Neurosurgery notes/Vascular/Haemorrhagic diseases/SAH/Investigation SAH

Investigation SAH

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SAH
  • PCOM or AVM lying next to the free edge of the tentorium cerebelli can cause ASDH.
    Multimodal monitoring
    • CBF monitoring (theoretically superior)
      • CT perfusion - CPP < 70mmHg tends to be associated with cerebral infarction
      • Brain-tissue oxygen catheter
      • Cerebral metabolism (microdialysis)
    • Vessel diameter assessment
      • Transcranial Doppler
      • Conventional angiography
      • CT angiography
    Multimodal monitoring • CBF monitoring (theoretically superior) CT perfusion - CPP < 7()mmHg tends to be associated cerebral infarction Brain-tissue oxygen catheter - Cerebral metabolism (microdialysis) • Vessel diameter assessment Transcranial Doppler - Conventional angiography - CT angiography Pbt02 GEEG
    Initial assessment and referral for diagnostic investigation Person presents with unexplained acute severe headache • Havea high index of suspicion for subarachnoid haemorrhage (SAH) • Take a history to check rate of onset and time to peak intensity of headache • Bear in mind thundercla$ headache is a red-flag symptom for SAH (sudden agonising headache peaking in intensity within 1 to 5 minutes) • Bearin mind other causes of thunderclap headache, such as migraine, cough, coitus and exertion. Most people with thunderclap headache do not have SAH • Check for other symptoms and signs Of SAH (not an inclusive list): - neck pain or stiffness - photophobia - nausea and vomiting - altered brain function - limited or painful neck flexion If SAH suspected • Refer immediately to emergency care if outside an acute hospital setting • Ensure urgent review by senior clinical decision maker in an acute hospital setting If senior clinical decision maker confirms suspected SAH • Refer for urgent non-contrast CT head scan. Diagnostic accuracy is highest within 6 hours Of Symptom onset NICE National Institute for Health and Care Excellence Aneurysmal subarachnoid haemorrhage: assessment and diagnosis First diagnostic investigation: non-contrast CT head scan (urgent, to be done as soon as possible) Positive CT head scan (blood in subarachnoid space) Diagnose subarachnoid haemorrhage and offer CT angiography (CTA) of the head without delay Negative CT head scan done more than 6 hours after symptom onset Consider lumbar puncture, done at least 12 hours after symptom onset puncture pos (elevated bilirubin on Aneurysm n aneu A does n ow aneu Aneurysrn still suspected um r puncture negative or not ndicated Think about other diagnoses SA or MRA does not show Negative CT head scan done within 6 hours of symptom onset and reported by a radiologist Think about other diagnoses and seek advice from a specialist Do not routinely offer lumbar puncture This is a summary of the recommendations on assessment and diagnosis from NICE's guideline on subarachnoid haemorrhage caused by a ruptured aneurysm. NICE 2022. All rights reserved. Subject to Notice of riqhts. Consider digital subtraction angiography (OSA) or magnetic resonance angiography (MRA) or MRA shows aneurys Is the pattem of subarachnoid blood compatible with aneurysm rupture? Diagnose aneurysmal subarachnoid haemorrhage Seek advice from neuroradiologist and neurosurgeon without delay
    • ECG
    • CXR
    • Blds
    • Cardiac enzymes
    • Non contrast CT scan
      • Good quality (no motion) can detect SAH in > 95% if scan within 48hrs
        • CT is highly sensitive (98% to 100%) for the detection of subarachnoid hemorrhage if performed within 6 hours of haemorrhage - Perry 2011 and backes 2012
      • For subtle SAH look at gravity areas:
        • Occipital horns of lateral ventricles
        • Sylvian fissure
      • Look for
        • Hydrocephalus:
        • Infarction:
        • Amount of bld in cistern and fissure: prognosticator for spasm
      • CT can predict aneurysm position in 78% cases (mainly for MCA and ACOM)
            • Vessel
            Location of blood
            MCA or PCOM
            Blood in sylvian fissure
            Basilar apex or SCA
            Pre-pontine or peduncular cistern
            ACOM
            Anterior interhemispheric fissure
            PICA or VA dissection
            3rd or 4th ventricle
            Basilar apex
            3rd ventricle only
        • Location of SAH and aneurysm
