Autoimmune GFAP astrocytopathy: Prospective evaluation of 90 patients in 1 year

Case report: Autoimmune glial fibrillary acidic protein astrocytopathy misdiagnosed as tuberculous meningitis

Introduction

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a new form of autoimmunity-mediated central nervous system disease. It is especially easy to misdiagnose when clinical symptoms and cerebrospinal fluid (CSF) indicators are similar to those observed in patients with tuberculous meningitis (TBM).

Methods

We retrospectively analyzed five cases of autoimmune GFAP astrocytopathy that were initially misdiagnosed as TBM.

Results

In the five reported cases, all but one patient had meningoencephalitis in the clinic, and all patients exhibited increased pressure, lymphocytosis, increased protein levels, and decreased glucose levels in their CSF results and did not have typical imaging findings of autoimmune GFAP astrocytopathy. TBM was the initial diagnosis in all five patients. However, we found no direct evidence of tuberculosis infection, and anti-tuberculosis treatment had inconclusive effects. Following a GFAP antibody test, the diagnosis of autoimmune GFAP astrocytopathy was made.

Conclusion

When there is a suspected diagnosis of TBM but TB-related tests are negative, the possibility of autoimmune GFAP astrocytopathy should be considered.

Origins and immunopathogenesis of autoimmune central nervous system disorders

The field of autoimmune neurology is rapidly evolving, and recent discoveries have advanced our understanding of disease aetiologies. In this article, we review the key pathogenic mechanisms underlying the development of CNS autoimmunity. First, we review non-modifiable risk factors, such as age, sex and ethnicity, as well as genetic factors such as monogenic variants, common variants in vulnerability genes and emerging HLA associations. Second, we highlight how interactions between environmental factors and epigenetics can modify disease onset and severity. Third, we review possible disease mechanisms underlying triggers that are associated with the loss of immune tolerance with consequent recognition of self-antigens; these triggers include infections, tumours and immune-checkpoint inhibitor therapies. Fourth, we outline how advances in our understanding of the anatomy of lymphatic drainage and neuroimmune interfaces are challenging long-held notions of CNS immune privilege, with direct relevance to CNS autoimmunity, and how disruption of B cell and T cell tolerance and the passage of immune cells between the peripheral and intrathecal compartments have key roles in initiating disease activity. Last, we consider novel therapeutic approaches based on our knowledge of the immunopathogenesis of autoimmune CNS disorders.

A case of glial fibrillary acidotic protein (GFAP) meningoencephalitis with rheumatoid arthritis

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is an inflammatory disease of the central nervous system (CNS), which affects various regions in the CNS, presenting by variable clinical manifestations. Meningoencephalitis is the most common clinical presentation and association with autoimmune disorders has been reported in about 20% of these patients. Diagnosis is confirmed by the presence of CSF or serum immunoglobulin-G (IgG) against GFAP. The reported case is a 53-year-old woman with the history of long-standing rheumatoid arthritis who first presented with acute-onset dizziness and gait disturbance, periventricular linear and radial enhancement pattern on MRI, and normal CSF analysis, successfully treated with an increase in the dose of oral steroids. After a year she had a subacute-onset, moderate to severe holocephalic headache, normal neurologic examination and CSF analysis, and bilateral diffuse, pachymeningeal, and leptomeningeal enhancement on MRI. According to her Brain MRI imaging with relapsing remitting course steroid responsive ataxia and aseptic meningitis, her serum was tested for GFAP IgG antibodies which was positive. The reported patient is the first in the literature reported pachymeningitis in GFAP astrocytopathy. This case highlights the co-occurrence of rheumatoid arthritis with GFAP-associated astrocytopathy, and expands on the previously reported cases with similar association. This might also suggest a common immune pathogenesis.

Non-infectious meningitis and CNS demyelinating diseases: A conceptual review

Many cases of aseptic meningitis or meningoencephalitis, unresponsive to antimicrobial treatments, have been reported recently in patients with established/new-onset central nervous system (CNS) inflammatory demyelinating diseases (CNSIDDs). Given the higher probability of infectious etiologies, CNSIDDs are rarely considered among the differentials in meningitis or meningoencephalitis cases. We gathered and tabulated cases of non-infectious, steroid-responsive meningitis or meningoencephalitis associated with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein-associated disease (MOGAD). This conceptual review highlights the need to bolster routine infectious workups with immunological workups in cases of meningoencephalitis or meningitis where potential autoimmune etiologies can be suspected. Although differentiating CNSIDDs with meningeal involvement from infectious meningitis may not substantially affect acute treatment strategies, long-term management and follow-up of the two are entirely different. We also discuss future research directions and hypotheses on how CNSIDDs may be associated with meningitis-like presentations, e.g. overlapping glial fibrillary acidic protein astrocytopathy or autoimmune encephalitis, alterations in regulatory T-helper cells function, and undetected viral agents.

Small vessel childhood primary angiitis of the central nervous system with positive anti-glial fibrillary acidic protein antibodies: a case report and review of literature

BACKGROUND

Small vessel childhood primary angiitis of the central nervous system (SV-cPACNS) is a rare disease characterized by inflammation within small vessels such as arterioles or capillaries.

CASE PRESENTATION

We report a case of SV-cPACNS in an 8-year-old boy confirmed by brain biopsy. This patient was also incidentally found to have anti-glial fibrillary acidic protein (GFAP) antibodies in the cerebrospinal fluid (CSF) but had no evidence of antibody-mediated disease on brain biopsy. A literature review highlighted the rarity of SV-cPACNS and found no prior reports of CSF GFAP-associated SV-cPACNS in the pediatric age group.

CONCLUSION

We present the first case of biopsy proven SV-cPACNS vasculitis associated with an incidental finding of CSF GFAP antibodies. The GFAP antibodies are likely a clinically insignificant bystander in this case and possibly in other diseases with CNS inflammation. Further research is needed to determine the clinical significance of newer CSF autoantibodies such as anti-GFAP before they are used for medical decision-making in pediatrics.

[Clinical features of autoimmune glial fibrillary acidic protein astrocytopathy in children: an analysis of 34 cases]

OBJECTIVES

To study the clinical features of children with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A).

METHODS

A retrospective analysis was performed on the medical data of 34 children with GFAP-A who attended the Department of Neurology, Children's Hospital of Chongqing Medical University, from January 2020 to February 2022. The medical data included clinical manifestations, cerebrospinal fluid features, imaging examination results, treatment, and prognosis.

RESULTS

The median age of onset was 8.4 (range 1.9-14.9) years for the 34 children with GFAP-A. The main clinical manifestations included headache (50%, 17/34), fever (47%, 16/34), visual impairment (47%, 16/34), and disturbance of consciousness (44%, 15/34). Abnormal cerebrospinal fluid results were observed in 19 children (56%, 19/34), among whom 8 children had positive autoantibody. The children with overlap syndrome had significantly higher recurrence rate and rate of use of immunosuppressant than those without overlap syndrome (P<0.05). About 77% (24/31) of the children had good response to immunotherapy, and only 1 child had poor prognosis.

