Head Injury

Question 1

PATHOLOGY AND PATHOGENESIS:

a) Cerebral Injury
b) Intracranial haematomas
c) Skull fractures

Answer 1

a) - Direct disruption of brain, shearing of axons, intracerebral haemorrhage.
- Injuries at site of trauma and opposite site(contre-coup injury).
- Secondary brain injury due to brain oedema: raised ICP and cerebral herniation. This leads to hypoperfusion of the brain, hence cerebral ischaemia.
- Infratentorial lesions can obstruct CSF flow and lead to hydrocephalus

b) - Extradural haematomas due to middle meningeal artery bleeding into extradural space
- Subdural haematomas due to damage to cortical veins oozing into subdural space
- Intracerebral haematomas at site of direct trauma and contre-coup site. Most common
- Mass effects lead to cerebral herniation.

c) Simple and depressed fractures, and basal skull fractures.
- basal and compound fractures can cause a dural leak, providing route of entry of infection into the CNS.

Question 2

EXTRADURAL HAEMATOMA;

1. Pathology
2. Clinical features
3. Trauma

Answer 2

1. Bleeding into space between dura mater and skull.
   - often from acceleration-deceleration truama/blow to the side of the head.
   - majority occur in temporal region where skull fractures cause rupture of middle meningeal artery.
2. • Raised intracranial pressure
     - Lucid interval. Initial recovery from injury but later deteriorate again.
     * can also occur in neck trauma from carotid dissection and subdural haemorrhage.
3. Trauma, usually high velocity

Question 3

SUBDURAL HAEMATOMA:

1. Pathology
2. Clinical features
3. Causes

Answer 3

1. Bleeding into outermost meningeal layer.
   - most commonly frontal and parietal lobes
   - Risk f: Age, alcoholism
2. • Slower onset compared to extradural haematoma
3. Trauma, usually lower velocity

Question 4

SUBARACHNOID HAEMORRHAGE:

1. Clinical features

Answer 4

1. Usually spontaneous onset in context of ruptured cerebral aneurysm. Can be seen in association with other injuries when patient has sustained traumatic brain injury. Sentinel headache(10-43%), meningism: occipital headache, photophobia, neck stiffness.

Question 5

CLINICAL FEATURES:

Answer 5

1. Other injuries due to trauma
   - eg; chest, abdomen, cervical spine
2. Alterations in consciousness
   - GCS
3. Signs of basal skull fracture
   - periorbital bruising, Battle’s sign
   - Bleeding into middle ear presenting as blood behind ear drum/coming from external ear
   - CSF rhinorrhoea
   - Cranial nerve damage especially facial and auditory nerve.
4. Pupil reactions:
   - Unilaterally dilated with sluggish/fixed light response: 3rd nerve compression secondary to tentorial herniation.
   - Bilaterally dilated with sluggish/fixed light response: Poor CNS perfusion, bilateral 3rd nerve palsy.
   - Unilaterally dilated/equal. Marcus-Gunn/Relative afferent pupillary defect: Optic nerve injury.
   - Bilaterally constricted and difficult to assess light response: Opiates, pontine lesions, metabolic encephalopathy.
   - Unilaterally constricted with preserved light response: sympathetic pathway disruption.
5. Hyponatraemia due to SIADH

Question 6

MANAGEMENT:

Answer 6

1. IV mannitol/frusemide
   - if life-threatening rising ICP ie in extradural haematoma and while delay in transfer to theatre.
   - Mechanical ventilation and forced hyperventilation
2. Decompressive craniotomy may be required for diffuse cerebral oedema.
3. Exploratory Burr Holes if scanning unavailable
4. Surgical reduction and debridement if depressed skull fractures that are open.
5. ICP monitoring appropriate if GCS 3-8 and normal CT.
6. ICP monitoring mandatory if GCS 3-8 and abnormal CT.
7. Minimum cerebral perfusion pressure 70 mmHg in adults, 40-70 mmHg in children.
8. Can sent home with warning card if loss of consciousness <5 min, normal examination and no skull fracture.
9. Rehabilitation once stable
   - Physiotherapy
   - Occupational therapy
   - May require speech therapy

Question 7

COMPLICATIONS:

Answer 7

1. Behavioural difficulties with personality changes, frontal disinhibition and memory loss.
2. PTSD
3. Migraine-like headache
   - usually spontaneously improves over 2y
4. Anosmia
   - usually permanent
5. Post-traumatic vertigo
   - commonly BPPV
6. Post-traumatic epilepsy
   - Post-traumatic amnesia >24h has 12% risk of epilepsy in 5y

Question 8

PROGNOSIS:

Answer 8

Prognostic factors:

1. Age
2. Duration of post-traumatic amnesia
   - if ,1h, 90% back at work in 2/12.
   - if >24h, 80% back to work in 6/12.

Question 9

INTRACEREBRAL HAEMATOMA:

1. Definition:
2. Causes:

Answer 9

1. Haematomas ≥2cm, not in contact with surface of brain.

2. Trauma, Hypertension, Bleeding diathesis, lacunar aneurysm

Question 10

UNCAL HERNIATION(SECONDARY TO RAISED ICP):

1. Features
2. Management

Answer 10

1. a) With expanding intracranial haematoma, compression on ipsilateral cerebral peduncle and cranial nerve III.
   b) Contralateral limb weakness, ipsilateral pupil dilation
   c) Reduced consciousness
   d) Tonsillar descent/coning
   e) Cushing’s response: Hypertension, bradycardia, apnea/irregular breathing.

Question 11

DIFFUSE AXONAL INJURY GRADES:

1. Grade 1
2. Grade 2
3. Grade 3

Answer 11

1. Microscopic evidence of axonal injury.
   - Mild-moderate head injury with subtle cognitive and functional sequelae
2. Focal lesion in corpus callosum.
   - usually moderate-severe head injury
   - high risk of severe disability
3. Additional focal lesion in dorsolateral quadrant of rostral brainstem and corpus callosum.
   - high risk of death or persistent vegetative state

Question 12

NICE Guidance on Investigation:

Answer 12

1. CT head immediately(within 1h):
   - GCS <13 on initial assessment
   - GCS <15 at 2h post-injury
   - suspected open/depressed skull fracture.
   - Signs of basal skull fracture(haemotympanum, ‘panda’ eyes, CSF leakage from ear/nose, Battle’s sign)
   - post-traumatic seizure
   - focal neurological deficit
   - >1 episode of vomiting
2. CT head within 8h for adults with some loss of consciousness/amnesia since injury if following risk f present:
   - ≥65y
   - history of bleeding/clotting disorders
   - dangerous mechanism of injury
   - >30 mins retrograde amnesia

*if on warfarin and sustained head injury with no other indications for CT head, perform CT head within 8h of injury.