Moderate and severe traumatic brain injury: Case

This boy has severe traumatic brain injury with impending herniation. A Glasgow Coma Scale of 5 after resuscitation places him deep in the severe band, and the unilateral fixed dilated pupil is uncal herniation compressing the third nerve. His hypotension and his low oxygen saturation are secondary brain insults that will double his mortality if not corrected at once, so the resuscitation and the lowering of the intracranial pressure must proceed together. [4]

Clinical findings and assessment

The key findings are the Glasgow Coma Scale of 5, the unilateral fixed dilated right pupil, the hypotension, and the borderline oxygen saturation. A score of 5 is severe injury, well below the 8 that mandates intubation, and the fixed dilated pupil is uncal herniation until proven otherwise. The hypotension, with a systolic of 78 mmHg in a 9-year-old, is itself a secondary brain insult, because it lowers the mean arterial pressure and so the cerebral perfusion pressure, and a single hypotensive episode is said to double the mortality. The glucose is normal, which excludes hypoglycaemia as a contributor. [6]

The immediate assessment is the structured primary survey. The airway is not protected at a GCS of 5, the cervical spine is presumed injured and immobilised, the breathing is compromised with a saturation of 91 percent, and the circulation is failing with the hypotension. The pupil finding localises the lesion and grades the urgency, and the weight of 28 kilograms is confirmed for the drug doses. [4]

Immediate management

The first move is to secure the airway by rapid sequence intubation, because the boy has a GCS of 5, well below the threshold of 8, and his airway is not protected. The cervical spine is immobilised throughout. After intubation he is ventilated to a PaCO2 of 35 to 40 mmHg, the normocapnic range, with a brief period of mild hyperventilation justified here only as a temporary measure for the acutely herniating child while the hyperosmolar therapy is given. Prophylactic hyperventilation is otherwise avoided. [4]

The hypotension is treated at once with isotonic fluid boluses and blood if the response is poor, because the falling mean arterial pressure is collapsing the cerebral perfusion pressure. The head is elevated to 30 degrees and kept midline, and a hyperosmolar bolus of 3 percent saline 2 to 5 mL per kg, which is 56 to 140 mL for this 28 kg boy, is given to lower the intracranial pressure. The neurosurgical team is called in parallel, because the unilateral fixed dilated pupil with hypertension and bradycardia is uncal herniation and a neurosurgical emergency, and an urgent computed tomography of the head is arranged once the airway and circulation are stable. [4]

Intensive care and the pressure ladder

The boy is admitted to the paediatric intensive care unit, an intracranial pressure monitor is placed, and the pressure is treated above the guideline threshold of 20 mmHg while the cerebral perfusion pressure is kept at least 40 mmHg. The cerebral perfusion pressure is the mean arterial pressure minus the intracranial pressure, so the two numbers are managed together, with the blood pressure supported and the pressure actively lowered. [4]

The ladder moves through the bedside measures of head elevation, midline positioning, sedation and analgesia, and cerebrospinal fluid drainage, and then the hyperosmolar therapy with 3 percent saline 2 to 5 mL per kg titrated to the pressure and the serum sodium. If the pressure remains refractory, a barbiturate coma is started, titrated to burst suppression on the electroencephalogram, and decompressive craniectomy is reserved for the genuinely refractory case. Prophylactic anticonvulsants are given to prevent the early post-traumatic seizures, and the boy is kept normothermic, because the Hutchison trial showed that prophylactic hypothermia does not improve outcome and can cause harm. [7][8]

Appraising the evidence

The two trials that shaped the refractory end of the ladder both showed that an aggressive intervention could do harm. The Hutchison trial of 2008 randomised children to prophylactic hypothermia or normothermia and found that the cooling did not improve the outcome and raised a concern about harm, which is why the boy is kept normothermic and hypothermia is not used. The DECRA trial of Cooper and colleagues in 2011 showed that an early decompressive craniectomy for refractory pressure was associated with worse outcomes, which is why the craniectomy is reserved for the refractory case that has failed the medical ladder rather than used early. The DECRA trial was in adults, and its conclusion is applied cautiously to this child. [7][8]

Outcome and follow-up

The prognosis of a severe injury with a fixed pupil and hypotension is guarded. The determinants of the outcome are the initial score and pupil response, the presence of hypotension and hypoxia, the lesion on the scan, and the course of the intracranial pressure, and the mortality of severe paediatric traumatic brain injury in modern series is 10 to 30 percent, with a residual disability in the majority of survivors. The boy is followed up in a structured neurorehabilitation programme that addresses the cognition, the behaviour, the school reintegration, the motor function, and the family support, because the cognitive and behavioural sequelae often emerge over the months that follow. [6]

I would counsel the family honestly at every stage. I would explain that their son has a severe brain injury, that the swelling and the pressure inside his head are the main danger in the days ahead, and that the breathing machine and the pressure monitor are there to keep his brain well oxygenated and to watch the swelling. I would name the medicines and any operation as the steps taken in order to keep the blood flowing to his brain, and I would be honest that the full extent of his recovery is not known for weeks or months. I would reassure the family that the team will watch and support him throughout, and that I will return regularly to explain the findings, the plan, and the next steps as the picture becomes clearer. [6]