              • Frequent aneurysms
              Cistern
              MCA
              Sylvian
              Ophthalmic
              Carotid
              PCom
              Carotid
              ACom
              Lamina terminalis
              Pericallosal
              Callosal
              Basilar apex
              Interpeduncular
              Posteroinferior cerebellar artery (PICA)
              Lateral cerebellomedullary
      • Other differentials
        • Pus
        • Pachymeningeal thickening in spontaneous intracranial hypotension
    LP
        Xanthochromia 02 Heme Oxygenase Heme Cytochrome P4SO Reductase NADPH Biliverdin Reductase Biliverdin Bilirubin NADPH Carbon monoxide Fe2+ Ferritin
        Xanthochromia
          Oxyhaemoglot»n 0,250 0.225 0200 0.175 0.150 0125 o. 100 0.075 0050 0025 0.000 350 375 400 425 Bilirubin 450 475 500 Wavelen nm 525 550 575
      • Positive result
        • CSF absorbance at 476 nm is >0.007 and CSF protein is normal
      • Oxyhaem too high will mask Bilirubin as it's slope will mask the bilirubin
          • ELSEVIER Alzheimerk Dementia AlzheimeA & Dementia: Diagnosis, Assessment & Disease Monitoring 8 (2017) I I I-126 CSF Biomarkers Consensus guidelines for lumbar puncture in patients with neurological diseases Sebastiaan Engelborghsa•b l, Ellis Niemantsverdrieta•l, Hanne Struyfsa, Kaj Blennowc, Raf Brouns , Manuel Comabellae, Irena Dujmovicl, Wiesje van der Flierg, Lutz Frölich , Daniela Galimbertil, Sharmilee GnanapavanJ, Bernhard Hemmer k l, Erik Hoff n, Jakub Hortn Ellen IacobaeusP, Martin Ingelssonq, Frank Jan de Jongr, Michael Jonssons, Michael Khalilt, Jens KuhleU, Alberto Lle6V'W, Alexandre de Mendongax, José Luis MolinuevoY, Guy Nagelsd'Z aa Claire Paquet , Lucilla ParnettiCC, Gerwin Roksdd, Pedro Rosa-New If, Philip Scheltensg, Constance Skårsgardgg, Erik Stomrudhh, Hayrettin Tumani", Pieter Jelle VisserLJ Anders Wallin'. Benet Winbladll. Henrik Zetterberg"rnm, Flora Duitsg, Charlotte E. Teunissen1J'*
    • CI for LP
      • Pressure difference at falx
      • Pressure difference between craniocervical junction
    • MOST SENSITIVE TEST for SAH
      • Chu et al
        • Visual inspection for xanthochromia
          • Sensitivity of 84%,
          • Specificity of 96%,
          • Positive LR of 14.1
          • Negative LR of 0.35.
        • Spectrophotometry for bilirubin is not any better
          • Sensitivity of 87%,
          • Specificity of 86%,
          • Positive LR of 6.6
          • Negative LR of 0.29.
    • Timeline
      • Sensitivity is reduced if LP is performed less than 12 hours or more than 2 weeks after the bleed,
      • Blood breakdown products may be present at
        • 3 (70%) weeks to even 4 (40%) weeks.
    • Caution
      • LP —> lower ICP —> reduce tamponade effect —> inc. rebleed
      • Remove a small amount of CSF and use small <20Ga needle
    • Differentiating traumatic TAP
          • Feature
          Traumatic tap (TT)
          SAH
          RBC count (and gross appearance of bloodiness)
          Declines as CSF drains (compare first tube to last tube)
          Usually > 100,000 RBCs/mm³, changes little as CSF drains
          Ratio of WBC:RBC
          Similar to the ratio in peripheral blood (see Differentiating true leukocytosis from traumatic tap above)
          Usually promotes a leukocytosis (elevated WBC count)
          Supernatant
          Clear
          Xanthochromic (rarely in <2 hrs, present in 70% by 6 hrs, and >90% by 12 hrs after SAH)
          Clotting of fluid
          Usually clots if erythrocyte count >200,000/mm³
          Usually does not clot
          Protein concentration
          Fresh bleeding elevates CSF protein from normal by ≈ 1 mg per 1000 RBC
          Blood breakdown products elevate this more than TT (measured protein exceeds the sum of normal protein + 1 mg protein/1000 RBC)
          Repeat LP at higher level
          Usually clear
          Remains bloody
          Opening pressure
          Usually normal
          Usually elevated
      • Basically: bilirubin can only be formed in the body and if you see it = to SAH: formed after 12 hrs
      • Photospectometry
        • Doing after 12 hrs to wait for bilirubin to form
    • Protein is normal in SAH
    • Potential confounders that limit the specificity of xanthochromia are
      • High bilirubin levels,
      • High protein levels,
      • Traumatic lumbar puncture.
