Head Trauma and TBI

Question 1

assessing the patient

Answer 1

• serial exams!!
• extracranial vs intracranial priorities
• address life-threatening extracranial factors first

Question 2

extracranial priorities

Answer 2

• airway obstruction
• oxygenation
• ventilation
• volume status
• penetrating wounds

Question 3

neurologic assessment

Answer 3

• initial neuro exam
  
  • level of consciousness
  • motor activity
  • brain stem reflexes
• initial assessment may be brief and interpreted in light of the systemic status
• thorough exam can be performed once stabilizing therapy has been instituted

Question 4

Modified Glasgow Coma Scale (MGSC)

Answer 4

• three categories
  
  • level of consciousness (1-6)
  • motor activity (1-6)
  • brain stem reflexes (1-6)
• maximum score 18
• aid in prognosis
  
  • initial vs serial evals
  • objective assessment of progression of neuro signs

Question 5

MGCS: Motor Activity

Answer 5

• 6: normal gait, normal spinal reflexes
• 5: hemiparesis, tetraparesis, or decerebrate activity
• 4: recumbent, intermittent extensor rigidity
• 3: recumbent, constant extensor rigidity
• 2: recumbent, constant extensor rigidity with opisthotonus
• 1: recumbent, hypotonia of muscles, depressed or absent spinal reflexes

Question 6

MGCS: Brain Stem Reflexes

Answer 6

• 6: normal PLRs and oculocephalic reflexes
• 5: slow PLRs and normal to reduced oculocephalic reflexes
• 4: bilateral unresponsive miosis with normal to reduced oculocephalic reflexes
• 3: pinpoint pupils with reduced to absent OCRs
• 2: unilateral, unresponsive mydriasis with reduced to absent oculocephalic reflexes
• 1: bilateral, unresponsive mydriasis with reduced to absent oculocephalic reflexes

Question 7

MGCS: Level of Consciousness

Answer 7

• 6: occasional periods of alertness and responsive to environement
• 5: depression or delirium, capable of responding, but response may be inappropriate
• 4: semicomatose, responsive to visual stimuli
• 3: semicomatose, responsive to auditory stimuli
• 2: semicomatose, responsive only to noxious stimuli
• 1: comatose, unresponsive to noxious stimuli

Question 8

normal brain physiology

Answer 8

• brain receives 15-20% of CO
• CBF dependent on:
  
  • systemic BP
  • cerebral metabolic rate
  • PaO2 & PaCO2
• high metabolic demand (glucose)
• low tolerance for hypoxia
• autoregulation b/w MAP 50-150 mmHg

Question 9

primary injury

Answer 9

• occurs at time of accident
  
  • direct injury of intracranial structures-concussion, contusion, laceration
• little that can be done
  
  • exceptions: surgical mgmt of hematomes and depressed skull fxs and FBs

Question 10

secondary injury

Answer 10

• TBI triggers series of biochemical events ultimately resulting in neuronal cell death at local and distant sites from primary injury
• minutes to days following initial injury
• severity of secondary injury is the most important determinant of outcome
  
  • brain damage -> neuronal dysfunction -> cell death
• combo of systemic and intracranial insults

Question 11

extracranial phenomenon

Answer 11

• BP alterations
• anemia
• hypercapnia (vasodilation)
• infection
• electrolyte abnormalities (arterial BG)

Question 12

intracranial alterations

Answer 12

• ischemia
• cerebral edema
• increased ICP

Question 13

cerebral perfusion pressure

Answer 13

• worsening of cerebral injury due to compromised CPP (40-120 mmHg)
• CPP = MAP - ICP
• MAP >90 mmHg ideal
• ICP 5-12 mmHg

Question 14

Monro-Kellie Doctrine

Answer 14

V(IC) = V(brain) + V(CSF) + V(blood) + V(mass-lesion)

sudden increases in any of these volumes can lead to dramatic increases in ICP

Question 15

Cushing’s reflex

Answer 15

increased ICP -> decreased CBF -> accumulation of CO2 -> vasomotor center -> sympathetic response -> elevation of MAP -> baroreceptors -> reflex bradycardia

=HYPERTENSION AND REFLEX BRADYCARDIA

Question 16

treatment

Answer 16

• extracranial concerns must be addressed first
• oxygen (flow by, E-tube, ventilation)
• fluids (crystalloids, blood products)
• pain mgmt (neuro exam first! no meds that induce vomiting)
• hyperosmotic agents
• NO CORTICOSTEROIDS
• furosemide (not recommended)
• head elevation
• nutrition
• therapeutic hypothermia
• insulin?

Question 17

hypertonic saline

Answer 17

• smaller volume of resuscitation
• improves hemodynamic status
• imrpoved cardiac contractility
• decreases endothelial swelling
• possible immunodulatory effect
• will exacerbate hypernatremia
• 3-5 ml//kg IV over 15 min followed by crystalloids

Question 18

mannitol

Answer 18

• gold standard?
• osmotic diuretic
• free radical scavenger
• rheological properties
• may worsen hypovolemia and cause arterial hypotension
• can cause renal injury

Question 19

seizure prophylaxis

Answer 19

• no strong evidence to suggest that seizure prophylaxis is required
• if seizures develop, treat them!

Question 20

monitoring

Answer 20

• BP q1-2h
• continuous ECG monitoring
• continuous pulse-oxymetry
• frequent (q4-6h) neuro assessments (MGCS)
• blood gas analysis
• mgmt of recumbent patient
  
  • aspiration pneumonia
  • pressure sores

Question 21

prognosis

Answer 21

• dependent on severity of neuro signs and response to tx
  
  • use MGCS for objective assessment and px
• linear correlation b/w MGCS score and probability of survival w/i first 72 hours
• presence of hyperglycemia is poor prognostic indicator
• severely affected animals can achieve functional recovery with proper assessment, monitoring, aggressive tx and TIME