A 20 year-old man was admitted to his local district hospital with a severe head injury following an assault. On arrival in the Emergency Department he was agitated with a reduced conscious level, with evidence of blunt trauma to the head and neck. Prior to intubation, his Glasgow Coma Score (GCS) was recorded as 7 (E1V2M4), and with cervical spine precautions he underwent intubation with subsequent mechanical ventilation and sedation.
An urgent CT brain and cervical spine revealed early evidence of intracerebral contusions with diffuse areas of petechial intracerebral haemorrhage identified. Nasal and maxillary fractures were also seen, with no cervical spine pathology identified. He was transferred to the regional neurological centre for assessment and ongoing management.
On arrival in the Neurosurgical Intensive Care unit the patient underwent insertion of an intracranial pressure monitor revealing an intracranial pressure (ICP) of between 30-35 mmHg. Pupil reactivity was sluggish bilaterally. Sedation was changed to infusions of propofol, fentanyl and midazolam, positioning was optimised with 20 degree head-up tilt, endotracheal tube ties were replaced and targeted mechanical ventilation to EtCO2 4- 4.5kPa. Central venous access was established and an infusion of Noradrenaline was used to target cerebral perfusion pressure to 70mmHg.
Initial medical management stabilised ICP below 25mmHg, but within the next 12 hours this began to rise despite neuromuscular blockade and infusion of hypertonic saline. Further CT imaging revealed progression of the intracerebral contusions with developing oedema. The patient was transferred to the operating theatre for insertion of an external ventricular drain. CSF drainage resulted in an immediate but small improvement in ICP but again over the next 12 hours it began to rise, and decision was made for bifrontal decompressive craniectomy.
Subsequent recovery was slow and was complicated by ventilator-associated pneumonia, a protracted tracheostomy wean and severe agitation. The patient underwent intensive neuro-rehabilitation and had been decannulated, but was left with persistent cognitive impairment, seizures and depression.
What is the rationale for performing decompressive craniotomy in TBI?