introduction to traumatic brain injury brian l. edlow, ms4 university of pennsylvania school of...
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Introduction to Traumatic Brain Injury
Introduction to Traumatic Brain Injury
Brian L. Edlow, MS4Brian L. Edlow, MS4University of Pennsylvania University of Pennsylvania
School of MedicineSchool of MedicineDecember 4, 2006December 4, 2006
Brian L. Edlow, MS4Brian L. Edlow, MS4University of Pennsylvania University of Pennsylvania
School of MedicineSchool of MedicineDecember 4, 2006December 4, 2006
GoalsGoals
1. Understand that traumatic brain injury is a process, not an event
2. Understand the 4 main pathophysiologic mechanisms involved in traumatic brain injury
3. Understand basic strategies for treatment
Severe Traumatic Brain Injury (TBI)Severe Traumatic Brain Injury (TBI)
Definition: Head trauma associated with a Definition: Head trauma associated with a Glasgow Coma Score of ≤ 8Glasgow Coma Score of ≤ 8
Definition: Head trauma associated with a Definition: Head trauma associated with a Glasgow Coma Score of ≤ 8Glasgow Coma Score of ≤ 8
Best Eye Best Eye ResponseResponse
Best Verbal Best Verbal ResponseResponse
Best Motor Best Motor ResponseResponse
1. No eye opening2. Eye opening to
pain3. Eye opening to
verbal command
4. Eye opening spontaneously
1. No verbal response
2. Incomprehensible sounds
3. Inappropriate words
4. Confused words5. Appropriate
verbal responses
1. No motor response
2. Extension to pain3. Flexion to pain4. Withdrawal from
pain5. Localizing to pain6. Obeys
commands
Severe TBI - DemographicsSevere TBI - Demographics
1.5 million cases per year in U.S.1.5 million cases per year in U.S.
Causes: Causes: Motor vehicle Motor vehicle accidentaccident (~45%), falls (~30%), (~45%), falls (~30%), occupational accidents (~10%), occupational accidents (~10%), recreational accidents recreational accidents (~10%), assaults (~5%)(~10%), assaults (~5%)
Highest risk: children, Highest risk: children, adolescent/young adult adolescent/young adult menmen, elderly, elderly
1.5 million cases per year in U.S.1.5 million cases per year in U.S.
Causes: Causes: Motor vehicle Motor vehicle accidentaccident (~45%), falls (~30%), (~45%), falls (~30%), occupational accidents (~10%), occupational accidents (~10%), recreational accidents recreational accidents (~10%), assaults (~5%)(~10%), assaults (~5%)
Highest risk: children, Highest risk: children, adolescent/young adult adolescent/young adult menmen, elderly, elderly
(Population (Population 300 million)300 million)
Severe TBI - PathophysiologySevere TBI - Pathophysiology
TBI is a TBI is a processprocess, not an event!, not an event! Secondary injury can be more damaging than Secondary injury can be more damaging than
primary injuryprimary injury
4 Main Mechanisms of Brain Injury4 Main Mechanisms of Brain Injury1.1. Brain ContusionBrain Contusion
2.2. Increased intracranial pressure ( ICP)Increased intracranial pressure ( ICP)
3.3. Diffuse Axonal InjuryDiffuse Axonal Injury
4.4. Stroke (ischemic and/or hemorrhagic)Stroke (ischemic and/or hemorrhagic)
TBI is a TBI is a processprocess, not an event!, not an event! Secondary injury can be more damaging than Secondary injury can be more damaging than
primary injuryprimary injury
4 Main Mechanisms of Brain Injury4 Main Mechanisms of Brain Injury1.1. Brain ContusionBrain Contusion
2.2. Increased intracranial pressure ( ICP)Increased intracranial pressure ( ICP)
3.3. Diffuse Axonal InjuryDiffuse Axonal Injury
4.4. Stroke (ischemic and/or hemorrhagic)Stroke (ischemic and/or hemorrhagic)
Mechanism 1: Brain ContusionMechanism 1: Brain Contusion
A brain A brain contusioncontusion is defined by is defined by cell death accompanied by cell death accompanied by hemorrhage (leakage of blood)hemorrhage (leakage of blood)
The soft brain tissue is The soft brain tissue is vulnerable to contusion in head vulnerable to contusion in head traumatrauma
The contusion often occurs at a The contusion often occurs at a site distant from the point of site distant from the point of impactimpact
