Intracranial Hypotension and Diffuse Dural Enhancement

Intracranial hypotension refers to decreased CSF pressure leading to a headache (usually orthostatic). The four main imaging findings are:

1. downward displacement of the midbrain
2. diffuse, smooth dural enhancement
3. distended dural sinuses
4. subdural hematoma or hygroma

Absence of one of these signs does not preclude the diagnosis.

The dural enhancement in intracranial hypotension is pachymeningeal (dura-arachnoid) and is seen along the inner table of the skull, as opposed to leptomeningeal enhancement (arachnoid-pia) which is seen on the surface of the brain.

The differential for dural enhancement includes:

1. meningitis - leptomeningeal enhancement
2. dural metastases - scattered, "bumpy" enhancement
3. granulomatous disease (sarcoid, TB) - nodular enhancement
4. meningioma with focal enhancement of the dural tail
5. postoperative changes - transient

REFERENCES

Smirniotopoulous JG, Murphy FM, Rushing EJ, et al. Patterns of contrast enhancement in the brain and meninges. Radiographics 2007;27:525-51.