CONCLUSIONS

Children with GFAP-A often have non-specific clinical symptoms and show good response to immunotherapy. Children with overlap syndrome have a high recurrence rate, and early application of immunosuppressants may help to prevent recurrence and alleviate symptoms.

Clinical and electrophysiological characteristics of peripheral neuropathy in autoimmune glial fibrillary acidic protein astrocytopathy: an observational study and literature review

Background

The phenotype of peripheral neuropathy (PN) associated with glial fibrillary acidic protein-immunoglobulin G (GFAP-IgG) has not been well described.

Objectives

The aim of this study was to report the frequency, clinical, and electrophysiological characteristics of PN in GFAP-IgG-positive patients.

Design

This study is a single-center retrospective observational study.

Data Sources and methods

GFAP-IgG-positive patients with PN were retrospectively identified from the Huashan Hospital Autoimmune Encephalitis Cohort between 2017 and 2021. Eight patients who presented with PN from other published studies were also included in the analysis. The clinical and electrophysiological characteristics of GFAP-IgG-related PN were described.

Results

A total of 21 (31%) patients (7 females, 14 males; M _age: 42 ± 16 years) from a cohort of 68 GFAP-IgG-positive patients presented with PN. Twenty of 21 patients had symmetrical weakness. Sensory and autonomic symptoms were present in 16 and 15 patients, respectively. Lower extremities were the most frequently involved regions for both motor (20/21) and sensory (15/21) symptoms. Moreover, 13 patients (4 females, 9 males; M _age: 43 ± 13 years) had electrodiagnostic study data, and 12 of 13 patients had abnormal findings. Regarding clinical features, motor nerve fibers were predominantly involved (12/13), and symmetric lower extremities (12/13) were the most commonly affected regions. Axonal neuropathy is the typical underlying pathophysiologic process of PN. All 21 patients responded to immunotherapy. However, four patients with tetraplegia had poor outcomes, and PN was the major determinant of their long-term disability. Most cases (6/8) from the literature presented with similar clinical and electrophysiological features to those from our cohort.

Conclusion

Peripheral nerves could be involved in autoimmune GFAP astrocytopathy. Predominant motor axonal neuropathy mainly involving the lower extremities is the most common PN phenotype in this disorder. GFAP-IgG-related PN is responsive to immunotherapy.

Registration

Chinese Clinical Trial Registry: ChiCTR2000029115 (http://www.chictr.org).

Clinical, imaging features and outcomes of patients with anti-GFAP antibodies: a retrospective study

Objective

To evaluate and compare the clinical features, imaging, overlapping antibodies, and prognosis of pediatric and adult patients with anti-GFAP antibodies.

Methods

This study included 59 patients with anti-GFAP antibodies (28 females and 31 males) who were admitted between December 2019 and September 2022.

Results

Out of 59 patients, 18 were children (under 18 years old), and 31 were adults. The overall cohort's median age at onset was 32 years old, 7 for children, and 42 for adults. There were 23 (41.1%) patients with prodromic infection, 1 (1.7%) patient with a tumor, 29 (53.7%) patients with other non-neurological autoimmune diseases, and 17 (22.8%) patients with hyponatremia. Fourteen (23.7%) patients had multiple neural autoantibodies, with the AQP4 antibody being the most common. Encephalitis (30.5%) was the most common phenotypic syndrome. Common clinical symptoms included fever (59.3%), headache (47.5%), nausea and vomiting (35.6%), limb weakness (35.6%), and disturbance of consciousness (33.9%). Brain MRI lesions were primarily located in the cortex/subcortex (37.3%), brainstem (27.1%), thalamus (23.7%), and basal ganglia (22.0%). Spinal cord MRI lesions often involved the cervical and thoracic spinal cord. There was no statistically significant difference in the MRI lesion site between children and adults. Out of 58 patients, 47 (81.0%) had a monophasic course, and 4 died. The last follow-up showed that 41/58 (80.7%) patients had an improved functional outcome (mRS <3), and children were more likely than adults to have no residual disability symptoms (p = 0.001).

Conclusion

There was no statistically significant difference in clinical symptoms and imaging findings between children and adult patients with anti-GFAP antibodies; Patients with anti-GFAP antibodies may present with normal MRI findings or delayed MRI abnormalities, and patients with overlapping antibodies were common. Most patients had monophasic courses, and those with overlapping antibodies were more likely to relapse. Children were more likely than adults to have no disability. Finally, we hypothesize that the presence of anti-GFAP antibodies is a non-specific witness of inflammation.

[Clinical characteristics and short-term outcomes of autoimmune encephalitis in adults]

OBJECTIVE

To characterize clinical, paraclinical features and short-term outcomes in different types of autoimmune encephalitis (AE) in a one-center cohort of Russian patients, as well as to evaluate the frequency and significance of the joint expression of antineuronal and anti-glial antibodies (Abs) in AE.

MATERIAL AND METHODS

Forty-one patients were diagnosed with AE at the Research Center of Neurology from November 2020 to December 2022. Demographic, clinical characteristics, results of laboratory tests, MRI of brain, treatment and outcomes of disease were analyzed. The analysis of Abs to glial antigens (myelin-oligodendrocyte glycoprotein - MOG, glial fibrillar acidic protein - GFAP, aquaporin 4 - AQP-4) was performed by indirect immunofluorescence assay (Euroimmun, Germany).

RESULTS

In 24 (58.5%) patients was established definite AE, confirmed by specific Abs detection; in 2 (4.9%) - definite limbic encephalitis, in 15 (36.6%) - seronegative probable AE (including 3 cases of Hashimoto's encephalitis). GFAP-Abs in cerebrospinal fluid (CSF) were detected only in two patients - with clinical and MRI-picture of autoimmune GFAP-astrocytopathy (A-GFAP-A). GFAP- and MOG-Abs in the blood were detected in 25.7% and 6%, respectively, AQP-4-Abs were not detected. There were no correlations between co-expression with glial Abs and clinical characteristics. Systemic and antithyroid Abs were present in 15% and 31%, respectively. Paraneoplastic AE accounted for 22%. For the first time in the Russian population, 2 cases of A-GFAP-A, 6 cases of AE associated with COVID-19 were described. The most common first syndrome were epileptic seizure (34%), psychiatric (29%) and cognitive (14%) disorders. Relapses of AE was observed in 22%. Inflammatory changes in CSF were detected in 41%, focal changes on MRI in 68%. First-line immune therapy was performed in all patients, 85% of cases received pulse therapy with methylprednisolone. Second-line immune therapy (rituximab or cyclophosphamide intravenously) was performed in 19.5%, 78% of patients achieved significant improvement during treatment (scores ≤2 on the modified Rankin scale).

