From the Guidelines
Pachymeningitis is a rare inflammatory condition affecting the dura mater, and its evaluation should prioritize identifying the underlying cause, which can include infections, autoimmune disorders, malignancies, or idiopathic hypertrophic cranial pachymeningitis. The causes of pachymeningitis are diverse and can be attributed to various factors, including infections (bacterial, fungal, viral, or parasitic), autoimmune disorders (such as rheumatoid arthritis, IgG4-related disease, granulomatosis with polyangiitis), malignancies, and idiopathic hypertrophic cranial pachymeningitis where no specific cause is identified 1.
Key Considerations
- Evaluation begins with a thorough clinical assessment focusing on neurological symptoms like headaches, cranial nerve palsies, and visual disturbances.
- Diagnostic workup includes MRI with gadolinium enhancement, which typically shows thickening and enhancement of the dura mater.
- Cerebrospinal fluid analysis is essential to check for elevated protein, pleocytosis, and to rule out infections, as indicated by the presence of meningism, which is characterized by symptoms of headache, neck stiffness, and photophobia often associated with meningitis 1.
- Blood tests should include inflammatory markers, autoimmune panels, and specific tests for suspected underlying conditions.
Diagnostic Approach
- Meningeal biopsy may be necessary for definitive diagnosis, especially to rule out malignancy.
- The likelihood of any specific aetiology depends on a range of factors, and in many cases (34%-74%), no pathogen is identified 1.
Treatment
- Treatment depends on the underlying cause - antimicrobials for infections, immunosuppressants (corticosteroids, cyclophosphamide, rituximab, or methotrexate) for autoimmune causes, and appropriate oncologic therapy for malignancy-related cases.
- Early diagnosis and treatment are crucial to prevent permanent neurological damage, considering the high mortality rate of community-acquired bacterial meningitis, approximately 20% for all causes and up to 30% in pneumococcal meningitis, increasing with age 1.
From the Research
Causes of Pachymeningitis
- Pachymeningitis is a fibrosing and inflammatory process that involves the dura mater, with etiologies including infectious (syphilis, tuberculosis, etc.) or inflammatory (sarcoidosis, granulomatosis with polyangiitis, IgG4-related disease, idiopathic) 2
- The etiological investigation of pachymeningitis can be challenging, but prompt identification provides a treatment window, potentially leading to a reversal of symptoms 3
- Tuberculosis is a common cause of pachymeningitis, detected in 33.3% of cases in one study 3
- Idiopathic origin is also a possible cause, identified in 16.7% of patients in one study 3
- Pachymeningitis can also occur as a neuroinflammatory complication of Crohn's disease and relapsing polychondritis, although this is exceptionally rare 4
Evaluation of Pachymeningitis
- MRI is the reference examination for diagnosing pachymeningitis, allowing for early diagnosis, assessment of extent and importance, detection of possible complications, and suggestion of etiology 2, 3
- Cerebrospinal fluid study can unveil an inflammatory fluid characterized by a lymphocytic predominance and hyperproteinorrhea, noted in 50% of patients in one study 3
- Histopathological analysis of a stereotactic biopsy can be non-diagnostic, and a dural biopsy may be necessary in some cases 3
- Clinical symptoms of pachymeningitis can include headache, multiple cranial neuropathy, and impaired vision, with headache being the most common symptom (93.3%) in one study 5
- Neuroimaging findings can include diffuse or focal enhancement of the dura mater, especially in the tentorium cerebellum (80%) 5
Treatment of Pachymeningitis
- Corticosteroids are the main treatment for pachymeningitis, with high-dose and low-dose corticosteroids reducing headache and dural enhancement during the acute phase 2, 5
- Immunosuppressive drugs or rituximab may be used in some cases, although their use is yet to be determined and probably adapted to each etiology 2
- Mycophenolate mofetil and cyclophosphamide may be effective for preventing relapses in patients with idiopathic hypertrophic pachymeningitis 5
- Adalimumab and prednisone can be effective in treating pachymeningitis associated with Crohn's disease and relapsing polychondritis 4