head trauma Flashcards
What is the definition of traumatic brain injury?
a structural injury or physiological disruption of the brain induced by an external force, resulting in an acute onset of at least one of the following:
▪ A period of decreased or lost consciousness;
▪ An alteration in mental status;
▪ Neurological deficits; and/or
▪ The presence of an intracranial lesion.
How do you clincally assess dogs with traumatic brain injury?
modified Glasgow coma scale (MGCS), which evaluates motor activity, brainstem reflexes and level of consciousness.
An important predictor of outcome.
The MGCS total score ranges from 3 to 18, with the lowest score representing the worst neurological status and the lowest probability of survival within the first 48 hours after head trauma
How do you treat animals with traumatic brain injury?
successful therapy needs to focus on ensuring adequate blood and oxygen supplies to the brain, which ultimately necessitates fluid and oxygen therapy. General systemic stabilisation
Ensuring a patent airway, assessing breathing and evaluating blood pressure are vital first steps for any animal with head trauma before more specific evaluations and diagnostic testing take place. Treatment decisions should be based on the severity of the injury and the animal’s response to therapy, assessed using a tiered approach with frequent reassessment.
Sx may be needed
When should you image the brain?
CT and MRI should be reserved for patients that do not respond to initial treatment or for patients that deteriorate despite aggressive therapy. Both of these imaging modalities require anaesthesia, which can destabilise the head trauma patient, unless the animal is in a coma on presentation.
It should only be considered if a surgical option is a possibility after medical treatment has been attempted, as it provides information that may help with surgical decision‐making processes. It should probably never be a reason on its own to suggest euthanasia.
What can brain imaging identify?
Imaging of the brain may be performed to identify fractures, haemorrhage or parenchymal lesions, although TBI with severe neurological deficits can occur without the presence of skull fractures or other obvious lesions.
What does CT show?
CT allows superior evaluation of bony structures and is preferred over conventional radiography, especially considering the 3D reconstruction capabilities. It can also be used to diagnose intracranial haemorrhage, alterations in ventricular size or shape, midline shift of the falx cerebri, and brain oedema
Often CT chosen in humans as it is a lot quicker to get images and shows haemorrhage well
Outline the use of MRI
MRI provides very good soft tissue detail and is the preferred imaging technique for evaluation of the brain, especially the caudal cranial fossa, which does not give useful images with CT due to the presence of CT artefacts in this area
MRI can detect subtle parenchymal changes that may be missed on a CT scan and may provide information to aid the prognosis
Haematomas or haemorrhage, parenchymal contusions and oedema are also readily apparent on MRI images
Although CT is preferred for the evaluation of bony structures, fractures can also be identified on an MRI scan.
What on MRI is associated with worse px in people?
brain herniation, skull fractures and larger intraparenchymal lesions, possibly also brainstem lesions
What are the treatment guideline tiers?
▪ Tier 1 treatments are administered to all patients;
▪ Tier 2 treatments are administered to all patients with failure of tier 1 treatment;
▪ Tier 3 treatments are administered to all patients with a severe MGCS and failure of tier 2 treatments.
Outline tier one tx
Fluid therapy - get to normovolaemia. Need to ensure cerebral blood flow
Oxygen therapy and management of ventilation - Hypercapnia increases ICP and hypocapnia can produce cerebral vasoconstriction, resulting in a decreased ICP. A reduction in CBF and ICP following oxygenation is almost immediate, although peak ICP reduction may take up to 30 minutes
Outline tier 2 tx
Diuretics - should not be given to any patient without being certain that the patient has been volume resuscitated, Mannitol improves CBF and reduces ICP by decreasing oedema. After administration, mannitol expands the plasma volume and reduces blood viscosity, which improves CBF and delivery of oxygen to the brain. Mannitol (0.5 to 2 g/kg bodyweight) should be given as a bolus over 15 minutes to optimise the plasma‐expanding effect. It reduces brain oedema over about 15 to 30 minutes after administration and has an effect for approximately two to five hours.
Tx seizures if needed
How would you tx TBI seizures?
Diazepam (0.5 to 2 mg/kg bodyweight) can be given intravenously to treat seizures.
Phenobarbital (2 to 3 mg/kg bodyweight) may also be given intravenously or intramuscularly and continued parenterally following a loading dose (18 to 24 mg/kg bodyweight over a 24‐ to 48‐hour period) if necessary. Recently, the use of intravenous levetiracetam (20 to 60 mg/kg bodyweight) has been described for emergency seizure treatment. Levetiracetam is an attractive option because it works quickly and may be effective for up to eight hours without causing much sedation. Additionally, it is not metabolised by the liver and preclinical studies using animal models of TBI have shown efficacy of levetiracetam as a neuroprotectant.
Outline the use of sx as treatment
Surgical intervention is reserved for patients that do not improve or those that deteriorate despite aggressive medical therapy and may be indicated to remove haematomas, relieve ICP or address skull fractures. Advanced imaging (CT or MRI) is necessary for surgical planning. Compression of the ventricles due to brain oedema or haematoma and mass effects identified on advanced imaging should be considered strong indicators for surgical treatment if not responding to tx
Typically, skull fractures do not require surgical intervention. However, significantly contaminated, comminuted fractures may require surgical debridement, especially if open. In dogs, such fractures of the frontal sinus may be associated with traumatic pneumocephalus, which should be considered in any patient that deteriorates despite aggressive medical therapy. If surgical intervention is pursued, aggressive debridement should include removal of all devitalised tissues and bone, and should be guided by imaging. Large bone fragments may be spared and replaced after thorough debridement, cleaning and soaking in an antibiotic solution.
What untested options are there in tier 3?
Hyperventilation to decrease ICP
Hypothermia
