Head Trauma - Dogwood Veterinary Emergency & Specialty Center

download report

Transcript Head Trauma - Dogwood Veterinary Emergency & Specialty Center

Martin Young DVM , MS, DACVIM
Mike Higginbotham, DVM, DACVIM
Blackwater Falls
Common causes
Presenting signs
Hit by automobile
Primary injury – initial insult. Function of
trauma and forces.
Linear, rotational
Coup vs counter coup
Brief loss of consciousness
Bruising of parenchyma and secondary edema
Tissue laceration
Physical disruption of the parenchyma
Intra-axial and extra-axial hematomas
• Secondary injury
cascade of biochemical pathways initiated which lead to
further brain injury and increased intracranial pressure
• Edema
•Vasogenic and cytotoxic vicious cycle of tissue damage
• Occurs minutes to hours after initial insult
• Series of events that perpetuate and initiate
cellular damage
• Driven primarily by cerebral ischemia
Hypotension, hypoxia, and  perfusion
• Hypotension, hypoxia, and  perfusion
• ATP depletion
• Na+ and Ca++ influx
• Cytotoxic edema
Other cascades
Platt & Olby. BSAVA Manual of Canine and Feline Neurology
Pressure autoregulation
Chemical autoregulation
Intracranial compliance
Monroe-Kelly Doctrine
• Epidural
• Subdural /
• Parenchymal
Subdural / Subarachnoid
T2 image
Head Trauma
Looking for head trauma
25% of trauma patients have head trauma
MGCS – only evaluates BS function
PTE is a common cause of epilepsy 6.8%
36% of head trauma patients had seizures
DWI - hemorrhage detected by 30 min
MRI is useful for prognostication
Step 1:
• Focus on ABC’s
• Correct hypoxia and hypotension first, will help the brain as well
as the rest of the patient and will allow you to better assess your
patients neurological status
• Baseline labwork: PCV, TS, CBC, Chem, Urinalysis, and Wt.
• Can’t accurately assess the mentation of a shocky
Postures and respiration
• Postures: decerebrate vs decerebellate vs schiff
• Respiration:
 Cheyne-Stokes – deep cerebral and rostral BS –rapid
breathing followed by apnea
 Central hyperventilation – 25/min – regardless of CO2
content – midbrain to Pons
 Irregular gasping – caudal BS - terminal
Gait and Posture
Paresis, circling, paralysis
Normal, opisthotonus, decerebrate rigidity
Mental status
Bright, depressed, stuporous, comatose
Vestibular signs
Size, symmetry, response to light
Decerebrate rigidity
Step 2:
• Part 1 complete. Patient is normovolemic and normotensive
and we have established appropriate oxygenation and
• Assess the rest of the patient:
 Nervous system, vertebral fractures/ luxation, lungs, abdomen,
• Additional Diagnostics:
 Radiographs: skull, abdomen, thorax
 Additional bloodwork if indicated
 MRI/CT, electrodiagnostics
Modified Glasgow Coma Scale
• Published in a 2001 JVIM article by Dr. Simon Platt
• Evaluates the patient using 3 criteria and assigns a severity score
from 1-6 to each:
 Level of Mentation
 Motor Function
 Brainstem Reflexes
• Score assigned from 3-18; higher the score, better prognosis
Basic Levels of Mentation
• Bright, alert, responsive
• Obtunded
 Dull, depressed but responsive to all manner stimuli
• Semi-coma
 responsive to stimuli
• Stuporous
 responsive only to noxious stimuli
• Comatose
 unconscious, non-responsive to any stimuli
MGCS: Levels of Mentation
• 6 - BAR or intermittent periods BAR
• 5 – obtunded – clouded consciousness
• 4 – semi-coma - responsive to visual stimuli
• 3 – semi-coma - responsive to auditory stimuli
• 2 – stuporous – responsive to vigorous stimulation
• 1 - comatose
Brain Stem Reflexes
6 - Normal PLR and oculocephalic reflex (OcR)
5 - Slow PLR, normal to slow OcR
4 - Bilateral unresponsive miosis, normal to slow OcR
3 - Pinpoint pupils, reduced to absent OcR
2 - Unilateral, unresponsive mydriasis, reduced to absent OcR
1 - Bilateral, fixed dilated pupils
Pupil Chart
De Lahunta - Vet Neuroanatomy
Oculocephalic Reflex
• AKA - conjugate eye movements
• Pathway between the vestibular system and the extraocular muscles to
coordinate eye movements
• Pathway travels through the central brainstem in the medial longitudinal
fasciculus before connecting with CN III, IV and VI and exiting the brainstem
• Loss of oculocephalic reflex = Poor Prognosis
 Denotes severe brainstem damage
MGCS: Motor Assessment
• 6 - Normal gait, normal spinal reflexes
• 5 - Hemiparesis, tetraparesis
• 4 - Recumbent, intermittent extensor rigidity
• 3 - Recumbent, constant extensor rigidity
• 2 - Recumbent, constant extensor rigidity w/ opisthotonus (decerebrate
• 1 - Recumbent, hypotonia of muscles, depressed/absent spinal reflexes
MGCS Score
• Now, have your MGCS score, what does it mean?
 Score 15-18: Good prognosis
 Score 9-14: Guarded prognosis
 Score 3-8: Grave prognosis
• A linear association between score during first 48 hours
and patient overall prognosis
• Score = 8 in the JVIM paper resulted in 50% mortality
Cushing Reflex
• KEY: Decreased mentation, high systemic MAP, low heart rate suspect high ICP
 Increased ICP results in decreased CBF which regionally increases CO2
 High CO2 sensed by vasomotor center in the brain and triggers a massive
sympathetic discharge resulting in a peripheral vasoconstriction
 Result is a rise in MAP to maintain CPP
 Activates baroreceptors creating the reflex bradycardia