A brain A brain contusioncontusion is defined by is defined by cell death accompanied by cell death accompanied by hemorrhage (leakage of blood)hemorrhage (leakage of blood)
The soft brain tissue is The soft brain tissue is vulnerable to contusion in head vulnerable to contusion in head traumatrauma
The contusion often occurs at a The contusion often occurs at a site distant from the point of site distant from the point of impactimpact
Gross brain image from http://neuropathology.neoucom.edu/chapter4/chapter4bContusions_dai_sbs.html#contusion
Mechanism 2: ICP- Understanding the Determinants of
Intracranial Pressure -
Mechanism 2: ICP- Understanding the Determinants of
Intracranial Pressure - The volume of the intracranial vault =The volume of the intracranial vault =
Intracranial Contents:Intracranial Contents: 80% brain tissue80% brain tissue 10% blood10% blood 10% cerebrospinal fluid10% cerebrospinal fluid
An increase in the volume of any of these intracranial An increase in the volume of any of these intracranial contents causes increased intracranial pressurecontents causes increased intracranial pressure
The volume of the intracranial vault =The volume of the intracranial vault =
Intracranial Contents:Intracranial Contents: 80% brain tissue80% brain tissue 10% blood10% blood 10% cerebrospinal fluid10% cerebrospinal fluid
An increase in the volume of any of these intracranial An increase in the volume of any of these intracranial contents causes increased intracranial pressurecontents causes increased intracranial pressure
1. The brain can swell (edema)
2. Excess blood can accumulate due to hemorrhage
3. Cerebrospinal fluid can accumulate due to blockage of outflow
Mechanism 2: ICPMechanism 2: ICPKey Concept #1Key Concept #1: The intracranial vault : The intracranial vault
is a fixed volume --> Bone does not is a fixed volume --> Bone does not expand!expand!
Key Concept #1Key Concept #1: The intracranial vault : The intracranial vault is a fixed volume --> Bone does not is a fixed volume --> Bone does not expand!expand!
Skull image from www.mnsu.edu
Mechanism 2: ICP- Understanding the Physics of Intracranial
Pressure -
Mechanism 2: ICP- Understanding the Physics of Intracranial
Pressure -
Volume (mL)
Pressure
(mmHg)
Intracranial Pressure Rises as Brain+Bood+CSF volume Increases
ICP > 20 mmHg
Mechanism 2: ICP- Understanding the Physics of Intracranial
Pressure -
Mechanism 2: ICP- Understanding the Physics of Intracranial
Pressure -
ICP
CPP
This patient has dangerously high intracranial pressures, which increase the likelihood of morbidity and mortality
Mechanism 2: ICPMechanism 2: ICP Key Concept #2Key Concept #2: There is only one way out of the : There is only one way out of the
intracranial vault --> the opening at the base of intracranial vault --> the opening at the base of the skull known as the the skull known as the foramen magnumforamen magnum
Key Concept #2Key Concept #2: There is only one way out of the : There is only one way out of the intracranial vault --> the opening at the base of intracranial vault --> the opening at the base of the skull known as the the skull known as the foramen magnumforamen magnum
3D CT Angiogram from www.auntminnie.com/.../ 65000/66000/66173.asp
Skull base image from www.octc.kctcs.edu
Mechanism 2: ICPMechanism 2: ICP Key Concept #3Key Concept #3: :
When the brain is When the brain is squeezed through the squeezed through the foramen magnum foramen magnum ((herniationherniation)), the , the brainstem is brainstem is compressed, the compressed, the patient stops patient stops breathing, and the breathing, and the patient diespatient dies
Key Concept #3Key Concept #3: :
When the brain is When the brain is squeezed through the squeezed through the foramen magnum foramen magnum ((herniationherniation)), the , the brainstem is brainstem is compressed, the compressed, the patient stops patient stops breathing, and the breathing, and the patient diespatient dies
Herniation schematic from Robbins and Cotran. Pathologic Basis of Disease. 7th ed. Philadelphia: Elselvier; 2005.
