neurologic disorders
Lumbar Puncture (Spinal Tap)
Introduction
Lumbar puncture is used to do the following: Evaluate intracranial pressure and cerebrospinal fluid (CSF) composition (see table) Therapeutically reduce intracranial pressure (eg, Idiopathic Intracranial Hypertension ) Administer intrathecal drugs or a radiopaque contrast agent for Myelography None Relative contraindicationsinclude Infection at the puncture site Bleeding diathesis Increased intracranial pressure due to an intracranial mass lesion, obstructed CSF outflow (eg, due to aqueductal stenosis or Chiari I malformation), or spinal cord CSF blockage (eg, due to tumor cord compression) If papilledema or focal neurologic deficits are present, CT or MRI should be done before lumbar puncture to rule out the presence of a mass that could precipitate transtentorial or cerebellar Brain Herniation . 