Neuromyelitis Optica Presenting as Infectious Meningoencephalitis: Case Report and Literature Review

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.

Comparison of clinical and radiological characteristics in autoimmune GFAP astrocytopathy, MOGAD and AQP4-IgG+ NMOSD mimicking intracranial infection as the initial manifestation

OBJECTIVE

Several autoimmune CNS inflammatory diseases, including autoimmune glial fibrillary acidic protein astrocytopathy (A-GFAP-A), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and aquaporin-4-immunoglobulin-G-positive neuromyelitis optica spectrum disorders (AQP4-IgG⁺NMOSD) often presented initially with similar symptoms mimicking intracranial infection, are not easy to be differentiated during early-onset lacking the detection of autoantibody.

METHODS

In our single-center cohorts, those patients mimicking intracranial infection as initial symptoms, including 9 with A-GFAP-A, 17 with MOGAD and 11 with AQP4-IgG⁺NMOSD, were retrospectively included. The autoantibodies were detected by cell-based assays. The clinical, immunological and radiological characteristics were summarized.

RESULTS

In the cohort, tremor and positive Kernig's sign were predominated in A-GFAP-A (44.4% and 77.8%, respectively) over MOGAD (5.9%, p = 0.034; 29.4%, p = 0.038) and AQP4-IgG⁺NMOSD (0, p = 0.026; 18.2%, p = 0.022). Ten patients (A-GFAP-A, 4; MOGAD, 5; AQP4-IgG⁺NMOSD, 1) were initially misdiagnosed as tubercular or viral meningoencephalitis, however, resistant to empiric anti-tuberculosis or anti-viral treatment, and finally were in partial or complete remission with the immunotherapy when adjusted treatments. On cerebrospinal fluid (CSF) examination, white blood cell counts in CSF was higher in A-GFAP-A cohort (median, 90×10⁶/L [IQR, 41-209]) compared to AQP4-IgG⁺ NMOSD (median, 6 × 10⁶/L [IQR, 1-10], p = 0.018). Importantly, the higher increase in CSF protein (1319 mg/L [IQR, 1035-1519]), lactate dehydrogenase (LDH, 53.9 ± 37.2 U/L), lactic acid (3.50 ± 0.88 mmol/L), IgG (130.9 ± 60.4 mg/L), IgM (8.6 ± 6.1 mg/L) and IgA (23.0 ± 11.4 mg/L) levels in A-GFAP-A was found compared to MOGAD (CSF protein: 441 mg/L [IQR, 330-776], p = 0.004; LDH: 53.9  ±  37.2 U/L, p = 0.005; lactic acid: 2.15 ± 0.62 mmol/L, p = 0.001; IgG: 77.9 ± 71.3 mg/L, p = 0.018; IgM, 2.7 ± 2.9 mg/L, p = 0.015) and AQP4-IgG⁺ NMOSD (CSF protein: 386 mg/L [IQR, 369-453], p = 0.002; LDH: 23.7 ± 11.0 U/L, p = 0.048; lactic acid: 2.40  ±  0.66 mmol/L, p = 0.040; IgG, 53.2 ± 30.3 mg/L, p = 0.015; IgM, 2.1 ± 3.9 mg/L, p = 0.004; IgA, 5.2 ± 5.0 mg/L, p < 0.001). Of Note, smaller (< 2 cm), symmetrical lesions in ganglia and thalamus (5/8, 62.5%) were showed in over half of the A-GFAP-A patients (5/8, 62.5%), but never in MOGAD (0%, p = 0.001) and AQP4-IgG⁺NMOSD (0%, p = 0.026). In addition, diffuse meningeal enhancement was more common in A-GFAP-A (8, 88.9%) compared to MOGAD (5, 29.4%, p = 0.011) and AQP4-IgG⁺NMOSD (1/6, 16.7%, p = 0.011), respectively. Acute disseminated encephalomyelitis (ADEM) -like lesions occurred more frequently in MOGAD (6/16, 37.5%) but never in A-GFAP-A and AQP4-IgG⁺NMOSD (p = 0.02).

CONCLUSION

Our study demonstrates that several distinct features including the symptom of tremor, higher CSF immunological profiles, bilateral symmetrical lesions in ganglia, and diffuse meningeal enhancement are frequent in A-GFAP-A, whereas ADEM-like lesions seem to occur mainly in MOGAD. These signs provide crucial clinical implications in differential diagnosis for those mimicking intracranial infection as initial symptoms. Clinicians should consider the possibility of these autoimmune CNS inflammatory diseases masquerading as intracranial infection.