Cerebrospinal Fluid Findings in Patients With Autoimmune Encephalitis-A Systematic Analysis

Multimodal prognostication of autoimmune encephalitis: an Australian autoimmune encephalitis consortium study

BACKGROUND AND OBJECTIVES

To identify factors predictive of a favourable modified Rankin score (mRS) at 12 months in patients with autoimmune encephalitis (AE). To evaluate predictors of a binary composite clinical-functional outcome measure, encompassing mRS, drug-resistant epilepsy (DRE) and memory impairment, at 12 months.

METHODS

Univariable and multivariable logistic regression analyses for predictors of a favourable mRS (i.e. mRS ≤ 2) and a composite clinical-functional outcome at 12 months were used.

RESULTS

A total of 231 patients with AE were recruited. Multivariable logistic regression identified factors predictive of reduced odds of favourable mRS at 12 months were older age (OR 0.97; 95% CI 0.95, 0.98; p < 0.001), T2/FLAIR hyperintensity on initial MRI (OR 0.27; 95% CI 0.13, 0.56; p < 0.001), RSE (OR 0.17; 95% CI 0.06, 0.52; p = 0.002) and first-line immunotherapy failure (OR 0.18; 95% CI 0.09, 0.37; p < 0.001). Anti-LGI1 antibody-mediated encephalitis relative to other subtypes (OR 4.46; 95% CI 1.55, 12.80; p = 0.006) was associated with a better 12-month mRS. We found concordant associations for a composite outcome at 12 months, with the addition of a diagnosis of definite autoimmune limbic encephalitis (AILE) predicting a poor outcome.

DISCUSSION

Older age, MRI T2/FLAIR hyperintensity, RSE and first-line immunotherapy failure predicted worse mRS and composite clinical-functional outcome at 12 months, while a diagnosis of anti-LGI1 antibody-mediated encephalitis was associated with favourable outcomes. Our data highlight acute clinical factors predictive of a more severe clinical and functional course at 12 months.

Neurodegeneration and the immune system: lessons from autoimmune encephalitis

The spectrum of autoimmune encephalitis (AE) is expanding to atypical clinical presentations that can mimic neurodegenerative disorders. Among the autoantibodies most frequently associated with manifestations mimicking neurodegenerative disorders-such as dementia, parkinsonism, ataxia and motor neuron disease-IgLON5-, LGI1- and CASPR2-antibodies, predominantly of the IgG4 subclass and associated with specific HLA haplotypes, are the most common. Since these forms of autoimmune encephalitis often lack inflammatory findings in cerebrospinal fluid or magnetic resonance imaging, recognizing clinical 'red flags' suggestive of an autoimmune etiology is crucial for accurate diagnosis and timely initiation of immunotherapy. Interestingly, in these forms of autoimmune encephalitis, both inflammatory and neurodegenerative disease mechanisms may be involved. The neurodegenerative component may result directly from antibody effects (e.g., tau deposition in IgLON5-antibody disease) or arise through other mechanisms (e.g., seizures or exacerbation of pre-existing pathology). Moreover, neuroinflammation has recently emerged as a key contributor to primary neurodegenerative disorders. For instance, microglial activation promotes tau pathology propagation, as observed in Alzheimer's disease and other primary neurodegenerative disorders. While the precise mechanisms linking inflammation and neurodegeneration remain to be fully understood, further research into the interplay between autoimmunity and neurodegeneration may enhance our understanding of disease mechanisms and expand therapeutic opportunities in both autoimmune and neurodegenerative neurological disorders.

From immunobiology to intervention: Pathophysiology of autoimmune encephalitis

Autoimmune encephalitides (AEs) are neurological disorders caused by autoantibodies against neuronal and glial surface proteins. Nearly 20 years after their discovery, AE have evolved from being frequently misdiagnosed and untreated to a growing group of increasingly well-characterized conditions where patients benefit from targeted therapeutic strategies. This narrative review provides an immunological perspective on AE, focusing on NMDAR, CASPR2 and LGI1 encephalitis as the three most common forms of AE associated with anti-neuronal surface autoantibodies. We examine the autoreactive B cell subsets, the tolerance checkpoints that may fail, and the known triggers and predispositions contributing to disease. In addition, we discuss the roles of other immune cells, including T cells and microglia, in the pathogenesis of AE. By analyzing therapeutic strategies and treatment responses we draw insights into AE pathophysiology. Written at a time of transformative therapeutic advancements through cell therapies this work underscores the synergy between detailed immunological research and the development of innovative therapies.

Three cases with chronic obsessive compulsive disorder report gains in wellbeing and function following rituximab treatment

Immunological aetiology is supported for a subgroup with obsessive compulsive disorder (OCD) and conceptualized as autoimmune OCD. The longitudinal clinical course is detailed for three severely ill cases with OCD and indications of immunological involvement with off-label rituximab treatment every six months. All cases showed clear and sustained gains regarding symptom burden and function for over 2.5 years. Brief Psychiatric Rating Scale and Yale-Brown Obsessive-Compulsive Inventory Scale scores decreased 67-100% and 44-92%, respectively. These complex cases, prior to rituximab, had very low functioning and disease duration has been eight, nine and 16 years respectively. All three patients had been unsuccessfully treated with at least two antidepressants or anxiolytics, one neuroleptic and cognitive behavioural therapy. Clinical phenotypes and findings were suggestive of possible autoimmune OCD. Indirect immunohistochemistry detected cerebral spinal fluid (CSF) antibodies in all three cases including a novel anti-neuronal staining pattern against mouse thalamic cells. Exploratory analyses of CSF markers and proteomics identified elevated levels of sCD27 and markers indicative of complement pathway activation when compared to CSF from healthy controls. Multidisciplinary collaboration, advanced clinical investigations and rituximab treatment are feasible in a psychiatric setting. The case histories provide a proof of principle for the newly proposed criteria for autoimmune OCD. The findings suggest that clinical red flags and biological measures may predict rituximab response in chronic treatment-resistant OCD. The report provides orientation that may inform the hypotheses and design of future treatment trials.

Clozapine and rapamycin reverse behavioral abnormalities in an animal model of autoimmune schizophrenia

OBJECTIVE

Autoantibody-associated psychosis represents a distinct disease subgroup of patients with schizophrenia with a suspected autoimmune origin. Although preliminary studies have suggested adjunctive drug treatment strategies targeting the immune system, further validation of these findings is warranted. Autoantibodies against SFT2D2 have been identified in patients with schizophrenia. ApoE-/- mice immunized with SFT2D2-peptides can be used as a model for testing immunotherapy in this subgroup of patients. We used the atypical antipsychotic drug clozapine and immunosuppressant rapamycin to test their effects in this mouse model.

METHODS

The mice were evaluated for cognitive and schizophrenia-like behaviors. Following behavioral testing, brain samples were collected for analyzing specific pathological changes and dendritic spine formation.

RESULTS

Clozapine and rapamycin reversed impaired pre-pulse inhibition, motor impairment, and improved cognitive ability in ApoE -/- mice exposed to anti-SFT2D2 immunoglobulin G. Immunohistochemical assays revealed that both clozapine and rapamycin significantly reduced activated microglial infiltration and restored neuronal dendritic spine density.

CONCLUSIONS

Our study results suggested that clozapine and rapamycin possess therapeutic benefits for managing autoimmune psychosis and provide mechanistic insights into immunotherapies involving immunosuppressive agents.

[Clinical Features and Functional Prognosis in Patients with Possible Autoimmune Encephalitis in a Neurological Emergency Department]

INTRODUCTION

Autoimmune encephalitis (AE) represents a severe neuropsychiatric disorder that requires early diagnosis. This study describes the frequency, clinical characteristics, and paraclinical findings in patients with possible autoimmune encephalitis treated in a neurological emergency department, as well as factors associated with poor functional prognosis at discharge.

MATERIAL AND METHODS

This was an observational ambispective cohort study including patients diagnosed with AE who were treated in a neurological emergency department in 2022. Demographic, clinical, and paraclinical characteristics were evaluated, along with functional outcomes using the modified Rankin scale (mRS); ≤2 points, was considered as good prognosis. In the statistical analysis we used the chi-squared test, Fisher's exact test, Student's T-test, and Mann-Whitney U test.

RESULTS

Out of 9046 patients, 31 (0.3%) met the criteria for probable autoimmune encephalitis (PAE). The average age was 28.4 ± 12.1 years and 51.6% were female. Cognitive alterations (90.3%), psychosis (74.2%), abnormal movements (71%), catatonia (67.7%), seizures/status epilepticus (64.5%, 19.4%), and dysautonomia (58.1%) were observed; 58.1% had a good functional prognosis. Factors associated with poor prognosis included older age (24.8 ± 5.0 vs. 33.4 ± 16.8, p = 0.049), status epilepticus (0% vs. 46.2%, p = 0.002), and lower frequency of headache (61.1% vs. 15.4%, p = 0.025).

CONCLUSIONS

AE represents a rare diagnosis even in a neurological emergency center; older age, status epilepticus and absence of headache were associated with poor functional prognosis at discharge.

Use of intrathecal rituximab in autoimmune epilepsy: A retrospective study

BACKGROUND

Autoimmune encephalitis (AE) is a significant challenge in neurological practice, often proving refractory to conventional treatments. It typically manifests with recurrent seizures or status epilepticus, necessitating early diagnosis and tailored therapy for optimal outcomes. Early institution of effective treatment has been reported to reduce the mortality and morbidity associated with this condition. A subpopulation presenting with acute seizures due to autoimmune encephalitis later develop chronic epilepsy, which can be refractory to conventional modes of treatments. In addition, there is a group of chronic epilepsy patients who did not have acute symptomatic seizures who have autoimmune antibodies suggesting an immunological origin of their seizures. This study aims at evaluating the use of rituximab administered intrathecally, for treating these patients, taking pharmacodynamic properties into account.