    CT
    • The sensitivity of a CT scan to SAH
      • Is decreased to
        • 90% within 24hrs
        • 70% after 48 hrs
        • 60% after 5 days
        • 50% after 7 days
        A close-up of a brain scan AI-generated content may be incorrect.
        Acute subarachnoid haemorrhage imagining sequences
      • Acute blood is bright on FLAIR
    MRI
    • Benefits
      • Supplemental imaging technique that is useful for the investigation of large or giant aneurysms.
      • Can give information about
        • Adjacent brain structures such as the optic nerve or brainstem and their relationship to the aneurysm,
        • The degree to which the aneurysm contains thrombosed blood
    • Not sensitive for SAH <48 hrs (too little metHb-paramagnetic effect)
    • Good at sub acute SAH detection >10-20 days
    • mitchell 2001
      • The gradient echo T2* was the most sensitive sequence
        • Sensitivities
          • 94% in the acute phase (< 4 days)
          • 100% in the subacute phase. (4 and 14 days)
      • FLAIR
        • Sensitivity
          • 81% acute phase
          • 87% subacute phases
        • MetHb is not bounded by RBC —> stops static magnetic field from causing dephasing of NMR —> slows down T2 time to a MRI detectable range. —> bright on T2 Flair
      • Other sequences were considerably less sensitive.
        • T1: metHb (paramagnetic effect) come into contact with H20 forming aqua-metHb —> AquaMetHb steals electromagnetic energy from water —> quicken longitudinal relaxation back to B0 —> T1 shorter —> bright on T1
    • Blackblood MRI to look at vessel wall to check for bleeding
      • Useful to look for evidence of bleed and source of bleed
    MRA
    • For detection of IA
      • Sensitivity 97%
      • Specificity 92%
    • Significant poorer sensitivity for aneurysm <3mm
    • 3T for follow up and repeat evaluation
    • Depends on
      • Velocity of flow of blood in aneurysm
      • Direction of blood flow in aneurysm
      • Size
      • Presence of thrombosis and calcification
    • Imaging sensitivity
        • ㅤ
        CTA
        MRA
        >5 mm aneurysm
        95–100%
        85–100%
        <5 mm aneurysm
        64–83%
        56%
    CTA:
    • 1st line
    • Regions for review (Check in all 3 planes)
      • ACOM
      • MCA bifurcation
      • PCOM
      • Distal ACA
      • Basilar tip
      • PICA
    • Sensitive 97% for aneurysm
    • Can detect SPASMs
    • How to look for aneurysm
      • MIP: will miss <3mm Aneurysm
      • Imaging from C6-Vertex
      • Aneurysm Types
        • Side wall
        • Bifurcation aneurysm
      • Axial slice
        • Identify 4 vessel in the C1 level
          • ICA + VA
          • Follow up to bifurcation
        • Identify ACA and follow up
        • Identify MCA and f/u
        • Check Pcom and Ophthalmic artery
        • Distal vessels cannot be bigger than proximal vessels
        • Good for identifying
      • Coronal
        • Good for identifying
          • ACOM
          • MCA
          • Post circulation
      • Sagittal
        • Good for identifying
          • PCOM
          • Pericallosal
      • 3D
        • PICA
        • Will shows small aneurysm better than MIP
    DSA
    • Gold standard
    • The limitations of DSA
      • Provider availability,
      • Vasospasm preventing adequate contrast filling
      • Very small risk of procedure- related complications
        • Stroke
        • Groin haematoma
    • Demonstrate source of bleed in 80%, other are unknown aetiology
      • Repeat angiogram reveals an abnormality in 1–2%
    • Can show presents spasm
    • If no aneurysm seen before you can say its truly negative
      • Visualise both PICA origin
      • Flow contrast through the ACoA
      • If an infundibulum is within area of SAH do not call it negative as some can bleed.
    • Things to take note of on reviewing anatomy of aneurysm
      • Size of dome
        • Because some part of aneurysm might be thrombosed (non-filling) can we can under estimate the size
        • Large aneurysm >15mm are associated with lower rates of complete occlusion by coiling
      • Neck size
        • Narrow neck <5mm ideal for coiling
        • Broad neck >5mm associated with inc. risk of incomplete occlusion and recanalization with coiling
          • Can try to user stent or balloon assisted coiling for wide necked aneurysm
            • Try avoid because pt need dual anti-platelets therapy for life which inc. risk if you need shunting
      • Dome:neck ratio - >=2 high success of coil occlusion
    Intracranial Hemorrhage and Related Conditions | Anesthesia Key