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Pachymeningeal enhancement refers to contrast enhancement of the dura mater (outer meningeal layer) on post-contrast MRI, typically appearing as diffuse, smooth, linear thickening along the inner table of skull.
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https://www.youtube.com/watch?v=g0XaAE9yfTQ
| Cause | Mechanism |
|---|---|
| Intracranial Hypotension | |
| (most important) | • Due to CSF volume depletion |
| • Mechanism: venous dilation and dural hyperemia | |
| • Associated with: Brain sagging, subdural collections | |
| • Classic entity: ‣ | |
| Post-procedural / Iatrogenic | • Lumbar puncture |
| • Postoperative state | |
| • Transient and self-limited | |
| Inflammatory / Infectious | • Meningitis (usually leptomeningeal predominance but dura may enhance) |
| • Neurosarcoidosis | |
| • Tuberculosis (chronic pachymeningitis) | |
| Inflammatory / Infectious | • Meningitis (usually leptomeningeal predominance but dura may enhance) |
| • Neurosarcoidosis | |
| • Tuberculosis (chronic pachymeningitis) | |
| Neoplastic | • Dural metastases |
| • Meningioma en plaque | |
| • Lymphoma | |
| Other | • Intracranial hypotension secondary to shunts |
| • Idiopathic hypertrophic pachymeningitis |
MRI Features:
Pachymeningeal vs Leptomeningeal Enhancement
| Feature | Pachymeningeal | Leptomeningeal |
|---|---|---|
| Layer | Dura | Pia + arachnoid |
| Pattern | Smooth, linear | Gyriform, sulcal |
| Distribution | Along skull, falx, tentorium | Follows sulci, cisterns |
| Common cause | Intracranial hypotension | Infection, carcinomatosis |
Key Diagnostic Clues
| Etiology | Imaging features |
|---|---|
| Intracranial hypotension | • Diffuse smooth dural enhancement |
| • Associated brain sagging | |
| • Subdural collections | |
| • Venous sinus engorgement | |
| Neoplastic/inflammatory | • Nodular or irregular thickening |
| • Focal mass-like enhancement | |
| • Adjacent bone involvement |