessments revealed that most patients had persistent impairments, with frequent deficits in cognitive function, especially memory and attention. Depression and anxiety were also common. Many of these sequelae continued to improve over months or even years after the acute illness. While we found that lasting impairments were common among survivors of autoimmune encephalitis, additional research is needed to better understand the nature and impact of these sequelae. Standardized evaluation protocols are needed to improve the ability to compare outcomes across studies, guide rehabilitation strategies, and inform outcomes of interest in treatment trials as the field advances.

Neuropsychological Testing in Autoimmune Encephalitis: A Scoping Review

BACKGROUND AND OBJECTIVES

Identifying optimal methods for evaluation and monitoring of cognitive outcomes in AE is important for clinical care and research. This scoping review aimed to evaluate neuropsychological tests (NPT) that are most frequently impaired in AE cohorts to provide recommendations for a standardized NPT battery for AE outcome.

METHODS

PubMed search for studies examining NPT in patients with AE was conducted on June 9, 2023. Studies were screened for inclusion/exclusion criteria as follows: at least 1 NPT, individual NPT test scores with comparison with healthy controls or normative data and neural-IgG status, total sample size ≥5, and English manuscript available.

RESULTS

The search yielded 5,393 studies, of which 3,359 were screened, 107 were full text reviewed, and 32 met inclusion/exclusion criteria, anti-NMDA-R (k = 18), anti-LGI1 (k = 10), anti-GABAB-R (k = 2), anti-GAD-65 (k = 4), and anti-CASPR2 (k = 3). The cognitive domains most frequently impaired were visual and verbal episodic memory, attention/working memory, processing speed, and aspects of executive functions.

DISCUSSION

Given the dearth of literature examining NPT in AE in combination with small sample sizes and methodological differences, more research in this area is needed. However, we provide recommendations for a test battery to be used in future studies, with the aim of standardizing research in this area. Based on the available literature, we recommend the use of comprehensive NPT batteries, spanning all cognitive domains. The highest yield measures may include the tests of (1) visual and verbal learning/memory, (2) basic and sustained attention, (3) processing speed, and (4) executive functions.

Efficacy of immunotherapy and prognosis in anti-LGI1 encephalitis patients: A meta-analysis

OBJECTIVE

To assess the efficacy and safety of immunotherapy for LGI1 antibody encephalitis, and consider the predictors of poor outcomes following immunotherapy.

METHODS

We searched PubMed and Embase for articles reporting the immunotherapy data of anti-LGI1 encephalitis patients. The proportions of patients with poor outcomes (modified Rankin Scale [mRS] score > 2) at 3 months, 12 months, and the last follow-up, as well as the odds ratio [OR] of predictors were pooled.

RESULTS

The review included 162 articles with 1066 patients. The proportion of patients with poor functional outcomes was 21% at 3 months, 14% at 12 months, and 14% at the last follow-up after receiving immunotherapy. The proportion of patients with reported relapse was 16.6%. The mean duration from onset to the first relapse was 15.6 months. Predictors significantly associated with poor outcomes were age (increase of 1 year), the presence of cognitive impairment, and CSF LGI1 antibody positive. We did not find a statistically significant association between the worst mRS score in the acute phase, the presence of faciobrachial dystonic seizures (FBDS), days from symptom onset to immunotherapy, second-line treatment, maintenance immunotherapy, or follow-up time and outcomes.

INTERPRETATION

Although most patients respond to immunotherapy, a minority of patients still have poor outcomes. Advanced age, cognitive impairment, and CSF LGI1 antibody positive are associated with an increased risk of poor outcomes. However, due to the insufficiency of the data, these conclusions need to be interpreted with caution.