MATERIALS AND METHODS

We retrospectively evaluated the efficacy and safety of intrathecal rituximab (ITR) in 15 patients with autoimmune-related epilepsy (9 of them with acute presentation with seizures and 6 with chronic intractable epilepsy). The nature of these seizures, laboratory findings, imaging and EEG findings were compared over the course of treatment and follow up.

RESULTS

No significant long term side effects related to administration of ITR were noted in the 15 patients reported in this series. Improvement was noted in seizure control in the majority of the patients, especially in the acute presentation category, although definitive conclusions about efficacy could not be made since these patients were also receiving additional modes of therapies. Better seizure control was noted in all patients in 12 months follow up.

CONCLUSIONS

Our findings underscore the safety of intrathecal rituximab in treating autoimmune-related status epilepticus and refractory epilepsy related to autoimmune etiology.

Frequency, Clinical Features, and Imaging Comparisons of Seropositive versus Seronegative Autoimmune Encephalitis in a Tertiary Care Setting

BACKGROUND AND OBJECTIVES

Seronegative autoimmune encephalitis (SNAIE) is an enigmatic entity which lacks detectable autoantibodies, leading to a diagnostic delay. Our objective was to study the frequency of SNAIE and compare the clinical, electrophysiological, and imaging characteristics of patients with SNAIE to those in patients with seropositive autoimmune encephalitis (SPAIE).

METHODS

This ambispective observational study was undertaken at a tertiary care center in South India for 7 years. The demographic data, clinical features, cerebrospinal fluid (CSF) analysis findings, electroencephalogram (EEG), and 3 T magnetic resonance imaging (MRI), and 18F fluoro-2-deoxy-d-glucose positron emission tomography computerized tomography (18F FDG PET-CT) findings were compared.

RESULTS

Of the 64 subjects enrolled, SNAIE frequency was 62.5%, with a notable 3:1 male-to-female ratio. Seizure was the predominant clinical presentation in SNAIE compared to SPAIE (50% vs. 20%, P value 0.02). Refractory seizures (45% vs. 4.5%) and status epilepticus (37.5% vs. 0%) were more common in SNAIE ( P value 0.001), whereas involuntary movements and faciobrachial dystonic seizures were common in SPAIE (66% vs. 16%, P value 0.04). CSF pleocytosis was frequently seen in SPAIE (50% vs. 17%, P value 0.006). EEG findings in SNAIE included increased epileptiform discharges and built-up rhythms. FDG PET abnormalities were observed in both groups (91% SPAIE, 97% SNAIE), but the seropositive group exhibited more temporal lobe involvement (58% vs. 30%, P = 0.036) and SNAIE had more diffuse involvement.

CONCLUSIONS

SNAIE exhibited male predominance, primarily presenting with isolated seizure as the initial presentation. EEG and FDG PET findings distinguished the two groups, emphasizing the importance of these modalities as biomarkers in the early detection and management of SNAIE.

The clinical significance of mirror patterns of cerebrospinal fluid oligoclonal immunoglobulin G bands (IgG-OCBs) in peripheral neuropathy disorders

BACKGROUND

CSF (cerebrospinal fluid) oligoclonal immunoglobulin G bands (IgG-OCBs) analysis plays a crucial role in diagnosis of various neurological disorders. However, the clinical significance of mirror pattern bands remains unclear, and their precise application is not well understood.

METHODS

We retrospectively reviewed a total of 7597 IgG-OCB records detected using isoelectric focusing from May 2020 and August 2023 at Huashan Hospital. Among these, 121 mirror pattern bands (62 type IV and 59 type V) were identified in patients with neurological disorders. Basic clinical data, including discharge diagnosis, gender, and age, were collected. Additionally, CSF and serum immunological parameters, as well as monoclonal protein (M protein) detection, were reviewed.

RESULTS

Although mirror pattern bands are rarely observed in neurological diseases, approximately half of these patterns were found in patients with peripheral neuropathy (PN). In the type IV group, 40.74 % of cases were associated with immune-mediated PN, while type V pattern was predominantly observed in cancer-related/lymphoproliferative PN, comprising 63.33 % of the cases. Patients with cancer-related or lymphoproliferative PN showed significantly higher IgG-CSF concentrations (p = 0.017) and 24-h intrathecal IgG synthesis rate (p = 0.022), indicating a stronger humoral immune response. Additionally, both patients with immune-mediated PN and cancer-related/lymphoproliferative PN exhibited abnormal intrathecal synthesis rate and moderate to severe blood-brain barrier impairment. Furthermore, the type V group also exhibited a high prevalence of M protein positivity.

CONCLUSIONS

The differential immunological responses and distinct patterns of OCBs observed in our study underscore the critical role of OCB analysis in the diagnostic workup of PN.

Autoimmune dementia

PURPOSE OF REVIEW

The aim of this review is to summarize clinical, radiological and laboratory findings in autoimmune dementia, to help clinicians in promptly identify this elusive condition.

RECENT FINDINGS

The rapid advances in the field of autoimmune neurology have led to the discovery of novel antibodies and associated disorders, which are more frequent than previously hypothesized. The correct and prompt identification of cognitive decline of autoimmune origin is vital to ensure early treatment and better outcomes. The diagnosis of autoimmune dementia relies on specific clinical and radiological features and on the detection of specific autoantibodies. Autoantibody specificities predict response to treatment and the occurrence of cancer. In recent years, the differential diagnosis of autoimmune dementia has become more relevant, as the overinterpretation of antibody results, clinical and radiological findings may lead to an erroneous diagnosis of autoimmune dementia, with potential harm to patients due to inappropriate exposure to immunosuppressants.

SUMMARY

Autoimmune dementia is a potentially treatable condition and should not be missed in clinical practice given the potential for reversibility with immunotherapy. The diagnosis of autoimmune dementia relies on a comprehensive review of clinical, radiological and laboratory data, and exclusion of other causes of dementia.

Abnormal CSF-Specific OCBs in Neuronal Surface Antibody-Associated Autoimmune Encephalitis Differentiating from Viral Encephalitis

Purpose

The present study aimed to examine the clinical distinctions among patients with neuronal surface antibody-associated autoimmune encephalitis (NSAE) diagnosed with anti-N-methyl-D-aspartate receptor encephalitis (NMDAR-E), anti-leucine-rich glioma-inactivated 1 encephalitis (LGI1-E), and anti-gamma aminobutyric acid-B receptor encephalitis (GABABR-E), compared with those with viral encephalitis (VE). Additionally, the study aimed to assess the impact of cerebrospinal fluid (CSF) oligoclonal bands (OCBs) on the severity and prognosis of NSAE.

Patients and Methods

This retrospective analysis included patients with NSAE, encompassing NMDAR-E, LGI1-E, and GABABR-E, alongside individuals with VE. Participants with NSAE were categorized into two groups based on the presence or absence of CSF-specific OCBs. Data regarding demographics, clinical manifestations, magnetic resonance imaging (MRI) findings, CSF analyses and prognosis were collected and analyzed.

Results

The findings indicated that younger female with NSAE exhibited a higher incidence of seizure onset, disruption of the blood-CSF barrier (BCSFB), and elevated QAlb/QLim ratios compared to VE patients, with NSAE patients demonstrating more severe clinical outcomes at discharge. Among the 185 NSAE patients, 43 (23.24%) were positive for OCBs, while 142 (76.76%) negative. The OCB-positive cohort displayed a greater prevalence of younger females and NMDAR-E (both P<0.05). No significant differences were observed in CSF white blood cell counts, protein concentrations, or immunoglobulin G levels between the two groups (all P>0.05). The modified Rankin Scale (mRS) scores at discharge and the final follow-up were higher in the OCB-positive group than the OCB-negative group (both P<0.05). Both univariate and multivariate analyses identified OCBs and NSAE subtypes as independent risk factors influencing the clinical prognosis of NSAE.

Conclusion

In comparison to VE patients, NSAE patients with positive OCBs were more frequently female and exhibited CSF pleocytosis, particularly among those with NMDAR-E. Importantly, the presence of positive OCBs emerged as an independent predictor of unfavorable outcomes in patients with NMDAR-E, LGI1-E, and GABABR-E.

Anti-dipeptidyl-peptidase-like protein-6 encephalitis with late-onset gastric cancer: A case report and 2-year follow-up

RATIONALE

Anti-dipeptidyl-peptidase-like-protein 6 (DPPX) encephalitis is a rare form of autoimmune encephalitis, with no more than 80 cases reported to date. Cases of anti-DPPX encephalitis comorbid malignancy are exceedingly rare. Limited cases and diverse clinical presentations bring difficulties in the understanding of this disease, including the etiology, diagnosis, treatment, and prognosis. Herein, we report a case of insidious-onset anti-DPPX encephalitis in a patient with a prior history of Epstein-Barr Virus (EBV) meningitis diagnosed with gastric cancer after 2 years of follow-up.

PATIENT CONCERNS

A 72-year-old emaciated male presented with recurrent seizures over the last 20 years, personality changes over 10 years, and memory loss lasting 2 years.

DIAGNOSES

The patient was diagnosed with epilepsy, psychiatric symptoms (agitation and irritability), and mild cognitive impairment. Anti-DPPX encephalitis and prior EBV infection were ultimately diagnosed based on the combination of his symptoms and positive DPPX antibody in serum (titer 1:10) and positive EBV-IgG antibody in cerebrospinal fluid.

