the diagnosis of subarachnoid hemorrhage rob hall pgy2 emergency medicine january 10th, 2002
TRANSCRIPT
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The Diagnosis of
SUBARACHNOIDHEMORRHAGE
Rob Hall
PGY2 Emergency Medicine
January 10th, 2002
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SubarachnoidHEMORRHAGE
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OBJECTIVESWhat does the Literature Say?
• What is the sensitivity of CT?
• When should the LP be done?
• What is a positive LP?
• Should we be using spectophotometry?
• Does a -ve CT and -ve LP rule out SAH?
• Is lumbar puncture without CT safe?
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The Diagnosis of SUBARACHNOID HEMORRHAGE
•WHY?• Misdiagnosis
• Mortality
• Angiography
• Literature
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SENSIVITITY OF CT
L ite ra tu re R eview o f3 rd G en era tion C T scan n ers
S id m an 1 9 9 6 S am es 1 9 9 6
van d er W ee 1 9 9 5 M org en s te rn 1 9 9 8
K asse l 1 9 9 0
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Reading Literature on CT and SAH
• Generation
• Technique
• Radiologist
• Time
• Prospective
• Spectrum Bias
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SPECTRUM BIAS
• POSITIVE CT NEUROSURG
WARD
• POSITIVE CT EMERG PT (R/O SAH)
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TIMING OF CT:Kassel 1990
Cooperative Aneurysm Study
0102030405060708090
100
day 0 day 1 day 2 day 3 day 4 day 5
Sensitivity of CT
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Sensitivity of CT
• Sidman 1996– Retrospective
– Sensitivity 100% < 12hrs
• Sames 1996– Retrospective
– Sensitivity 93% < 24hrs
• SPECTRUM BIAS
• IGNORE RESULTS
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van der Wee 1995Journal of Neurology, Neurosurgery, and Psychiatry
• Prospective, N=175
• All <12hrs with SUDDEN ONSET H/A
• 3rd generation CT done < 12hrs
• Neuroradiologist + 2 general radiologists
• Diagnosis of SAH in -ve CT – LP > 12 hrs– Xanthochromia by spectophotometry
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Van der Wee 1995
• CT +ve in 117/175 ---->LP +ve in 2/58
• Sensitivity < 12 hrs 98% (94.0 - 99.8)
• Comments– probably the best study available– good diagnosis of SAH in CT -ve group– rate of SAH 68% (?spectrum bias)– note CI as low as 94%– note who read the films
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Morgenstern 1998Annals of Emergency Medicine
• Prospective, N = 107
• Spectrum: “worst headache ever”
• Only 107 enrolled of eligible 170
• 3rd generation CT
• 2 Neuroradiologists
• Diagnosis of SAH in -ve CT questionable
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Morgenstern 1998:Annals of Emergency Medicine
• Diagnosis of SAH in CT -ve patients:
• rbcs > 1000 in 1st tube and no decrease of 25% w.r.t. 3rd tube PLUS one of ……– visual xanthochromia– spec xanthocrhomia– positive d-dimer
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Morgenstern 1998:Annals of Emergency Medicine
• Negative Predictive Value Overall
– 97.5% (CI 91.2 - 99.7%)
• Sensitivity < 24hrs
– 93% (no confidence interval)
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Morgenstern 1998:Annals of Emergency Medicine
• Only 107/170 enrolled• 10% refused LP• 25% of LPs < 12hrs• Questionable
definition of +ve LP – 20 patients with +ve
spec defined as NO SAH, but no problems at 2yr follow up
• What if they missed even ONE patient < 24hrs
– 14/15 = 93.3%
– 13/15 = 86.7%
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SUMMARY ON CT AND SAH
• TRUE sensitivity UNKNOWN
• EARLIER is BETTER• PGY2 versus NEURORAD• BEST estimate of sensitivity
– 0-24hrs 95%
– 24-48hrs 85%
– 48-72% 75%
• TO RULE OUT SAH, A LUMBAR PUNCTURE IS REQUIRED AFTER A NEGATIVE CT HEAD
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LUMBAR PUNCTUREPathophysiology
• RBCs passively lysed and oxidized to OXYHEMOGLOBIN – detectible as early as 2 hrs (Barrows 1955)
• Oxyhemoblobin is actively converted to BILIRUBIN by hemoxidase enzyme found in choriod plexus and leptomeninges – bilirubin present by 6hrs (Barrows 1955)– max hemoxidase activity by 12hrs (Roost 1972)
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What is Xanthochromia?
