Neurotrauma
What you must own
Traumatic brain injury is a core topic. Understand the primary injury (contusion, diffuse axonal injury, haematoma) versus secondary injury (hypoxia, hypotension, raised ICP, seizures). Know the Glasgow Coma Scale components and severity bands (mild 13-15, moderate 9-12, severe 3-8).
Haematomas: epidural (lens-shaped, middle meningeal artery, lucid interval), subdural (crescent-shaped, bridging veins, elderly/anticoagulated), subarachnoid haemorrhage, intracerebral contusion (classically frontal and temporal poles). Recognise diffuse axonal injury (grey-white junction, corpus callosum, brainstem; often normal CT).
Management principles: ABCDE, avoid hypoxia and hypotension (both worsen outcome), maintain cerebral perfusion pressure (MAP minus ICP), head elevation, avoid hypercapnia, hypertonic saline or mannitol for raised ICP, and surgical indications (e.g. epidural haematoma >30 cm³ or >15 mm thickness, midline shift >5 mm).
Spinal trauma: know the ASIA scale, clearance of the cervical spine, and the role of steroids (not routine; controversial).
Traps
Questions test the lucid interval (epidural) versus progressive decline (subdural). Another trap: knowing that hypotension is the most common avoidable cause of secondary injury. Beware over-reliance on CT in diffuse axonal injury.
Rule of thumb
CPP = MAP - ICP. Aim to keep CPP adequate (~60-70 mmHg) while avoiding hypotension and hypoxia.
Worked example
A young patient struck on the temple has a brief loss of consciousness, a lucid interval, then rapid decline. CT shows a biconvex hyperdense collection. This is an epidural haematoma from middle meningeal artery injury, and urgent surgical evacuation is indicated.