The diagnosis of anti-LGI1 encephalitis varies with the type of immunodetection assay and sample examined

Detection of Leucine-rich glioma inactivated 1 (LGI1) antibodies in patients with suspected autoimmune encephalitis is important for diagnostic confirmation and prompt implementation of immunomodulatory treatment. However, the clinical laboratory diagnosis can be challenging. Previous reports have suggested that the type of test and patient's sample (serum or CSF) have different clinical performances, however, there are no studies comparing different diagnostic tests on paired serum/CSF samples of patients with anti-LGI1 encephalitis. Here, we assessed the clinical performance of a commercial and an in house indirect immunofluorescent cell based assays (IIF-CBA) using paired serum/CSF of 70 patients with suspected anti-LGI1 encephalitis and positive rat brain indirect immunohistochemistry (IIHC). We found that all (100%) patients had CSF antibodies when the in house IIF-CBA was used, but only 88 (83%) were positive if the commercial test was used. In contrast, sera positivity rate was higher with the commercial test (94%) than with the in house assay (86%). If both serum and CSF were examined with the commercial IIFA-CBA, 69/70 (98.5%) patients were positive in at least one of the samples. These findings are clinically important for centers in which rat brain IIHC and in house IIFA-CBA are not available. Moreover, the observation that all patients with anti-LGI1 encephalitis have antibodies in CSF is in line with the concept that these antibodies are pathogenic.

Prognostic significance and extra-hypothalamus dysfunction of hyponatremia in anti-leucine-rich glioma-inactivated protein 1 encephalitis

This study aimed to investigate prognostic significance and brain metabolic mechanism of hyponatremia in anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis. After adjusting for confounders, patients with moderate and severe hyponatremia had significantly increased risk of poor functional outcome and sequelae of seizures. In addition, serum sodium was negatively correlated with normalized ratio of the standardized uptake value of medial temporal lobe (MTL), basal ganglia (BG), and hypothalamus on positron emission tomography (PET) and which was further validated using voxel-wise analysis, suggesting an extra-hypothalamus (BG and MTL) localization for hyponatremia.

Early-Stage Contactin-Associated Protein-like 2 Limbic Encephalitis: Clues for Diagnosis

Background and Objectives

Previous studies suggested that autoimmune limbic encephalitis with antibodies against contactin-associated protein-like 2 (CASPR2-encephalitis) is clinically heterogeneous and progresses slowly, preventing its early recognition. We aimed to describe the onset and progression of CASPR2-encephalitis and to assess long-term outcomes.

Methods

We retrospectively analyzed the medical records of all patients whose CSF tested positive for anti-CASPR2 antibodies in our center between 2006 and 2020. Standardized telephone interviews of all available patients and relatives were conducted, assessing long-term functional independence using the Functional Activity Questionnaire (FAQ) and quality of life using the 36-Item Short-Form Survey (SF36).

Results

Forty-eight patients were included (98% males; median age 64 years), and 35 participated in telephone interviews (73%). At onset, 81% had at least 1 neurologic symptom among the following: limbic (54%), peripheral nerve hyperexcitability (PNH; 21%), and/or cerebellar symptoms (17%). Most of the patients (75%) had initially symptoms of only one of these categories. Limbic symptoms at onset included mostly seizures (33%), while memory disturbances were less frequent (10%). PNH signs were mostly neuropathic pain (9/10 patients). Other symptoms seen at onset included asthenia (33%), mood disorders (25%), and insomnia (21%); 19% of patients did not show any limbic, peripheral, or cerebellar symptom at onset but only asthenia (15%), mood disorders (6%), weight loss (8%), dysautonomia (4%), and/or insomnia (2%). The peak of the disease was attained in median 16.7 months after onset. Over the study period (median follow-up, 58.8 months, range 10.6–189.1), 77% of patients developed ≥3 core CASPR2 symptoms and 42% fulfilled the diagnostic criteria for autoimmune limbic encephalitis, although all patients ultimately developed limbic symptoms. At the last visit, most interviewed patients (28/35 patients, 80%; median, 5 years after onset) had recovered functional independence (FAQ <9) while only the vitality subscore of the SF36 was lower than normative data (mean 49.9 vs 58.0, p = 0.0369).

Discussion

CASPR2-encephalitis has a progressive course and is highly heterogeneous at the early stage. In men older than 50 years, otherwise unexplained seizures, cerebellar ataxia, and/or neuropathic pain are suggestive of early-stage CASPR2-encephalitis, especially if they coincide with recent asthenia, mood disorders, or insomnia.