• The change in coloration of CSF
• Due to oxyhemoblobin, bilirubin, or methemoglobin
• BUT ----------> detected by VISION or SPECTOPHOTOMETRY?
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What can cause a false +ve LP for Xanthochromia?
• Jaundice
• Rifampin
• Previous traumatic LP
• Traumatic tap -----> CSF sits in lab > few hours
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TIMING OF LUMBAR PUNCTURE
• Barrows 1955: oxyHb in 2hrs, bili in 6hrs
• Roost 1972: hemoxidase max at 12hrs
• Where does the 12hr delay come from?– Vermeulen 1989– Walton 1956
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TIMING OF LP:Vermeulen 1989
Journal of Neurology, Neurosurgery, and Psychiatry
• Retrospective review of 111 patients with SAH diagnosed by blood on CT
• ALL lumbar punctures done > 12hrs
• Xanthochromia detected by spectophotometry
• DOES NOT LOOK AT CT -ve PATIENTS
• DOES NOT LOOK AT LP < 12hrs
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TIMING OF LP:Vermeulen 1989
Journal of Neurology, Neurosurgery, and Psychiatry
• TIMING SENSITIVITY– 12hrs - 2weeks 100%
– 2 - 3 weeks 91%
– 3 - 4 weeks 71%
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TIMING OF LP:Walton 1956
Subarachnoid Hemorrhage. E & S Livingstone LTD.
• Retrospective look at 256 cases of SAH
• How was SAH diagnosed?
• Xanthochromia detected visually.
• Some results missing
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TIMING OF XANTHOCHROMIA:Walton 1956
0102030405060708090
100
0-2hr 2-4hr 4-6hr 6-12hr 12-24hr
>24hr
XanthochromiaBlood
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What is a positive LP?
• RED BLOOD CELL COUNT?– LEAK versus MAJOR HEMORRHAGE
– NO literature (Tourtelloote 1964 - none < 1000/mm3)
– How can you tell from traumatic tap?
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SAH versus Traumatic LP
• Opinion, crenated rbcs, erythrophages, d-dimer unreliable
• Repeat LP only helpful if clear
• FOUR tube method UNRELIABLE and does not detect SAH + traumatic tap– Vandermeulen 1996– Buruma 1981
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SAH versus Traumatic LP
• XANTHOCHROMIA is the only way to reliably distinguish between SAH and traumatic LP
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So how should we detect Xanthochromia?
• Visual detection?– ? Poor
sensitivity
• Spectophoto-metry?– ? Poor
specificity
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LITERATURE REVIEW:Visual versus spectophotometric
detection of Xanthochromia
X an th och rom ia
S od ers trom 1 9 7 7 M acD on a ld 1 9 8 8
V isu a l d e tec tionIN S E N S ITIV E
M org en s te rn 1 9 9 8 F oo t 2 0 0 1
S p ec top h o tom etryN O N S P E C IF IC
L ite ra tu re R eview
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Visual detection of Xanthochromiais INSENSITIVE:
Soderstrom 1977:
• N=32
• 12 ICH, 12 SDH, 8 SAH
• Dx by CT + OR, angiogram, or autopsy
• Vision detected 16 of 32 cases of xanthochromia on spectophotometry– Sensitivity 50%– ?when spec done
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Visual detection of Xanthochromiais INSENSITIVE:
MacDonald 1988
• Retrospective review of 61 patients with angiographically proven aneurysms who had LP done
• 28/61 had xanthochromia by vision for sensitivity of 46%
• 13 LPs were done < 24hrs (any < 12hrs?)– exlcude LP < 24hrs….28/48 ------> 67%
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Spectophotometry is NONSPECIFIC: Morgenstern 1998
• 18 patients with +ve spectophotometry who didn’t meet their criteria for +ve LP
• Followed for 2 years with no problems
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Spectophotometry is NONSPECIFIC: Foot 2001
• Retrospective study looking at the use/results of CT and LP in ED r/o SAH
• +ve Xanthochromia = > 0.02 absorbance units at 415nm
• 21 CT-ve, Xanthochromia +ve– 19 angiograms normal– 2 aneurysms
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Xanthochromia
• Cruikshank 2001– “A prospective study of LP on CT -ve patients
undergoing r/o SAH to compare visual and spectophotometric detection of xanthochromia has never been done”.
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UNPUBLISHED DATA:J. Croft, G. Sutherland, A. Gibb
• ALL CSF samples from calgary ED over a 14 months period
• R/O SAH in 110• Recorded
– rbcs count– visual xanthochromia– spectophotometry absorption peak– spectophotometry optical density criteria
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LOCAL DATAN Blood
(<10)Visual Spec Peak Spec O.D.
