====== Cerebrospinal fluid in subarachnoid hemorrhage ====== If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the [[lumbar puncture]] [[LP]]. In these instances the LP is looking for two elements that raise the concern for SAH: 1) [[RBC]]s; and 2) [[xanthochromia]] (bilirubin in cerebrospinal fluid [CSF]). ---- Given the [[sensitivity]] of the CT discussed above, [[shared decision-making]] should be conducted with regard to LP. In particular, with a sensitivity of nearly 99% for an adequate study, if completed within six hours, and meeting the criteria outlined above (Dubosh), patients should be made aware of the low diagnostic utility of LP if completed after a CT ((Dubosh NM, Bellolio MF, Rabinstein AA, Edlow JA. Sensitivity of Early Brain Computed Tomography to Exclude Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis. Stroke. 2016 Mar;47(3):750-5. doi: 10.1161/STROKEAHA.115.011386. Epub 2016 Jan 21. Review. PubMed PMID: 26797666. )). ---- Despite improved computed tomography scanning technology, cerebrospinal fluid xanthochromia interpretation aids in the definitive diagnosis of [[subarachnoid haemorrhage]]. When requested appropriately cerebrospinal fluid xanthochromia analysis remains a vital service as results impact on clinical decision making, especially when computed tomography scan results are equivocal and is also important in later presenting patients when computed tomography accuracy decreases ((Goyale A, O'Shea J, Marsden J, Keep J, Vincent RP. Analysis of cerebrospinal fluid for xanthochromia versus modern computed tomography scanners in the diagnosis of subarachnoid haemorrhage: experience at a tertiary trauma referral centre. Ann Clin Biochem. 2016 Jan;53(Pt 1):150-4. doi: 10.1177/0004563215579454. Epub 2015 Mar 12. PubMed PMID: 25766384.)). A guide to define a subpopulation of patients who would benefit from a lumbar puncture after an NHCT would be desirable ((Gangloff A, Nadeau L, Perry JJ, Baril P, Émond M. Ruptured aneurysmal subarachnoid hemorrhage in the emergency department: Clinical outcome of patients having a lumbar puncture for red blood cell count, visual and spectrophotometric xanthochromia after a negative computed tomography. Clin Biochem. 2015 Jul;48(10-11):634-9. doi: 10.1016/j.clinbiochem.2015.03.011. Epub 2015 Mar 26. PubMed PMID: 25819839. )). No xanthochromia and red blood cell count <2000 × 10(6)/L reasonably excludes the diagnosis of aneurysmal subarachnoid hemorrhage. Most patients with acute headache who meet this cut off will need no further investigations and aneurysmal subarachnoid hemorrhage can be excluded as a cause of their headache ((Perry JJ, Alyahya B, Sivilotti ML, Bullard MJ, Émond M, Sutherland J, Worster A, Hohl C, Lee JS, Eisenhauer MA, Pauls M, Lesiuk H, Wells GA, Stiell IG. Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study. BMJ. 2015 Feb 18;350:h568. doi: 10.1136/bmj.h568. PubMed PMID: 25694274; PubMed Central PMCID: PMC4353280. )). Patients without a [[subarachnoid hemorrhage]] (SAH) on brain CT scan (CT-negative), but a [[lumbar puncture]] (LP)-proven SAH, are a challenging patient category. The optimal diagnostic approach is still a matter of debate. Also, there is little knowledge on the probability of finding an underlying vascular lesion. A guide to define a subpopulation of patients who would benefit from a lumbar puncture after an negative CT would be desirable ((Gangloff A, Nadeau L, Perry JJ, Baril P, Émond M. Ruptured aneurysmal subarachnoid hemorrhage in the emergency department: Clinical outcome of patients having a lumbar puncture for red blood cell count, visual and spectrophotometric xanthochromia after a negative computed tomography. Clin Biochem. 