Neuromonitoring Techniques in the NeuroICU: Jed Hartings, PhD Department of Neurosurgery University of Cincinnati [email_a...
Electrocorticography (ECoG) ECoG = practice of using electrodes placed directly on the exposed surface of the brain to rec...
Spreading depression in human cortex Strong et al., Stroke 33:2738-43, 2002
Spreading depression in rabbit cortex
What are spreading depolarizations? ECoG DC potential Spreading depolarizations = class of pathologic waves characterized ...
What are spreading depolarizations? Dreier JP, Nature Medicine 17(4):439-47, 2011 <ul><li>Loss of transmembrane ion gradie...
SD incidence in acute brain injury Traumatic brain injury:  50-60% Intracerebral hematomas: 50-60% Aneurysmal subarachnoid...
ECoG in neurosurgical patients <ul><li>Clinical need for surgery provides opportunity to place ECoG electrodes with resear...
Peri-lesion placement of electrode strip Pre-op Post-op
Removal of electrode strip <ul><li>Continuous ECoG recordings during intensive care </li></ul><ul><li>Electrode strip remo...
Recording requirements frequency (Hz) DC Shifts Depression (Traditional EEG Band) EEG Amplifier ECoG, 0.02 HPF attenuation...
Recording equipment Conventional Clinical EEG System Low Frequency Limit: 0.1 Hz 1 st  Generation Research System ADInstru...
Recording equipment
Analysis 2 3 4 5 a b c 6 d depression  period propagation velocity = 10 mm/3 min = 3.3 mm/min
1 sec
5 min
Clinical relevance: SAH and stroke
Clinical relevance: TBI <ul><li>103 patients monitored for 72 hr (quartiles: 40,102)  </li></ul><ul><li>surgery at 10 hr p...
SD and ICP Spreading Depolarizations Hartings et al., J Neurotrauma 26:1857-66, 2009 O’Phelan et al., Neurocrit Care 10:28...
SD associated with hypotension, fever Hartings et al., J Neurotrauma 26:1857-66, 2009 280 SD in 17 of 32 (53%) patients
TBI case example rCBF   (ml/100g/min) Brain temp  ( ° C)  depolarizations 0 2 4 6 8 Days post-TBI Licox P br O 2  > 20 mm ...
tSAH is a risk factor for spreading depolarizations Fisher Scale Morris-Marshall Scale Depolarization Incidence (%) 4/17 1...
SD and cerebral microdialysis Days post-trauma μ M SD (n=8) no SD (n=10) glutamate LPR
Seizures and spreading depolarizations Fabricius et al., Clin Neurophysiol 119:1973-1984, 2008
Seizures and spreading depolarizations 10 min 4  m V 1 sec 1000  μ V
ECoG-detected seizures are often focal 10 min 500  μ V
Sensitive seizure detection with ECoG
Depolarizations are independently associated with poor outcomes *p=0.26 ^p<0.001 Multivariate ordinal regression analysis ...
The Future? Smart catheter : CSF drainage Glucose Lactate Oxygen Temperature Pressure CBF ECoG
Summary <ul><li>ECoG is a novel modality to monitor TBI patients </li></ul><ul><li>Currently, it is only a research tool t...
Acknowledgments COSBID-Europe Anthony Strong – London Martin Fabricius – Copenhagen Martin Lauritzen – Copenhagen  Jens Dr...
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Hartings, Jed - EcoG