INTERVENTIONS

The patient received a course of intravenous methylprednisolone and oral sodium valproate to treat the seizures.

OUTCOMES

After 10 days of treatment, no seizures reoccurred, although the psychiatric symptoms persisted, and his serum antibody against DPPX was still positive (titer 1:10). Unfortunately, the family members asked for the patient to be discharged automatically and refused oral steroids after discharge. Through regular telephone follow-ups for 2 years after discharge, we learned that the patient did not experience any similar convulsions but still showed irritability when administered perphenazine. Unfortunately, the patient had gastric cancer with multiple metastases and was receiving palliative care.

LESSONS

This report illustrates a rare case of EBV meningitis in childhood, resulting in a long-standing, stable course of anti-DPPX encephalitis, and subsequent gastric cancer. This case broadens the atypical presentation spectrum of anti-DPPX encephalitis and emphasizes the need for screening for malignant tumors, including lymphoma, nasopharyngeal carcinoma, and gastric cancer, particularly in patients with latent EBV infection.

Stiff-person syndrome

Stiff-person syndrome (SPS) is an autoimmune disease associated mainly with antibodies to glutamic acid decarboxylase (GAD) or to glycine, characterised by intermittent painful spasms, stiffness and rigidity of the proximal and truncal muscles. Neuro-ophthalmological and gastrointestinal symptoms also occur. The symptoms are caused by neuronal excitability due to impaired inhibitory (gamma amino butyric acid [GABA] and glycine) neurotransmission. SPS is part of a larger spectrum of GAD antibody-spectrum disorders, which overlaps with autoimmune epilepsy, cerebellar ataxia, myoclonus, progressive encephalomyelitis, rigidity and myoclonus (PERM) and limbic encephalitis. PERM is often caused by antibodies against the glycine receptor. Some SPS cases are paraneoplastic. Diagnostic delay is often associated with irreversible disability, and therefore, clinicians need a high degree of clinical suspicion to make an earlier diagnosis. This review updates the various clinical presentations that should raise suspicion of SPS and its related conditions and includes a diagnostic algorithm and various treatment strategies including immunotherapy and GABA-ergic drugs.

Primary large B-cell lymphoma of the central nervous system misdiagnosed as autoimmune encephalitis: a case report

Primary central nervous system lymphomas (PCNSL) are rare, constituting 2 - 3% of intracranial malignancies. A 49-year-old male presented with a 20-day history of dizziness and a 15-day history of right-sided weakness. Physical examination revealed various abnormal signs. Initial cerebrospinal fluid (CSF) analysis was unremarkable, while MRI scans (both plain and contrast-enhanced) showed abnormal signals in the left brainstem, thalamus, and basal ganglia regions, with specific enhancement patterns, and arterial spin labeling (ASL) demonstrated hyperperfusion. The patient was initially diagnosed with autoimmune encephalitis (AE) and treated with methylprednisolone with dose reduction and subsequent discharge. However, two months later, his condition deteriorated. Re-evaluation of MRI data, along with magnetic resonance spectroscopy (MRS) results, suggested a neoplastic process. A stereotactic brain biopsy led to a PCNSL diagnosis. The patient was then transferred for high-dose methotrexate chemotherapy but due to lack of regular follow-up, the disease progressed, resulting in cerebral herniation and respiratory failure and ultimately death. The coexistence of PCNSL and AE is diagnostically difficult because of atypical clinical features and non-specific imaging. Thus, for patients with suspected CNS immune-mediated diseases who relapse after steroid treatment improvement, comprehensive evaluation including CSF examination, MRI, and prompt pathological examination is crucial to consider the possibility of PCNSL.

CSF and blood signatures support classification of limbic encephalitis subtypes

Autoimmune limbic encephalitis (ALE) represents a heterogeneous disease associated with antibodies targeting extracellular (ALEextra) epitopes, intracellular (ALEintra) epitopes, anti-glutamic acid decarboxylase65 ALE (ALEGAD65), and ALE without detectable antibodies (ALEabneg). Combining analysis of cellular parameters, investigated by flow cytometry, and soluble parameters in the blood and cerebrospinal fluid (CSF) from a large cohort of 148 ALE patients (33 ALEextra, 12 ALEintra, 28 ALE-GAD65, 37 ALEabneg) in comparison to paradigmatic examples for neuro-inflammatory (51 relapsing remitting MS patients (RRMS)), and neuro-degenerative (34 Alzheimer's disease patients (AD)) diseases revealed discrete immune signatures in ALE subgroups. Identification of ALE-subtype specific markers facilitated classification of rare ALE-associated tumors, which may prompt further diagnostic efforts in clinical practice. While ALEintra exhibited features of neuro-inflammation, ALEextra displayed features of neuro-inflammation as well as neuro-degeneration. Moreover, ALEGAD65 and ALEabneg lacked hallmarks of inflammation. This may explain the low efficacy of anti-inflammatory treatment regimens in ALEGAD65 and presumably also ALEabneg.

Clinical Utility of CSF Correction Factors for Traumatic Lumbar Puncture in Adults

Objectives

To identify indicators of false pleocytosis in adults with traumatic lumbar puncture (LP), and determine specificities and sensitivities of commonly used CSF correction factors.

Methods

Adults who underwent 4-tube CSF collection were reviewed. Study inclusion required elevated tube 1 red blood cell (RBC) count, tube 1 pleocytosis, and normalized tube 4 RBC count. Tube 4 white blood cell (WBC) count served as the reference standard. Specificities and sensitivities of 3 correction factors (1 WBC:500 RBC, 1 WBC:1000 RBC, and 1 WBC:1500 RBC) were calculated.

Results

One hundred ninety-five adults were included. Among them, 106 (54%) had false tube 1 pleocytosis; these patients had a significantly higher median CSF RBC count and lower median CSF WBC count than those with true tube 1 pleocytosis. Specificities and sensitivities of correction factors ranged from 71.7% to 29.2% and 84.3% to 97.8%, respectively; 1 WBC:500 RBC had highest specificity for pleocytosis, while 1 WBC:1500 RBC had highest sensitivity. Irrespective of correction factor used, false-positive and false-negative determinations of pleocytosis were usually mild (≤20 WBCs/μL).

Discussion

Indicators of false pleocytosis in adults with traumatic LP include bloodier CSF and milder pleocytosis, suggesting that correction factors are most useful in such cases. Across correction factors, an expected specificity/sensitivity tradeoff is observed. Corrected CSF WBC counts suggesting only mild pleocytosis should be interpreted cautiously.

Development of a novel nomogram for predicting prognosis of North Chinese with autoimmune cerebellar ataxia

PURPOSE

The aim of this study was to develop a prognostic nomogram which could predict the prognosis of north Chinese patients with autoimmune cerebellar ataxia (ACA) after immunotherapy.

METHODS

Patients with an initial diagnosis of ACA who accepted first-line immunotherapy at our hospital from March 2018 to May 2023 were retrospectively reviewed. Modified Rankin Scale (mRS) was used to evaluate neurological outcomes. According to the mRS scores after immunotherapy, patients with ACA were divided into good prognosis group (mRS 0-2) and poor prognosis group (mRS 3-6). The nomogram for poor prognosis of ACA patients were built based on logistic regression analysis. The validation of the prognostic model was evaluated by concordance index (C-index), calibration curves, and decision curve analyses (DCAs).

RESULTS

A total of 86 patients with ACA who received immunotherapy at our hospital were included in this study. They were randomly divided into a training cohort (n = 60) and a validation cohort (n = 26) at a ratio of 7:3. Multivariate analyses revealed that that prognostic variables significantly related to the poor prognosis of ACA were age, elevated cerebrospinal fluid (CSF) albumin (ALB) and abnormal magnetic resonance imaging (MRI). The nomogram was constructed based on above 3 factors. The C-index of the nomogram was 0.935 (95% CI: 0.884-0.991) in the training set and 0.933 (95% CI: 0.763-0.994) in the validation set. The calibration plots for the nomogram showed that predictions of risk of poor prognosis were almost consistent with actual observations. The DCAs showed great clinical usefulness of the nomograms.

CONCLUSION

We successfully developed a nomogram to predict poor prognosis for ACA patients using risk factors of age, elevated CSF-ALB and abnormal MRI.

Cerebrospinal fluid soluble CD27 is a sensitive biomarker of inflammation in autoimmune encephalitis

BACKGROUND

Autoimmune encephalitis (AE) comprises a group of rare, severe neuroinflammatory conditions. Current biomarkers of neuroinflammation are often normal in AE which therefore can be difficult to rule out in patients with seizures, cognitive and/or neuropsychiatric symptoms. Cerebrospinal fluid (CSF) soluble CD27 (sCD27) and soluble B-cell maturation antigen (sBCMA) have high sensitivity for neuroinflammation in other neuroinflammatory conditions. In this exploratory study we investigate the potential of sCD27 and sBCMA in CSF as biomarkers of neuroinflammation in AE.

METHODS

Concentrations of sCD27 and sBCMA were measured in CSF from 40 AE patients (20 patients were untreated (12 with anti-N-Methyl-d-Aspartate receptor antibodies (NMDA) and 8 with anti-Leucine-rich Glioma-Inactivated 1 antibodies (LGI1)), and 37 symptomatic controls (SCs).

RESULTS

CSF concentrations of sCD27 were increased in untreated NMDA AE patients (median 1571 pg/ml; p < 0.001) and untreated LGI1 AE patients (median 551 pg/ml; p < 0.05) compared to SCs (median 250 pg/ml). CSF sBCMA was increased in untreated NMDA AE patients (median 832 pg/ml) compared to SCs (median 429 pg/ml). CSF sCD27 and sBCMA correlated with the CSF cell count. Receiver operating characteristic curve analysis of untreated AE patients versus SCs showed an area under the curve of 0.97 for sCD27 and 0.76 for sBCMA.

