Fact-sheet: Intracranial hypotension
Updated on 08/04/2017 at 8:22 AM
View all RADEOS cases associated with this fact-sheet
Definition
Decrease in CSF pressure below 70 mm H2O due to a reduction in CSF volume.
Rostro-caudal displacement of the brain, resulting in painful traction on vascular structures, cranial nerves, and nerve roots.
Clinical features
Severe, orthostatic, pulsatile headache +/- neck stiffness.
CT
May be normal.
Subdural collections, usually bilateral
Effacement of the basal cisterns
Dural thickening
Collapsed appearance of the lateral ventricles
CT myelography: to search for the leak (contrast agent leakage)
MRI
On sagittal images:
Downward displacement of the brain, resulting in several findings:
- Effacement of the cisterns, particularly the prepontine cistern (pons flattened against the clivus)
- Sagging of the splenium of the corpus callosum
- Descent of the cerebellar tonsils through the foramen magnum
- Bulging pituitary gland within the sella turcica
- Distension of the venous sinuses, which appear engorged after injection, with closure of the angle between the vein of Galen and the internal cerebral veins
On axial images:
- Subdural collections, often bilateral (transudate)
- Anteroposterior elongation of the midbrain with closure of the interpeduncular angle
- Effacement of the basal cisterns
- Filling of the foramen magnum by the cerebellar tonsils
- Small size of the lateral ventricles, with a "slit-like" third ventricle appearance
In addition, T2 FLAIR hyperintensity of the dura mater, related to pachymeningeal thickening.
Intense, diffuse pachymeningeal enhancement.
Management
Further work-up to search for the leak with spinal MRI.
Blood patch.
Differential diagnosis
- Meningitis
- Meningeal metastases
- Chronic subdural hematomas