User Tools

Site Tools


head_injury_adult

head injury in the adult patient

see also:

introduction

  • the far majority of patients with minor head injury do NOT develop serious intracranial complications
    • less than 10 percent of patients with minor head injury have positive findings on CT scanning, and less than 1 percent require neurosurgical intervention
  • nevertheless, there are high risk patients (eg. those on anticoagulants) and high risk trauma which substantially increase the risk of such bleeds and for these patients, CT scan is almost mandatory (see below for indications).
  • when considering a CT brain, also consider whether a CT cervical spine is warranted at the same time.
    • in patients with brain injury after trauma, 7-20% will have Cx spine injury
    • in particular, elderly patients who have fallen over and hit their head have a high risk of C2 fractures and should have a low threshold for CT scan of cervical spine if they had complained of neck pain at any stage after the fall or if they have neck tenderness.
  • patients deemed safe for discharge home should be discharged with a carer who is given a patient information sheet so they know what to look out for, how to manage concussion and when to bring the patient back if there is deterioration or warning signs.
  • one should avoid using aspirin (acetylsalicylic acid) as an analgesic for headache in such patients due to the theoretical risk of potential for increased bleeding
  • patients should not be allowed self-discharge as a duty of care if they are significantly cognitively impaired (eg. intoxicated) and at risk, particularly if they have no suitable carer to keep an eye on them.

intracranial injuries

initial brief loss of consciousness (LOC)

  • thought to be mainly due to rotational forces acting on the reticular activating system resulting in impaired neuronal cellular function

concussion

  • impaired cognitive, emotional, memory, sleep &/or behavioural function (+/- headache, vomits, impaired balance, tinnitus) following head injury
  • post-traumatic amnesia, in which events following the injury cannot be recalled, is a hallmark of concussion
    • these patients should be considered for admission to hospital whilst they are failing a PTA score
  • the neural damage involved in causing concussion is NOT detectable on CT scan or MRI and is thought to be a milder form of diffuse axonal injury
  • ~90% resolve within 10 days
  • it appears resting of the brain is helpful in allowing early resolution
  • risk factors for delayed recovery include:
    • age > 55yrs
    • previous head injury
    • substance abuse
    • depression
    • stress
    • other major injuries
  • premature return to work may not only prolong the impairment, but the impairment may result in occupational accidents from the impaired judgement or skills.
  • post-concussion syndrome:
    • concussion symptoms which may last for weeks or months, or occasionally even become permanent
  • second impact syndrome
    • in rare cases, it is possible that a 2nd head injury in the days or weeks after an initial concussion during the post-concussion syndrome period may result in catastrophic brain injury
  • multiple episodes may lead to either:
    • chronic traumatic encephalopathy (CTE)
      • associated with accumulation of tau protein in the brain
      • may also be associated with repeated “sub-concussions” in contact sports
      • 3 or more concussions are thought to increase risk of long term memory problems by 3x and early onset dementia by 5x
    • dementia pugilistica
      • usually commences some 12-16yrs after commencement of a boxing career and occurs in some 15-20% of professional boxers
      • appears to be a genetic pre-disposition
      • also tends to have parkinosinian features

diffuse axonal injury (DAI)

  • usually results from acceleration injury due to traumatic rotation of the head causing mechanical forces to act on the long axons leading to axonal structural failure.
  • the usual cause for persistent impaired consciousness
  • the deeper the white matter lesion, the more profound and persistent the impairment of consciousness
  • this is present on post-mortem in 30-40% of those with traumatic brain injury who die
  • this injury is not visible on CT scan but requires MRI
  • DAI and younger age may contribute to an increased risk of developing dysautonomia

extradural haematoma

  • 85% result from bleeding from the middle meningeal artery
  • often associated with a “lucid interval” until the mass effect compromises the brainstem and consciousness falls.
  • convex on CT scan
  • may require emergency neurosurgical drainage to prevent death

subdural haematoma

  • the most common surgical intracranial lesion and is found in 20-40% of patients with severe injuries
  • concave appearance on CT scan +/- midline shift
  • discuss with NSurg:
    • patients with GCS 15 and normal PTA score with a small subdural may be considered for discharge home if a repeat CT brain 24hrs later shows no progression
    • other patients may require immediate transfer to a tertiary neurosurgical centre

intraventricular haemorrhage

  • an indicator of severe brain injury and may result in post-traumatic hydrocephalus and require emergent placement of an intraventricular catheter or a V-P shunt if chronic hydrocephalus develops

