Defination:
Lumber puncture (or LP, and colloquially known as a spinal tap) is a diagnostic and at times therapeutic procedure that is performed in order to collect a sample of cerebrospinal fluid (CSF) for biochemical, microbiological, and cytological analysis, or very rarely as a treatment ("therapeutic lumbar puncture") to relieve increased intracranial pressure.
indication
to collect cerebrospinal fluid in a case of suspected meningitis Young infants commonly require lumbar puncture as a part of the routine workup for fever without a source, as they have a much higher risk of meningitis than older persons and do not reliably show signs of meningeal irritation
to inject medications into the cerebrospinal fluid ("intrathecally"), particularly for spinal anesthesia or chemotherapy to detect the presence of malignant cells in the CSF, as in carcinomatous meningitis or medulloblastoma.
Contraindications
Idiopathic (unidentified cause) increased intracranial pressure (ICP
± Rationale: lumbar puncture in the presence of increased ICP may cause uncal herniation ± Exception: therapeutic use of lumbar puncture to reduce ICP
± Precaution
CT brain is advocated by some, especially in the following situations
± ± ± ±
Age >65 Reduced GCS or conscious stat Recent history of seizure Focal neurological signs