Absent headache despite CSF volume depletion (intracranial hypotension).

CSF volume depletions, whether from leak or shunt overdrainage, typically cause low CSF opening pressures, orthostatic headaches, and diffuse pachymeningeal gadolinium enhancement on MRI. The authors report three patients-two with overdraining CSF shunts and one with proven CSF leak-with the typical pachymeningeal enhancement but without headaches. In CSF leaks and CSF shunt overdrainage, like MRI abnormalities and CSF alterations, the clinical features also show considerable variability. The independent variable remains the CSF volume depletion.