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

Pearls & Oy-sters: Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy Presenting as Encephalomyelitis With Leptomeningeal Enhancement

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is an uncommon diagnosis in the differential for leptomeningeal enhancement. This case highlights the presentation, imaging features, and investigations important for diagnosis of GFAP astrocytopathy to ensure timely treatment of this corticosteroid-responsive disease. A 50-year-old man from Hong Kong presented with 10 days of progressive urinary retention, dysarthria, diplopia, and gait ataxia after a viral illness. Initial nonenhanced MRI brain was negative. After he developed encephalopathy, repeat MRI with gadolinium on admission day 6 revealed diffuse basal and spinal cord leptomeningeal enhancement. This imaging pattern, in combination with CSF eosinophilia and epidemiologic risk factors, precipitated empiric treatment for tuberculosis meningitis (including dexamethasone). Extensive investigations for an alternate infectious, autoimmune, or malignant diagnosis were negative. Dexamethasone cessation after a gastrointestinal bleed led to clinical and radiologic deterioration. This prompted further CSF and serum testing, which showed positive CSF GFAP-IgG immunofluorescence assay (IFA) (1:128) solidifying the diagnosis of autoimmune GFAP astrocytopathy. Induction with high-dose corticosteroids, intravenous immunoglobulins, and rituximab produced clinical and radiologic remission. Autoimmune GFAP astrocytopathy is an autoimmune disorder with a characteristic perivascular radial enhancement imaging pattern. However, a variety of other clinical and radiologic presentations may be seen, including leptomeningeal enhancement and T2/FLAIR hyperintensities. Diagnosis is confirmed with CSF GFAP-IgG testing. We provide a differential diagnosis for leptomeningeal enhancement and highlight clinical pearls for the diagnosis and management of autoimmune GFAP astrocytopathy.

Autoimmune glial fibrillary acidic protein astrocytopathy misdiagnosed as intracranial infectious diseases: case reports and literature review

Background

Autoimmune glial fibrillary acidic protein astrocytopathy (A-GFAP-A) is an autoimmune central nervous system(CNS) disease characterized by GFAP IgG as a biomarker. Several cases of individuals with A-GFAP-A initially misdiagnosed as infectious diseases of the central nervous system have been reported in research. We report three cases of A-GFAP-A misdiagnosed as viral meningitis or tuberculous meningitis (TBM). We summarize recent cases of A-GFAP-A misdiagnosed as central nervous system infections through a literature review.

Materials and methods

Three cases of A-GFAP-A were initially misdiagnosed as tuberculous or viral meningitis. Their diagnoses of A-GFAP-A were confirmed with positive GFAP-IgG in cerebrospinal fluid (CSF). We searched the PubMed database with the key words of "GFAP astrocytopathy", "GFAP autoimmunity", "GFAP autoantibody", "intracranial infection", "meningitis", "misdiagnose", and within the literature from Jan 1, 2015 to Mar 15, 2024, 40 cases with A-GFAP-A with positive GFAP-IgG in CSF who were previously misdiagnosed with intracranial infection were reported. The causes of misdiagnoses were summarized and analyzed.

Results

Case 1 was a 41-year-old female, presenting with headache, fever, diplopia, and altered consciousness level. Anti-tuberculosis treatment was ineffective. Finally, with positive GFAP IgG in CSF, she was diagnosed with A-GFAP-A. Case 2 was a 74-year-old male, presenting with fever, excessive sweating, fatigue, and memory loss. Anti-tuberculosis treatment was ineffective. With positive GFAP IgG in CSF, he was diagnosed with A-GFAP-A. Case 3 was a 54-year-old male, presenting with fever, personality changes, and memory decline. Antiviral treatment was ineffective. His diagnosis was revised to A-GFAP-A after testing positive for GFAP IgG in CSF. Our study summarized a total of 40 patients with A-GFAP-A who were initially misdiagnosed as intracranial infections. The most common clinical phenotypes among 40 patients were mimicked meningitis, meningoencephalitis, meningoencephalomyelitis, encephalitis and encephalomyelitis.

Conclusion

A-GFAP-A is a specific autoimmune meningoencephalomyelitis associated with GFAP-IgG, with lesions involved the brain, meninges, and spinal cord. It commonly presents with symptoms such as fever, headache, altered consciousness, tremor, seizures, and autonomic dysfunction. Brain MRI often shows characteristic linear perivascular radial enhancement perpendicular to the ventricles or nonspecific leptomeningeal enhancement. Early detection of GFAP-IgG in serum and CSF is essential for differential diagnosis.

Nanopore-targeted sequencing (NTS) for intracranial tuberculosis: a promising and reliable approach

BACKGROUND

The World Health Organization predicted 10.6 million new tuberculosis cases and 1.5 million deaths in 2022. Tuberculous meningitis, affecting 1% of active TB cases, is challenging to diagnose due to sudden onset, vague symptoms, and limited laboratory tests. Nanopore-targeted sequencing (NTS) is an emerging third-generation sequencing technology known for its sequencing capabilities. We compared its detection efficiency with Xpert, MTB culture, PCR, and AFB smear in cerebrospinal fluid samples to highlight the substantial potential of NTS in detecting intracranial tuberculosis.