CONCLUSIONS

The results allow us to consider COVID-19 as a trigger of AE. The absence of detection of GFAP-Abs in CSF in patients with other types of AE contributes to the confirmation of the specificity of GFAP-seropositivity of CSF for the diagnosis of A-GFAP-A. The expression of GFAP- and MOG-Abs in AE can serve as confirmation of the immuno-mediated etiology of the disease, which is especially important for the AE diagnosis in the absence of antineuronal Abs.

Case 309: Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy

HISTORY

A 64-year-old man presented with a 6-month history of lightheadedness and intermittent balance and coordination difficulties. Two months before admission, symptoms became more substantial and persistent, with a worsening sense of disequilibrium and unsteady gait. He reported difficulties pronouncing words and mild word-finding difficulties. His wife noted a change in his cognition and memory over the same time. His medical history included well-controlled chronic obstructive pulmonary disease (COPD) secondary to a long history of smoking with associated unintentional 30-lb (13.6-kg) weight loss over the previous 3 years, for which chest CT scanning was performed, revealing no abnormality. On clinical examination, the patient was alert and oriented but had slurred speech. A positive Romberg sign was noted, finger-to-nose and hand rapid alternating movement tests revealed impairment on the right side, and his gait was ataxic. The motor examination revealed normal muscle tone, bulk, and power in the upper and lower extremities. Sensory testing results were normal. Initial MRI of the brain at admission revealed abnormal findings in the left supratentorial brain. Of note, this patient's presentation predated the COVID-19 pandemic. Cerebrospinal fluid (CSF) analysis revealed predominant pleocytosis (23 × 106/L; normal range, [0-5] × 106/L) (78% lymphocytes, 22% monocytes), elevated protein level (1.23 g/L; normal range, 0.19-0.64 g/L), oligoclonal bands (faint one or two), and a high immunoglobulin G (IgG) index (0.130 g/L; normal reference, ≤0.059 g/L). Despite extensive initial work-up for inflammatory, infectious, autoimmune, or neoplastic causes, a definitive diagnosis was not reached. Thus, repeat MRI of the brain was performed 2 weeks after admission.

GFAP astrocytopathy presenting with profound intracranial hypertension and vision loss

BACKGROUND

Glial fibrillary acidic protein (GFAP) astrocytopathy is a steroid-responsive autoimmune meningoencephalomyelitis commonly preceded by a viral illness. It is clinically characterized by encephalopathy, myelopathy and papillitis without significant effect on visual acuity. It can be associated with an underlying malignancy or autoimmune condition.

OBJECTIVE

To report a novel case of GFAP astrocytopathy presenting with profound intracranial hypertension and bilateral vision loss.

METHODS

Case report.

RESULTS AND CONCLUSION

GFAP astrocytopathy should be considered when evaluating patients with intracranial hypertension or bilateral vision loss, particularly when other features of autoimmune encephalitis are present.

[Autoimmune encephalitis-An update]

Detection of autoantibodies against neurons and glia cells has brought about the early and specific diagnosis of autoimmune encephalitis in patients with variable neurological and psychiatric symptoms. Growing knowledge not only resulted in profound changes in treatment algorithms including immunotherapy but also in the understanding of disease mechanisms and etiological factors. The still increasing numbers of new autoantibodies calls for continuous updates on the state of the art in antibody diagnostics, frequencies of associated tumors and the clinical spectrum linked to each antibody, which can range from mood changes, cognitive impairment and epileptic seizures to abnormal movements, autonomic dysfunction and impaired levels of consciousness. This article summarizes the recent developments in the predominant clinical presentations of autoimmune encephalitis patients in imaging and cerebrospinal fluid diagnostics and also in prognostic markers, in the establishment of innovative immunotherapies, in the use of diagnostic pathways even before the results of the antibody tests are available and the understanding of the autoimmune etiology.

Clinical Manifestation, Auxiliary Examination Features, and Prognosis of GFAP Autoimmunity: A Chinese Cohort Study

OBJECTIVE

This paper reports the clinical manifestation and auxiliary examination features of 15 Chinese patients with glial fibrillary acidic protein (GFAP) autoimmunity.

METHODS

From June 2016 to December 2019, patients suspected to have neurological autoimmune disease after having their serum and cerebrospinal fluid (CSF) tested for conventional neural antibodies were scanned for additional autoantibodies by immunohistochemistry. Samples that showed a characteristic immunoreactive pattern reminiscent of the GFAP of astrocytes were selected and confirmed by cell-based assay using cells-expressing human GFAPα.

RESULTS

A total of 15 patients (eight male and seven female) with a median age at onset of 53 years (range 28-72) were identified as GFAP-IgG-positive. Fourteen cases had GFAP-IgG detected in the CSF, while serum GFAP-IgG was detected in 11 cases. Eleven of the fifteen patients (73.3%) presented with an acute monophasic course, of which 10 (90.9%) had antecedent flu-like symptoms. The predominant phenotype was meningoencephalitis (46.7%), followed by meningoencephalomyelitis in 40% of the cases. The most common clinical features included long tract signs, brainstem symptoms, tremors, headaches, and psychiatric symptoms. Magnetic resonance imaging (MRI) revealed the enhancement of the meninges, the surface of the brainstem, the cerebellum, and the spinal cord as predominant. Inflammatory CSF showed mild lymphocyte-predominant pleocytosis with a median of 51/μL and elevated protein with a median of 87.5 mg/dL. Five patients had coexisting antibodies, including NMDAR-IgG in three patients and Yo and MOG-IgG in one patient each. One patient underwent a stereotactic brain biopsy, and the neuropathology diagnosis was diffuse large B-cell lymphoma. One patient had ovarian teratoma. Eleven of the fifteen (73.3%) patients received both intravenous immunoglobulin and steroids. Among them, three patients also received immunosuppressive agents later. During a two-year follow-up, 9 of the 15 (60%) patients achieved complete clinical remission.

CONCLUSIONS

The clinical presentation of GFAP astrocytopathy is heterogeneous. It can be characterized by an acute monophasic course and a chronic relapsing course. Tremors are a prominent clinical manifestation in patients with an acute monophasic course with GFAP-IgG antibodies only. Most patients responded well to immunotherapy. In patients with GFAP autoimmunity, presenting with a chronic relapsing course, one should actively search for immunogenic factors and the culprit antibodies. In the case of primary central nervous system lymphoma, GFAP autoimmunity does not always equate to autoimmune GFAP astrocytopathy.

A pediatric case of autoimmune glial fibrillary acidic protein astrocytopathy with unique brain imaging patterns and increased cytokines/chemokines

BACKGROUND

Autoimmune anti-glial fibrillary acidic protein (GFAP) astrocytopathy represents a new spectrum of autoimmune inflammatory central nervous system disorders. In recent years, there have been an increasing number of reports on pediatric patients with this disease other than those in Japan.

