Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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April 20, 2023
Rheumatoid Meningitis
- Background:
- Rheumatoid meningitis (RM) is a rare extra-articular complication of rheumatoid arthritis (RA) and has been commonly associated with long-standing active disease.
- This neurologic complication can affect the pachymeninges, leptomeninges, or both. Some reports have also described cases of patients with parenchymal involvement.
- Clinical Presentation:
- RM can manifest as meningitis, resulting in focal neurologic deficits, strokelike episodes, headache, seizures, and/or encephalopathy.
- No diagnostic criteria have been established, and RM has been classically described as a diagnosis of exclusion.
- Because of its rarity, there is a shortage of data regarding the epidemiology of RM, but in diverse studies, men and women seem to be equally affected.
- Mortality from RM has previously been reported to be as high as 60%, despite treatment.
- Key Diagnostic Features:
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MRI has been the predominant neuroimaging modality of choice for the investigation of this disease. The expected MRI findings include leptomeningeal or pachymeningeal thickening or contrast enhancement and FLAIR signal hyperintensities. Sulcal hyperintensities have been described in several series as one of the key imaging features for the diagnosis, as seen in the patient in our case.
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There are 4 types of image patterns on MRI:
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Pure pachymeningeal involvement: Dural thickening
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Pure leptomeningeal involvement: Sulcal FLAIR hyperintensity and/or gadolinium enhancement
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Pure parenchymal involvement: Parenchymal FLAIR hyperintensity and/or restricted diffusion and/or gadolinium enhancement
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Mixed: Any combination of types 1, 2, and 3
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The diagnosis was made based on the history of rheumatoid arthritis, clinical symptoms, and MRI findings; no biopsy was performed.
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- Differential Diagnoses:
- Infectious meningitis: Leptomeningeal enhancement only. The lesions on DWI match the lesions on FLAIR imaging in patients with subdural empyema, contrary to what is seen in RM, where a mismatch between DWI and FLAIR lesions can be detected.
- Subarachnoid hemorrhage: There is no prominent leptomeningeal enhancement.
- Subarachnoid FLAIR hyperintensity artifact: The hyperintensities appear only on FLAIR sequence.
- Treatment:
- Traditionally, pulse steroid administration with methylprednisolone has been considered the first-line treatment for RM, and plenty of authors have reported excellent clinical response to this treatment. The best steroid regimen has remained unclear owing to the heterogeneity of the regimens used that have led to favorable outcomes. Other immunomodulators and immunosuppressants have been described as therapeutic options, such as cyclophosphamide, hydroxychloroquine, zidovudine, methotrexate, etanercept, mycophenolate, and adalimumab.
- The patient received a pulse of steroids. After a week of treatment, the gait disturbance markedly improved.
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