CONCLUSION

CSF sCD27 is a suitable biomarker of neuroinflammation in AE with an ability to discriminate patients with NMDA AE and LGI1 AE from symptomatic controls. CSF sCD27 may be suited for ruling out AE and other neuroinflammatory conditions in the early phase of the diagnostic work-up.

Anti-GABAB receptor encephalitis: clinical and laboratory characteristics, imaging, treatments and prognosis

Introduction

Anti-GABABR encephalitis is a rare disease reported to be often associated with tumors. The current study aims to summarize the clinical characteristics, imaging features, treatments, outcomes and explore the potential prognosis risk factors of patients with anti-GABABR encephalitis.

Methods

Patients tested positive for anti-GABABR were retrospective studied from a single medical center in China over a period of 3 years. They were followed up for a maximum period of 18 months. Clinical data were summarized and prognostic factors including demographic characteristics, laboratory tests, and neurological functions were compared between survived and deceased patients at 18 months follow-up.

Results

Twenty-six patients, 10 females (38.5%) and 16 males (61.5%), diagnosed with anti-GABABR encephalitis were studied. The median age was 58 years. Of the 23 cases with complete clinical data, their main manifestations were epileptic seizures (65%), mental and behavioral abnormalities (52%), and cognitive impairment (48%). 7 (30.4%) cases had tumors: 5 small cell lung cancer (SCLC), 1 rectum adenocarcinoma (moderately differentiated) and 1 esophageal squamous cell carcinoma. MRI showed 5 (22%) cases had T2 FLAIR increased signals in cortex but with different regions affected. One of the two patients scanned for PET-CT showed hypermetabolism in the left temporal lobe region. The disease course ranged from 5 days to 3 years. 2 patients (one had esophageal carcinoma) without immunotherapy and 3 patients (one had SCLC) that did not response to immunotherapy died soon after diagnosis. 18 patients improved after immunotherapy while 3 (all had SCLC) died after relapses. The prevalence of epileptic seizures and malignancies was significantly lower in the survival group than in the deceased group at 18-months follow-up, the same as the admission mRs score. Serum fibrinogen, cerebrospinal fluid immunoglobulin G quotient, and 24-hour intrathecal synthesis rate were significantly lower in the survival groups as well.

Conclusions

Cortex T2 FLAIR abnormalities were only observed in a small proportion of anti-GABABR encephalitis patients with heterogeneous MRI phenotypes. High mRS score at admission, epileptic seizures and the presence of a tumor indicated a poor prognosis, while the underlying mechanism of the later two factors should be investigated further.

Clinical features, cerebrospinal fluid changes, and prognosis in Chinese patients with autoimmune encephalitis

INTRODUCTION

Autoimmune encephalitis (AE) is a rare, treatable disease of the central nervous system (CNS) caused by an antibody-related immune response. This study is to investigate the correlation of clinical features, cerebrospinal fluid (CSF) characteristics, and prognosis in patients with AE.

METHODS

A total of 71 patients diagnosed with antibody-positive AE were retrospectively analyzed. The patients were divided into three groups: anti-NMDAR group, anti-LGI1 group, and other types. Clinical data were collected to analyze clinical features and CSF results, and prognosis was determined by modified Rankin Scale (mRS).

RESULTS

There was statistical difference in the incidences of decreased consciousness level (P < 0.001), memory loss (P = 0.017), speech disorders (P = 0.035), and dyskinesia (P = 0.001) in different antibodies groups. Younger age (P = 0.018), elevated CSF chloride content (P = 0.006), and white blood cells > 50/mm3 (P = 0.026) were highly correlated with ICU admission. Anti-LGI1 encephalitis had a relatively small risk for ICU admission (P = 0.034), and a lower risk of poor functional recovery (P = 0.048) and recurrence (P = 0.041). Patients with first-line treatment failure (P = 0.021) had an increased risk of poor functional recovery. Delayed treatment (P = 0.011) would increase the risk of recurrence.

CONCLUSION

There are differences in age, gender, clinical characteristics, and CSF results in different subtypes of AE. First-line therapy failure would have poor functional recovery, and delayed therapy would increase the risk of relapse. Chloride ion content and white blood cell count in cerebrospinal fluid are positively correlated with the patient's exacerbation and admission to ICU. These indicators have certain clinical value for the prognosis of AE patients.

Cognitive impairments in autoimmune encephalitis: the role of autoimmune antibodies and oligoclonal bands

INTRODUCTION

The presence of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) is a pivotal diagnostic marker for multiple sclerosis (MS). These bands play a crucial role in the diagnosis and understanding of a wide array of immune diseases. In this study, we explore the relationship between the cognitive profile of autoimmune encephalitis (AIE) and the presence of OCBs in CSF, with a particular emphasis on NMDA receptor antibodies.

METHODS

We studied a cohort of 21 patients across five tertiary centers, segregated into two distinct categories. One group comprised individuals who tested positive only for autoimmune encephalitis antibodies indicative of encephalitis, while the other group included patients whose CSF was positive for both autoimmune encephalitis antibodies and OCBs. Our investigation focused primarily on cognitive functions and behavioral alterations, supplemented by auxiliary diagnostic assessments such as CSF cell count, magnetic resonance imaging (MRI), and electroencephalogram (EEG) results, evaluated for the two patient groups. To validate our findings, we employed statistical analyses such as Fisher's exact test with Benjamini-Hochberg correction.

RESULTS

Our study included 21 patients, comprising 14 who were presented with only autoimmune encephalitis antibodies, and 7 who were dual-positive. Among these patients, we focused on those with NMDA receptor antibodies. Of these, five were dual positive, and nine were positive only for NMDA receptor antibodies. The dual-positive NMDA group, with an average age of 27 ± 16.47 years, exhibited significantly higher CSF cell counts (p=0.0487) and more pronounced language and attention deficits (p= 0.0264). MRI and EEG results did not differ significantly between the groups.

CONCLUSIONS

Our results point to OCBs as an additional marker of disease severity in AIE, especially in NMDA receptor-antibody positive patients, possibly indicating a broader inflammatory process, as reflected in elevated CSF lymphocytes. Regular testing for OCBs in cases of suspected AIE may aid in disease prognosis and identification of patients more prone to language and attention disorders, improving diagnosis and targeting treatment for these cognitive aspects.

Oligoclonal bands

Oligoclonal bands (OCBs) represent the presence of intrathecal immunoglobulin G (IgG) as detected by isoelectric focusing and immunofixation. Cerebrospinal fluid (CSF) analysed alongside a paired serum sample gives five different immunofixation patterns. These are: type 1-the normal physiological state with no intrathecal IgG synthesis; type 2-evidence for intrathecal IgG synthesis, with CSF-restricted OCBs; type 3-evidence for intrathecal IgG synthesis, with CSF-restricted OCBs, but with additional, identical bands in the CSF and serum; type 4-absence of intrathecal IgG synthesis, but with identical OCBs in CSF and serum; and type 5-absence of intrathecal IgG synthesis, with a monoclonal band in CSF and serum. Analysis of these patterns can help to diagnose a range of neurological conditions, including multiple sclerosis. However, it is important to interpret OCB results alongside other CSF tests and their clinical context.

Emerging Biomarkers for the Early Detection of Autoimmune Encephalitis: A Narrative Review

Autoimmune encephalitis (AE) is a rare yet critical neurological disorder characterized by inflammation of the brain, typically triggered by an abnormal immune response. The early detection and diagnosis of AE are crucial for effective treatment and improved patient outcomes. However, the diagnostic process is often complicated by the diverse clinical presentations of AE, which can mimic other neurological and psychiatric conditions. Currently, diagnosis relies on a combination of clinical evaluation, neuroimaging, cerebrospinal fluid analysis, and the detection of specific autoantibodies. Despite advances in these areas, challenges remain, particularly in cases where patients are seronegative or present with nonspecific symptoms. This narrative review provides a comprehensive overview of emerging biomarkers for the early detection of AE, highlighting their potential to enhance diagnostic accuracy and speed. We explore a variety of biomarkers, including novel autoantibodies, inflammatory markers, cytokines, and neuronal damage indicators, and discuss their clinical implications. This review emphasizes the need for biomarkers that are not only sensitive and specific but also accessible and rapid to facilitate earlier diagnosis and treatment. By synthesizing current research, this review aims to contribute to the ongoing efforts to refine the diagnostic approach to AE, ultimately improving outcomes for patients affected by this challenging condition.

Case report: a co-occurring case of severe Mycoplasma pneumoniae pneumonia and Anti-IgLON5 antibody-associated encephalitis in a pediatric patient

This case report details the clinical course of a 16-year-old female student with Mycoplasma pneumoniae infection complicated by autoimmune encephalitis, spanning from 6 February 2022, to 12 April 2022, with a one-year follow-up. The patient presented with a two-week history of cough and fever, followed by altered consciousness and neuropsychiatric symptoms, including hyperactivity and incoherent speech. Despite normal brain MRI findings, cerebrospinal fluid (CSF) analysis confirmed Mycoplasma pneumoniae with titers of, and positive IgLON5 antibodies. Initial treatment included azithromycin, ceftriaxone, and acyclovir, followed by mechanical ventilation and ECMO due to respiratory failure. The antibiotic regimen was switched to intravenous omadacycline based on genetic testing results. Autoimmune encephalitis was managed with intravenous methylprednisolone, intravenous immunoglobulin (IVIG), and plasma exchange. The patient's condition improved, and she was discharged on 12 March 2022, with normal cognitive and behavioral functions. However, she was readmitted one month later due to cognitive decline and sleep disturbances, with a Mini-Mental State Examination (MMSE) score of 20/30 and a modified Rankin Scale (mRS) score of 3. At the one-year follow-up, her MMSE score had improved to 28/30, and her mRS score was 1. This case underscores the importance of comprehensive diagnostic approaches and personalized treatment strategies in managing complex cases of mycoplasma-related infections and associated autoimmune conditions.

