Head / Neuro trauma Flashcards
What are the layers of the scalp and cranium?
SCALP MAP
- Skin - dermis
- sub-Cutaneous tissue + blood supply
- Aponeurosis - Galea
- Loose areolar tissue - where sub-galeal haematomas form
- Pericranium -> firmly attached to the skull
- Meningeal dura mater
- Arachnoid mater
- Pia mater
What tissue produces CSF?
Where is it located?
The choroid plexus is located in the lateral ventricles.
What is the pathway of flow of CSF?
Lateral ventricles -> foramen of Munro -> third ventricle -> aqueduct of Sylvius -> fourth ventricle -> foramina of Magendie and Luschka -> subarachnoid space over brain and spinal cord -> reabsorbed into venous sinus blood via arachnoid granulations.
What are the functions of CSF?
- Protection
- Transport of nutrients and hormones
- Removal of waste
What are the functions of the Blood Brain Barrier?
Barrier to pathogens and hormones - NB also prohibits passage of some drugs and antibiotics
What is the effect of cerebral oedema on the BBB?
The permeability of the BBB increases - it becomes leaky.
List the seven secondary insults that pertain to brain injury.
- Hypotension - SBP < 90mmHg
- Ischaemia
- Infarct
- Hypoxia - paO2 < 60mmHg
- Apnoea
- Obstruction
- Poor ventilation
- Pulmonary injury
- Poor airway mgt/intubation
- -> anaerobic celluar metabolism
- Anaemia
- Reduced O2 carrying capacity
- Hyperpyrexia (T >38.5)
- Inc’d metabolic demands
- Hypercarbia
- Inc’d CO2 -> inc’d IC blood flow -> inc’d ICP
- Coagulopathy
- Inc’d IC haemorrhage
- Seizures
- Inc’d metabolic demands and toxic metabolites
What is the normal level of CSF ICP?
6-20cm H2O
List three methods of acutely decreasing ICP.
- Hyperventilation -> dec’d pCO2 -> dec’d IC blood flow -> dec’d ICP
- Osmotic and diuretic agents (hypertonic saline or mannitol) -> fluid shifts -> dec’d ICP
- Facilitate CSF drainage (ventricular or lumbar drain)
What is Cushing’s reflex?
Why does it occur?
- Hypertension
- Bradycardia
- Irregular breathing
- Inc’d ICP approaches and surpasses IC MABP -> reduced IC perfusion -> sympathetic activation -> peripheral vasoconstriction and inc’d HR -> inc’d BP to restore IC perfusion
- Aortic arch baroceptors sense inc’d BP and inc vagal tone -> bradycardia
- Inc’g ICP -> pressure on brainstem (medulla oblongata) -> irregular breathing
List the 7 causes of ALOC.
- Hypotension
- Hypoglycaemia
- Hypoxia
- Post-ictal (think stunned neurons)
- Post-intoxicating drugs
- Brain or brainstem compression due swelling or a mass
- Bleeding
What are the drugs and doses of diruetic agents that can be used to treat inc’d ICP?
- Mannitol 0.25-1g/kg IV bolus
- Hypertonic 3% normal saline - 0.1-1ml/kg/hr
How is the severity of head injuries classified?
What is the mortality rate for each?
- Mild TBI - GCS 14-15 - <0.1% mortality
- Moderate TBI - GCS 8-13 - <20%
- Severe TBI - GCS 3-8 - ~40%
Describe the age and sex distribution of head injuries.
- Age - tri-modal
- Infants 0-4y
- Adolscents 15-24y
- Elderly - >75y
- Sex M:F = 2:1
What is the target MAP for the head injured patient?
Why is this the case?
- Aim for MAP >= 80mm Hg
- Needs to be higher due to diminished ability to auto-regulate in the injured brain
What are the two types of brain oedema?
- Cytotoxic oedema -> caused by cellular damage -> ion shifts, cell membrane damage, release of free radicals etc
- Extracellular oedema -> caused by damage to the BBB
What are the indications for seizure prophylaxis?
- GCS <10
- Abnormal CT head
- Already seized
List ten clinical signs of raised ICP.
Think:
- Head injury signs
- Cushing’s reflex
- Herniation
- Severe headache
- N+V
- Focal neurological findings
- Visual disturbances
- Dec’d LOC/GCS
- Pupillary dilatation (or constriction)
- Hypertension
- Bradycardia
- Seizures
- Coma
- Agonal respirations
Which skull fractures require prophylactic IV Ab treatment?
