July 15, 2021
A 41-year-old woman with acute confusional syndrome and no significant medical history
Sarcoid Meningoencephalitis
- Background:
- Sarcoidosis is an idiopathic multisystem granulomatous disease that may affect the central nervous system.
- Neurosarcoidosis may be the first presentation of disease in up to 50% of cases and may herald systemic sarcoidosis.
- Leptomeningeal involvement is the most frequent manifestation, localized preferentially at the base of the skull, the hypothalamic-pituitary axis, and the optic chiasm. Diffuse involvement is relatively rare and poses a diagnostic challenge.
- Clinical Presentation:
- Clinical manifestations are nonspecific, dominated by signs of involvement of cranial nerves, headaches, seizures, and impaired consciousness.
- Vascular involvement can lead to cerebral ischemia.
- Key Diagnostic Features:
- MRI shows leptomeningitis and/or pachymeningitis with micronodular enhancement after gadolinium injection.
- Dural involvement may manifest as extra-axial masses that show intermediate T1 signal and T2 hyposignal, as well as significant enhancement after gadolinium.
- Associated encephalitis appears as parenchymal T2 and FLAIR hypersignal.
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Secondary hydrocephalus may be present.
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Pathologic confirmation of systemic sarcoidosis is essential to prove the diagnosis. (Chest abnormalities are found in up to 90% of patients.)
- Differential Diagnoses:
- Infectious meningitis: Presence of clinical signs of infection, corresponding cerebrospinal fluid abnormalities, imaging may demonstrate abscesses or empyema
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Carcinomatous meningitis: Known primary tumor, corresponding abnormal cytology on cerebrospinal fluid analysis
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Meningioma (may simulate dural involvement of neurosarcoidosis): Usually solitary extra-axial mass with local dural tail
- IgG4-related sclerosing meningitis: Diffuse thickening of the dura mater that is typically hypointense on T2-weighted images with enhancement after contrast
- Rosai-Dorfman disease: Dural-based extra-axial masses that are generally hypo- to isointense on T1-weighted imaging, hypointense on T2, and enhance after gadolinium; may have adjacent bony erosion; may have associated painless cervical lymphadenopathy
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Treatment:
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Corticosteroid and immunosuppressive therapy
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MRI is used to monitor the effectiveness of treatment.
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