Magnetic resonance imaging findings of intracranial hypotension syndrome and the pathophysiological mechanism

Objective To evaluate magnetic resonance imaging (MRI) findings of intracranial hypotension syndrome (IHS) and the pathophysiological mechanism.Methods Precontrast and postcontrast MRI was performed in 9 cases with IHS.MR venography (MRV) was completed in 5 cases and 3 cases spinal magnetic resonance was performed.The thickness,morphology,distribution,pattern of meningeal enhancement and subdural fluid collection,the descent of the brain,cerebral veins and appearance of the collateral venous sinuses were evaluated.Results Clearly orthostatic headache and lower cerebrospinal fluid (CSF) pressure (0-60 mm H2O) were seen in all patients.Diffuse,continuous,homogeneous linear pachymengieal enhancement were present in all patients on MRI.Downward displacement of the brain and small cerebral ventricle in 5 cases.Enlargement of pituitary gland in 3 cases and subdural fluid collection in 3 cases.Dilation of venous sinuses and cerebral veins were observed in 3 cases on MRV.Distended epidural veins of spine were observed in 2 cases.The thickness of dura,the sagging of brain,subdural fluid collection and dilation of venous sinuses were evident in patients with very low CSF.Conclusions Diffuse pachymengieal thickening and enhancement are characteristic MRI manifestation of IHS.The low CSF capacity is the pathophysiological basis for MRI imaging.