Cerebrospinal fluid characteristics of patients presenting for evaluation of pediatric acute-neuropsychiatric syndrome

Objectives

This study characterizes cerebral spinal fluid (CSF) indices including total protein, the albumin quotient, IgG index and oligoclonal bands in patients followed at a single center for pediatric acute-neuropsychiatric syndrome (PANS) and other psychiatric/behavioral deteriorations.

Methods

In a retrospective chart review of 471 consecutive subjects evaluated for PANS at a single center, navigational keyword search of the electronic medical record was used to identify patients who underwent lumbar puncture (LP) as part of the evaluation of a severe or atypical psychiatric deterioration. Psychiatric symptom data was ascertained from parent questionnaires and clinical psychiatric evaluations. Inclusion criteria required that subjects presented with psychiatric deterioration at the time of first clinical visit and had a lumbar puncture completed as part of their evaluation. Subjects were categorized into three subgroups based on diagnosis: PANS (acute-onset of severe obsessive compulsive disorder (OCD) and/or eating restriction plus two other neuropsychiatric symptoms), autoimmune encephalitis (AE), and "other neuropsychiatric deterioration" (subacute onset of severe OCD, eating restriction, behavioral regression, psychosis, etc; not meeting criteria for PANS or AE).

Results

71/471 (15.0 %) of patients underwent LP. At least one CSF abnormality was seen in 29% of patients with PANS, 45% of patients with "other neuropsychiatric deterioration", and 40% of patients who met criteria for autoimmune encephalitis. The most common findings included elevated CSF protein and/or albumin quotient. Elevated IgG index and IgG oligoclonal bands were rare in all three groups.

Conclusion

Elevation of CSF protein and albumin quotient were found in pediatric patients undergoing LP for evaluation of severe psychiatric deteriorations (PANS, AE, and other neuropsychiatric deteriorations). Further studies are warranted to investigate blood brain barrier integrity at the onset of the neuropsychiatric deterioration and explore inflammatory mechanisms.

Fluid biomarkers unveil signatures of pathological aging

Aging is a multifaceted and highly varied process in the brain. Identifying aging biomarkers is one means of distinguishing pathological from physiological aging. The aim of this narrative review is to focus on two new developments in the field of fluid biomarkers and draw attention to this excellent tool for the early detection of potential brain pathologies that delay, alter, or enable physiological aging to become pathological. Pathological aging can lower the threshold for the development of specific diseases such as late-onset epilepsy. Fluid biomarkers can reveal pathological levels at an early stage and thus indicate disease processes in the brain that begin before symptoms develop; they thus differ from physiological aging.

Advancements in Cerebrospinal Fluid Biosensors: Bridging the Gap from Early Diagnosis to the Detection of Rare Diseases

Cerebrospinal fluid (CSF) is a body fluid that can be used for the diagnosis of various diseases. However, CSF collection requires an invasive and painful procedure called a lumbar puncture (LP). This procedure is applied to any patient with a known risk of central nervous system (CNS) damage or neurodegenerative disease, regardless of their age range. Hence, this can be a very painful procedure, especially in infants and elderly patients. On the other hand, the detection of disease biomarkers in CSF makes diagnoses as accurate as possible. This review aims to explore novel electrochemical biosensing platforms that have impacted biomedical science. Biosensors have emerged as techniques to accelerate the detection of known biomarkers in body fluids such as CSF. Biosensors can be designed and modified in various ways and shapes according to their ultimate applications to detect and quantify biomarkers of interest. This process can also significantly influence the detection and diagnosis of CSF. Hence, it is important to understand the role of this technology in the rapidly progressing field of biomedical science.

HLA dependency and possible clinical relevance of intrathecally synthesized anti-IgLON5 IgG4 in anti-IgLON5 disease

Background

Anti-IgLON5 disease is a rare chronic autoimmune disorder characterized by IgLON5 autoantibodies predominantly of the IgG4 subclass. Distinct pathogenic effects were described for anti-IgLON5 IgG1 and IgG4, however, with uncertain clinical relevance.

Methods

IgLON5-specific IgG1-4 levels were measured in 46 sera and 20 cerebrospinal fluid (CSF) samples from 13 HLA-subtyped anti-IgLON5 disease patients (six females, seven males) using flow cytometry. Intervals between two consecutive serum or CSF samplings (31 and 10 intervals, respectively) were categorized with regard to the immunomodulatory treatment active at the end of the interval, changes of anti-IgLON5 IgG1 and IgG4 levels, and disease severity. Intrathecal anti-IgLON5 IgG4 synthesis (IS) was assessed using a quantitative method.

Results

The median age at onset was 66 years (range: 54-75), disease duration 10 years (range: 15-156 months), and follow-up 25 months (range: 0-83). IgLON5-specific IgG4 predominance was observed in 38 of 46 (83%) serum and 11 of 20 (55%) CSF samples. Anti-IgLON5 IgG4 levels prior clinical improvement in CSF but not serum were significantly lower than in those prior stable/progressive disease. Compared to IgLON5 IgG4 levels in serum, CSF levels in HLA-DRB1*10:01 carriers were significantly higher than in non-carriers. Indeed, IgLON5-specific IgG4 IS was demonstrated not only in four of five HLA-DRB1*10:01 carriers but also in one non-carrier. Immunotherapy was associated with decreased anti-IgGLON5 IgG serum levels. In CSF, lower anti-IgLON5 IgG was associated with immunosuppressive treatments used in combination, that is, corticosteroids and/or azathioprine plus intravenous immunoglobulins or rituximab.

Conclusion

Our findings might indicate that CSF IgLON5-specific IgG4 is frequently produced intrathecally, especially in HLA-DRB1*10:01 carriers. Intrathecally produced IgG4 may be clinically relevant. While many immunotherapies reduce serum IgLON5 IgG levels, more intense immunotherapies induce clinical improvement and may be able to target intrathecally produced anti-IgLON5 IgG. Further studies need to confirm whether anti-IgLON5 IgG4 IS is a suitable prognostic and predictive biomarker in anti-IgLON5 disease.

Hook-effect in MAGLUMI immunoassay for serum anti-GAD antibodies in neurological disorders: When "wrong" matrix is the right choice

Antibodies against glutamic acid decarboxylase (anti-GAD) are a valuable diagnostic tool to detect severe autoimmune conditions as type 1 diabetes mellitus (T1DM) and anti-GAD related neurological disorders, having the latter more often anti-GAD concentrations in serum multiple times higher than in the former. Automated immunoassays, either with ELISA or chemiluminescent technology, are validated for diagnostic use in serum with analytical ranges suitable for T1DM diagnosis. In a patient presenting with a suspected autoimmune ataxia, anti-GAD testing on an automated chemiluminescent immunoassay (CLIA) resulted in slightly abnormal concentrations in serum (39.2 KIU/L) and very high concentrations in CSF (>280 KIU/L), thus prompting to proceed to serum dilutions to exclude a false negative result and a misdiagnosis. Different dilutions of serum resulted in nonlinear concentrations with endpoint result of 276,500 KIU/L at dilution 1:1000. CSF dilution was instead linear with endpoint result of 4050 KIU/L. In this case report we found that anti-GAD testing in CSF was essential to establish the clinical diagnosis and to suspect hook-effect in serum due to the excess of autoantibodies in this severe autoimmune condition.

Autoimmune encephalitis in glial fibrillary acidic protein astrocytopathy

Autoimmune encephalitis due to glial fibrillar acidic protein (GFAP) astrocytopathy is a rare cause of subacute neuropsychiatric changes. In this case, a young patient presented with a viral prodrome and meningismus, followed by progressive encephalopathy and movement disorders over the span of 2 weeks. Due to his clinical trajectory, inflammatory cerebrospinal fluid (CSF) analysis, initial normal brain imaging and negative serum autoimmune encephalopathy panel, his initial diagnosis was presumed viral meningoencephalitis. The recurrence and progression of neuropsychiatric symptoms and myoclonus despite antiviral treatment prompted further investigation, inclusive of testing for CSF autoimmune encephalopathy autoantibodies, yielding a clinically meaningful, positive GFAP autoantibody. This case highlights the importance of appropriately testing both serum and CSF autoantibodies when an autoimmune encephalitic process is considered. Through this case, we review the clinical and radiographic manifestations of GFAP astrocytopathy, alongside notable pearls pertaining to this autoantibody syndrome and its management.

Expanding the clinical spectrum of anti-DPPX encephalitis: a multicenter retrospective study

Objective

Anti-dipeptidyl-peptidase-like protein-6 (DPPX) encephalitis is a rare autoimmune encephalitis, and clinical and experimental information regarding this disease is limited. We conducted this study to comprehensively describe the clinical characteristics, ancillary test results, neuroimaging results, and treatment response in a group of Chinese patients with anti-DPPX encephalitis for better understanding this disease.

Methods

We recruited 14 patients who tested positive for anti-DPPX antibodies in the serum and/or cerebrospinal fluid from 11 medical centers between March 2021 and June 2023. This retrospective study evaluated data on symptoms, autoantibody test, auxiliary examinations, treatments, and outcomes.