Cognitive outcomes in anti-LGI-1 encephalitis

OBJECTIVE

Cognitive impairment is one of the most common symptoms of anti-leucine rich glioma inactivated 1 (anti-LGI-1) encephalitis, but little is known about the cognitive profile of these patients. This study characterized the cognitive profile of patients with anti-LGI-1 encephalitis and compared patterns of impairment to healthy controls and other patient groups with known temporal lobe/limbic involvement.

METHODS

A retrospective analysis of adult patients with anti-LGI-1 encephalitis who underwent neuropsychological assessment was conducted. Performance patterns of anti-LGI-1 patients were compared to patients deemed cognitively healthy (HC), as well as patients with amnestic mild cognitive impairment (aMCI) and temporal lobe epilepsy (TLE).

RESULTS

Among 10 anti-LGI encephalitis patients (60% male, median age 67.5 years) who underwent neuropsychological testing (median = 38.5 months from symptom onset), cognitive deficits were common, with 100% of patients showing impairment (≤1.5 SD below mean) on 1+ measures and 80% on 2+ measures. Patients with anti-LGI-1 encephalitis performed worse than controls on measures of basic attention, vigilance, psychomotor speed, complex figure copy, and aspects of learning/memory. Of measures which differed from controls, there were no differences between the anti-LGI-1 and TLE patients, while the anti-LGI-1 patients exhibited higher rates of impairment in basic attention and lower rates of delayed verbal memory impairment compared to the aMCI patients.

CONCLUSIONS

Long-term cognitive deficits are common in patients with anti-LGI-1 encephalitis and involve multiple domains. Future research in larger samples is needed to confirm these findings.

Telemedicine in epilepsy and encephalitis: previous research and indication guidelines in Korea

Telemedicine is an emerging field of medicine that has become more important during the coronavirus disease 2019 (COVID-19) pandemic era and is being studied actively in various medical fields. In neurology, the introduction of telemedicine is accelerating worldwide under the label of teleneurology. So far, few studies have been conducted on telemedicine for patients with epilepsy. In nonmetropolitan areas, video-based clinics have been demonstrated to be effective for seizure control, and smartphone-based diagnosis has also been confirmed to be accurate. Indeed, after the onset of the COVID-19 pandemic, telemedicine has been used to treat patients with epilepsy around the world. Few studies have examined the use of telemedicine for patients with autoimmune encephalitis. One showed that telephone-based evaluation is sufficient to assess the cognitive reserve of leucine-rich glioma inactivated-1-antibody encephalitis patients, thereby diagnosing their dementia. Telephone-based outpatient clinics are temporarily permitted under Korean medical law, and telemedicine can be attempted for clinically stable patients with epilepsy in Korea. In addition, patients with autoimmune encephalitis in stable or improving status may also be candidates for treatment with telemedicine. This review presents evidence for the safety and efficacy of telemedicine to treat epilepsy and encephalitis patients and discusses indication guidelines. Based on our literature review and current Korean medical law, we suggest tentative guidelines for telemedicine in the fields of epilepsy and autoimmune encephalitis.

Predicting the functional outcomes of anti-LGI1 encephalitis using a random forest model

OBJECTIVES

To establish a model in order to predict the functional outcomes of patients with anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis and identify significant predictive factors using a random forest algorithm.

METHODS

Seventy-nine patients with confirmed LGI1 antibodies were retrospectively reviewed between January 2015 and July 2020. Clinical information was obtained from medical records and functional outcomes were followed up in interviews with patients or their relatives. Neurological functional outcome was assessed using a modified Rankin Scale (mRS), the cutoff of which was 2. The prognostic model was established using the random forest algorithm, which was subsequently compared with logistic regression analysis, Naive Bayes and Support vector machine (SVM) metrics based on the area under the curve (AUC) and the accuracy.