CASE REPORT

A 6-year-old previously healthy boy presented with fever persisting for approximately 10 days, consciousness disturbance, anorexia, and hyponatremia (Na, 121 mEq/L). Even after appropriate correction of hyponatremia, consciousness disturbance was prolonged and was accompanied by gait disturbance, visual hallucinations, and autonomic dysfunction (bradycardia and urinary dysfunction). On a plain MRI, T2-weighted and fluid-attenuated inversion recovery images showed abnormal hyperintense lesions in the bilateral basal ganglia, thalamus, and periventricular white matter. The cerebrospinal fluid was positive for anti-GFAP antibody before treatment, and cytokines/chemokines were increased. He received three courses of intravenous methylprednisolone, followed by gradually tapered oral prednisolone for 6 months, without relapse after 1 year of observation.

CONCLUSION

In cases of autoimmune encephalitis with prolonged consciousness disturbance, hyponatremia, urinary dysfunction, and MRI findings with hyperintensities in the bilateral basal ganglia, thalamus, and periventricular white matter, anti-glial fibrillary acidic protein antibodies should be examined.

Repeated Brain Magnetic Resonance Imaging Provides Clues for the Diagnosis of Autoimmune Glial Fibrillary Acid Protein Astrocytopathy

We herein report a 47-year-old man with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) revealed by periventricular radial linear enhancement on repeated brain magnetic resonance imaging (MRI). He presented with a history of headache and a fever followed by somnolence and worsening of consciousness. On admission (16 days from the onset), although lymphocytic pleocytosis and hypoglycorrhachia in the cerebrospinal fluid (CSF) were noted, initial brain MRI demonstrated non-specific findings. At 30 days from the onset, repeated brain MRI revealed characteristic findings of GFAP-A, and we detected anti-GFAP antibodies in the CSF. Thus, repeated brain MRI provides clues for the diagnosis of GFAP-A.

The Discovery of Anti-Yo (Anti-PCA1) Antibody in Patients with Paraneoplastic Cerebellar Degeneration: Opening a Window into Autoimmune Neurological Disease

Prior to 1982, ovarian and certain other cancers were known to have a rare complication of progressive cerebellar ataxia, a disorder characterized pathologically by severe-often total-obliteration of cerebellar Purkinje cells. However, the cause of cerebellar injury in these patients was unknown. In that year, we began studies in which sera from individuals with this disorder were reacted with frozen sections of human cerebellum. These studies revealed that patients with ovarian cancer and cerebellar degeneration had high titers of antibodies directed against cytoplasmic antigens of Purkinje cells and deep cerebellar nuclei-a previously undescribed pattern of antibody response which was subsequently found not to be present in ovarian cancer patients who remained neurologically normal. This antibody, now known as "anti-Yo" or "anti-PCA1" provides a marker for rapidly progressive cerebellar ataxia and is heavily associated with gynecological and breast malignancies. Although the role of anti-Yo antibody in cerebellar injury has not been established in living animals, in vitro studies have demonstrated that anti-Yo antibody causes Purkinje cell death in the absence of T lymphocytes. In this commentary, we describe our studies leading to initial discovery of anti-Yo antibody, discuss the relationship of this discovery to current knowledge of paraneoplastic neurological disease, and outline some important questions which remain to be resolved before we fully understand the pathogenesis and optimal treatment of this disorder.

[Recurrent autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy with long cervical cord lesions: a case report]

A 61-year-old man who had suffered two episodes of generalized convulsion in a two-year period was admitted to our hospital because of progressive gait disturbance during the previous five months. Neurological examination revealed cognitive impairment, spasticity of the lower limbs, truncal ataxia, and dysautonomia including orthostatic hypotension, dysuria and hypohydrosis. Brain fluid-attenuated inversion recovery (FLAIR) MRI detected high-signal-intensity lesions in the periventricular white matter and centrum semiovale, with punctate gadolinium (Gd) enhancement. Spinal MRI detected swollen cervical long cord lesions extending from C2 to C6. Although methylprednisolone pulse treatment initially ameliorated the symptoms and MRI abnormal findings, clinical symptoms and MRI abnormalities including new cervical lateral column lesions reminiscent of those in autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP-A) relapsed two months later. At this point, anti-GFAPα antibody was detected in the cerebrospinal fluid. Although the clinical course of GFAP-A has been well reported, the present case showed a chronic refractory course.

Characteristics of Movement Disorders in Patients with Autoimmune GFAP Astrocytopathy

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP-A) is a type of autoimmune corticosteroid-responsive meningoencephalitis that occurs with or without myelitis. Movement disorders have been reported in GFAP-A patients but have not been characterized. In this study, we examined the characteristics of movement disorders in GFAP-A patients. We retrospectively reviewed clinical data from 87 consecutive patients with GFAP-A attending Gifu University Hospital in Japan. We compared the demographics, clinical features, cerebrospinal fluid characteristics, and neuroimaging findings from patients with and without movement disorders. Seventy-four patients (85%) had movement disorders, including ataxia (49%), tremor (45%), myoclonus (37%), dyskinesia (2%), opsoclonus (2%), rigidity (2%), myokymia (1%), and choreoathetosis (1%). GFAP-A patients with movement disorders were significantly older than those without. Movement disorders are therefore common in GFAP-A patients, and the main types of movement disorders observed in this population were ataxia, tremor, and myoclonus. These abnormal movements can serve as clinical features that facilitate the early diagnosis of GFAP-A. Elderly GFAP-A patients are more likely to have movement disorder complications than younger patients.

Rapidly progressive dementia: Extending the spectrum of GFAP-astrocytopathies?

Autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) is a steroid-responsive meningoencephalomyelitis, sometimes presenting with atypical clinical signs such as movement disorders or psychiatric and autonomic features. Beyond clinical presentation and imaging, diagnosis relies on detection of GFAP-antibodies (AB) in CSF. Using quantitative behavioral, serologic, and immunohistochemical analyses, we characterize two patients longitudinally over 18-24 months who presented with rapidly progressive neurocognitive deterioration in the context of GFAP-AB in CSF and unremarkable cranial MRI studies. Intensified immunotherapy was associated with clinical stabilization. The value of GFAP-AB screening in selected cases of rapidly progressive dementias is discussed.

Immunopsychiatry: An Update on Autoimmune Encephalitis for Neuropsychiatrists

INTRODUCTION

Autoimmune encephalitis (AIE) is a group of immune-mediated inflammatory processes of the brain with marked psychiatric features. Although relatively rare, they might offer difficult differential diagnosis with psychiatric conditions, especially catatonia and psychotic syndromes. Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is the most common AIE, presenting with psychiatric syndromes in 90% of cases. The associated psychopathology is complex, pleomorphic and best characterized when there is involvement of a psychiatrist in the assessment.

AREAS COVERED

This text will review the main aspects of AIE to psychiatrists and/or neuropsychiatrists.

EXPERT OPINION

Immune system dysfunction has been implicated in the pathophysiology of psychiatric symptoms and disorders. The use of diagnostic criteria of possible AIE, especially when specific antibodies of AIE are not available, allows early diagnosis and prompt treatment which are associated with better clinical outcomes. The study of the psychiatric aspects of AIE can broaden our knowledge of the underlying mechanisms of various psychiatric manifestations.

