We studied a patient with spontaneous intracranial hypotension whose gadolinium-enhanced MRI revealed an extraordinary degree of dural enhancement and striking displacement of the optic chiasm, flattening of the pons, and downward displacement of the cerebellar tonsils. These changes were reversed when a CSF leak at the site of a T12-L1 arachnoid cyst was closed following an epidural blood patch. Such diffuse meningeal enhancement results from the dural venous dilatation that accompanies a reduced CSF volume, a consequence of the Monro-Kellie rule.