INTRACRANIAL HYPOTENSION

Intracranial hypotension (IH) is present when cerebrospinal fluid (CSF ) pressure is 60 mm H2O or lower and there has been no previous dural puncture. IH is more common in women than in men (3:1), Orthostatic he adache is the cardinal symptom. Visual, auditory, and other symptoms o ccur. Postulated mechanisms include sagging of the brain, dilation of intracranial veins, and activation of adenosine receptors. Examination may disclose visual field defects. The condition may be primary (prob ably related to an occult dural leak) or secondary to many causes that include lumbar puncture, trauma, pneumonectomy, diabetic coma, and ur emia. Patients with postural headache should undergo neuroimaging prio r to lumbar puncture. Radionuclide cisternography is the most sensitiv e means of demonstrating a CSF fistula. Severe, intractable headache a ssociated with IH may respond to intravenous or oral caffeine. An epid ural blood patch and epidural infusion of normal saline are treatment measures for symptoms of IH that follow lumbar puncture.