Mechanisms of brain injury Evaluation of head injury



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Definitions



1995 – 1st edition

  • 1995 – 1st edition

  • 2000 – 2nd edition

  • 2007 – 3rd edition

  • Level I – Accepted principles reflecting high degree of clinical certainty

  • Level II – Strategies reflecting moderate degree of clinical certainty

  • Level III – Degree of clinical certainty not established



Definitions

  • Definitions

    • Glasgow Coma Scale
    • Intracranial Pressure
  • Mechanisms of brain injury

  • Evaluation of head injury

  • Management of head injury

    • Operative
    • Nonoperative


Introduced by Teasdale and Jennett in 1974

  • Introduced by Teasdale and Jennett in 1974

  • Consists of 3 clinical signs that have

    • Prognostic significance
    • Good reproducibility between observers
  • Scale range 3-15

  • GCS < 8 has generally become accepted as representing coma / severe head injury





Normal CPP > 50 mm Hg

  • Normal CPP > 50 mm Hg

  • Autoregulatory mechanisms maintain CBF at CPP’s down to 40 mm Hg



In head injury, ICP > 20-25 mm Hg may be more detrimental than low CPP (increasing CPP may not afford protection from intracranial hypertension).

  • In head injury, ICP > 20-25 mm Hg may be more detrimental than low CPP (increasing CPP may not afford protection from intracranial hypertension).

  • Aggressive attempts to maintain CPP > 70 should be avoided due to ARDS (Level II)

  • CPP<50 should be avoided (Level III)



Definitions

  • Definitions

    • Glasgow Coma Scale
    • Intracranial Pressure
  • Mechanisms of brain injury

  • Evaluation of head injury

  • Management of head injury

    • Operative
    • Nonoperative


Impact injury

  • Impact injury

      • Cerebral or brainstem contusions
      • Cerebral lacerations
      • Diffuse axonal injury (DAI)
  • Secondary injury

      • Intracranial hematoma
      • Edema
      • Ischemia


Statistics

  • Statistics

  • Definitions

    • Glasgow Coma Scale
    • Intracranial Pressure
  • Mechanisms of brain injury

  • Evaluation of head injury

  • Management of head injury

    • Operative
    • Nonoperative


History

  • History

    • LOC +/-
    • Intoxicants
    • Seizure
    • Posttraumatic amnesia


CT

  • CT

      • Imaging study of choice for initial work-up
  • MRI

      • More helpful later in hospital course
  • Skull x-rays

  • Arteriography



Presence of any criteria placing patient at moderate or high risk for intracranial injury

  • Presence of any criteria placing patient at moderate or high risk for intracranial injury

  • Assessment prior to general anesthesia for other procedures



Definitions

  • Definitions

    • Glasgow Coma Scale
    • Intracranial Pressure
  • Mechanisms of brain injury

  • Evaluation of head injury

  • Management of head injury

    • Operative
    • Nonoperative


Nonoperative

  • Nonoperative

      • Seen in absence of significant intracranial mass lesion.
      • Typically consists of assessment and/or treatment of intracranial pressure (ICP).
  • Operative

      • Typically required when a significant intracranial mass lesion is present.
      • Decompressive craniectomy or brain resection less common.


Nonoperative

  • Nonoperative

      • Seen in absence of significant intracranial mass lesion.
      • Typically consists of assessment and/or treatment of intracranial pressure (ICP).
  • Operative

      • Typically required when a significant intracranial mass lesion is present.
      • Decompressive craniectomy or brain resection less common.


Frequent neuro checks

  • Frequent neuro checks

  • Frequent neuro checks

  • Frequent neuro checks

  • ICP monitoring



No data to support Level I recommendation

  • No data to support Level I recommendation

  • Severe head injury (GCS 3-8) with abnormal CT (Level II)

  • Severe head injury (GCS 3-8) with normal CT and 2 of the following (Level III):

  • Mild-moderate head injury at discretion of treating physician



Loss of neurological examination

  • Loss of neurological examination

      • Sedation
      • General anesthesia


20 y.o. male in MVA

  • 20 y.o. male in MVA

    • Intubated
      • Score 1T
    • Eyes open to pain
      • Score 2
    • Briskly localizes
      • Score 5
      • Total GCS 8T






First tier

  • First tier

      • Positioning
      • Ventricular drainage
      • Osmotic diuresis
      • Hyperventilation (Level III – temporizing measure)
  • Second tier

      • Sedation
      • Neuromuscular blockade
      • Hypothermia
      • Barbiturate coma
  • Glucocorticoids not recommended (Level I)



Nonoperative

  • Nonoperative

      • Seen in absence of significant intracranial mass lesion.
      • Typically consists of assessment and/or treatment of intracranial pressure (ICP).
  • Operative

      • Typically required when a significant intracranial mass lesion is present.
      • Decompressive craniectomy or brain resection less common.


Types of mass lesions

  • Types of mass lesions

      • Epidural hematoma
      • Subdural hematoma
      • Cerebral contusion
  • Decompressive craniectomy/brain resection





1% of head trauma admissions

  • 1% of head trauma admissions

  • Male: Female = 4:1

  • Source of bleeding is arterial in 85% of cases (middle meningeal artery)

  • Mortality ranges from 5-10% with optimal management

  • Neurological injury caused by secondary mechanisms







About twice as common as EDH

  • About twice as common as EDH

  • Mortality 50-90%

      • Impact injury much higher than with EDH
      • Often associated brain injury
  • Two common sources of bleeding



Often little mass effect

  • Often little mass effect

  • Not often operative







2 mechanisms of brain injury

  • 2 mechanisms of brain injury

      • Impact injury
      • Secondary injury
  • GCS < 8 has generally become accepted as representing coma / severe head injury

  • CT is generally the imaging study of choice in the acute assessment of head injury

  • Operative and nonoperative strategies are generally aimed at reducing mass effect and, therefore, reducing ICP

  • Nothing beats a neuro exam.




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