Mild traumatic brain injury defined by Glasgow Coma Scale: Is it really mild?

Introduction: Conventionally, a Glasgow Coma Scale (GCS) score of 13-15 defines mild traumatic brain injury (mTBI). The aim of this study was to identify the factors that predict progression on repeat head computed tomography (RHCT) and neurosurgical intervention (NSI) in patients categorized as mild TBI with intracranial injury (intracranial haemorrhage and/or skull fracture).

Methods: This study performed a retrospective chart review of all patients with traumatic brain injury who presented to a level 1 trauma centre. Patients with blunt TBI, an intracranial injury and admission GCS of 13-15 without anti-platelet and anti-coagulation therapy were included. The outcome measures were: progression on RHCT and need for neurosurgical intervention (craniotomy and/or craniectomy).

Results: A total of 1800 patients were reviewed, of which 876 patients were included. One hundred and fifteen (13.1%) patients had progression on RHCT scan. Progression on RHCT was 8-times more likely in patients with subdural haemorrhage ≥10 mm, 5-times more likely with epidural haemorrhage ≥10 mm and 3-times more likely with base deficit ≥4. Forty-seven patients underwent a neurosurgical intervention. Patients with displaced skull fracture were 10-times more likely and patients with base deficit >4 were 21-times more likely to have a neurosurgical intervention.

Conclusion: In patients with intracranial injury, a mild GCS score (GCS 13-15) in patients with an intracranial injury does not preclude progression on repeat head CT and the need for a neurosurgical intervention. Base deficit greater than four and displaced skull fracture are the greatest predictors for neurosurgical intervention in patients with mild TBI and an intracranial injury.