Causes of ICP: Epidural HematomasCauses of ICP: Epidural Hematomas
Figure 7-15 Examples (A, B-arrows) of epidural hematomas in CT scans on the patient's right side. The smaller lesion in A is obviously of traumatic origin; this patient has soft tissue damage, a fractured skull, blood in the substance of the brain, and blood in the anterior horn of the lateral
ventricle and in the third ventricle. The cause of the larger lesion (B) is not obvious.
Slides from Haines:Fundamental Neuroscience for Basic and Clinical Applications 3e -www.studentconsult.com
Causes of ICP: Sudural HematomasCauses of ICP: Sudural Hematomas
Slide from Haines:Fundamental Neuroscience for Basic and Clinical Applications 3e -www.studentconsult.com
Figure 7-16 An example of a subdural hematoma (arrows) in CT scan on the patient's left side. This lesion is long and thin and extends for considerable distance over the surface of the
hemisphere: note the shift in the midline.
Causes of ICP: SwellingCauses of ICP: Swelling
Head CT from rad.usuhs.mil/rad/ home/peds/ihsdarrow.jpg
Observe swelling (darker tissue) on brain CT scan of a 7-month-old victim of child abuse. What other injuries are present?
Causes of ICP: SwellingCauses of ICP: Swelling
Gross brain specimen from neuropathology.neoucom.edu
Observe diffuse swelling (yellow tissue) and expansion of brain tissue into ventricles
Causes of ICP: SwellingCauses of ICP: Swelling
Brain surface image from www-medlib.med.utah.edu
Observe widening and flattening of gyri on brain surface
Mechanism 3: Diffuse Axonal InjuryMechanism 3: Diffuse Axonal Injury
Occurs in up to 1/2 of traumatic brain Occurs in up to 1/2 of traumatic brain injuriesinjuries11
Is a Is a diffusediffuse form of injury, meaning that form of injury, meaning that damage occurs over a more widespread damage occurs over a more widespread area than in focal brain injuryarea than in focal brain injury
Involves the shearing of axons in the white Involves the shearing of axons in the white matter tractsmatter tracts
Occurs in up to 1/2 of traumatic brain Occurs in up to 1/2 of traumatic brain injuriesinjuries11
Is a Is a diffusediffuse form of injury, meaning that form of injury, meaning that damage occurs over a more widespread damage occurs over a more widespread area than in focal brain injuryarea than in focal brain injury
Involves the shearing of axons in the white Involves the shearing of axons in the white matter tractsmatter tracts
1: http://en.wikipedia.org/wiki/Diffuse_axonal_injury
Mechanism 3: Diffuse Axonal InjuryMechanism 3: Diffuse Axonal Injury
Is one of the major causes of Is one of the major causes of unconsciousness and persistent vegetative unconsciousness and persistent vegetative state after head trauma.state after head trauma.
Over Over 90%90% of patients with severe DAI of patients with severe DAI never never regaining consciousnessregaining consciousness (those that do wake (those that do wake up often remain significantly impaired)up often remain significantly impaired)
Is one of the major causes of Is one of the major causes of unconsciousness and persistent vegetative unconsciousness and persistent vegetative state after head trauma.state after head trauma.