2015 Jul;48(10-11):634-9. doi: 10.1016/j.clinbiochem.2015.03.011. Epub 2015 Mar 26. PubMed PMID: 25819839. )). The decision to follow a negative CT with an LP in all cases needs careful consideration, as CSF results may only rarely confer therapeutic benefit to patients suspected of SAH ((Cooper JG, Smith B, Hassan TB. A retrospective review of sudden onset severe headache and subarachnoid haemorrhage on the clinical decision unit: looking for a needle in a haystack? Eur J Emerg Med. 2015 Apr 2. [Epub ahead of print] PubMed PMID: 25851332. )). Results support a change of practice wherein a lumbar puncture can be withheld in patients with a head CT scan performed <6 hours after headache onset and reported negative for the presence of SAH by a staff radiologist in the described nonacademic setting ((Blok KM, Rinkel GJ, Majoie CB, Hendrikse J, Braaksma M, Tijssen CC, Wong YY, Hofmeijer J, Extercatte J, Kerklaan B, Schreuder TH, ten Holter S, Verheul F, Harlaar L, Pruissen DM, Kwa VI, Brouwers PJ, Remmers MJ, Schonewille WJ, Kruyt ND, Vergouwen MD. CT within 6 hours of headache onset to rule out subarachnoid hemorrhage in nonacademic hospitals. Neurology. 2015 May 12;84(19):1927-32. doi: 10.1212/WNL.0000000000001562. Epub 2015 Apr 10. PubMed PMID: 25862794.)). For Martin et al. LP has a high diagnostic yield, eliminating the need for neurosurgical opinion or investigation in almost 90% of cases. The test is both cost and time efficient and subjects only a small number of patients to the radiation and contrast risks of angiography ((Martin SC, Teo MK, Young AM, Godber IM, Mandalia SS, St George EJ, McGregor C. Defending a traditional practice in the modern era: The use of lumbar puncture in the investigation of subarachnoid haemorrhage. Br J Neurosurg. 2015 Sep 16:1-5. [Epub ahead of print] PubMed PMID: 26373397. )). ====Findings in cerebrospinal fluid==== ↑ [[opening pressure]] (OP) (cm H2O). Appearance bloody; supernatant xanthochromic. Cells (per mm3) early: ↑RBCs. Protein (mg%) 50–400 Glucose (% serum) nl or ↓ Miscellaneous RBCs disappear in 2 wks, xanthochromia may persist for weeks. ---- No [[xanthochromia]] and [[red blood cell count]] <2000 × 10(6)/L reasonably excludes the diagnosis of [[aneurysmal subarachnoid hemorrhage]]. Most patients with acute headache who meet this cut off will need no further investigations and aneurysmal subarachnoid hemorrhage can be excluded as a cause of their headache ((Perry JJ, Alyahya B, Sivilotti ML, Bullard MJ, Émond M, Sutherland J, Worster A, Hohl C, Lee JS, Eisenhauer MA, Pauls M, Lesiuk H, Wells GA, Stiell IG. Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study. BMJ. 2015 Feb 18;350:h568. doi: 10.1136/bmj.h568. PubMed PMID: 25694274; PubMed Central PMCID: PMC4353280.)) All patients in a case series with aSAH had either a CSF RBC count greater than 2000 × 10(6)/L or visible CSF xanthochromia, increasing the likelihood that this proposed cutoff strategy may safely identify patients who warrant further investigation for an aneurysmal cause of subarachnoid hemorrhage ((Mark DG, Kene MV, Offerman SR, Vinson DR, Ballard DW; Kaiser Permanente CREST Network. Validation of cerebrospinal fluid findings in aneurysmal subarachnoid hemorrhage. Am J Emerg Med. 2015 Sep;33(9):1249-52. doi: 10.1016/j.ajem.2015.05.012. Epub 2015 May 15. PubMed PMID: 26022754. )). ====Case series==== ===2015=== In patients presenting to the emergency department with acute severe [[headache]], LP to diagnose or exclude SAH after negative head CT has a very low diagnostic yield, due to low prevalence of the disease and uninterpretable or inconclusive samples. A clinical decision