Editing Cerebrospinal fluid (section)

===Lumbar puncture===
[[Image:4 vials of human cerebrospinal fluid.jpg|thumb|Vials containing human cerebrospinal fluid]]
{{Main|Lumbar puncture}}
CSF can be tested for the diagnosis of a variety of [[neurological disease]]s, usually obtained by a procedure called lumbar puncture.<ref name=AMP2003>{{cite journal | vauthors = Seehusen DA, Reeves MM, Fomin DA | title = Cerebrospinal fluid analysis | journal = American Family Physician | volume = 68 | issue = 6 | pages = 1103–8 | date = September 2003 | pmid = 14524396 | url = http://www.aafp.org/afp/20030915/1103.html | access-date = 2009-03-05 | archive-date = 2008-05-15 | archive-url = https://web.archive.org/web/20080515204056/http://www.aafp.org/afp/20030915/1103.html | url-status = dead }}</ref> Lumbar puncture is carried out under sterile conditions by inserting a needle into the subarachnoid space, usually between the third and fourth [[lumbar vertebrae]]. CSF is extracted through the needle, and tested.<ref name=DAVIDSONS2010 /> About one third of people experience a headache after lumbar puncture,<ref name=DAVIDSONS2010 /> and pain or discomfort at the needle entry site is common. Rarer complications may include bruising, [[meningitis]] or ongoing post lumbar-puncture leakage of CSF.<ref name=WRIGHT2012/>

Testing often includes observing the colour of the fluid, measuring CSF pressure, and counting and identifying [[white blood cell|white]] and [[red blood cell]]s within the fluid; measuring protein and glucose levels; and [[Microbiological culture|culturing]] the fluid.<ref name=DAVIDSONS2010 /><ref name="AMP2003" /> The presence of red blood cells and [[xanthochromia]] may indicate [[subarachnoid hemorrhage]]; whereas [[central nervous system]] infections such as [[meningitis]], may be indicated by elevated white blood cell levels.<ref name=AMP2003/> A CSF culture may yield the [[microorganism]] that has caused the infection,<ref name="DAVIDSONS2010"/> or [[Polymerase chain reaction|PCR]] may be used to identify a viral cause.<ref name="AMP2003" /> Investigations to the total type and nature of proteins reveal point to specific diseases, including [[multiple sclerosis]], [[paraneoplastic syndrome]]s, [[systemic lupus erythematosus]], [[neurosarcoidosis]], [[cerebral angiitis]];<ref name="WRIGHT2012" /> and specific [[antibodies]] such as [[aquaporin-4]] may be tested for to assist in the diagnosis of [[autoimmune]] conditions.<ref name=WRIGHT2012/> A lumbar puncture that drains CSF may also be used as part of treatment for some conditions, including [[idiopathic intracranial hypertension]] and [[normal pressure hydrocephalus]].<ref name=WRIGHT2012/>

Lumbar puncture can also be performed to measure the [[intracranial pressure]], which might be increased in certain types of [[hydrocephalus]]. However, a lumbar puncture should never be performed if increased intracranial pressure is suspected due to certain situations such as a tumour, because it can lead to fatal [[brain herniation]].<ref name=DAVIDSONS2010 />