My headache does not get better when I lie down: spontaneous intracranial hypotension complicated by venous thrombosis.

Two patients with spontaneous intracranial hypotension (SIH) subsequently developed cerebral venous thrombosis (CVT) when their headache lost its distinctive orthostatic characteristic. In addition to typical MRI features of tonsillar descent, subdural fluid collections, and diffuse pachymeningeal enhancement, hyperintense thrombi were detected in the dural sinuses, and filling defects on magnetic resonance venography. Knowledge of the typical neuroimaging features of SIH and CVT and change in headache characteristics are important for prompt diagnosis and treatment.