rule may improve diagnostic yield by selecting patients requiring further evaluation with LP following nondiagnostic or normal noncontrast CT brain imaging ((Sayer D, Bloom B, Fernando K, Jones S, Benton S, Dev S, Deverapalli S, Harris T. An Observational Study of 2,248 Patients Presenting With Headache, Suggestive of Subarachnoid Hemorrhage, Who Received Lumbar Punctures Following Normal Computed Tomography of the Head. Acad Emerg Med. 2015 Oct 19. doi: 10.1111/acem.12811. [Epub ahead of print] PubMed PMID: 26480290.)). ---- A study included 302 patients, including 2 (0.66%) who were diagnosed with SAH based on LP (number needed to diagnose, 151); both of these patients had a known intracranial aneurysm. Eighteen (5.96%) patients experienced an LP-related complication (P < .01 compared with number with SAH diagnosed; number needed to harm, 17). Complications included 12 patients with low-pressure headaches, 4 with pain at the LP site, and 2 with contaminated CSF cultures. The yield of LP for diagnosing SAH in adults with nontraumatic headache after a normal head CT was very low. The severity of LP-related complications was low, but complications were more common than SAH diagnoses. Lumbar puncture may not be advisable after a normal head CT to evaluate for SAH, particularly in patients with low-risk clinical features for SAH ((Migdal VL, Wu WK, Long D, McNaughton CD, Ward MJ, Self WH. Risk-benefit analysis of lumbar puncture to evaluate for nontraumatic subarachnoid hemorrhage in adult ED patients. Am J Emerg Med. 2015 Jun 23. pii: S0735-6757(15)00534-3. doi: 10.1016/j.ajem.2015.06.048. [Epub ahead of print] PubMed PMID: 26189054.)). ---- Visual inspection for [[xanthochromia]] is used to diagnose [[subarachnoid hemorrhage]] (SAH), to validate computed tomography subarachnoid hemorrhage diagnosis and was used to determine the Walton rule. No study has assessed the reliability of xanthochromia. This simple laboratory study would be expected to maximize agreement relative to clinical practice. Although non-color-blind female observers significantly outperformed non-color-blind male observers, both intraobserver agreement and interobserver agreement for xanthochromia were prohibitively poor regardless of sex or illumination. Yellow was most frequently misclassified, 88% as clear (ie, true positives were commuted to false negatives). Xanthochromia is therefore highly unreliable for subarachnoid hemorrhage diagnosis and computed tomography validation. The Walton rule requires urgent clinical revalidation ((Marshman LA, Duell R, Rudd D, Johnston R, Faris C. Intraobserver and interobserver agreement in visual inspection for xanthochromia: implications for subarachnoid hemorrhage diagnosis, computed tomography validation studies, and the walton rule. Neurosurgery. 2014 Apr;74(4):395-400. doi: 10.1227/NEU.0000000000000291. PubMed PMID: 24448178.)). ===2013=== The chance of finding a vascular lesion in a patient with CT-negative, LP-positive SAH was 43%, underlining the need for an adequate diagnostic workup. In general, the patient outcome was favourable. Female gender was found to be predictive for detecting a vascular lesion. In contrast with previous reports, the interval between ictus and LP was not associated with the presence of an aneurysm ((Bakker NA, Groen RJ, Foumani M, Uyttenboogaart M, Eshghi OS, Metzemaekers JD, Luijckx GJ, Van Dijk JM. Appreciation of CT-negative, lumbar puncture-positive subarachnoid haemorrhage: risk factors for presence of aneurysms and diagnostic yield of imaging. J Neurol Neurosurg Psychiatry. 2013 Dec 19. doi: 10.1136/jnnp-2013-305955. [Epub ahead of print] PubMed PMID: 24357683.)).