Duret haemorrhages

  • small punctate hemorrhages that are often caused by arteriole stretching during either primary injury, or secondarily due to transtentorial herniation
  • commonly lethal when they occur in the brainstem

secondary injuries

  • following head injury for a period of days, the brain is especially vulnerable to changes in intracranial pressure, blood flow, and anoxia
  • ischaemia
    • neurons in the injured brain are very sensitive to even moderate hypoxia perhaps due to left shift of Hb-O2 dissociation curve from respiratory alkalosis, and from regional vasospasm and impaired autoregulation of cerebral blood flow
  • cerebral oedema
    • vasogenic due to breach of BBB
    • cytotoxic due to cellular damage
  • raised inctracranial pressure (ICP)
  • vasospasm
  • infection
  • seizures
  • hydrocephalus
  • hypoxic insult
  • hypercapnia
  • metabolic insults from deranged metabolic states eg. hyperglycaemia, hyponatraemia, etc.

role of CT brain in head injury

  • helps exclude acute haemorrhage such as extradural (epidural), subdural and intraventricular bleeds as well as intracerebral bleeds
  • helps define anatomic location of lesions although posterior fossa tends to be poorly depicted
  • demonstrates mass effect and midline shift, and evidence of uncal herniation
  • helps identify skull fractures although depressed fractures at the vertex can be difficult to see
  • sensitive in detecting intracranial air indicating penetrating injury
  • sensitive in detecting foreign bodies
  • NOT sensitive for concussion which is a clinical diagnosis, nor is it sensitive for cerebral contusions in the early phases
  • NOT sensitive for detecting diffuse axonal injury (DAI) nor tiny haemorrhages such as Duret haemorrhages

indications for CT brain in adults with head injury

NICE 2014: scan within 1 hour

  • GCS < 13 on arrival
  • GCS < 15 at 2hrs
  • suspected open/depressed skull #
  • signs of base of skull #
  • post-traumatic seizure
  • focal neurology
  • > 1 episode of vomiting

NICE 2014: scan within 8hrs if

  • on warfarin, or,
  • some LOC/amnesia and one of:
    • age > 65
    • history of bleeding/clotting disorder including clopidogrel or aspirin (acetylsalicylic acid)
    • dangerous mechanism (eg. pedestrian/cyclist hit by car, ejection from car, fall > 1m or 5 stairs)
    • >30 mins retrograde amnesia for events prior to injury

older indications

  • decreased GCS or falling GCS
  • penetrating injury
  • clinical evidence of fracture base of skull - CSF rhinorrhoea, haemotympanum, Battle's sign, or racoon eyes, etc.
  • drug or alcohol intoxication
    • be aware that these patients may be slow bleeders and initial CT scan may be normal
  • persistent vomiting
  • seizures
  • increasing headache
  • suspected depressed skull fracture
  • some2) would also consider CT scan if either:
    • age > 60 years
    • new deficits in short-term memory
    • physical evidence of trauma above the clavicles
    • any headache or vomiting

references

1)
JAMA Neurology 2016. Brophy G, Welch R, Papa L, et al. Time Course and Diagnostic Accuracy of Glial and Neuronal Blood Biomarkers GFAP and UCH-L1 in a Large Cohort of Trauma Patients With and Without Mild Traumatic Brain Injury.
head_injury_adult.txt · Last modified: 2020/05/25 11:09 by gary1