Autoimmune glial fibrillary acidic protein astrocytopathy in children: a retrospective study

Objective

To describe the clinical features of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy in children.

Method

Data from 11 pediatric patients with autoimmune GFAP astrocytopathy were retrospectively analyzed.

Results

All of the patients showed encephalitis and meningoencephalitis or meningoencephalomyelitis with or without myelitis. 45.4% of the patients had fever, 27.3% headaches, 18.2% dizziness, 18.2% drowsiness, and 18.2% mental disorders. Cerebrospinal fluid (CSF) was detected in all patients. The white blood cell counts (WBC) (90.9%), lactic dehydrogenase levels (72.7%), protein level (36.4%), and adenosine deaminase activity (ADA) level (27.3%) were elevated, and the CSF glucose levels (72.7%) were slightly reduced. Nine patients (90%) were found to have brain abnormalities, of which five (50.0%) patients had abnormal symmetrical laminar patterns or line patterns hyperintensity lesions on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images in the basal ganglia, hypothalamus, subcortical white matter and periventricular white matter. The linear radial enhancement pattern of the cerebral white matter was only seen in two patients, with the most common being abnormal enhancement of leptomeninges (50%). Five patients had longitudinally extensive spinal cord lesions.

Conclusion

The findings of pediatric patients with autoimmune GFAP astrocytopathy are different from previous reports.

Leptomeningeal enhancement in multiple sclerosis and other neurological diseases: A systematic review and Meta-Analysis

BACKGROUND

The lack of systematic evidence on leptomeningeal enhancement (LME) on MRI in neurological diseases, including multiple sclerosis (MS), hampers its interpretation in clinical routine and research settings.

PURPOSE

To perform a systematic review and meta-analysis of MRI LME in MS and other neurological diseases.

MATERIALS AND METHODS

In a comprehensive literature search in Medline, Scopus, and Embase, out of 2292 publications, 459 records assessing LME in neurological diseases were eligible for qualitative synthesis. Of these, 135 were included in a random-effects model meta-analysis with subgroup analyses for MS.

RESULTS

Of eligible publications, 161 investigated LME in neoplastic neurological (n = 2392), 91 in neuroinfectious (n = 1890), and 75 in primary neuroinflammatory diseases (n = 4038). The LME-proportions for these disease classes were 0.47 [95%-CI: 0.37-0.57], 0.59 [95%-CI: 0.47-0.69], and 0.26 [95%-CI: 0.20-0.35], respectively. In a subgroup analysis comprising 1605 MS cases, LME proportion was 0.30 [95%-CI 0.21-0.42] with lower proportions in relapsing-remitting (0.19 [95%-CI 0.13-0.27]) compared to progressive MS (0.39 [95%-CI 0.30-0.49], p = 0.002) and higher proportions in studies imaging at 7 T (0.79 [95%-CI 0.64-0.89]) compared to lower field strengths (0.21 [95%-CI 0.15-0.29], p < 0.001). LME in MS was associated with longer disease duration (mean difference 2.2 years [95%-CI 0.2-4.2], p = 0.03), higher Expanded Disability Status Scale (mean difference 0.6 points [95%-CI 0.2-1.0], p = 0.006), higher T1 (mean difference 1.6 ml [95%-CI 0.1-3.0], p = 0.04) and T2 lesion load (mean difference 5.9 ml [95%-CI 3.2-8.6], p < 0.001), and lower cortical volume (mean difference -21.3 ml [95%-CI -34.7--7.9], p = 0.002).

CONCLUSIONS

Our study provides high-grade evidence for the substantial presence of LME in MS and a comprehensive panel of other neurological diseases. Our data could facilitate differential diagnosis of LME in clinical settings. Additionally, our meta-analysis corroborates that LME is associated with key clinical and imaging features of MS. PROSPERO No: CRD42021235026.

Autoimmune Encephalitis and Autoantibodies: A Review of Clinical Implications

BACKGROUND

Autoimmune encephalitis (AE) is a common cause of encephalitis. We review the most recent evidence on this neuroimmune condition and autoantibody testing currently available.

CONTENT

Clinical criteria, neuroimaging and electroencephalography can facilitate the diagnosis of AE prior to obtaining autoantibody testing results, and lead to a diagnosis of AE even in the absence of a recognized antibody. Early treatment of AE has been found to correlate with improved long-term functional and cognitive outcomes. We suggest a clinical approach to diagnosis based on the predominant area of nervous system involvement and the results of ancillary testing that are widely available. We also propose a 2-tiered approach to the acute management of probable or definite AE. We, finally, provide guidance on the long-term management of AE-a challenging and understudied area.

SUMMARY

Much work remains to be done to improve the care of patients with AE. As understanding of the pathophysiology and predisposing factors underlying this condition steadily increases, a more evidence-based, targeted approach to the treatment of AE is still desired. Nonetheless, looking at the progress made over the past 2 decades, since the discovery of the first autoantibodies associated with AE, one cannot help but feel optimistic about the road ahead.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: To Identify Its Diagnosis, Management and Prognosis (GFAP-AID) Registry: Study Protocol for an Ambispective, Multicenter Registry in China

PURPOSE

Currently, no uniform diagnostic criteria or treatment consensus is available for patients with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A). The aim of this registry is to develop diagnostic and therapeutic recommendations for GFAP-A based on clinical features, neuroimaging, neuroelectrophysiological examinations, laboratory tests, specific antibody tests, immunotherapy, and prognosis.

PATIENTS AND METHODS

This multicenter, nationwide ambispective registry includes twenty-seven hospitals in China. From January 2020 to December 2022, consecutive hospitalized patients with symptoms of meningoencephalitis, as well as GFAP-IgG positive cerebrospinal fluid (CSF) or serum will be invited to join this study. It is conservatively estimated that over 300 patients will join the study. Data on demographics, medical history, treatment details and imaging features will be collected after discharge. Outcome events of interest will include modified Rankin Scale (mRS) and Expanded Disability Status Scale (EDSS), readmission with relapsed meningoencephalomyelitis, all-cause mortality, and mortality resulting from complications of GFAP-A. The follow-up will be conducted at six months and twelve months after discharge. Univariate and multivariate regression models will be used to calculate identify independent predictors of outcomes. Stratification analysis will be used to test whether results are similar between key subgroups.

DISCUSSION

This study will describe the risk factors, disease course, response to immunotherapy, and long-term prognosis of a large cohort of GFAP-A patients. By using these data, a relatively rational recommendation process for the diagnosis and treatment of GFAP-A will be developed.

TRIAL REGISTRATION NUMBER

ChiCTR2000041291.

Uncommon inflammatory/immune-related myelopathies

The differential diagnosis for immune-mediated myelopathies is broad. Although clinical manifestations overlap, certain presentations are suggestive of a particular myelopathy etiology. Spine MRI lesion characteristics including the length and location, and the pattern of gadolinium enhancement, help narrow the differential diagnosis and exclude an extrinsic compressive cause. The discovery of specific antibodies that serve as biomarkers of myelitis such as aquaporin-4-IgG and myelin-oligodendrocyte -glycoprotein-IgG (MOG-IgG), has improved our understanding of myelitis pathophysiology and facilitated diagnosis. In this review we will focus on the pathophysiology, clinical presentation, imaging findings and treatment and outcomes of uncommon immune-mediated myelopathies.