METHODS

This study included 122 patients suspected of having intracranial tuberculosis at the Second Hospital of Nanjing in Jiangsu Province, China, between January 2021 and January 2024. The Univariate logistic regression and random forest regression identified risk factors and clinical markers. A chi-square test evaluated diagnostic accuracy for different image types of intracranial tuberculosis.

RESULTS

The research involved 100 patients with intracranial tuberculosis. Among them, 41 had tuberculous meningitis, 27 had cerebral parenchymal tuberculosis, and 32 had mixed intracranial tuberculosis. Besides, 22 patients were diagnosed with other brain conditions. In diagnosing intracranial tuberculosis, NTS demonstrated a sensitivity of 60.0% (95% CI: 49.7-69.5%) and a specificity of 95.5% (95% CI:75.1-99.8%), with an AUC value of 0.78 (95% CI: 0.71 to 0.84), whose overall performance was significantly better than other detection methods. There was no notable difference (P > 0.05) in diagnostic accuracy between NTS and the final diagnosis for intracranial tuberculosis patients with varying imaging types. Furthermore, patients who tested positive had a 31.500 (95% CI: 6.205-575.913) times higher risk of having intracranial tuberculosis compared to those with negative results.

CONCLUSION

Due to its convenience, efficiency, quick turnaround time, and real-time sequencing analysis, NTS might become a promising and reliable method for providing microbiological diagnoses for patients with intracranial tuberculosis and for screening populations at risk.

Glial Fibrillary Acidic Protein Astrocytopathy: Review of Pathogenesis, Imaging Features, and Radiographic Mimics

Glial fibrillary acidic protein (GFAP) astrocytopathy is a recently described autoimmune inflammatory disorder of the CNS characterized by the presence of specific antibodies targeting the intracellular filament protein in mature astrocytes. The pathogenesis is heterogeneous and poorly understood, with around 20%-34% of cases occurring as a paraneoplastic syndrome, most frequently associated with ovarian teratomas. It presents clinically as acute or subacute encephalomyelitis, and the diagnosis relies on imaging and detection of GFAP-Immunoglobulin (GFAP-IgG) in the CSF. Characteristic imaging findings include linear perivascular enhancement in the white matter extending in a radial pattern. Other imaging findings include periependymal enhancement, longitudinally extensive cord signal changes, intramedullary enhancement, optic neuritis, and papillitis. There is significant imaging overlap with other neuroinflammatory diseases like neuromyelitis optica spectrum disorder and lymphoproliferative conditions. GFAP astrocytopathy is characteristically responsive to steroids with, however, a significant rate of relapse. Currently, literature on this novel entity is limited with no established diagnostic criteria or standard treatment regimen. This comprehensive review explores the clinical, radiographic, and histopathologic aspects of GFAP astrocytopathy, shedding light on its complex nature and potential diagnostic challenges. The paper highlights the neuroimaging findings with a focus on differentiating GFAP astrocytopathy from other neuroinflammatory disorders.

Clinical characteristics of overlapping syndrome in patients with GFAP-IgG and MOG-IgG: a case series of 8 patients and literature review

OBJECTIVE

The overlapping syndrome of anti-GFAP and anti-MOG antibodies is extremely rare. This retrospective study reports 8 adult cases of the GFAP-MOG overlapping syndrome.

METHODS

We reviewed the clinical characteristics of 8 adult patients with the GFAP-MOG overlapping syndrome from Jan 2019 and Sep 2023 at the Third Affiliated Hospital, Sun Yat-sen University. Moreover, we searched the literature and included all case reports with this overlapping syndrome since 2018 on PubMed.

RESULTS

The predominant clinical syndrome was meningoencephalomyelitis (5/8), followed by meningoencephalitis (2/8), and myelitis (1/8). Five patients had a flu-like prodromal symptom or diarrhea. No neoplasms were found in these patients. Regarding brain MRI, T2-weighted/fluid-attenuated inversion recovery hyperintensities were in 7 patients and leptomeningeal enhancement was in 4 patients. However, only one patient had periventricular radial linear enhancement. Besides, two patients had large space-occupying lesions. For spinal MRI, T2-hyperintensities were observed in 4 patients, in which 3 patients had longitudinally extensive lesions. All patients were treated with immunotherapy, the median follow-up period was 18 months (range, 3-36 months). Three patients presented relapses during the follow-up, but all cases recovered to mRS scores ≤ 2 at last follow-up. In addition, we also reviewed 14 cases (including 7 adults and 7 children) with this overlapping syndrome by literature review.

CONCLUSION

Our findings provide data to understand the clinical features and prognosis of the GFAP-MOG overlapping syndrome. Recognizing this overlapping syndrome will expand our knowledge, allowing for better management of these patients.