Over Over 90%90% of patients with severe DAI of patients with severe DAI never never regaining consciousnessregaining consciousness (those that do wake (those that do wake up often remain significantly impaired)up often remain significantly impaired)
Mechanism 3: Diffuse Axonal InjuryMechanism 3: Diffuse Axonal Injury
A microscopic view of axonal degeneration
Mechanism 4: StrokeMechanism 4: Stroke
Ischemic StrokeIschemic Stroke Caused by decreased oxygen delivery to brain Caused by decreased oxygen delivery to brain
tissuetissue Can occur in trauma secondary to swelling, which Can occur in trauma secondary to swelling, which
compresses nearby arteriescompresses nearby arteries
Hemorrhagic StrokeHemorrhagic Stroke Decreased oxygen delivery because blood is Decreased oxygen delivery because blood is
leaking into brain tissue and not entering the leaking into brain tissue and not entering the capillary networkcapillary network
Can occur as a primary Can occur as a primary or secondaryor secondary injury injury
Ischemic StrokeIschemic Stroke Caused by decreased oxygen delivery to brain Caused by decreased oxygen delivery to brain
tissuetissue Can occur in trauma secondary to swelling, which Can occur in trauma secondary to swelling, which
compresses nearby arteriescompresses nearby arteries
Hemorrhagic StrokeHemorrhagic Stroke Decreased oxygen delivery because blood is Decreased oxygen delivery because blood is
leaking into brain tissue and not entering the leaking into brain tissue and not entering the capillary networkcapillary network
Can occur as a primary Can occur as a primary or secondaryor secondary injury injury
Severe TBI - Basic Principles of Clinical Management
Severe TBI - Basic Principles of Clinical Management
Monitor intracranial pressure (invasively) and intervene Monitor intracranial pressure (invasively) and intervene to lower ICP when necessaryto lower ICP when necessary Elevate head of bedElevate head of bed Medications to decrease swellingMedications to decrease swelling Decrease brain activity to reduce blood delivery and swelling --Decrease brain activity to reduce blood delivery and swelling --
> “medically induced coma”> “medically induced coma” HypothermiaHypothermia Surgical Decompression when risk for herniation is highSurgical Decompression when risk for herniation is high
Seizure prophylaxisSeizure prophylaxis Seizures occur in up to 20% of severe TBI patients, with ~50% Seizures occur in up to 20% of severe TBI patients, with ~50%
occurring within first 24 hoursoccurring within first 24 hours11
Other prioritiesOther priorities Adequate nutrition, correction of electrolyte abnormalities, Adequate nutrition, correction of electrolyte abnormalities,
strict control of blood sugar, strict temperature regulationstrict control of blood sugar, strict temperature regulation
Monitor intracranial pressure (invasively) and intervene Monitor intracranial pressure (invasively) and intervene to lower ICP when necessaryto lower ICP when necessary Elevate head of bedElevate head of bed Medications to decrease swellingMedications to decrease swelling Decrease brain activity to reduce blood delivery and swelling --Decrease brain activity to reduce blood delivery and swelling --
> “medically induced coma”> “medically induced coma” HypothermiaHypothermia Surgical Decompression when risk for herniation is highSurgical Decompression when risk for herniation is high
Seizure prophylaxisSeizure prophylaxis Seizures occur in up to 20% of severe TBI patients, with ~50% Seizures occur in up to 20% of severe TBI patients, with ~50%
occurring within first 24 hoursoccurring within first 24 hours11
Other prioritiesOther priorities Adequate nutrition, correction of electrolyte abnormalities, Adequate nutrition, correction of electrolyte abnormalities,
strict control of blood sugar, strict temperature regulationstrict control of blood sugar, strict temperature regulation
1: “Post-traumatic Seizures and Epilepsy.” www.uptodate.com. May 29, 2006.
