What are the causes of dural thickening?

Causes of Dural Thickening

Dural thickening has multiple etiologies including CSF hypovolemia (most common after dural puncture, occurring in 83% of cases), isolated cortical vein thrombosis, neoplastic disorders (65% of cases), pachymeningitis (infectious, autoimmune, or IgG4-related), and less commonly meningioma variants. 1, 2

Primary Vascular Causes

CSF Hypovolemia and Post-Dural Puncture

• Diffuse dural enhancement after dural puncture is present in 83% of patients with CSF hypovolemia and represents the most common iatrogenic cause 1, 2
• Pachymeningeal enhancement overlying the cerebral convexities is a hallmark imaging finding of intracranial hypotension from CSF leak 2
• The positional nature of headache (worsening upright, improving with recumbency within 20 seconds) is pathognomonic for this condition 2

Isolated Cortical Vein Thrombosis (ICVT)

• Ipsilateral (unilateral) dural thickening and enhancement may indicate ICVT, particularly when combined with persistent position-independent headache 1, 3
• This represents a critical diagnostic finding as ICVT occurs in approximately 6% of all intracranial venous thromboses 1
• The ipsilateral dural enhancement is thought to result from blood congestion and venous stasis 1, 3
• Pregnancy and puerperium are the highest risk factors (35% occurrence rate) 1
• Urgent anticoagulation therapy may be indicated to prevent intracranial hemorrhage and improve outcomes 3

Neoplastic Causes

Primary and Metastatic Disease

• Neoplastic disorders account for 65% of cases presenting with diffuse dural enhancement 1
• En-plaque meningioma can cause linear dural thickening and enhancement, sometimes with an unusual granulomatous reaction 4
• Dural-based lesions mimicking meningioma are common radiographic presentations, particularly in Rosai-Dorfman-Destombes disease 1
• Lymphoma and dural carcinomatosis must be considered in the differential diagnosis 5

Infectious Causes

Tuberculous Pachymeningitis

• Primary tuberculous pachymeningitis should be suspected in patients with prolonged headache and focal neurological signs when MRI shows dural thickening 6
• Presents with chronic headache over months to years, often with recurrent neurological abnormalities including optic neuritis, cranial nerve palsies, and hemisensory loss 6
• Strongly positive Mantoux test with caseating necrotizing granulomatous inflammation on dural histology confirms diagnosis 6
• Requires antituberculous medication with steroids for one year 6

Autoimmune and Inflammatory Causes

IgG4-Related Hypertrophic Sclerosing Pachymeningitis (IHSP)

• IHSP is a relatively novel entity that should be included in the differential diagnosis of dural thickening 5
• Associated with elevated serum IgG4 levels and characteristic histopathological findings 5
• The fibrosis accompanying IHSP may not respond to medical treatment with steroids and immunosuppressive agents 5
• Neurological deficits, seizures, spinal decompression needs, hydrocephalus, or brainstem compression necessitate early surgical intervention 5
• Continued vigilance is necessary as the disease may relapse long-term following surgical treatment 5

Idiopathic Hypertrophic Pachymeningitis

• Presents with headache with or without varied focal neurologic deficits 7
• MRI findings show dural enhancement in linear, nodular, or combined patterns 7
• Treatment with high-dose corticosteroids is typically recommended 7
• Disease commonly progresses with relapsing-remitting course requiring other immune modulators such as methotrexate, azathioprine, or cyclophosphamide 7
• Rare cases may show spontaneous resolution 8

Other Autoimmune Conditions

• Polychondritis with positive ANA can present with dural thickening 5
• Sarcoidosis and granulomatous polyangiitis should be considered 1

Rosai-Dorfman-Destombes Disease

• The most common radiographic appearance of intracranial RDD is a solitary extraaxial, homogeneously enhancing dural mass mimicking meningioma, although RDD can cause diffuse pachymeningitis 1
• Presents with headache, visual difficulty, motor or sensory abnormalities, and cranial nerve deficits evolving over weeks or months 1

Critical Diagnostic Pitfalls

Distinguishing Unilateral from Bilateral Enhancement

• Unilateral (ipsilateral) dural enhancement is highly suspicious for ICVT and warrants immediate venographic workup 1
• Bilateral diffuse enhancement is more consistent with CSF hypovolemia, pachymeningitis, or neoplastic processes 1, 2

Timing and Clinical Context

• Post-dural puncture headaches typically develop within 5 days of the procedure 2
• ICVT has a mean time between symptom appearance and diagnosis of 7 days 1
• Chronic presentations (months to years) suggest tuberculous pachymeningitis, IHSP, or idiopathic hypertrophic pachymeningitis 5, 7, 6

When Surgical Intervention is Required

• Neurological deficits, seizures, spinal cord compression, hydrocephalus, or brainstem compression necessitate early surgical intervention 5
• Biopsy may be required for definitive diagnosis when imaging and serological studies are inconclusive 5, 4, 6