Clinical and neuroimaging phenotypes of autoimmune glial fibrillary acidic protein astrocytopathy: A systematic review and meta-analysis

OBJECTIVE

This study was undertaken to provide a comprehensive review of neuroimaging characteristics and corresponding clinical phenotypes of autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A), a rare but severe neuroinflammatory disorder, to facilitate early diagnosis and appropriate treatment.

METHODS

A PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis)-conforming systematic review and meta-analysis was performed on all available data from January 2016 to June 2023. Clinical and neuroimaging phenotypes were extracted for both adult and paediatric forms.

RESULTS

A total of 93 studies with 681 cases (55% males; median age = 46, range = 1-103 years) were included. Of these, 13 studies with a total of 535 cases were eligible for the meta-analysis. Clinically, GFAP-A was often preceded by a viral prodromal state (45% of cases) and manifested as meningitis, encephalitis, and/or myelitis. The most common symptoms were headache, fever, and movement disturbances. Coexisting autoantibodies (45%) and neoplasms (18%) were relatively frequent. Corticosteroid treatment resulted in partial/complete remission in a majority of cases (83%). Neuroimaging often revealed T2/fluid-attenuated inversion recovery (FLAIR) hyperintensities (74%) as well as perivascular (45%) and/or leptomeningeal (30%) enhancement. Spinal cord abnormalities were also frequent (49%), most commonly manifesting as longitudinally extensive myelitis. There were 88 paediatric cases; they had less prominent neuroimaging findings with lower frequencies of both T2/FLAIR hyperintensities (38%) and contrast enhancement (19%).

CONCLUSIONS

This systematic review and meta-analysis provide high-level evidence for clinical and imaging phenotypes of GFAP-A, which will benefit the identification and clinical workup of suspected cases. Differential diagnostic cues to distinguish GFAP-A from common clinical and imaging mimics are provided as well as suitable magnetic resonance imaging protocol recommendations.

[Peripheral neuropathy associated with severe glial fibrillary acidic protein (GFAP) astrocytopathy: a case report]

A 44-year-old man was admitted due to a fever. He developed unconsciousness and respiratory failure, necessitating mechanical ventilation. After the administration of methylprednisolone and intravenous immunoglobulin for suspected autoimmune encephalitis, his consciousness and respiratory state improved. However, he exhibited pronounced tetraparalysis and impaired sensation below the neck. A spinal MRI revealed swelling of the entire spinal cord, indicating myelitis. Deep tendon reflexes were diminished in all extremities, and a nerve conduction study confirmed motor-dominant axonal polyneuropathy. Subsequently, he developed a fever and headache. Brain MRI demonstrated FLAIR hyperintensities in the basal ganglia and brain stem. CSF analysis for anti-glial fibrillary acidic protein (GFAP) antibody turned out positive, leading to the diagnosis of GFAP astrocytopathy. Although the steroid re-administration improved muscle strength in his upper limbs and reduced the range of diminished sensation, severe hemiparalysis remained. Severe GFAP astrocytopathy can be involved with polyneuropathy. Early detection and therapeutic intervention for this condition may lead to a better prognosis.

The discrimination between autoimmune glial fibrillary acidic protein astrocytopathy and tuberculous meningitis

OBJECTIVE

The differential diagnosis between autoimmune glial fibrillary acidic protein astrocytopathy (AGFAPA) mimicking tuberculous meningitis and tuberculous meningitis (TBM) remains challenging in clinical practice. This study aims to identify the clinical, laboratory parameters, and clinical score systems that may be helpful in differentiating AGFAPA from TBM.

METHOD

Overall 22 AGFAPA patients who were initially misdiagnosed as TBM (AGFAPA-TBM) and 30 confirmed TBM patients were included. The clinical, laboratory, imaging parameters, Thwaites systems, and Lancet consensus scoring systems (LCSS) of all patients were reviewed. Logistic regression was employed to establish a diagnostic formula to differentiate AGFAPA-TBM from TBM. The receiver operating characteristic (ROC) curve was applied to determine the best diagnostic critical point of the formula.

RESULTS

Urinary retention was more frequent in AGFAPA-TBM patients (72.7% vs 33.3%, p = 0.012). A significantly lower ratio of T-SPOT. TB was noted in AGFAPA-TBM patients (9.1% vs 82.1%, p < 0.001). We found the LCSS was able to differentiate AGFAPA-TBM from TBM (AUC value 0.918, 95% CI=0.897-0.924). Furthermore, we set up a new scoring system with three variables: urinary retention, T-SPOT. TB, and cerebral imaging criteria in LCSS. The proposed diagnostic score ranges from -8 to 2, and a score of ≥ 0 was suggestive of AGFAPA-TBM (AUC value 0.938, 95% CI=0.878-0.951).

CONCLUSIONS

This study is the first to evaluate the Thwaites system and LCSS in AGFAPA-TBM and TBM. We provide an alternative diagnostic formula to differentiate AGFAPA-TBM from TBM and suggest testing for GFAP antibodies to avoid misdiagnosis when this scoring system meets AGFAPA-TBM.