Intracranial hypotension.

Intracranial hypotension (IH) is present when cerebrospinal fluid (CSF) pressure is 60mm H2O or lower and there has been no previous dural puncture. IH is more common in women than in men (3:1). Orthostatic headache is the cardinal symptom. Visual, auditory, and other symptoms occur. 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 (probably related to an occult dural leak) or secondary to many causes that include lumbar puncture, trauma, pneumonectomy, diabetic coma, and uremia. Patients with postural headache should undergo neuroimaging prior to lumbar puncture. Radionuclide cisternography is the most sensitive means of demonstrating a CSF fistula. Severe, intractable headache associated with IH may respond to intravenous of oral caffeine. An epidural blood patch and epidural infusion of normal saline are treatment measures for symptoms of IH that follow lumbar puncture.