CriteriaSAHdx
71 - - - 20+,51- 0
11 + - - 5+,6- 0
4 + + Hb/Bili 4+ 4
14 +/- 3+11-
Hb 12+,2- 0
9 +/- 1+8-
Bili 9+ 1
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Optical Density Criteria
• SAH No SAH• OD+ve 5 45 • OD-ve 0 60
• Sensitivity– 5/5 = 100%
• Specificity– 60/105 = 57%
• NPV– 60/60 = 100%
• PPV– 5/50 = 10%
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Visual Detection
• SAH NO SAH• Visual 5 4
xantho• No visual 0 101
xantho
• Sensitivity– 5/5 = 100%
• Specificity– 101/105 = 96%
• NPV– 101/101= 100%
• PPV– 5/9 = 56%
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LOCAL DATA
• CONCLUSIONS– Visual Xanthochromia
did NOT miss any SAH
– Spectophotometry was not specific for SAH
• COMMENTS– NO gold standard for
SAH diagnosis
– NO long term f/u to prove that SAH wasn’t missed
– Small numbers
– One missed SAH ---> 5/5 to 5/6 ---> 83%
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Summary on Lumbar Puncture
• LP isn’t perfect either
• LP should be done > 10 - 12 hrs (spectrum)
• Xanthochromia is only way to reliably distinguish SAH from traumatic tap
• Literature is unclear whether visual or spectophotometric detection of xanthochromia is superior
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Does a negative CT and LP rule out SAH?
• Evidence this does NOT occur….– van Ginn1988: 71 patients
followed to 3 years, no problems
– Markus 1991: 16 patients followed to 20 months, no problems
– Harling 1994: 14 pts followed 18-30 mo, no problems
• Evidence that this DOES occur…..– Nine case reports
in literature
– Some had LP < 12hrs
– Some used visual, some used spec
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PERSPECTIVE ON POSSIBLE MISSED DIAGNOSIS RATE
2 0 0 ,0 0 0 E D V is its in C a lg ary p er year
L P 5 0 % sen s it ive5 m issed S A H
5 /2 0 0 0 = 0 .2 5 %
L P 9 0 % sen s it ive1 m issed S A H
1 /2 0 0 0 = 0 .0 5 %
C T 9 5 % sen s it iveC T m isses 1 0
R /O S A H in 1 /1 0 H ead ach es2 0 0
H ead ach e 1 % o f E D vis its2 ,0 0 0
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Does a -ve CT and LP rule out SAH?
• If LP done > 12hrs --------->
YES• Risk of angiogram > chance of
SAH with -ve CT and LP
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DIAGNOSTIC ALGORITHM
R /O S u b arach n o id H em orrh ag e
D iag n os is = S A H
V isu a l X an th och rom ia
V ery s tron gc lin ica l su sp ic ion
con su lt N S xcon s id er an g io
R u led ou t S A HD /C h om e
N o N S x con su lt
N o V isu a l X an th och rom ia
C T h eadL P > 1 0 - 1 2 h rs
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LP without CT
• Why wouldn’t you want to do this?– Risk of herniation– CT provides much additional information – How do you know this is a SAH?– How do you know there aren’t complications of
the SAH that increase the risk of herniation
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LP without CT
• Herniation– Mass effect from hematoma or hydrocephalus
with a SAH, or a different dx (ICH, tumor, etc)
• Normal LOC and NO focal signs – Hillman 1986: 2.2% acute deterioration after
LP; 10% had hematomas associated with SAH– Duffy 1982: 12% with proven SAH (spectrum
bias) deteriorated while needle in back
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LP without CT
• Additional information on CT– dx of non-aneurysmal causes: AVM, tumor,
ICH, hypertensive hem, perimesencephalic– look for acute complications: hydrocepahlus,
ICH, intraventricular blood requiring a drain– amount of bleeding is prognostic– bleeding on CT can help localize aneurysm and
identify multiple aneurysms
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LP without CT
• How do you know that the acute H/A isn’t due to an intraparenchymal hemorrhage?– Van Gijn 1980: retrospective review of all
patients with initial dx as SAH – 15% had intraparenchymal hemorrhage– 8% were in posterior fossa
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LP without CT
• Summary– There is NO literature supporting LP without
CT (Schull 1999: model only)– There is SOME literature documenting the risks – Risks and lack of additional information are not
justified in a tertiary care center– May be reasonable in periphery if no access to
CT although transfer in for CT is preferable