Neurosurgery notes/CSF/CSF and ICP/subitem 2

subitem 2

View Details
logo
Parent item
CSF and ICP

Infusion test

  • Set up
      • notion image
      notion image
  • Output
    • Measure mean ICP, heart rate, pulse amplitude of ICP and RAP index
      • notion image
       
      • Using ICM+ software
        • Identification of the Marmarou model
      notion image
  • Clinical report
    • SAH, delayed hydrocephalus, low OP in LP. Increase in ventricle size in CT. Low GCS (9). LP study on A5
        • Parameter
        Value
        ICP baseline [mmHg]
        4.39
        AMP baseline [mmHg]
        0.94
        Rcsf [mmHg*min/ml]
        16.27
        PVI [ml]
        17.07
        CSF production rate [ml/min]
        0.27
        Infusion duration [min]
        19.66
        ICP plateau [mmHg]
        25.52
        AMP plateau [mmHg]
        2.79
        Elastance [1/ml]
        0.14
        Pss [mmHg]
        0.00
        Volume infused [ml]
        29.48
        Normalised error [%]
        1.351
        Normal baseline pressure with increased resistance to CSF outflow. Strong regular vasogenic waves recorded during the study. Overall: disturbed CSF dynamics.
        Normal baseline pressure with increased resistance to CSF outflow. Strong regular vasogenic waves recorded during the study. Overall: disturbed CSF dynamics.
    • Normal CSF circulation
        • Rcsf = 8.6 mmHg/(ml/min)
        • Opening pressure = 6 mmHg
        • Elasticity = 0.12 [1/ml]
        notion image
    • Normal pressure hydrocephalus (NPH)
    • Atrophic brain
        • Low baseline ICP
        • AMP shows small and relatively stable amplitude changes
        • RAP remains low or variable throughout
        notion image
    • Idiopathic Intracranial Hypertension (IIH)
        • Resistance is normal and elasticity is increased
            • Parameter
            Value
            ICP baseline [mmHg]
            29.11
            AMP baseline [mmHg]
            2.73
            Rcsf [mmHg*min/ml]
            4.23
            ICP plateau [mmHg]
            33.34
            AMP plateau [mmHg]
            3.61
            Elasticity [1/ml]
            0.41
        notion image
    • Transcranial Doppler (TCD)
        • Good synchronization of B waves in ICP and FV
        notion image
    • Who needs a shunt
      • If there is increased pulse amplitute with infusion then Shunt will help.
          • notion image
          notion image
          notion image
          notion image

Positron Emission Tomography (PET)

  • To measure CBF in the white matter during infusion test
      • notion image
  • NPH patient to a healthy patient
      • NPH patient
        • CBF in white matter decreases as a function of distance from the surface of ventricles.
      • Healthy patient
        • Distribution of CBF in white matter is flat
      notion image
      • Autoregulation is worse closer to surface of ventricles than further away from ventricles
      • SRoR: static rate of autoregulation
        • SRoR = 100% (good autoregulation)
        • SRoR = 0% (disturbed autoregulation)
      notion image

Classification of CSF disorder

  • Using baseline ICP and Rcsf
    • Should consider
      • RAP
      • AMP
      • Slow vasogenic waves
      • Slope of AMP/p line
notion image

Global model

  • To understand vascular components of CSF circulation
notion image

Summary

  • All parameters of CSF compensatory model may be estimated during infusion test
  • Not a single parameter but whole profile of recorded variables characterize disorder of CSF compensation
    • Rout > 13
    • E > 0.21
    • ICP baseline > 18 mmHg
    • AMPp > 5 mm Hg
    • Slow waves > 2 mmHg
    • RAP baseline > 0.5
    • Slope of AMPp line > 0.15
    • Presence of plateau wave during infusion.
  • In NPH white matter CBF is depleted – closer to ventricles.
  • Infusion test is minimally invasive: < 1% infections