Severe TBI - PrognosisSevere TBI - Prognosis
The Impact of ICP: Patients with mean ICP greater than 20 mmHg during hospitalization have 47% mortality vs. patients with mean ICP below 20 mmHg, who have 17% mortality (p < 0.001)1
17% will have seizures during the 2-year post-trauma period2
The length of time a patient spends in a coma The length of time a patient spends in a coma correlates to both post-traumatic amnesia and correlates to both post-traumatic amnesia and recovery timesrecovery times
The Impact of ICP: Patients with mean ICP greater than 20 mmHg during hospitalization have 47% mortality vs. patients with mean ICP below 20 mmHg, who have 17% mortality (p < 0.001)1
17% will have seizures during the 2-year post-trauma period2
The length of time a patient spends in a coma The length of time a patient spends in a coma correlates to both post-traumatic amnesia and correlates to both post-traumatic amnesia and recovery timesrecovery times
1: Balestreri M, Czosnyka M et al. Impact of intracranial pressure and cerebral perfusion pressure on severe disability and mortality Balestreri M, Czosnyka M et al. Impact of intracranial pressure and cerebral perfusion pressure on severe disability and mortality after head injury. Neurocrit Care. 2006,;4(1):8-13. after head injury. Neurocrit Care. 2006,;4(1):8-13.
2: Englander J; Bushnik T et al. Analyzing risk factors for late posttraumatic seizures: a prospective, multicenter investigation. Arch 2: Englander J; Bushnik T et al. Analyzing risk factors for late posttraumatic seizures: a prospective, multicenter investigation. Arch Phys Med Rehabil 2003 Mar;84(3):365-73.Phys Med Rehabil 2003 Mar;84(3):365-73.
Severe TBI - Prognosis- The Stories of DM and PV -
Severe TBI - Prognosis- The Stories of DM and PV -
Case 1 - DMCase 1 - DM 18-year-old boy hit by car while riding bike18-year-old boy hit by car while riding bike Severe TBI with frequent spikes in ICP, ventilator dependantSevere TBI with frequent spikes in ICP, ventilator dependant 2 weeks in coma2 weeks in coma Walked out of hospital after 2.5 weeks, able to communicate with Walked out of hospital after 2.5 weeks, able to communicate with
familyfamily
Case 2 - PVCase 2 - PV 38-year-old man falls down stairs in bar38-year-old man falls down stairs in bar Severe TBI --> goes in and out of coma for 2 weeksSevere TBI --> goes in and out of coma for 2 weeks 2 weeks into hospital course, swelling increases so much that 2 weeks into hospital course, swelling increases so much that
temporal lobe herniates into brain stem, causing permanent loss of temporal lobe herniates into brain stem, causing permanent loss of consciousnessconsciousness
Dies after 1.5 months in hospital of brain infection, respiratory failureDies after 1.5 months in hospital of brain infection, respiratory failure
Case 1 - DMCase 1 - DM 18-year-old boy hit by car while riding bike18-year-old boy hit by car while riding bike Severe TBI with frequent spikes in ICP, ventilator dependantSevere TBI with frequent spikes in ICP, ventilator dependant 2 weeks in coma2 weeks in coma Walked out of hospital after 2.5 weeks, able to communicate with Walked out of hospital after 2.5 weeks, able to communicate with
familyfamily
Case 2 - PVCase 2 - PV 38-year-old man falls down stairs in bar38-year-old man falls down stairs in bar Severe TBI --> goes in and out of coma for 2 weeksSevere TBI --> goes in and out of coma for 2 weeks 2 weeks into hospital course, swelling increases so much that 2 weeks into hospital course, swelling increases so much that
temporal lobe herniates into brain stem, causing permanent loss of temporal lobe herniates into brain stem, causing permanent loss of consciousnessconsciousness
Dies after 1.5 months in hospital of brain infection, respiratory failureDies after 1.5 months in hospital of brain infection, respiratory failure
Looking to the future…Looking to the future…
Will new imaging technologies lead to advances in patient care?