Hypertrophic Pachymeningitis - Differential Diagnosis Framework



Pachymeningitis is a rare condition that causes areas of a layer of tissue that surrounds the spinal cord and brain (dura mater) to thicken and become inflamed. This thickening can cause different symptoms based on its location. Some people may have vision changes, headaches, or hearing loss.



Idiopathic



Infective

 • Neurosyphilis

 • CNS tuberculosis: tuberculous pachymeningitis

 • CNS cryptococcosis

 • Bacterial meningitis



Inflammatory

 • IgG4-related hypertrophic pachymeningitis

 • GPA

 • Neurosarcoidosis

 • Polyarteritis nodosa

 • Rheumatoid arthritis

 • Relapsing polychondritis

 • Behçet disease



Other

 • Rosai-Dorfman disease

 • Hemodialysis

 • Mucopolysaccharidoses



Tumors

 • Dural metastases



CT Imaging:

 • Subdural collection

 • Acquired tonsillar ectopia

 • Dural venous sinus distention

 • Layer cake skull: diffuse layered calvarial hyperostosis seen in 14-32% of patients



MRI Imaging:

 • The most common qualitative finding is pachymeningeal thickening and enhancement

 • dural venous engorgement

 • tonsillar herniation

 • Subdural collection



Changes in Perfusion/Pressure

 • Intracranial hypotension

	- Primary: spontaneous intracranial hypotension

	- Secondary: iatrogenic (lumbar puncture or surgery)

	- Frontotemporal brain sagging syndrome (FBSS)

	- type 1: dural tear

	- type 2: lateral leak

	- type 3: CSF-venous fistula

	- type 4: distal nerve root sleeve leaks

 • Cerebral venous thrombosis



CT

 • Subdural collection

 • Acquired tonsillar ectopia

 • Dural venous sinus distention

 • Layer cake skull: diffuse layered calvarial hyperostosis seen in 14-32% of patients



MRI

 • The most common qualitative finding is pachymeningeal thickening and enhancement

 • dural venous engorgement

 • tonsillar herniation

 • Subdural collection



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