Results

The average age at diagnosis was 45.93 ± 4.62 years (range: 11-72 years), and 9 of the 14 patients were males. The main symptoms included cognitive impairment (50.0%, 7/14), central nervous system hyperexcitability (42.9%, 6/14), gastrointestinal dysfunction (35.7%, 5/14), and psychiatric disorders (35.7%, 5/14). Notably, we discovered specific findings on 18F-fluorodeoxyglucose positron-emission tomography (PET)/magnetic resonance imaging in two patients. Co-existing autoantibodies were identified in two patients. Parainfection was identified in four patients. One patient had other autoimmune diseases, and one had tumor. Eleven patients received immunotherapy and most patients improved at discharge. Surprisingly, three male patients but no female patients relapsed during the 6 months of follow-up.

Conclusion

The development and outcome of anti-DPPX encephalitis are variable. Male patients were predominant in our cohort. The most common symptoms were the classical triad of prodromal gastrointestinal dysfunction, cognitive and mental disorders, and central nervous system hyperexcitability. Infections, immune dysregulation, and tumors may be important etiologies. Long-term monitoring of disease development should be done in male patients. Overall, our results highlight novel clinical characteristics of anti-DPPX encephalitis.

CSF Findings in Chinese Patients with NMDAR, LGI1 and GABABR Antibody-Associated Encephalitis

Purpose

CSF inflammation in subtypes of antibody-defined autoimmune encephalitis (AE) ranges in intensity from moderate to severe. In a retrospective, cross-sectional study, we characterized CSF findings in Chinese patients with anti-N-methyl-D-aspartate receptor encephalitis (NMDAR-E), anti-leucine-rich glioma-inactivated 1 encephalitis (LGI1-E), and anti-gamma aminobutyric acid-B receptor encephalitis (GABABR-E).

Patients and Methods

The AE cases, including 102 NMDAR-E, 68 LGI1-E and 15 GABABR-E, were included. CSF inflammatory parameters consisted primarily of CSF leukocytes, oligoclonal bands (OCBs), and CSF/serum albumin ratios (QAlb). Ten serum cytokines were evaluated in order to classify AE subtypes.

Results

88% of NMDAR-E, 80% of GABABR-E, and 51% of LGI1-E patients had aberrant CSF features. In NMDAR-E, the CSF leukocyte count, CSF protein concentration, and age-adjusted QAlb were significantly higher than in LGI1-E, but did not differ from GABABR-E. Blood-CSF barrier dysfunction was less common in NMDAR-E patients with >40 years old. On admission, inflammatory CSF response was more prevalent in NMDAR-E patients with a higher CASE score. With age <60 years, CSF inflammatory changes were less frequent in LGI1-E patients, but more common in GABABR-E patients. MCP-1, IL-10, IL-1β, and IL-4 were potential classifiers for NMDAR-E, LGI1-E, and GABABR-E, and correlated substantially with CSF leukocyte count and QAlb.

Conclusion

Subtype-specific patterns are formed by the various inflammatory CSF parameters in NMDAR-E, LGI1-E, and GABABR-E, and their correlation with disease severity, age, and disease duration. CSF inflammatory characteristics associated with MCP-1, IL-10, IL-1β, and IL-4 may be potential immunopathogeneses targeting markers for these AE subtypes.

Bickerstaff encephalitis in childhood: a review of 74 cases in the literature from 1951 to today

Bickerstaff brainstem encephalitis (BBE) is a rare autoimmune disease characterized by the subacute onset of bilateral external ophthalmoplegia, ataxia, and decreased level of consciousness. BBE is part of a group of rare autoimmune diseases in children that can affect the nervous system at any level. The onset of neurological deficits is often sudden and nonspecific. The diagnosis is based on clinical findings and abnormal findings on cerebrospinal fluid (CSF), electroencephalography (EEG), electromyography (EMG), and magnetic resonance imaging (MRI). BBE is associated with the presence of the antiganglioside antibody, anti-GQ1b and anti-GM1. Intravenous immunoglobulin (IVIg) and plasma exchange are often used as treatments for these patients. We conducted a review on clinical presentation, diagnosis, treatment and outcome of reported cases of BBE. 74 cases are reported in the literature from the first cases described in 1951 to today. The prevalence is unknown while the incidence is higher in males. In 50% of cases, BBE occurs following respiratory or gastrointestinal tract infections. The most frequent initial symptoms were consciousness disturbance, headache, vomiting, diplopia, gait disturbance, dysarthria and fever. During illness course, almost all the patients developed consciousness disturbance, external ophthalmoplegia, and ataxia. Lumbar puncture showed pleocytosis or cytoalbuminological dissociation. Abnormal EEG and MRI studies revealed abnormalities in most cases. Anti-GQ1b antibodies were detected in more than half of the patients; anti-GM1 antibodies were detected in almost 40% of patients. Treatment guidelines are missing. In our analysis, steroids and IVIg were administered alone or in combination; as last option, plasmapheresis was used. BBE has a good prognosis and recovery in childhood is faster than in adulthood; 70% of patients reported no sequelae in our analysis. Future studies need to investigate pathogenesis and possible triggers, and therapeutic possibilities.

Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults

Autoimmune encephalitis is increasingly recognized as a neurologic cause of acute mental status changes with similar prevalence to infectious encephalitis. Despite rising awareness, approaches to diagnosis remain inconsistent and evidence for optimal treatment is limited. The following Canadian guidelines represent a consensus and evidence (where available) based approach to both the diagnosis and treatment of adult patients with autoimmune encephalitis. The guidelines were developed using a modified RAND process and included input from specialists in autoimmune neurology, neuropsychiatry and infectious diseases. These guidelines are targeted at front line clinicians and were created to provide a pragmatic and practical approach to managing such patients in the acute setting.

Comparing clinical features, severity and prognosis of autoimmune encephalitis and with and without oligoclonal bands

Objective

This study aimed to examine the clinical distinctions among patients diagnosed with autoimmune encephalitis (AE) based on the presence or absence of cerebrospinal fluid (CSF) oligoclonal bands (OCBs). Additionally, it sought to explore the relationship between OCBs and the severity and prognosis of autoimmune encephalitis.

Methods

A retrospective analysis was conducted on 94 patients diagnosed with AE at the People's Hospital of Zhengzhou University between October 2016 and June 2022. The patients were divided into OCB-positive and OCB-negative groups based on CSF-OCBs. Patient severity at admission was assessed utilizing the Clinical Assessment Scale for Autoimmune Encephalitis (CASE) and the modified Rankin scale (mRS). Additionally, some oligoclonal-positive patients underwent dynamic longitudinal analysis of cerebrospinal fluid test indices. The mRS score was ultimately employed to evaluate patients' short-term prognosis (6 months) and long-term prognosis (at least 12 months) following immunotherapy.

Results

Of the 94 patients, 34 (36.2%) belonged to the OCB-positive group, while 60 (63.8%) belonged to the OCB-negative group. The group with anti-n-methyl-d-aspartate receptor (anti-NMDAR) encephalitis exhibited the highest rate of oligoclonal positivity at 27 (49.1%), followed by anti-aminobutyric acid B receptor (GABABR) encephalitis with 4 cases (30.8%), anti-contactin-associated protein-like 2 (CASPR2) encephalitis with 2 cases (20%), and anti-leucine-rich glioma inactivating protein 1 (LGI1) encephalitis with 1 case (6.25%). No statistically significant differences were found between the two groups regarding gender, age, prodromal symptoms, psychiatric disorders, seizures, language disorders, motor dysfunction, cognitive dysfunction, tumor incidence, and magnetic resonance imaging (MRI) abnormalities (p > 0.05). The OCB-positive group exhibited higher rates of autonomic dysfunction, intensive care unit (ICU) admission, CSF leukocytes, and IgG index compared to the OCB-negative group (p < 0.05). Additionally, the OCB-positive group had significantly higher median CASE and mRS scores prior to immunotherapy than the OCB-negative group (p < 0.001 and p < 0.001). Furthermore, in both short-term follow-up and long-term follow-up, the OCB-positive group had a significantly lower proportion of patients with a favorable prognosis compared to the OCB-negative group (50% vs. 71.7, 61.8% vs. 83.3%; p = 0.036, p = 0.002).

Conclusion

Autonomic dysfunction, ICU admission, leukocytes in the cerebrospinal fluid, and elevated IgG index are more commonly observed in OCB-positive patients. OCB-positivity has also been linked to the severity and prognosis of AE, making it a potential biomarker. Initial OCB testing aids clinicians in identifying potentially critically ill patients early and monitoring disease progression, thereby optimizing clinical treatment decisions.

Adult inflammatory leukoencephalopathies

Inflammatory white matter disorders may commonly mimic genetic leukoencephalopathies. These include atypical presentations of common conditions, such as multiple sclerosis, together with rare inflammatory disorders. A structured approach to such cases is essential, together with judicious use of the many available diagnostic biomarkers. The potential for such conditions to respond to immunotherapy emphasizes the importance of an accurate and prompt diagnosis in improving patient outcomes.

The association between autoimmune encephalitis mediated by N-methyl-ᴅ-aspartate receptor autoantibodies and COVID-19: a systematic review

Neurological complications related to coronavirus disease 2019 (COVID-19) infection have been increasingly reported. One of the most serious neurological complications is encephalitis, which could be due either to direct viral invasion or an immune-mediated inflammatory reaction. In this study, we conducted a systematic review of reported cases of autoimmune encephalitis mediated by N-methyl-ᴅ-aspartate receptor antibodies in conjunction with or after diagnosis of COVID-19 infection.