RESULTS

A total of 79 patients were included in the final analysis. After a median follow-up of 24 months (range, 8-60 months), 20 patients (25%) experienced poor functional outcomes. A random forest model consisting of 16 variables used to predict the poor functional outcomes of anti-LGI1 encephalitis was successfully constructed with an accuracy of 83% and an F1 score of 60%. In addition, the random forest algorithm demonstrated a more precise predictive performance for poor functional outcomes in patients with anti-LGI1 encephalitis compared with three other models (AUC, 0.90 vs 0.80 vs 0.70 vs 0.64).

CONCLUSIONS

The random forest model can predict poor functional outcomes of patients with anti-LGI1 encephalitis. This model was more accurate and reliable than the logistic regression, Naive Bayes, and SVM algorithm.

The Assessment of Cognitive Reserve: A Systematic Review of the Most Used Quantitative Measurement Methods of Cognitive Reserve for Aging

The cognitive reserve (CR) is widely accepted as the active ability to cope with brain damage, using preexisting cognitive and compensatory processes. The common CR proxies used are the number of formal years of education, intelligence quotient (IQ) or premorbid functioning, occupation attainment, and participation in leisure activities. More recently, it has employed the level of literacy and engagement in high-level cognitive demand of professional activities. This study aims to identify and summarize published methodologies to assess the CR quantitatively. We searched for published studies on PubMed, ScienceDirect, and Web of Science between September 2018 and September 2021. We only included those studies that characterized the CR assessment methodology. The search strategy identified 1,285 publications, of which 25 were included. Most of the instruments targeted proxies individually. The lack of a gold standard tool that incorporates all proxies and cognitive tests highlights the need to develop a more holistic battery for the quantitative assessment of CR. Further studies should focus on a quantitative methodology that includes all these proxies supported by normative data to improve the use of CR as a valid measure in clinical contexts.

LGI1 antibody encephalitis: acute treatment comparisons and outcome

OBJECTIVE

To compare acute treatment responses and long-term outcome in leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis.

METHODS

Retrospective case series of 118 patients with LGI1 antibody encephalitis evaluated at Mayo Clinic across all US sites from 1 May 2008 to 31 March 2019. Patient clinical data were identified and analysed through the neuroimmunology laboratory and electronic medical record. LGI1 antibody detection was by cell-based indirect immunofluorescence assay of serum, cerebrospinal fluid or both. Clinical outcomes were faciobrachial dystonic seizure (FBDS) resolution, modified Rankin Scale (mRS) score, Kokmen Short Test of Mental Status (STMS) score (0-38 point scale) and neuropsychometric testing results.

RESULTS

Compared with intravenous immunoglobulin (IVIg) (n=21), patients treated with single-agent acute corticosteroids (intravenous, oral or both) (n=49) were more likely to experience resolution of FBDS (61% vs 7%, p=0.002) and improvements in mRS score (ΔmRS score 2 vs 0, p=0.008) and median Kokmen STMS scores (ΔKokmen STMS score 5 points vs 0 points, p=0.01). In 54 patients with long-term follow-up (≥2 years), the median mRS score was 1 (range 0-6) and the median Kokmen STMS score was 36 (range 24-38) after all combinations of immunotherapy. Neuropsychometric testing in 32 patients with long-term follow-up (≥2 years) demonstrated short-term memory impairments in 37%.

CONCLUSIONS

Corticosteroids appeared more effective acutely than IVIg in improving LGI1 antibody encephalitis in this retrospective comparison of immunotherapies. While improvement with immunotherapy is typical and long-term outcome is favourable, short-term memory deficits are noted in approximately a third of the patients.

Neurofunctional outcomes in patients with anti-leucine-rich glioma inactivated 1 encephalitis

OBJECTIVE

To evaluate the cognitive and neurofunctional outcomes in patients with anti-leucine-rich glioma inactivated 1 (LGI1) encephalitis.

