In a patient with a major head injury, which ONE of the following secondary insults should be given the HIGHEST priority for correction in the emergency department (ED)?
Answer: C: One of the aims of ED resuscitation of a severe traumatic brain injury patient is to prevent any secondary insults to the brain. Secondary insults are the clinical conditions that may worsen the outcomes of traumatic brain injury (TBI). These differ from secondary brain injury, which are changes that occur at a cellular level resulting in expansion of the primary brain injury. Known secondary insults are increased intracranial pressure, hypotension, hypoxaemia, hypercarbia, hyperglycaemia and hyperthermia. Hypercapnia causes cerebral vasodilation and increased cerebral blood flow (CBF) and subsequently increases the intracranial pressure (ICP). Hypocapnia, secondary to hyperventilation, causes cerebral vasoconstriction. Although it potentially decreases ICP, prolonged hypocapnia through over enthusiastic hyperventilation causes cerebral ischaemia with a subsequent worse outcome. Hyperglycaemia in severe head injury is associated with a worse outcome, but the exact mechanism is still unknown. Even a single event of hypotension or hypoxaemia has been described as causing significant increase in the mortality in severe TBI. In addition to rapid correction of hypoxaemia with advanced airway management and ventilation, hypotension should be corrected with rapid fluid resuscitation and early use of vasopressors such as noradrenaline. Although not ideal, vasopressors may be commenced with peripheral intravenous access until central access is obtained. Fluid resuscitation to correct hypotension will not increase the ICP. In a trauma patient with severe TBI, early hypotension is not due to intracranial haemorrhage and therefore other sites for haemorrhage should be sought and rapidly controlled. Hypotensive resuscitation is contraindicated in these patients. In adults, to maintain an adequate cerebral perfusion pressure (CPP), a systolic BP of at least 100 mm Hg is required with a mean arterial pressure (MAP) of 80 mm Hg. This should overcome any modest rise in ICP due to TBI.
References:
Prediction of an intracranial injury visible on CT is one of the main objectives in the assessment of an adult patient with head injury.
Which ONE of the following statements is TRUE regarding this assessment?
Answer: C: Adults presenting with a Glasgow Coma Scale (GCS) of 15 and a history of head injury with loss of consciousness usually are investigated with a head CT to exclude intracranial injury. These patients are considered as having minor head injury or TBI. However, assessment of patients presenting with minor head injury but without a history of loss of consciousness can be challenging. The absence of a history of loss of consciousness alone may not be the best predictor to rule out intracranial injury. About 2% of such patients have intracranial injury visible on CT and < 1% will require neurosurgery. These rates are similar for patients who had loss of consciousness.
In addition to loss of consciousness, other clinical features in the history and examination, for example vomiting after head injury, posttraumatic seizure and posttraumatic amnesia, have similar odds ratios for having an intracranial lesion visible on head CT (positive head CT). Subsequently, there are a number of evidence-based decision rules developed to identify patients who have minor head injury and who need to have CT to exclude intracranial injury.
Reference:
Regarding a patient with diffuse axonal injury (axonal shear injury) of the brain, all of the following are correct EXCEPT:
Answer: B: Diffuse axonal injury is a severe form of traumatic brain injury secondary to severe blunt trauma such as that occurring in sudden decelerations. Additionally, it is also a well-described finding in ‘shaken baby syndrome’ due to NAI.
The axonal injury occurs at the grey–white matter interface in the cerebral hemispheres and in the brainstem. In its severest form, cerebral oedema develops rapidly, increasing ICP. This acts as a secondary insult and worsens the neurological outcome. Therefore, ED interventions should be directed at preventing and reducing any increase in ICP.
Diffuse axonal injury can be classified into four categories according to the CT appearance. In category I there are no visible abnormalities on the CT. In all other categories, lesions are present but are not of high or mixed density and always < 25 mm. In category III, significant swelling is present and in category IV this is associated with significant midline shift. However, the majority do not show any lesions or haemorrhage on CT.
Regarding intracranial haemorrhage associated with traumatic brain injury, all of the following are correct EXCEPT:
Answer: D: Although traumatic subarachnoid haemorrhage is common in TBI, this can be missed on early CT scan done within the first 6–8 hours from the time of injury. It carries a very high mortality and risk of significant permanent neurological injury. Mortality from an acute subdural haematoma is nearly three times higher than mortality from an extradural haematoma (75% vs 20–30%). This may be related to the significant neuronal injury that is often associated with acute subdural haematoma.
On non-contrast CT, an acute subdural haematoma appears over cerebral hemispheres as a hyperdense, medially concave haematoma that crosses the suture lines. A subacute subdural haematoma may appear isodense and a chronic subdural haematoma appears hypodense. In contrast, the extradural haematoma appears hyperdense (white), characteristically elliptical shaped and not crossing suture lines of the skull. Usually, it is over the temporal or temperoparietal areas and occasionally occurs in the posterior fossa. Although the history of loss of consciousness is well known to be associated with blunt trauma causing extradural haemorrhage, this feature may not be present. Even if present it is very brief in half of the patients.
Which ONE of the following statements is TRUE regarding cervical spine injuries in children?
Answer: A: The incidence of cervical spine fractures or spinal cord injury is very uncommon in children. When suspected, the application of immobilisation to children especially to infants and young children can be a challenge. In infants, the relatively large head may cause the neck to flex when immobilising in the supine position. This can be prevented by carefully placing adequate padding under the shoulders.
The common site of cervical spine fractures in children is in the upper cervical spine where the fulcrum for the flexion-extension is situated in children. In contrast, fractures occur more commonly in the lower cervical spine in adults.
Children are more likely to have spinal cord injury without radiological abnormalities (SCIWORA). Because of increasingly easy accessibility to MRI, SCIWORA appears to be a misnomer as these injuries can be detectable on MRI. The child may initially complain of transient neurological symptoms such as paraesthesia or weakness soon after the injury and a large number of these children may not get further symptoms up to a few days.
Neither NEXUS nor the Canadian cervical spine decision rules can be safely applied to children because these studies had only small numbers of children. These rules have not been validated in children.
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