Antibodies to neural cell surface and synaptic proteins in paraneoplastic neurologic syndromes

Among patients with paraneoplastic neurologic syndromes (PNS), emphasis has historically been placed on neural antibodies against intracellular proteins that have a strong association with malignancy. Because of the intracellular location of their antigenic targets, these antibodies are typically considered to be non-pathogenic surrogate markers of immune cell-mediated neural injury. Unfortunately, patients with these antibodies often have suboptimal response to immunotherapy and poor prognosis. Over the last two decades, however, dramatic advancements have been made in the discovery and clinical characterization of neural antibodies against extracellular targets. These antibodies are generally considered to be pathogenic, given their potential to directly alter antigen structure or function, and patients with these antibodies often respond favorably to prompt immunotherapy. These antibodies also associate with tumors and may thus occur as PNS, albeit more variably than neural antibodies against intracellular targets. The updated 2021 PNS diagnostic criteria, which classifies antibodies as high-risk, intermediate-risk, or lower-risk for an associated cancer, better clarifies how neural antibodies against extracellular targets relate to PNS. Using this recently created framework, the clinical presentations, ancillary test findings, oncologic associations, and treatment responses of syndromes associated with these antibodies are discussed.

General features, pathogenesis, and laboratory diagnostics of autoimmune encephalitis

Autoimmune encephalitis (AE) is a group of inflammatory conditions that can associate with the presence of antibodies directed to neuronal intracellular, or cell surface antigens. These disorders are increasingly recognized as an important differential diagnosis of infectious encephalitis and of other common neuropsychiatric conditions. Autoantibody diagnostics plays a pivotal role for accurate diagnosis of AE, which is of utmost importance for the prompt recognition and early treatment. Several AE subgroups can be identified, either according to the prominent clinical phenotype, presence of a concomitant tumor, or type of neuronal autoantibody, and recent diagnostic criteria have provided important insights into AE classification. Antibodies to neuronal intracellular antigens typically associate with paraneoplastic neurological syndromes and poor prognosis, whereas antibodies to synaptic/neuronal cell surface antigens characterize many AE subtypes that associate with tumors less frequently, and that are often immunotherapy-responsive. In addition to the general features of AE, we review current knowledge on the pathogenic mechanisms underlying these disorders, focusing mainly on the potential role of neuronal antibodies in the most frequent conditions, and highlight current theories and controversies. Then, we dissect the crucial aspects of the laboratory diagnostics of neuronal antibodies, which represents an actual challenge for both pathologists and neurologists. Indeed, this diagnostics entails technical difficulties, along with particularly interesting novel features and pitfalls. The novelties especially apply to the wide range of assays used, including specific tissue-based and cell-based assays. These assays can be developed in-house, usually in specialized laboratories, or are commercially available. They are widely used in clinical immunology and in clinical chemistry laboratories, with relevant differences in analytic performance. Indeed, several data indicate that in-house assays could perform better than commercial kits, notwithstanding that the former are based on non-standardized protocols. Moreover, they need expertise and laboratory facilities usually unavailable in clinical chemistry laboratories. Together with the data of the literature, we critically evaluate the analytical performance of the in-house vs commercial kit-based approach. Finally, we propose an algorithm aimed at integrating the present strategies of the laboratory diagnostics in AE for the best clinical management of patients with these disorders.

Clinical characteristics and prognosis in patients with neuronal surface antibody-mediated autoimmune encephalitis: a single-center cohort study in China

Objective

This retrospective observational study primarily aimed to analyse the clinical characteristics of patients with neuronal surface antibody-mediated autoimmune encephalitis (AE) in China and report their prognosis after immunotherapy.

Methods

Clinical characteristics, laboratory or imaging examinations, and treatment outcomes of 103 patients diagnosed with AE between 1 September 2014 and 31 December 2020 were collected. Univariate and multivariate logistic regression analyses were performed to determine the predictors of poor prognosis.

Results

Overall, 103 patients were enrolled in the study. The main clinical symptoms included seizures (74.8%), psychiatric and behavior disorders (66.0%), cognitive deficits (51.5%), disturbances of consciousness (45.6%), and movement disorders/involuntary movements (26.2%). The distribution of clinical syndromes also differed for different AE subtypes. The efficacy rates of first-line immunotherapy for anti-NMDAR, anti-LGI1, anti-GABABR, and anti-CASPR2 encephalitis were 70.2%, 92.3%, 70%, and 83.3%, respectively, and rituximab was administered to 21 patients as second-line immunotherapy, including 14 patients with anti-NMDAR encephalitis, 4 with anti-LGI1 encephalitis, 2 with anti-GABABR encephalitis, and 1 with anti-CASPR2 encephalitis. Five patients with poor effect of the second-line treatment received bortezomib. According to the results of the last follow-up, 78 patients had a good prognosis (mRS 0-2), and 21 patients had a poor prognosis (mRS 3-6). The proportion of patients with a poor prognosis was significantly higher in anti-GABABR encephalitis compared to the other AE subtypes (p<0.001). Multivariate analysis indicated that elevated neutrophil-to-lymphocyte ratio (NLR) and tumour presence were independent risk factors for poor prognosis. The regression equation of the model was logit(P)=-3.480 + 0.318 NLR+2.434 with or without tumour (with assignment =1, without assignment =0). The prediction probability generated by the regression model equation was used as the independent variable for receiver operating curve (ROC) analysis. The results showed that the area under the curve (AUC) of the prediction probability was 0.847 (95% CI, 0.733-0.961; p < 0.001).

Conclusions

Different AE subtypes demonstrated different clinical symptom spectra throughout the disease stage. Anti-LGI1 encephalitis and anti-CASPR2 encephalitis were more sensitive to first-line and second-line treatments. Anti-GABABR encephalitis had the worst prognosis among the abovementioned subtypes. The regression equation constructed using NLR and tumour presence effectively predicted the poor prognosis.

Cerebrospinal fluid indices as predictors of treatment response in autoimmune encephalitis

BACKGROUND

Cerebrospinal fluid (CSF) indices reflecting intrathecal antibody production and blood-brain barrier impairment are not routinely assessed in patients with autoimmune encephalitis (AE). We aimed to study CSF indices and their association with the prognosis of AE.

METHODS

This retrospective cohort study conducted at Amrita Institute of Medical Sciences (AIMS), Kochi, India, included 60 patients aged more than 18 years with definite/probable/possible AE admitted to the Department of Neurology from August 2016 to November 2021. We introduced a classification of treatment response based on modified Rankin Scale change over time and treatment modalities.

RESULTS

In our cohort of 60 patients (six [10%] seropositive cases), a good rapid treatment response was associated with CSF white blood cell count of more than 4 cells/mm3 (OR, 4.57; 95% CI 1.31-15.96; P = .02) and positive immunoglobulin G (IgG) Local Synthesis (OR, 7.27; 95% CI 1.56-33.86; P = .01). Albumin Index had association with a poor Glasgow Coma Scale score at the nadir of the disease (OR, 1.17; 95% CI 1.01-1.34; P = .04). Similar results were yielded in the seronegative cohort. IgG Local Synthesis appeared to be a strong predictor for good rapid treatment response in both univariate and multivariate (adjusted OR, 28.71; 95% CI 2.12-389.22; P= .01) analysis. Time to immunotherapy was reversely correlated with good response overall (in the cohort with outliers removed [N = 49]: unadjusted OR 0.97, 95% CI 0.95-0.99; P= .01; adjusted OR 0.97; 95% CI 0.95-0.99; P= .008).

CONCLUSION

CSF indices reflecting intrathecal antibody production and blood-brain barrier impairment appear to be promising predictors of disease severity and therapeutic response in patients with autoimmune encephalitis.

The gut microbiome in intravenous immunoglobulin-treated chronic inflammatory demyelinating polyneuropathy

BACKGROUND AND PURPOSE

The gut microbiome is involved in autoimmunity. Data on its composition in chronic inflammatory demyelinating polyneuropathy (CIDP), the most common chronic autoimmune disorder of peripheral nerves, are currently lacking.

METHODS

In this monocentric exploratory pilot study, stool samples were prospectively collected from 16 CIDP patients (mean age 58 ± 10 years, 25% female) before and 1 week after administration of intravenous immunoglobulin (IVIg). Gut microbiota were analyzed via bacterial 16S rRNA gene sequencing and compared to 15 age-matched healthy subjects (mean age 59 ± 15 years, 66% female).

RESULTS

The gut microbiota of CIDP patients showed an increased alpha-diversity (p = 0.005) and enrichment of Firmicutes, such as Blautia (p = 0.0004), Eubacterium hallii (p = 0.0004), or Ruminococcus torques (p = 0.03), and of Actinobacteriota (p = 0.03) compared to healthy subjects. IVIg administration did not alter the gut microbiome composition in CIDP in this short-term observation (p = 0.95).

CONCLUSIONS

The gut microbiome in IVIg-treated CIDP shows distinct features, with increased bacterial diversity and enrichment of short-chain fatty acid producing Firmicutes. IVIg had no short-term impact on the gut microbiome in CIDP patients. As the main limitation of this exploratory pilot study was small cohort size, future studies also including therapy-naïve patients are warranted to verify our findings and to explore the impact of long-term IVIg treatment on the gut microbiome in CIDP.