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Hartings, Jed - EcoG

  1. 1. Neuromonitoring Techniques in the NeuroICU: Jed Hartings, PhD Department of Neurosurgery University of Cincinnati [email_address] 513-558-3567 ECoG
  2. 2. Electrocorticography (ECoG) ECoG = practice of using electrodes placed directly on the exposed surface of the brain to record electrical activity from the cerebral cortex <ul><li>developed in 1950’s </li></ul><ul><li>similar to EEG, but provides greater spatial resolution and higher signal-to-noise </li></ul><ul><li>used to localize epileptic foci prior to surgery in patients with intractable epilepsy </li></ul><ul><li>electrodes used for recording and stimulation to generate functional maps of cortex </li></ul><ul><li>brain-computer interfaces for neural prosthetics </li></ul><ul><li>neuromonitoring of acute brain injury </li></ul>
  3. 3. Spreading depression in human cortex Strong et al., Stroke 33:2738-43, 2002
  4. 4. Spreading depression in rabbit cortex
  5. 5. What are spreading depolarizations? ECoG DC potential Spreading depolarizations = class of pathologic waves characterized by near-complete sustained depolarization of neurons/astrocytes that propagate through gray matter at 1-5 mm/min Sustained depolarization
  6. 6. What are spreading depolarizations? Dreier JP, Nature Medicine 17(4):439-47, 2011 <ul><li>Loss of transmembrane ion gradients </li></ul><ul><li>Persistent (min’s) neuronal depolarization to -10 mV </li></ul><ul><li>Cytotoxic edema (ECV: 20%  5%) </li></ul><ul><li>BBB breakdown and vasogenic edema </li></ul><ul><li>Induction of pro-inflammatory cytokines </li></ul><ul><li>Activation of astrocytes and microglia </li></ul><ul><li>Cumulative depletion of brain glucose </li></ul>
  7. 7. SD incidence in acute brain injury Traumatic brain injury: 50-60% Intracerebral hematomas: 50-60% Aneurysmal subarachnoid hemorrhage: 75% Malignant ischemic stroke: 100% > 200 neurosurgical patients monitored in 12 centres (Europe and USA)
  8. 8. ECoG in neurosurgical patients <ul><li>Clinical need for surgery provides opportunity to place ECoG electrodes with research consent </li></ul><ul><li>Subdural electrode strip placed on peri-lesion cortex </li></ul><ul><ul><li>Open craniotomy field or tunneled under intact dura/skull </li></ul></ul>
  9. 9. Peri-lesion placement of electrode strip Pre-op Post-op
  10. 10. Removal of electrode strip <ul><li>Continuous ECoG recordings during intensive care </li></ul><ul><li>Electrode strip removed at bedside by gentle traction </li></ul><ul><li>Lead wire exits craniotomy margin at bevel/burrhole to prevent snag during removal </li></ul>
  11. 11. Recording requirements frequency (Hz) DC Shifts Depression (Traditional EEG Band) EEG Amplifier ECoG, 0.02 HPF attenuation 0 1
  12. 12. Recording equipment Conventional Clinical EEG System Low Frequency Limit: 0.1 Hz 1 st Generation Research System ADInstruments, Inc. • Amplifier, low freq limit: 0.02 Hz • A-to-D converter • Multi-modal data: ICP, ABP, Licox
  13. 13. Recording equipment
  14. 14. Analysis 2 3 4 5 a b c 6 d depression period propagation velocity = 10 mm/3 min = 3.3 mm/min
  15. 15. 1 sec
  16. 16. 5 min
  17. 17. Clinical relevance: SAH and stroke
  18. 18. Clinical relevance: TBI <ul><li>103 patients monitored for 72 hr (quartiles: 40,102) </li></ul><ul><li>surgery at 10 hr post-trauma (quartiles: 5, 26) </li></ul><ul><li>SD observed in 58 of 103 patients monitored (56%) </li></ul><ul><li>total of 1,328 depolarizations (average: 23 / patient; range: 1-100+) </li></ul>500 μ V 1 mV 60 20 mm Hg ICP HF-ECoG LF-ECoG 8 hr a b c a b c
  19. 19. SD and ICP Spreading Depolarizations Hartings et al., J Neurotrauma 26:1857-66, 2009 O’Phelan et al., Neurocrit Care 10:280-6, 2009
  20. 20. SD associated with hypotension, fever Hartings et al., J Neurotrauma 26:1857-66, 2009 280 SD in 17 of 32 (53%) patients
  21. 21. TBI case example rCBF (ml/100g/min) Brain temp ( ° C) depolarizations 0 2 4 6 8 Days post-TBI Licox P br O 2 > 20 mm Hg throughout ICP < 20 mm Hg throughout GCS: 7T  10T hypovolemic shock metabolic acidosis hyponatremia
  22. 22. tSAH is a risk factor for spreading depolarizations Fisher Scale Morris-Marshall Scale Depolarization Incidence (%) 4/17 13/26 8/10 4/16 5/12 16/25 p=0.01; χ 2 p=0.04; χ 2 No significant association with status of basal cisterns, midline shift, parenchymal lesions, subdural hemorrhage, or Rotterdam score.
  23. 23. SD and cerebral microdialysis Days post-trauma μ M SD (n=8) no SD (n=10) glutamate LPR
  24. 24. Seizures and spreading depolarizations Fabricius et al., Clin Neurophysiol 119:1973-1984, 2008
  25. 25. Seizures and spreading depolarizations 10 min 4 m V 1 sec 1000 μ V
  26. 26. ECoG-detected seizures are often focal 10 min 500 μ V
  27. 27. Sensitive seizure detection with ECoG
  28. 28. Depolarizations are independently associated with poor outcomes *p=0.26 ^p<0.001 Multivariate ordinal regression analysis † based on age, GCS motor score, pupils, hypoxia, hypotension, tSAH, Marshall CT category Estimated common odds ratio 95% confidence interval p-value Prognostic Score † 1.76 1.26 to 2.46 <0.001 Depolarization None 1.0 reference <0.001 CSD 1.56* 0.72 to 3.37 ISD 7.58^ 2.64 to 21.8
  29. 29. The Future? Smart catheter : CSF drainage Glucose Lactate Oxygen Temperature Pressure CBF ECoG
  30. 30. Summary <ul><li>ECoG is a novel modality to monitor TBI patients </li></ul><ul><li>Currently, it is only a research tool to monitor spreading depolarizations </li></ul><ul><li>The only method to monitor a mechanism of evolving cortical pathology </li></ul><ul><li>Depolarizations are associated with fever, hypotension, high ICP, and worse outcome in human TBI </li></ul><ul><li>Promising method for real-time monitoring to guide treatments tailored to individual patients; automated methods for data processing and interpretation are needed </li></ul><ul><li>Electrode strips are limited to patients requiring surgery; depth electrodes and μECoG are options for non-surgical TBI </li></ul>
  31. 31. Acknowledgments COSBID-Europe Anthony Strong – London Martin Fabricius – Copenhagen Martin Lauritzen – Copenhagen Jens Dreier – Berlin Rudolf Graf – Cologne Johannes Woitzik – Berlin Oliver Sakowitz – Heidelberg COSBID-USA Ross Bullock - Miami David Okonkwo – Pittsburgh Bruce Mathern – Virginia Lori Shutter – Cincinnati Adam Wilson - Cincinnati COSBID

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