Inferior descent of the cerebellar tonsils by approximately 12 mm bilaterally, with anteroinferior displacement of the midbrain and pons and effacement of the prepontine cistern. Reduced mamillopontine distance.
There is crowding of the suprasellar cistern, with the optic chiasm draped over the pituitary gland, which is plump and protrudes above the sella. No focal pituitary lesions are demonstrated, and the posterior pituitary bright spot is preserved.
Post-contrast images demonstrate diffuse, smooth enhancement of the dura, with no nodularity or focal mass lesion. The dural venous sinuses are engorged.
Conclusion:
The findings are highly suggestive of spontaneous intracranial hypotension and a spinal CSF leak or CSF-venous fistula should be sought.