Ver el código de «EBQ:Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage»

{{JC info
| title= Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study
| abbreviation= 
| expansion=
| published= 18 February 2015
| author= Perry, J et al.
| journal= BMJ
| year= 2015
| volume= 18
| issue= 350
| pages= epub
| pmid= 25694274
| fulltexturl= http://www.bmj.com/content/350/bmj.h568.full.pdf+html
| pdfurl= http://www.bmj.com/content/bmj/350/bmj.h568.full.pdf
| status = Complete
}}
==Clinical Question==
*Can cerebrospinal fluid from patients with acute headache after traumatic lumbar puncture be distinguished from subarachnoid hemorrhage?

==Conclusion==
*No xanthochromia and red blood cell count < 2000 × 10<sup>6</sup>/L can reasonably excludes the diagnosis of aneurysmal subarachnoid hemorrhage.  

==Major Points== 
*In ruling out traumatic subarachnoid hemorrhage, the traumatic tap which causes blood to mix with cerebrospinal fluid can complicate the diagnosis of subarachnoid hemorrhage in up to 30% of [[Lumbar puncture|LPs]].<ref>Gorchynski J, Oman J, Newton T. Interpretation of traumatic lumbar punctures in the setting of possible subarachnoid hemorrhage: who can be safely discharged? Cal J Emerg Med 2007;8:3–7.</ref>

This study was a predefined subsidy of the Canadian subarachnoid hemorrhage (SAH) rule and provides data to classify the likelihood of a subarachnoid hemorrhage based on LP results.  Using a threshold of 2000x10<sup>6</sup>/L in the final CSF tube provides for a sensitivity of 100% (CI 74.7-100%) and specificity of 91.2% (88.6-93.3%). For xanthochromia however the sensitivity was only 46.6% (CI 22-72.6%) for diagnosing subarachnoid. Combining the RBC threshold with xanthochromia the sensitivity for subarachnoid hemorrhage is 100%<ref>Perry JJ et al. Should spectrophotometry be used to identify xanthochromia in the cerebrospinal fluid of alert patients suspected of having subarachnoid hemorrhage? Stroke 2006;37:2467–72.</ref>



==Study Design==
*Planned substudy from the prospective multi center cohort study, designed to derive and validate the Ottawa SAH (subarachnoid hemorrhage) rule
*Conducted between November 2000 - December 2009
*Multicenter at 12 canadian academic EDs
 
==Population==
N=1739
===Patient Demographics===
*Mean Age: 43yo
*Sex: 40% Men/60% Women

===Inclusion Criteria===
*Age >15
*Alert patients (GCS =15)
*ED patents with acute non-traumatic headache undergoing LP to rule out subarachnoid hemorrhage
*Within 14 days of headache onset

===Exclusion Criteria===
*Recurrent headaches (3 or more with similar character/intensity over 6 month or greater period
*Transfered from other hospital with  confirmed subarachnoid
*Presence of focal neurologic deficits or papilledema
*History of
**Subarachnoid hemorrhage
**Aneurysm
**VP shunt
**Brain neoplasm

==Interventions== 
*Computed tomography and/or lumbar puncture was performed at the discretion of the treating physician
**Some LPs were performed before CT scans

*Patients discharged without having both computed tomography imaging and a normal result on lumbar puncture were assessed by telephone interview one month and six months after assessment in the emergency department as well as a review of medical records to identify any recorded subarachnoid hemorrhage.

*Patients without telephone follow-up or subsequent hospital encounters at the enrolling sites were further checked against the coroner’s records to identify any deaths compatible with subarachnoid hemorrhage 

==Outcomes==
Subarachnoid hemorrhage definition:
*Blood in the subarachnoid space on CT brain
*Xanthochromia on examination of CSF 
*Red blood cells in the final tube of CSF fluid and aneurysm shown with cerebral angiography requiring any neurovascular intervention or resulting in death. 

Normal LP = 1098
Abnormal LP = 641 (36.9%)
*No aneurysmal subarachnoid = 626
*Aneurysmal subarachnoid 15
*Xanthochromia = 7
*No Xanthochromia = 8
===Primary Outcome===
There were 15 (0.9%) patients with aneurysmal subarachnoid hemorrhage based on abnormal results of a lumbar puncture.

===Secondary Outcomes=== 
The presence of less than 2000 × 10<sup>6</sup>/L red blood cells in addition to no xanthochromia excluded the diagnosis of aneurysmal subarachnoid hemorrhage
*Sensitivity of 100% (95% confidence interval 74.7% to 100%)
*Specificity of 91.2% (88.6% to 93.3%).


===Subgroup analysis===
====Characteristics or patients in Canadian SAH Rule Study====
''All patients in the SAH Rule derivation and validation cohort''<ref>Perry JJ. et al. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013 Sep 25;310(12):1248-55. </ref>
*Neck Pain or stiffness: 33.7%
*Median time of headache onset to peak: 60 seconds
*CT performed: 81.7%
*Mean time from headache onset to LP: 18 hours
*Median RBC count in last tube: 0
*Aneurysmal subarachnoid hemorrhage: 3.5%

====Characteristics of patients with abnormal LP====
'''Positive xanthochromia'''
*Aneurysmal subarachnoid hemorrhage: 46.6%
*No Subarachnoid: 2.6%
'''Median RBC count in last tube (x10<sup>6</sup>)'''
**Aneurysmal subarachnoid: 28741
**No subarachnoid: 20
'''Angiography rate'''
*Aneurysmal subarachnoid hemorrhage: 15%
*No subarachnoid: 64.5%

==Criticisms & Further Discussion==
*Although this study is useful for defining the number of RBCs concerning for a SAH it does not help guide the workup for patients with a negative CT and positive lumbar puncture.  There was also a great percentage of patients who underwent CT angiography for a small percentage of SAH.  

*A study by Gorchynski found that RBC counts ≤ 500 x10<sup>6</sup>/L in the 4th CSF tube had a 100% negative predictive value for subarachnoid hemorrhage<ref>Gorchynski J. et al. Interpretation of traumatic lumbar punctures in the setting of possible subarachnoid hemorrhage: who can be safely discharged? Cal J Emerg Med 2007;8:3–7.</ref>

*Caution should be used for assessing [[abscess]] of SAH based on the percentage drop in RBC count since the presence of SAH was demonstrated in patients with a 25% reduction of RBCs between the 1st and 4th tubes<ref>Heasley DC et al. Clearing of red blood cells in lumbar puncture does not rule out ruptured aneurysm in patients with suspected subarachnoid hemorrhage but negative head CT findings. Am J Neuroradiol 2005;26:820–4.</ref>

==External Links==
*[http://www.emlitofnote.com/2015/02/the-case-of-bloody-lumbar-punctures.html  The Case of the Bloody Lumbar Punctures emlitofnote.com]

==Funding==
Funded by the Canadian Institutes of Health Research (grants: 67107, 153742), the Ontario Ministry of Health and Long Term Care, and the physicians of Ontario through the Physician’s Services Incorporated Foundation

==References==
<references/>

[[Category:EBQ]][[Category:Neurology]]