Autoimmune glial fibrillary acidic protein astrocytopathy resembling isolated central nervous system lymphomatoid granulomatosis

We report two patients with meningoencephalomyelitis without evidence of extra central nervous system (CNS) involvement. Brain MRI showed linear perivascular radial gadolinium enhancement patterns and spinal cord MRI showed longitudinal extensive T2-hyperintensity lesions. Pathological findings from brain biopsies were angiocentric T-cell predominant lymphoid infiltrates that lacked Epstein-Barr virus-positive atypical B cells. The patients were initially suspected to have isolated CNS-lymphomatoid granulomatosis (LYG). Thereafter, glial fibrillary acidic protein (GFAP)-immunoglobulin G were detected in their cerebrospinal fluid. This finding suggested autoimmune GFAP astrocytopathy. We speculate there is a link between isolated CNS-LYG and autoimmune GFAP astrocytopathy.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy in Children: A Retrospective Analysis of 35 Cases

Objective

To analyze the clinical manifestations, imaging, electroencephalography, treatment, and prognosis of 35 cases of autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) in children.

Methods

Children hospitalized in the Department of Neurology, Hunan Children’s Hospital, China, between January 2015 and June 2021, owing to autoimmune diseases of the central nervous system were subjected to a cell-based assay (CBA). The assay identified 40 children positive for GFAP-immunoglobulin (Ig)G antibodies in the serum and/or the cerebrospinal fluid. Based on clinical manifestations and imaging characteristics, five children who were only positive for GFAP-IgG antibodies in serum were excluded, and the remaining 35 children were diagnosed with autoimmune GFAP-A. The clinical data derived from the 35 children were retrospectively analyzed.

Results

A total of 35 children, including 23 males and 12 females with a mean age of 6.3 ± 0.6 years, manifested clinical symptoms of fever (62.9%), headache (42.9%), convulsions (42.9%), abnormal mental behavior (51.4%), disorders of consciousness (54.3%), visual disturbance (22.9%), ataxia (11.4%), paralysis (40%), and autonomic dysfunction (25.7%). One child exhibited only the clinical symptom of peripheral facial nerve palsy. Eleven out of 35 children were also positive for other antibodies. In addition to the common overlapping autoimmune syndromes, one case of autoimmune GFAP-A also manifested as Bickerstaff’s brainstem encephalitis. Linear periventricular enhancement upon MRI was significantly less frequent in children (8.5%) than in adults. In pediatric patients, MRI contrast enhancement was principally seen in the meninges and brain lobes. Although repeated relapse (17.1%) and sequelae symptoms (20%) occurred in some cases, most children showed a favorable prognosis. Spearman’s rank correlation showed that the antibody titer was not significantly associated with the severity of the initial disease conditions.

Conclusions

The disease diagnosis in children seropositive for GFAP antibodies only should receive a comprehensive diagnosis based on their clinical symptoms, imaging, electroencephalographic characteristics, and treatment responses. Some patients with relapses should receive repeated gamma globulin and corticosteroid therapy or the addition of immunosuppressants to their therapeutic regimen, and slow-dose tapering of corticosteroids and extended treatment are recommended for patients with overlapping autoimmune syndromes.

Glial Fibrillary Acidic Protein Autoimmunity: A French Cohort Study

Background and Objectives

To report the clinical, biological, and imaging features and clinical course of a French cohort of patients with glial fibrillary acidic protein (GFAP) autoantibodies.

Methods

We retrospectively included all patients who tested positive for GFAP antibodies in the CSF by immunohistochemistry and confirmed by cell-based assay using cells expressing human GFAPα since 2017 from 2 French referral centers.

Results

We identified 46 patients with GFAP antibodies. Median age at onset was 43 years, and 65% were men. Infectious prodromal symptoms were found in 82%. Other autoimmune diseases were found in 22% of patients, and coexisting neural autoantibodies in 11%. Tumors were present in 24%, and T-cell dysfunction in 23%. The most frequent presentation was subacute meningoencephalitis (85%), with cerebellar dysfunction in 57% of cases. Other clinical presentations included myelitis (30%) and visual (35%) and peripheral nervous system involvement (24%). MRI showed perivascular radial enhancement in 32%, periventricular T2 hyperintensity in 41%, brainstem involvement in 31%, leptomeningeal enhancement in 26%, and reversible splenial lesions in 4 cases. A total of 33 of 40 patients had a monophasic course, associated with a good outcome at last follow-up (Rankin Score ≤2: 89%), despite a severe clinical presentation. Adult and pediatric features are similar. Thirty-two patients were treated with immunotherapy. A total of 11/22 patients showed negative conversion of GFAP antibodies.

Discussion

GFAP autoimmunity is mainly associated with acute/subacute meningoencephalomyelitis with prodromal symptoms, for which tumors and T-cell dysfunction are frequent triggers. The majority of patients followed a monophasic course with a good outcome.

Clinical, neuroradiological, diagnostic and prognostic profile of autoimmune glial fibrillary acidic protein astrocytopathy: A pooled analysis of 324 cases from published data and a single-center retrospective study

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a recently defined autoimmune meningoencephalomyelitis, associated with GFAP-IgG antibody. A pooled analysis of 324 cases from published literature and a retrospective single-center study were performed, firstly reveals the possibility that patients with myelitic lesions respond better to initial immunotherapy, but are prone to relapse, suggesting a more aggressive and long-term immunosuppressive medication for them. Moreover, our results showed using tacrolimus at maintenance stage exhibited a less tendency to relapse, providing a possibly new choice to future clinical treatments.

Update on Paraneoplastic Cerebellar Degeneration

Purpose of review: To provide an update on paraneoplastic cerebellar degeneration (PCD), the involved antibodies and tumors, as well as management strategies. Recent findings: PCD represents the second most common presentation of the recently established class of immune mediated cerebellar ataxias (IMCAs). Although rare in general, PCD is one of the most frequent paraneoplastic presentations and characterized clinically by a rapidly progressive cerebellar syndrome. In recent years, several antibodies have been described in association with the clinical syndrome related to PCD; their clinical significance, however, has yet to be determined. The 2021 updated diagnostic criteria for paraneoplastic neurologic symptoms help to establish the diagnosis of PCD, direct cancer screening, and to evaluate the presence of these newly identified antibodies. Recognition of the clinical syndrome and prompt identification of a specific antibody are essential for early detection of an underlying malignancy and initiation of an appropriate treatment, which represents the best opportunity to modulate the course of the disease. As clinical symptoms can precede tumor diagnosis by years, co-occurrence of specific symptoms and antibodies should prompt continuous surveillance of the patient. Summary: We provide an in-depth overview on PCD, summarize recent findings related to PCD, and highlight the transformed diagnostic approach.