Can have fewer signs
Menace deficit
Behavior changes
Sensory/proprioceptive deficits (contralateral)
Large circles to the lesion
Altered homeostasis (temperatue, heart rate, blood pressure)
• Radiographs Unlikely to reveal additional clinically useful information but
may show depressed skull fractures
• Presence of a skull fracture has not been shown to be a negative
• Often, CT or MRI warranted to assess for severity of injury, hemorrhage, and
Head Trauma
Treating the Head Trauma Patient
• Therapeutic Options:
 Mannitol/hypertonic
 Fluids
 Anticonvulsants
 Antibiotics
 Steroids?
Patient care
Mannitol: MOA
Osmotic diuretic: decreases vasogenic cerebral edema and
decreases ICP
Reflex cerebral vasoconstriction as a result of decreased blood
Free-radical scavenger
Improves microvascular flow; shrinks RBCs by 15% and improves
deformation and cell wall flexibility hence improving tissue
Hypertonic saline MOA
• Osmotic draw: pulls fluid from interstitial and intracellular space
• Improves: MAP, CBP and CBF
• Volume expansion: not used in dehydration or hypernatremia.
• Can cause vago-reflex – may need atropine
Mannitol/hypertonic saline
• Indications:
 Clinical indication of increased ICP
 Progressive decline in neurological status
 Cushing’s reflex
• Dose:
• mannitol 1 to 1.5 g/kg IV over 20 minutes
• Hypertonic saline 3-5 ml/kg over 10 minutes
• Effect
• Mannitol max effect in 20 min last 2-5 hrs repeat q6-8
• Hypertonic saline max effect in minutes, last 1 hour
Mannitol/hypertonic saline
• Do not give if dehydrated/volume depleted
• Monitor electrolytes
• Monitor weight/hydration
• No hypertonic saline if hypernatremic
Maintain Oxygenation
• Evaluate mucous membrane and tongue color, respiratory rate,
pattern and thoracic auscultation
 Arterial Blood Gas: PaO2 > 90 mmHg
 Pulse Oximetry: Maintain SpO2 > 95%
• Provide supplemental oxygen
Flow-by or mask oxygenation or tent
O2 cage does not allow frequent patient assessment
Nasal O2 - avoid sneeze induction which increases ICP
Intubation / Ventilation
No Corticosteroids
• Are contra-indicated in both veterinary and
human medicine for the treatment of head
• All studies show either no improvement or a worsening of the
• Commonly associated with iatrogenic hyperglycemia and worse
• Does not help with cytotoxic edema only vasogenic edema
• Promote anaerobic metabolism – increase lactate
• Increase glutamate levels and neuronal death.
Hyperglycemia and Head Trauma
• Hyperglycemia > 200 mg/dL has been associated with
increased mortality in severely brain injured people
• JAVMA, 2001 paper positively correlated degree of
hyperglycemia with severity of brain injury
 Paper failed to correspond to overall patient prognosis but parallels
human papers which correlated higher BG with lower GCS score
• Current guideline:
 Avoid iatrogenic elevation of blood glucose
• Ideal Analgesic
 Agent that provides pain relief without inducing respiratory
depression or hypotension
• Options:
Opioids – fentanyl
Benzodiazepines (reduce anxiety, muscle relaxation)
Alpha-2 agonists
Fluid Resuscitation
• Goal is to restore normovolemia and normotension
• Fluid Choices:
Crystalloids - 90 ml/kg/hr
Colloids e.g. hetastarch - 10-20 mL/kg to effect
Hypertonic saline - 4-5 mL/kg over 3-5 minutes
Blood products if indicated
• No one fluid proven to be better than another, important point is to give to
effect, don’t want to create hypertension!
• Ideal MAP = 70 - 90 mmHg, remember, CPP = MAP – ICP! (Minimum CPP 70
• Serial neurological exams necessary as the patient will change,
better or worse every 1-2h depending on patient
• Continuous BP, ECG and O2 monitoring recommended
• Serial ABG indicated if patient having difficulty breathing
appropriately to determine if ventilation is needed
• Monitor electrolytes, PCV/TS and weight twice daily
Supportive Care
Circulatory support
Padded bedding
Rotate patients
Elevation of the head 15-30° above the heart
Lubricated eyes to prevent ulceration
Anticonvulsants if indicated
Avoid jugular compression
• Not just an auditory test
• Can be a useful assessment of brainstem
• Behavior changes
• Post traumatic epilepsy (weeks to years)
• Persistent deficits
• Ventricular anomalies
Post trauma
• With time and good supportive care, many head
trauma patients can do quite well
• Most important aspect in management is
maintaining good MAP and oxygenation
Dewey, CW. Emergency Management of the Head Trauma Patient. Veterinary Clinics
of North America: Common Neurological Problems. 2000: 207-25.
Syring RS. Hyperglycemia in dogs and cats with head trauma: 122 cases (1997-1999).
JAVMA. 2001; 218(7): 1124-29.
Syring RS. Assessment and treatment of CNS abnormalities in the emergency patient.
Vet Clin Small Anim. 2005; 35: 343-358.
Platt SR. The Prognostic Value of the Modified Glasgow Coma Scale in Head Trauma
Dogs. JVIM. 2001; 15: 581-84.
Armitage-Chan EA. Anesthetic management of the head trauma patient. JVECC.
2007; 17(1):5-14.
Kalita J. Current Status of osmotherapy in intracerebral hemorrhage. Neurology
India. 2003; 51(1): 104-9.
Oliver and Lorenz. Handbook of Veterinary Neuroanatomy.
DeLahunta A. Veterinary Neuroanatomy and clinical neurology. Saunders Elsevier.