The role of intrathecal free light chains kappa for the detection of autoimmune encephalitis in subacute onset neuropsychiatric syndromes

Intrathecal synthesis of free light chains kappa (FLCK) is increasingly recognized as a marker of inflammatory CNS pathologies. Here, we tested the performance of FLCK in differentiating autoimmune encephalitis (AIE) from non-inflammatory etiologies in subacute onset neuropsychiatric syndromes. Patients undergoing diagnostic work-up for suspected autoimmune encephalitis at our department between 2015 and 2020 were retrospectively assessed for definitive diagnosis, available CSF and blood samples, as well as complete clinical records. Intrathecal FLCK was measured along with established CSF markers of CNS inflammation. The study cohort consisted of 19 patients with antibody-mediated AIE (AIE+), 18 patients with suspected AIE but without detectable autoantibodies (AIE-), 10 patients with infectious (viral) encephalitis (INE), and 15 patients with degenerative encephalopathies (DGE). 25 age- and sex-matched patients with non-inflammatory neurological diseases (NIND) were used as a control group. All AIE+ patients exhibited intrathecal synthesis of FLCK compared to only 39% of AIE- patients and 81% of patients in the INE group. No intrathecal synthesis of FLCK was found in DGE and NIND patients. While intrathecal FLCK was equally specific for an inflammatory etiology as oligoclonal bands (OCB) in the cerebrospinal fluid (CSF), the sensitivity of intrathecal FLCK for any inflammatory intrathecal process was higher than that of OCB (83% vs. 38%). Intrathecal FLCK synthesis was found to discriminate AIE+ from non-inflammatory encephalopathies and AIE- when the CSF cell count was normal [receiver operating characteristic (ROC) analysis area under the curve (AUC): 0.867, p = 0.002], while it failed to differentiate between AIE+ and INE in the presence of CSF pleocytosis (AUC: 0.561, p = 0.607). In conclusion, in the absence of CSF pleocytosis, intrathecal FLCK discriminated AIE+ from competing diagnoses in our cohort of subacute onset neuropsychiatric syndromes. In addition to established markers of CSF inflammation, intrathecal FLCK might support clinical decision-making and contribute to selecting patients for (repeated) antibody testing.

Stiff Person Spectrum Disorders-An Update and Outlook on Clinical, Pathophysiological and Treatment Perspectives

Stiff person spectrum disorders (SPSD) are paradigm autoimmune movement disorders characterized by stiffness, spasms and hyperekplexia. Though rare, SPSD represent a not-to-miss diagnosis because of the associated disease burden and treatment implications. After decades as an enigmatic orphan disease, major advances in our understanding of the evolving spectrum of diseases have been made along with the identification of multiple associated autoantibodies. However, the most important recent developments relate to the recognition of a wider affection, beyond the classic core motor symptoms, and to further insights into immunomodulatory and symptomatic therapies. In this review, we summarize the recent literature on the clinical and paraclinical spectrum, current pathophysiological understanding, as well as current and possibly future therapeutic strategies.

What is autoimmune encephalitis-associated epilepsy? Proposal of a practical definition

Seizures resulting from cerebral autoimmunity are either acutely symptomatic in the context of autoimmune encephalitis (AIE) with neural surface antibodies, or they are indicative of an enduring predisposition to seizures, that is, epilepsy. Here, we propose a practical definition for autoimmune encephalitis-associated epilepsy (AEAE): Seizures associated with antibodies against glutamic acid decarboxylase, paraneoplastic syndromes, or Rasmussen encephalitis are classified as AEAE. AEAE secondary to AIE with antibodies against the N-methyl-D-aspartate receptor, leucine-rich glioma inactivated protein 1, contactin-associated protein-2, or γ-aminobutyric acid-B receptor can be diagnosed if the following criteria are met: seizures persist for at least 2 years after immunotherapy initiation; no signs of encephalitis on magnetic resonance imaging and no fluorodeoxyglucose positron emission tomography hypermetabolism; normal cerebrospinal fluid cell count; and a substantial decrease in antibody titers. This classification corresponds to different disease mechanisms. While AIE results from the pathogenic effects of neural antibodies, AEAE is probably the consequence of encephalitis-related tissue damage and thereby mainly structurally mediated. The distinction between AIE and AEAE also has practical consequences: In AIE, immunotherapy is usually highly beneficial, whereas anti-seizure medication has little effect. In AEAE, immunotherapy is less promising and the usual anti-seizure interventions are preferable. In addition, the diagnosis of AEAE has social consequences in terms of driving and professional limitations.

Gliomatosis cerebri with blindness: A case report with literature review

Cerebral gliomatosis (GC) is a rare diffuse infiltrative growth pattern of glioma with nonspecific clinical manifestations like visual impairment that may involve bilateral temporal lobes. Herpes simplex encephalitis (HSE) and limbic encephalitis (LE) can also lead to temporal lobe involvement. Differentiating these entities is necessary for patients with misleading presentations and imaging findings. To the best of our knowledge, this is the third case of GC presenting with blindness. The patient was a 35 years-old male in a drug rehabilitation center for heroin addiction. He presented with a headache, a single episode of seizure, and a 2-month history of bilateral decrease in visual acuity, which had acutely worsened. Magnetic resonance imaging (MRI) and computed tomography (CT) showed bilateral temporal lobe involvement. Ophthalmological studies showed bilateral papilledema, absence of visual evoked potential, and thickening of the retinal nerve fiber layer. Due to this clinical presentation, normal laboratory data, and suspicious MRI findings, further investigation with magnetic resonance spectroscopy (MRS) was performed. Results showed a greatly increased ratio of choline to creatinine(Cr) or N-acetyl aspartate (NAA), suggesting a neoplastic nature of the disease. Subsequently, the patient was referred for a brain tissue biopsy with a suspicion of malignancy. The pathology results revealed adult-type diffuse glioma with isocitrate dehydrogenase (IDH) mutation. Bilateral blindness, as well as bilateral temporal lobe involvement, each has many different causes. However, as demonstrated in this study, adult-type diffuse glioma must be considered a rare cause of concomitant bilateral temporal lobe involvement and blindness.

The relevance of NMDA receptor antibody-specific index for diagnosis and prognosis in patients with anti-NMDA receptor encephalitis

The clinical implications of the presence of anti-N-methyl-D-aspartate receptor (NMDAR)-specific intrathecal immunoglobulin G synthesis and whether it determines the diagnosis of anti-NMDAR encephalitis have not been thoroughly investigated yet. Thus, the aim of this study was to investigate whether the detection of intrathecal anti-NMDAR-specific IgG synthesis contributes to the diagnostic confirmation of anti-NMDAR encephalitis, to disease severity, and to prognosis in patients with positive serum anti-NMDAR-IgG. In this study, patients with detectable anti-NMDAR IgG in serum and/or cerebrospinal fluid (CSF) were included and separated into two groups that either met the 2016 criteria by Graus et al. of definite anti-NMDAR encephalitis (n = 27) or did not (n = 15). In a total, of 80 paired CSF/serum samples, antibody titers were titrated manually and end-point titer levels were carefully determined in a blinded manner to the subgroup attribution. The disease course was assessed via the modified Rankin Scale (mRS) and prognosis was estimated by the anti-NMDAR Encephalitis One-Year Functional Status (NEOS) score. With respect to whether the diagnostic Graus criteria for definite anti-NMDAR encephalitis were fulfilled, a significantly unequal distribution of intrathecal anti-NMDAR antibody-specific synthesis could be shown with a high negative predictive value in case of a negative anti-NMDAR antibody-specific index (NMDAR AI, p = .008. OR = 23.9, sensitivity = 1.0, specificity = 0.4, negative predictive value = 1). A weak correlation was found between the CSF antibody titer and mRS value at the time of sample collection (rs = .37, p = .008, 95% CI [.09, .59]). During the disease course a higher delta-mRS value formed of the mRS at initial presentation minus that at the last recorded presentation correlated with a higher NMDAR AI at first lumbar puncture (rs = - .56, p = .017, 95% CI [- .83, - .11]). No association with the prognostic NEOS score was found. In conclusion, a negative antibody-specific index for anti-NMDAR IgG antibodies has a highly negative predictive value for the diagnosis of anti-NMDAR encephalitis. Yet, a positive NMDAR AI alone does not allow the diagnosis of anti-NMDAR encephalitis.

Development and validation of an artificial intelligence model for the early classification of the aetiology of meningitis and encephalitis: a retrospective observational study

Background

Early diagnosis and appropriate treatment are essential in meningitis and encephalitis management. We aimed to implement and verify an artificial intelligence (AI) model for early aetiological determination of patients with encephalitis and meningitis, and identify important variables in the classification process.

Methods

In this retrospective observational study, patients older than 18 years old with meningitis or encephalitis at two centres in South Korea were enrolled for development (n = 283) and external validation (n = 220) of AI models, respectively. Their clinical variables within 24 h after admission were used for the multi-classification of four aetiologies including autoimmunity, bacteria, virus, and tuberculosis. The aetiology was determined based on the laboratory test results of cerebrospinal fluid conducted during hospitalization. Model performance was assessed using classification metrics, including the area under the receiver operating characteristic curve (AUROC), recall, precision, accuracy, and F1 score. Comparisons were performed between the AI model and three clinicians with varying neurology experience. Several techniques (eg, Shapley values, F score, permutation feature importance, and local interpretable model-agnostic explanations weights) were used for the explainability of the AI model.

Findings

Between January 1, 2006, and June 30, 2021, 283 patients were enrolled in the training/test dataset. An ensemble model with extreme gradient boosting and TabNet showed the best performance among the eight AI models with various settings in the external validation dataset (n = 220); accuracy, 0.8909; precision, 0.8987; recall, 0.8909; F1 score, 0.8948; AUROC, 0.9163. The AI model outperformed all clinicians who achieved a maximum F1 score of 0.7582, by demonstrating a performance of F1 score greater than 0.9264.

Interpretation

This is the first multiclass classification study for the early determination of the aetiology of meningitis and encephalitis based on the initial 24-h data using an AI model, which showed high performance metrics. Future studies can improve upon this model by securing and inputting time-series variables and setting various features about patients, and including a survival analysis for prognosis prediction.

Funding

MD-PhD/Medical Scientist Training Program through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare, Republic of Korea.