Autoimmune GFAP astrocytopathy presenting with remarkable CNS hyperexcitability and oculogyric crises

The autoimmune GFAP astrocytopathy has been associated with meningoencephalomyelitis that usually responds to glucocorticoids. We report a 20-year-old man that developed an acute and severe meningoencephalomyelitis with remarkable CNS hyperexcitability and oculogyric crises. CSF analysis showed hypoglycorrhachia, pleocytosis, elevated ADA, and CSF-immunofluorescence characteristic of autoimmune GFAP astrocytopathy. MRI showed lesions at thalamus, corpus-callosum, dorsal pons and dentate nucleus with associated myelitis. Immunotherapy led to a full recovery, although MRI activity was observed at follow-up. CNS hyperexcitability, typically seen in other immune-mediated syndromes, represents a novel presenting form to be included as part of the clinical spectrum of this entity.

Subacute Blindness Revealing an Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is an autoimmune disease of the central nervous system characterized by positive GFAP autoantibody. The most common are encephalitis, meningoencephalitis or meningoencephalomyelitis. Antibodies in cerebrospinal fluid (CSF) against GFAP are biomarkers and expressed in most cases with autoimmune GFAP astrocytopathy. Diagnosis by biopsy is not common practice and has been rarely performed in the literature. This is the particularity of our reported case of autoimmune GFAP astrocytopathy presented as opticopyramidal syndrome, all paraclinical investigations were normal, only the biopsy allowed the diagnosis.

Update in Autoimmune Movement Disorders: Newly Described Antigen Targets in Autoimmune and Paraneoplastic Cerebellar Ataxia

Movement disorders are a common feature of many antibody-associated neurological disorders. In fact, cerebellar ataxia is one of the most common manifestations of autoimmune neurological diseases. Some of the first autoantibodies identified against antigen targets include anti-neuronal nuclear antibody type 1 (ANNA-1 or anti-Hu) and Purkinje cell cytoplasmic antibody (PCA-1) also known as anti-Yo have been identified in paraneoplastic cerebellar degeneration. Historically these antibodies have been associated with an underlying malignancy; however, recently discovered antibodies can occur in the absence of cancer as well, resulting in the clinical syndrome of autoimmune cerebellar ataxia. The pace of discovery of new antibodies associated with autoimmune or paraneoplastic cerebellar ataxia has increased rapidly over the last few years, and pathogenesis and potential treatment options remains to be explored. Here we will review the literature on recently discovered antibodies associated with autoimmune and paraneoplastic cerebellar ataxia including adaptor protein-3B2 (AP3B2); inositol 1,4,5-trisphophate receptor type 1 (ITPR1); tripartite motif-containing (TRIM) proteins 9, 67, and 46; neurochondrin; neuronal intermediate filament light chain (NIF); septin 5; metabotropic glutamate receptor 2 (mGluR2); seizure-related 6 homolog like 2 (SEZ6L2) and homer-3 antibodies. We will review their clinical characteristics, imaging and CSF findings and treatment response. In addition, we will discuss two clinical case examples of autoimmune cerebellar ataxia.

Paraneoplastic AQP4-IgG-Seropositive Neuromyelitis Optica Spectrum Disorder Associated With Teratoma: A Case Report and Literature Review

Objectives

To assess a case of paraneoplastic aquaporin-4 (AQP4)-immunoglobulin G (IgG)–seropositive neuromyelitis optica spectrum disorder (NMOSD) associated with teratoma and determine whether it is a paraneoplastic neurologic disorder.

Methods

A single case study and literature review of 5 cases.

Results

A 27-year-old woman presented with diplopia, facial nerve palsy, paraplegia, sensory dysfunction of lower limbs, dysuria, nausea, and vomiting. Spinal cord MRI detected an extensive longitudinal lesion in the spinal cord, and brain MRI detected abnormal lesions in the right cerebral peduncle and tegmentum of the pons. CSF analysis revealed positive oligoclonal IgG bands (OCBs). The patient tested positive for AQP4-IgG, confirming a diagnosis of NMOSD. An abdominal CT scan detected an ovarian tumor. After steroid therapy and tumor removal, the patient progressively improved, with only mild sensory dysfunction. Histopathologic analysis of the tumor revealed a teratoma and the presence of glial fibrillary acidic protein (GFAP)⁺ neural tissue with AQP4 immunoreactivity, accompanied by lymphocyte infiltration. Including the present case, there have been 6 reported cases of AQP4-IgG–seropositive NMOSD associated with ovarian teratoma (mean onset age, 32.7 years). Of these patients, 5 (83%) presented with nausea and/or vomiting, positive OCB, and dorsal brainstem involvement. Pathologic analyses of the teratoma were available in 5 cases, including the present case, revealing neural tissue with AQP4 immunoreactivity and lymphocyte infiltration in all cases.

Conclusions

This study suggests that ovarian teratoma may trigger the development of AQP4-IgG–seropositive NMOSD. Further studies are needed to elucidate the pathogenesis of teratoma-associated NMOSD.

[Differential diagnostics of autoimmune inflammatory spinal cord diseases]

Myelitis is an acute or subacute inflammatory syndrome of the spinal cord. Myelopathy, often used as a synonym and presenting with similar symptoms in clinical practice, can be caused by numerous, not primarily inflammatory etiologies and might also show a progressive disease course. Within the last decade the spectrum of autoimmune myelitis was significantly broadened as was the spectrum of diagnostic methods. Apart from the characteristic example of multiple sclerosis with short-length myelitis and neuromyelitis optica spectrum disorders with longitudinally extensive transverse myelitis, multiple rare but important differential diagnoses should also be considered. Magnetic resonance imaging and laboratory analyses of serum antibodies and cerebrospinal fluid are the most important diagnostic methods and are fundamental for rapid treatment decisions, subsequently with better prognosis. This article reviews representative diseases within the spectrum of autoimmune spinal cord diseases and their differential diagnoses.

[Treatment of antibody-mediated encephalomyelitis : Strategies for the treatment of neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease]

BACKGROUND

Antibody-mediated encephalomyelitis, such as neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and glial fibrillary acidic protein (GFAP) antibody-associated astrocytopathy belong to a group of newly described autoimmune diseases.

AIM

Presentation of the treatment of antibody-mediated encephalomyelitis with a focus on NMOSD and MOGAD.

METHODS

Selective literature search in PubMed taking the consultation version of the S2k guidelines of the German Society of Neurology (DGN) on the diagnosis and treatment of multiple sclerosis (MS), NMOSD and MOG IgG-associated diseases into account.

RESULTS

Acute relapses are treated with high-dose steroid pulse therapy or apheresis therapy (plasma exchange or immunoadsorption). It is crucial to start treatment as quickly as possible and apheresis therapy can also be used as first-line treatment under certain conditions. For prophylactic immunotherapy, steroids, classical immunosuppressants and monoclonal antibodies with specific mechanisms of action are used. Eculizumab, inebilizumab and satralizumab are the first drugs approved for NMOSD. Symptomatic treatment and neurorehabilitation are important complementary measures.