METHODS

A cohort follow-up study was performed after a median of 33 months (range 6-78) from disease onset to the last follow-up in patients diagnosed with anti-LGI1 encephalitis, to assess the neurofunctional outcomes using modified Rankin Scale (mRS), activities of daily living (ADL), neuropsychiatric inventory (NPI) and modified telephone interview for cognitive status (TICS-M). Remote symptomatic seizure and clinical relapses were also recorded. The clinical, laboratory features, and treatment responses that characterize the disability were analyzed.

RESULTS

The results showed that 81 of 86 (94.2%) patients with anti-LGI1 encephalitis were successfully followed up, while eight (9.9%) died after discharge. Among the 73 survivors, clinical relapses occurred in 18 (24.7%) patients, and those with relapses were at a higher risk of developing remote symptomatic seizure (p = .019). Although 85.2% of the patients became functionally independent (mRS ≤2), the sequelae of symptomatic seizure, neuropsychiatric symptoms, and cognitive deficits were found in 11.0%, 21.9%, and 39.7% of the patients, respectively. Residual cognitive deficits primarily occurred in the elderly subjects as well as those with symptoms of memory deficit, psychiatric disorders, sleep disturbance, disturbance of consciousness at diagnosis, and higher CSF protein levels.

CONCLUSIONS

Although most patients survived and became functionally independent, a subset of patients could not return to all premorbid activities. They may have clinical relapses or suffer from remote symptomatic seizure, neuropsychiatric symptoms, and cognitive impairment.

Role of LGI1 protein in synaptic transmission: From physiology to pathology

Leucine-Rich Glioma Inactivated protein 1 (LGI1) is a secreted neuronal protein highly expressed in the central nervous system and high amount are found in the hippocampus. An alteration of its function has been described in few families of patients with autosomal dominant temporal lobe epilepsy (ADLTE) or with autoimmune limbic encephalitis (LE), both characterized by epileptic seizures. Studies have shown that LGI1 plays an essential role during development, but also in neuronal excitability through an action on voltage-gated potassium Kv1.1 channels, and in synaptic transmission by regulating the surface expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPA-R). Over the last decade, a growing number of studies investigating LGI1 functions have been published. They aimed to improve the understanding of LGI1 function in the regulation of neuronal networks using different animal and cellular models. LGI1 appears to be a major actor of synaptic regulation by modulating trans-synaptically pre- and post-synaptic proteins. In this review, we will focus on LGI1 binding partners, "A Disintegrin And Metalloprotease (ADAM) 22 and 23", the complex they form at the synapse, and will discuss the effects of LGI1 on neuronal excitability and synaptic transmission in physiological and pathological conditions. Finally, we will highlight new insights regarding N-terminal Leucine-Rich Repeat (LRR) domain and C-terminal Epitempin repeat (EPTP) domain and their potentially distinct role in LGI1 function.

Determinants of cognition in autoimmune limbic encephalitis-A retrospective cohort study

Autoimmune limbic encephalitis (ALE) is the most common type of autoimmune encephalitis (AIE). Subacute memory disturbance, temporal lobe seizures, and psychiatric symptoms are clinical hallmarks of the disease. However, little is known on the factors contributing to cognitive functioning in ALE. Hence, we here investigate major determinants of cognitive functioning in ALE. In a retrospective analysis of 102 patients with ALE, we first compared verbal learning capacity, nonverbal learning capacity, and attentional and executive functioning by absence or presence of different types of neural autoantibodies (AABs). Subsequently we established three linear regression models including 63, 38, and 61 patients, respectively to investigate how cognitive functioning in these domains may depend on common markers of ALE such as intrathecal inflammation, blood-cerebrospinal fluid (CSF)-barrier function, mesiotemporal epileptiform discharges and slowing, determined by electroencephalography (EEG) and structural mesiotemporal changes, measured with magnetic resonance imaging (MRI). We also accounted for possible effects of cancer- and immunotherapy and other centrally effective medication. There was no effect of AAB status on cognitive functioning. Although the regression models could not predict verbal and nonverbal learning capacity, structural mesiotemporal neural network alterations on T2-/fluid attenuated inversion recovery (FLAIR)-signal-weighted MRI and mesiotemporal epileptiform discharges or slowing on EEG exerted a significant impact on memory functions. In contrast, the regression model significantly predicted attentional and executive functioning with CSF white blood cell count and centrally effective medication being significant determinants. In this cohort, cognitive functioning in ALE does not depend on the AAB status. Common markers of ALE cannot predict memory functioning that only partially depends on structural and functional alterations of mesiotemporal neural networks. Common markers of ALE significantly predict attentional and executive functioning that is significantly related to centrally effective medication and CSF white blood cell count, which may point toward inflammation affecting brain regions beyond the limbic system.

