# Head Injury > Head injury for FMGE Surgery: GCS grading, CT first, extradural versus subdural haematoma, ICP control targets and herniation warning signs. - Canonical URL: https://prepelephant.com/topics/fmge/surgery/head-injury - Exam / course: FMGE · Subject: Surgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Head Injury", PrepElephant, https://prepelephant.com/topics/fmge/surgery/head-injury ## Direct answer Head injury is graded by the Glasgow Coma Scale — eye opening 4, verbal 5, motor 6 — into mild (13 to 15), moderate (9 to 12) and severe (8 or less), with the severe patient needing early intubation. Non-contrast CT of the head is the first-line investigation. Extradural haematoma from middle meningeal artery bleeding gives a biconvex clot with a lucid interval, while subdural haematoma from torn bridging veins gives a crescentic clot that crosses suture lines, both treated surgically when significant. ## What you must remember - Glasgow Coma Scale components: eye opening 4, verbal 5, motor 6; a score of 8 or less means severe injury and mandates airway protection, and a fall of 2 or more points on serial assessment demands re-imaging. - A unilaterally dilated, fixed pupil means tentorial herniation compressing the oculomotor nerve; the Cushing response of bradycardia with hypertension and irregular respiration is a late sign of raised intracranial pressure. - Extradural haematoma: temporoparietal fracture tearing the middle meningeal artery, classically after a brief loss of consciousness with a lucid interval; CT shows a hyperdense biconvex collection limited by sutures, treated by urgent craniotomy. - Subdural haematoma: torn bridging veins in the elderly, alcoholic or anticoagulated patient; CT shows a crescentic collection crossing suture lines but respecting the midline, and chronic cases may present weeks later with fluctuating confusion. - Basal skull fracture signs: raccoon eyes, Battle sign, cerebrospinal fluid rhinorrhoea or otorrhoea and haemotympanum; a depressed fracture beyond the skull thickness needs elevation. - Raised intracranial pressure management: head elevation to 30 degrees, sedation, osmotherapy with mannitol or hypertonic saline, and cerebral perfusion pressure targeted at 60 to 70 mmHg. - Diffuse axonal injury follows acceleration-deceleration forces, presents in coma with a deceptively normal early CT and carries a poor prognosis; secondary injury from hypoxia and hypotension is prevented aggressively. ## Common confusion The recurring discrimination is shape and boundary: extradural collections are biconvex and stopped by sutures, subdural collections crescentic and crossing sutures but held at the midline by dural reflections. The lucid interval is classical for extradural haematoma but can occur with subdural bleeding too. Concussion is transient dysfunction without structural injury, while diffuse axonal injury shows little on early CT — a normal scan is not a mild brain injury. ## Exam-focused takeaway FMGE head injury questions trade on three currencies: GCS arithmetic with the intubation cut-off of 8; the CT description naming the haematoma and its operation; and the herniation picture of a dilated pupil or Cushing triad demanding osmotherapy and surgery. Learn the extradural-subdural pairs — vessel, shape, suture behaviour, patient type — and the basal fracture signs as quick-recall lists. Prevention of secondary injury by oxygenation and blood pressure support answers several management stems, and 60 to 70 mmHg is the perfusion pressure to quote. ## Frequently asked questions ### How is head injury severity graded? By the Glasgow Coma Scale out of 15 — mild 13 to 15, moderate 9 to 12, severe 8 or less — with intubation indicated at 8 or below. ### Which CT features distinguish extradural from subdural haematoma? Extradural is biconvex and limited by sutures from middle meningeal arterial bleeding; subdural is crescentic, crosses sutures but not the midline, from bridging vein tearing. ### What is the lucid interval? A period of apparent recovery between the initial concussion and later deterioration from an expanding extradural haematoma. ### Which signs indicate basal skull fracture? Raccoon eyes, Battle sign, cerebrospinal fluid leak from nose or ear, and haemotympanum — all contraindications to blind nasal instrumentation. ### What is the target cerebral perfusion pressure? 60 to 70 mmHg, maintained by treating raised intracranial pressure while supporting mean arterial pressure. ### What is diffuse axonal injury? Widespread axonal shearing from acceleration-deceleration forces, presenting as coma with deceptively normal early CT and a guarded prognosis.