CONCLUSION

Treatment of antibody-mediated encephalomyelitis differs from treatment of multiple sclerosis and requires specific measures.

Paraneoplastic neurological syndrome: an evolving story

Paraneoplastic neurological syndrome (PNS) comprises a group of neurological disorders that result from a misguided immune response to the nervous system triggered by a distant tumor. These disorders frequently manifest before the diagnosis of the underlying neoplasm. Since the first reported case in 1888 by Oppenheim, the knowledge in this area has evolved rapidly. Several classic PNS have been described, such as limbic encephalitis, paraneoplastic cerebellar degeneration, encephalomyelitis, opsoclonus-myoclonus, sensory neuronopathy, Lambert-Eaton Myasthenic syndrome, and chronic gastrointestinal dysmotility. It is now recognized that PNS can have varied nonclassical manifestations that extend beyond the traditional syndromic descriptions. Multiple onconeural antibodies with high specificity for certain tumor types and neurological phenotypes have been discovered over the past 3 decades. Increasing use of immune checkpoint inhibitors (ICIs) has led to increased recognition of neurologic ICI-related adverse events. Some of these resemble PNS. In this article, we review the clinical, oncologic, and immunopathogenic associations of PNS.

Paraneoplastic neurological syndromes: clinical presentations and management

We provide an overview of the varied presentations of paraneoplastic neurological syndromes. We also review the onconeural antibodies and their particular oncological and neurological associations. Recognition of these syndromes and their oncological associations is crucial, as early diagnosis and management has been associated with better patient outcomes. Specific management strategies and prognosis vary widely depending on the underlying etiology. An understanding of the relevant clinical details, imaging findings, and other diagnostic information can help tailor treatment approaches. We provide an outline of the diagnostic evaluation and treatment of various paraneoplastic neurological disorders, presenting with central and/or peripheral nervous system involvement. We briefly discuss neurologic immune checkpoint inhibitor-related adverse events, which can occasionally present with paraneoplastic neurological syndrome phenotypes.

Purkinje cell (PC) antibody positivity in a patient with autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy

PURPOSE

This case report is the first to describe the detection of antibodies against inositol 1,4,5-trisphosphate receptor 1 (ITPR1, I3PR) in a patient diagnosed with autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy. ITPR1 is known as one of the Purkinje cell antibodies present in autoimmune cerebellar ataxia (ACA). Here, we described the association between autoimmune GFAP astrocytopathy and autoimmune cerebellar disease (ACD).

MATERIALS AND METHODS

Demographic features, clinical characteristics, cerebrospinal fluid (CSF) parameters and neuroimaging findings were collected from this patient. Specifically, antibodies against GFAP and other proteins associated with neurological disorders were measured by immunofluorescence staining in both serum and CSF samples.

RESULTS

A 52-year-old woman was diagnosed with autoimmune inflammatory meningoencephalitis. She presented with cognitive dysfunction, psychiatric/behavioral abnormalities and serious insomnia with subacute onset. Brain magnetic resonance imaging (MRI) showed bilateral hyperintensity in the semioval centers on axial images and perivascular linear enhancement oriented radially to the ventricles on sagittal images. GFAP-IgG, oligoclonal bands (OBs), N-methyl-D-aspartate receptor (NMDAR)-IgG and ITPR1-IgG co-existed in her CSF. She responded well to immunoglobulin and steroid treatments.

CONCLUSION

Here, we describe the case of a patient with autoimmune GFAP astrocytopathy whose CSF was positive for ITPR1-IgG; however, she did not show typical ataxia manifestations or cerebellar lesions on her MRI scan. This suggests that ITPR1-IgG is not pathogenic, and the positivity of this antibody in CSF is probably associated with the presence of autoimmune inflammation.

Neuronal intermediate filament IgGs in CSF: Autoimmune Axonopathy Biomarkers

Objectives

To describe CSF‐defined neuronal intermediate filament (NIF) autoimmunity.

Methods

NIF‐IgG CSF‐positive patients (41, 0.03% of 118599 tested, 1996–2019) were included (serum was neither sensitive nor specific). Criteria‐based patient NIF‐IgG staining of brain and myenteric NIFs was detected by indirect immunofluorescence assay (IFA); NIF‐specificity was confirmed by cell‐based assays (CBAs, alpha internexin, neurofilament light [NF‐L]), heavy‐[NF‐H] chain).

Results

Sixty‐one percent of 41 patients were men, median age, 61 years (range, 21–88). Syndromes were encephalopathy predominant (23), cerebellar ataxia predominant (11), or myeloradiculoneuropathies (7). MRI abnormalities (T2 hyperintensities of brain, spinal cord white matter tracts. and peripheral nerve axons) and neurophysiologic testing (EEG, EMG, evoked potentials) co‐localized with clinical neurological phenotypes (multifocal in 29%). Thirty patients (73%) had ≥ 1 immunological perturbation: cancer (paraneoplastic), 22; systemic infection (parainfectious [including ehrlichosis, 3] or HIV), 7; checkpoint‐inhibitor cancer immunotherapy, 4; other, 5. Cancers were as follows: neuroendocrine‐lineage carcinomas, 12 (small cell, 6; Merkel cell, 5; pancreatic, 1 [11/12 had NF‐L‐IgG detected, versus 8/29 others, P = 0.0005]) and other, 11. Onset was predominantly subacute (92%) and accompanied by inflammatory CSF (75%), and immunotherapy response (77%). In contrast, CSF controls (15684 total) demonstrated NIF‐IgG negativity (100% of test validation controls), and low frequencies of autoimmune diagnoses (20% of consecutively referred clinical specimens) and neuroendocrine‐lineage carcinoma diagnosis (3.1% vs. 30% of NIF cases), P < 0.0001. Median NF‐L protein concentration was higher in 8 NF‐L‐IgG‐positive patients (median, 6718 ng/L) than 16 controls.

Interpretation

Neurological autoimmunity, defined by CSF‐detected NIF‐IgGs, represents a continuum of treatable axonopathies, sometimes paraneoplastic or parainfectious.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy Presenting with Slowly Progressive Myelitis and Longitudinally Extensive Spinal Cord Lesions

We report a 65-year-old man with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A) who presented with gait disturbance that he had experienced for approximately half a year. On neurological examination, he displayed spastic paraplegia and autonomic dysfunctions including dysuria and constipation. Spinal cord magnetic resonance imaging showed longitudinally extensive spinal cord lesions (LESCLs) extending from the cervical to the thoracic cords. The patient was negative for anti-myelin oligodendrocyte glycoprotein and anti-aquaporin 4 antibodies. Treatment with corticosteroids and intravenous immunoglobulin resulted in a clinical improvement. It is important to distinguish GFAP-A from slowly progressive myelitis with LESCLs.