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?