Clinical and Prognostic Value of Immunogenetic Characteristics in Anti-LGI1 Encephalitis

Objective

Antibodies against leucine-rich glioma-inactivated 1 (LGI1-Abs) characterize a limbic encephalitis (LE) strongly associated with HLA-DRB1*07:01, although some patients lack LGI1-Abs in CSF or do not carry this allele. Whether they represent a different subtype of disease or have different prognoses is unclear.

Methods

Retrospective analysis of clinical features, IgG isotypes, and outcome according to LGI1-Ab CSF positivity and DRB1*07:01 in a cohort of anti-LGI1 LE patients.

Results

Patients with LGI1-Abs detected in both CSF and serum (105/134, 78%) were compared with those who were CSF negative (29/134, 22%). Both groups had similar clinical features and serum levels, but CSF-positive patients had shorter diagnostic delay, more frequently hyponatremia, inflammatory CSF, and abnormal MRI (p < 0.05). Human leukocyte antigen (HLA) genotyping was performed in 72/134 (54%) patients and 63/72 (88%) carried DRB1*07:01. Noncarriers (9/72, 12%) were younger, more commonly women, and had less frequently psychiatric and frontal symptoms (p < 0.05). No difference in IgG isotypes according to CSF positivity or HLA was found (p > 0.05). HLA and IgG isotypes were not associated with poor outcome (mRS >2 at last follow-up) in univariate analyses; CSF positivity was only identified as a poor outcome predictor in the multivariate analysis including the complete follow-up, whereas age and female sex also remained when just the first year was considered.

Conclusions

LE without CSF LGI1-Abs is clinically indistinguishable and likely reflects just a lesser LGI1-Ab production. HLA association is sex and age biased and presents clinical particularities, suggesting subtle differences in the immune response. Long-term outcome depends mostly on demographic characteristics and the intensity of the intrathecal synthesis.

Long-term cognitive and neuropsychiatric outcomes of anti-GABABR encephalitis patients: A prospective study

Long-term cognitive and neuropsychiatric outcomes of anti-gamma-aminobutyric-acid B receptor (anti-GABA_BR) encephalitis are unclear. In this prospective study, 31 patients with anti-GABA_BR encephalitis were underwent cognitive and neuropsychiatric evaluations every 6 months. At 24 months' follow-up, cognitive impairments were observed in 80% of patients that mainly included deficits in memory, executive functions and nonverbal reasoning; and neuropsychiatric symptoms were observed in 50% of patients that mainly included depressive symptoms and irritation. The risk factors associated with cognitive deficits was age > 45 years. This study demonstrated that most patients with anti-GABA_BR encephalitis had persistent cognitive deficits and neuropsychiatric symptoms.

Impact of Cognitive Reserve and Structural Connectivity on Cognitive Performance in Multiple Sclerosis

Background: Cognitive reserve (CR) could attenuate the impact of the brain burden on the cognition in people with multiple sclerosis (PwMS).

Objective: To explore the relationship between CR and structural brain connectivity and investigate their role on cognition in PwMS cognitively impaired (PwMS-CI) and cognitively preserved (PwMS-CP).

Methods: In this study, 181 PwMS (71% female; 42.9 ± 10.0 years) were evaluated using the Cognitive Reserve Questionnaire (CRQ), Brief Repeatable Battery of Neuropsychological tests, and MRI. Brain lesion and gray matter volumes were quantified, as was the structural network connectivity. Patients were classified as PwMS-CI (z scores = −1.5 SD in at least two tests) or PwMS-CP. Linear and multiple regression analyses were run to evaluate the association of CRQ and structural connectivity with cognition in each group. Hedges's effect size was used to compute the strength of associations.