Which drugs should be used?
- Open or depressed skull #s
- Involvment of a bony sinus
- Persence of pneumocephalus
Abs:
- 2g IV ceftriaxone PLUS
- 1g IV vancomycin
List six signs of base of skull #.
- CSF from nose or TMs
- Battle sign
- Raccoon eyes
- Hearing loss/deafness
- Vertigo
- Seventh nerve palsy
- Headache
What abs should be used for base of skull #’s?
- 2g IV ceftriaxone PLUS
- 1g IV vancomycin
Consult NROS first.
What is the most common CT abnormality in patients with mod-severe TBI?
SAH
A patient suffers a sig’t head injury with short LOC before regaining consciousness and returning to baseline. They then rapidly deteriorate with decreasing GCS in the ED.
What is the likely injury?
Sig’t head injury -> lucid interval -> rapid deterioration in GCS = extra-dural
Classic but uncommon.
What is the most common region and vessel injured that leads to an extra-dural haemorrhage?
Temporal injury -> middle meningeal artery injury
Damage to which vessel normally results in SDH?
Shearing of the bridging dural veins
If an ICH crosses the falx, what type of bleed is it?
SDH
What are the common CT findings in diffuse axonal injury?
What are two common mechanisms?
CT findings
- Normal CT
- Punctate haemorrhages at grey/white matter interface and in basal ganglia
Mechanisms
- Shearing forces
- MVA
- Shaken baby syndrome
What is second impact syndrome?
A second mTBI while the brain is still recovering from the first can lead to:
- Rapid cerebral oedema
- Death
List two tests that are validated for assessment of mTBI.
- Mini-Cog
- Quick Confusion Scale
What is the method of reversal of wafarin in head-injured patients with ICH?
- FFP, or
- 4-factor concentrate (II, VII, IX and X PLUS proteins C&S)
List three immediate actions to decrease ICP.
- Hyperventilation - transient
- Osmotic diuretics - mannitol and hypotonic saline
- CSF drainage - conservative or surgical
What are the indications for ICP monitoring?
- Severe TBI - GCS < 9
- Inability to monitor clinical signs of rising ICP
What are the criteria for Head CT according to the Canadian CT Head Rule? Who does this rule apply to?
Inclusion criteria:
- Adults
- Traumatic cause
- GCS 13-15
- LOC, amnesia or confusion
- Not anti-coagulated
- Absence of open skull #
High-risk factors for NROS intervention:
- Base of skull # signs
- Suspected open or depressed skull #
- GCS < 15 2h post injury
- Vomiting
- Age >65y
Medium-risk factors for CT id’d brain injury:
- Retrograde amnesia >30mins
- Dangerous mechanism
Discuss the sens and spec of the Canadian CT Head Rule and the New Orleans CT Head Rule.
List 3 differences in the rules.
- NOCTHR only includes patients with GCS 15
- BOTH rules 100% sensitive for NROS intervention
- CCHR more specific for all 3 endpoints, ie:
- NROS intervention
- Clinically sig’t injury
- Any CT Id’d injury
- NOCTHR identifies more injuries but results in A LOT more scans.
What are the indications for acute seizure prophylaxis in head trauma?
Think Severity, Seizures, Unable to assess, Type of injury
- Severity
- Severe TBI (GCS =<8)
- Seizures
- Seizure at time of injury
- Seizing on presentation
- Hx of pre-injury seizures
- Unable to assess:
- Paralysed, I&V
- Injury type
- Any penetrating injury
- Depressed skull #
- Acute SDH
- Acute EDH
- Any acute ICH
List complications of TBI.
- Neuro
- Seizures
- CNS infection
- Meningitis
- Abscess
- Cranial osteomyelitis
- Medical
- DIC - injured brain releases tissue thromboplastin
- Cardiac dysfunction
- Arrhythmias! - SVT ? due catecholamine surge
- Many ECG changes including
- STE
- Long QTc
- Peaked or inverted T-waves
- U-waves
- Neuro-cardiogenic pulm’y oedema
- Again ? due to catecholamine surge
List three CT findings in cerebral oedema.
- Loss of gray-white differentiation
- Compressed sulci
- Ventricular effacement
