<prompt> Answer this question truthfullyWhat diagnostic test should be done before performing a lumbar puncture for patients with idiopathic intracranial hypertension, and why?  <response>: <reason> When performing a lumbar puncture for patients with idiopathic intracranial hypertension, what diagnostic test should be done before and why? An MRIMRV should be done to rule out cerebral venous thrombosis. 