Results: We found a very low association between CRQ scores and connectivity metrics in PwMS-CP, while in PwMS-CI, this relation was low to moderate. The multiple regression model, adjusted for age, gender, mood, lesion volume, and graph metrics (local and global efficiency, and transitivity), indicated that the CRQ (β = 0.26, 95% CI: 0.17–0.35) was associated with cognition (adj R² = 0.34) in PwMS-CP (55%). In PwMS-CI, CRQ (β = 0.18, 95% CI: 0.07–0.29), age, and network global efficiency were independently associated with cognition (adj R² = 0.55). The age- and gender-adjusted association between CRQ score and global efficiency on having an impaired cognitive status was −0.338 (OR: 0.71, p = 0.036) and −0.531 (OR: 0.59, p = 0.002), respectively.

Conclusions: CR seems to have a marginally significant effect on brain structural connectivity, observed in patients with more severe clinical impairment. It protects PwMS from cognitive decline regardless of their cognitive status, yet once cognitive impairment has set in, brain damage and aging are also influencing cognitive performance.

Clinical Characteristics of Cognitive Impairment and 1-Year Outcome in Patients With Anti-LGI1 Antibody Encephalitis

Introduction: Anti-leucine-rich glioma-inactivated 1 antibody (anti-LGI1) encephalitis is one of the most common autoimmune encephalitis. Anti-LGI1 encephalitis presented with subacute or acute onset of cognitive impairment, psychiatric disturbances, faciobrachial dystonic seizures (FBDSs), convulsions, and hyponatremia. The common sequela of anti-LGI1 encephalitis is cognitive disorder, but there are few studies on the recovery of cognitive function after immunotherapy. This study aimed to explore clinical characteristics of cognitive impairment and 1-year outcome in patients with anti-LGI1 encephalitis.

Methods: The clinical data and characteristics of cognitive impairment of 21 patients with anti-LGI1 encephalitis from 2016 to 2019 in Nanjing Brain Hospital were analyzed retrospectively. At the time of onset of hospitalization and 1 year after discharge, the cognitive functions in these patients were assessed using two cognitive screening scales—Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment-Basic (MoCA-B).

Results: Among the 21 patients, 13 were male and 8 were female, aged 51.10 ± 14.69 (age range 20–72) years. Nineteen patients, comprising 90.48%, had recent memory deterioration. Routine electroencephalography (EEG) results of 13 cases were abnormal. EEG results were epileptic or slow-wave activity involving the temporal lobes. Eleven cases of brain MRI were abnormal, and the focus involved the hippocampus and mediotemporal lobe. The decrease of short-term memory [recall scores: 0.57 ± 0.81 (MMSE), 0.76 ± 1.34 (MoCA-B)] is the most obvious at the time of admission. After intravenous (IV) injection of methylprednisolone and/or immunoglobulin, the clinical symptoms of the patients improved obviously. Total MMSE and MoCA-B scores of patients were significant increased after 1 year (21.19 ± 3.54 vs. 26.10 ± 3.02, P < 0.001; and 19.00 ± 4.38 vs. 25.19 ± 4.25, P < 0.001, respectively). Recall scores and orientation scores of MoCA-B were significantly improved after 1 year (0.76 ± 1.34 vs. 3.24 ± 1.48, P < 0.001; and 3.10 ± 1.26 vs. 5.00 ± 1.22, P < 0.001, respectively). However, 3/21 (14.29%) patients still have obvious short-term memory impairment (recall scores ≤ 1).

Conclusion: Cognitive impairment is one of the most common manifestations of anti-LGI1 encephalitis, with the main prominent being acute or subacute short-term memory loss. Although most patients with anti-LGI1 encephalitis respond well to immunotherapy, a small number of patients still have cognitive disorders, mainly recent memory impairment, after 1 year.