The Diagnosis of SUBARACHNOID HEMORRHAGE Rob Hall PGY2 Emergency Medicine January 10th, 2002

Subarachnoid HEMORRHAGE

OBJECTIVES What 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?

The Diagnosis of SUBARACHNOID HEMORRHAGE WHY? Misdiagnosis Mortality Angiography Literature

SENSIVITITY OF CT

Reading Literature on CT and SAH Generation Technique Radiologist Time Prospective Spectrum Bias

SPECTRUM BIAS POSITIVE CT NEUROSURG WARD POSITIVE CT EMERG PT (R/O SAH)

TIMING OF CT: Kassel 1990 Cooperative Aneurysm Study

Sensitivity of CT Sidman 1996 –Retrospective –Sensitivity 100% < 12hrs Sames 1996 –Retrospective –Sensitivity 93% < 24hrs SPECTRUM BIAS IGNORE RESULTS

van der Wee 1995 Journal 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

Van der Wee 1995 CT +ve in 117/ >LP +ve in 2/58 Sensitivity < 12 hrs 98% ( ) 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

Morgenstern 1998 Annals 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

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

Morgenstern 1998: Annals of Emergency Medicine Negative Predictive Value Overall –97.5% (CI %) Sensitivity < 24hrs –93% (no confidence interval)

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%

SUMMARY ON CT AND SAH TRUE sensitivity UNKNOWN EARLIER is BETTER PGY2 versus NEURORAD BEST estimate of sensitivity –0-24hrs95% –24-48hrs85% –48-72%75% TO RULE OUT SAH, A LUMBAR PUNCTURE IS REQUIRED AFTER A NEGATIVE CT HEAD

LUMBAR PUNCTURE Pathophysiology 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)

What is Xanthochromia? The change in coloration of CSF Due to oxyhemoblobin, bilirubin, or methemoglobin BUT > detected by VISION or SPECTOPHOTOMETRY?

What can cause a false +ve LP for Xanthochromia? Jaundice Rifampin Previous traumatic LP Traumatic tap -----> CSF sits in lab > few hours

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

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

TIMING OF LP: Vermeulen 1989 Journal of Neurology, Neurosurgery, and Psychiatry TIMINGSENSITIVITY –12hrs - 2weeks100% –2 - 3 weeks91% –3 - 4 weeks71%

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

TIMING OF XANTHOCHROMIA: Walton 1956

What is a positive LP? RED BLOOD CELL COUNT? –LEAK versus MAJOR HEMORRHAGE –NO literature (Tourtelloote none < 1000/mm3) –How can you tell from traumatic tap?

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

SAH versus Traumatic LP XANTHOCHROMIA is the only way to reliably distinguish between SAH and traumatic LP

So how should we detect Xanthochromia? Visual detection? –? Poor sensitivity Spectophoto- metry? –? Poor specificity

LITERATURE REVIEW: Visual versus spectophotometric detection of Xanthochromia

Visual detection of Xanthochromia is 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

Visual detection of Xanthochromia is 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 67%

Spectophotometry is NONSPECIFIC: Morgenstern patients with +ve spectophotometry who didn’t meet their criteria for +ve LP Followed for 2 years with no problems

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

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”.

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

LOCAL DATA

Optical Density Criteria SAH No SAH OD+ve 545 OD-ve060 Sensitivity –5/5 = 100% Specificity –60/105 = 57% NPV –60/60 = 100% PPV –5/50 = 10%

Visual Detection SAH NO SAH Visual 5 4 xantho No visual xantho Sensitivity –5/5 = 100% Specificity –101/105 = 96% NPV –101/101= 100% PPV –5/9 = 56%

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%

Summary on Lumbar Puncture LP isn’t perfect either LP should be done > 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

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 mo, no problems Evidence that this DOES occur….. –Nine case reports in literature –Some had LP < 12hrs –Some used visual, some used spec

PERSPECTIVE ON POSSIBLE MISSED DIAGNOSIS RATE

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

DIAGNOSTIC ALGORITHM

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

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

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

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

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