Neurology

 

• Background

  Injury types

  Head injury types:

  • Skull fractures: linear, depressed, open, or basal.
  • Intracranial bleeds: acute extradural (aka epidural), acute subdural, subarachnoid, or intracerebral.
  • Diffuse brain injury: concussion (mild TBI), diffuse axonal injury.
  • Contusions: areas of focal brain injury, either coup – direct damage by impacted skull – or contre coup – brain squashed remotely from area of impact.

  Traumatic brain injury (TBI):

  • Describes any head or neck injury which results in disruption of brain function.
  • Classified as mild (GCS 13-15 at 30 mins post-injury), moderate (GCS 9-12), or severe (GCS ≤8), with mild TBI (concussion) accounting for the vast majority of cases.

  Pathophysiology

  Pathological consequences of head injury:

  • ↑ICP
  • Focal neurological deficits.
  • Secondary brain injury: ↓perfusion from ↑ICP, vascular damage, or hypovolaemia.

  Cerebral perfusion and the Cushing reflex:

  • Cerebral perfusion pressure (CPP) = mean arterial pressure (MAP) – intracranial pressure (ICP).
  • A CPP of ≥70 mmHg is usually sufficient, and as ICP is usually ~10 mmHg, there is sufficient cerebral perfusion within normal MAP ranges.
  • As ICP rises, MAP may rise in response to maintain CPP. The Cushing reflex is a combination of ↑BP, irregular breathing, and ↓HR in response to ↑ICP.

• Concussion

  Definition

  Concussion is often synonymous with mild traumatic brain injury (GCS 13-15 at 30 mins post-injury), though some use it specifically to refer to the symptoms that results from mild TBI.

  Symptoms

  • Mild behavioural or cognitive changes, including confusion.
  • Amnesia, which may include both the event (retrograde) and following (anterograde).
  • Loss of consciousness (up to 30 minutes).
  • Focal neurological deficits can occur, though should raise suspicion for more severe injury.
  • Initial symptoms often resolve within minutes, but others – headache, nausea, dizziness, imbalance, fatigue, irritability – may persist for hours, days, or even weeks. 90% recover within 1-2 weeks, but persistence beyond this is possible and is known as postconcussion syndrome.

• Subdural haematoma (SDH)

  Commonest type of bleed in traumatic head injury.

  Signs and symptoms

  • Drowsy
  • Physical or cognitive slowing, personality changes.
  • Nausea and vomiting
  • ↑Signs of ICP.
  • Urine incontinence (also suggests normal pressure hydrocephalus).
  • Can be acute or chronic, the latter not presenting until weeks or months post trauma.

  Risk factors

  3As:

  • Age
  • Anticoagulation
  • Alcohol

• Epidural haematoma and herniation

  Aka extradural haematoma/haemorrhage.

  Pathophysiology

  • Bleed from vessels supplying skull or dura, causing dura to separate from skull. Commonly the middle meningeal artery beneath the temple, and may have associated parietal or temporal fracture.
  • Rare but carries high mortality.

  Signs and symptoms

  • Loss of consciousness or concussion – from the initial impact – then lucid period as haematoma expands and is initially accommodated.
  • Eventually, expanding mass no longer accommodated, and ↑ICP leads to further loss of consciousness and uncal herniation through tentorium.
  • Compression of CN3 as it passes through tentorium leads to constricted then dilated pupil on affected side, with contralateral hemiparesis.
  • Eventually other pupil affected, followed by coning as brain stem is pushed through foramen magnum.

• Investigations

  Initial assessment:

  • Glasgow coma scale (GCS).
  • The extent of amnesia, both retrograde (before the accident) and anterograde (can't form new memories), is an indication of severity.
  • Consider cervical-spine injuries. X-ray ± CT if suspected.

  CT head

  Use guidelines or a clinical decision rule to decide whether or not to CT: NICE, Canadian CT head, or New Orleans.

  Common criteria for scanning are any one of CSF NOT BAD:

  • Comatose: GCS <13 on arrival or <15 2 hours post-accident.
  • Seizure
  • Suspected skull Fracture, including signs of basal fracture: panda eyes (periorbital ecchymosis), Battle's sign (mastoid ecchymosis), hemotympanum, or CSF leak from ear/nose.
  • Focal Neurological deficit.
  • Old i.e. age ≥65 plus amnesia, LOC, or dangerous mechanism.
  • Two or more vomiting episodes.
  • Blood thinners or bleeding disorder.
  • Amnesia (retrograde) of ≥30 mins pre-event.
  • Dangerous mechanism plus amnesia, LOC, or age ≥65: cyclist/pedestrian vs. car without helmet, MVC with ejection/rollover/other fatality, fall >1 m or >5 stairs.

  In kids, use PECARN and/or clinician judgement (CATCH and CHALICE are less validated alternatives). Basic approach:

  • Scan if GCS <15 or signs of skull fracture.
  • Observe if transient altered mental status (LOC >5 seconds, amnesia >5 minutes), severe symptoms (vomiting ≥3 times or severe headache), non-frontal scalp hematoma, or dangerous mechanism (as for adult plus struck by high-speed projectile).

• CT head findings

  • Extra-dural haemorrhage: lentiform shape, skull fracture.
  • Sub-dural haematoma: banana shape all along one side, midline shift, shrunken ventricles.
  • Sub-arachnoid haemorrhage: hyperdense (white) areas in the basal cisterns and sulci, highlighting their shape.
  • Ischaemic stoke: hypoattenuation in a vascular distribution.
  • Abscess and brain tumour: ring-enhancing lesion, as the walls are vascularised but the core isn't.

• Management

  Initial management:

  • Analgesia. Pain can increase ICP.
  • Neurosurgical referral if there are (a) persistent symptoms after initial management, (b) focal neurological deficits, or (c) significant findings on CT. Consider urgent referral – before CT – if GCS ≤8 and/or open fracture.

  Safe discharge:

  • Criteria: GCS 15, eating and drinking (not vomiting), neuro signs largely resolved.
  • Give verbal and written post-discharge advice. For concussion, avoid activities with risk of recurrent injury while still symptomatic. However, traditional advice of complete and prolonged rest from all activities now replaced by advising brief rest then early, controlled return to normal daily activities.
  • Need someone at home to monitor them for initial 24 hours.