Lumbar Puncture (Spinal Tap) By Michael C Levin, MD, College of Medicine, University of Saskatchewan Reviewed / Revised Jul 2021 | Modified Sep 2022 View Patient Education Topic Resources CSF Protein Concentration... CSF WBC Correction in Blood... Lumbar puncture Cerebrospinal Fluid Abnormalities... Lumbar Puncture Lumbar puncture is used to do the following: Evaluate intracranial pressure and cerebrospinal fluid (CSF) composition (see table Cerebrospinal Fluid Abnormalities in Various Disorders) Therapeutically reduce intracranial pressure (eg, idiopathic intracranial hypertension) Administer intrathecal drugs or a radiopaque contrast agent for myelography Lumbar Puncture VIDEO Table Relative contraindications include 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 presence of a mass that could precipitate transtentorial or cerebellar herniation.