CNS Injury I-III Flashcards
Types of forces resulting in cerebral trauma
- contact phenomena
- acceleration
- translational
- rotation
- penetrating
- secondary injury
Contact phenomenon
Layers of Scalp
- S = skin
- C = subcutaneous tissue
- A = galea
- L = loose connective tissue
- P = periosteum
Common causes of brain injury
- Motor vehicle accidents
- Violence
- Recreation
- Falls (elderly)
Populations @ risk for head injury
- economically disadvantaged populations in major cities
- males: females = 2:1
- peak ages:
- 24-35 yrs
- 0-4 yrs (child abuse)
- 65+ (falls)
Contact phenomena head injuries cause & effects
- result from an object striking the head
- ==> lacerations of the scalp
- ==> fractures of skull
- ==> epidural hematomas
- ==> cerebral contusions
Skull fracture types
- contact phenomenon to skull
- types: linear, depressed, basilar, diastatic, and growing
- linear = indicates high-impact injury
- depressed = comminuted bone fragments
- basilar = base of skull ==> CSF leaks ==> meningitis
- diastatic = separates at suture lines
- growing = infancy; from dural tears
Concussion definition
- =”mild traumatic brain injury”
- = laternation in mental status, distrubance of equilibrium caused by biomechanical forces which may/may not lead to loss of consciousness
- hallmarks = confusion & amnesia
Common concussion symptoms
- headache
- dizziness
- poor attention, inability to concentrate
- fatigue, sleep disturbance
- irritability, depressed mood
- intolerance of bright light or loud noise
Contact phenomena examples
- clubs, pool cues
- baseball bats
- rocks
- bottles
Types of acceleration injuries
- transalational: head movement in single plane after impact
- rotational: head movement in multiple planes
Signs of basilar skull fracture
•CSF rhinorrhoea •Bilateral periorbital haematomas (Racoon eyes) •Subconjunctival haemorrhage •Bleeding from external auditory meatus •CSF otorrhoea •Battle’s sign •Facial nerve palsy
Consequences of transalation acceleration injuries
- stretching/tearing of veins between brain and dura ==> subdural hematoma
- brain contusion
- coup/contrecoup injuries
Characteristics of brain contusion
- often due to transalational acceleration injuries
- often occurs @ frontal/temporal
- can lead to swelling, brain shift, increase in intracranial pressure, herniation
- low mortality alone
Examples of rotational acceleration injuries
- MVA ejection
- motorcycle accident
- auto-pedestrian accident
Consequences of rotational acceleration injury
- ==> microscopic tearing of nerve cells @ brain
Characteristics of epidural hematomas
- Caused by contact phenomena
- extradural arterial hemorrhage
- Associated with skull fractures
- Classic “lucid interval” after trauma occurs
- Low mortality rate
Characteristics of subdural hematoma
- caused by translational acceleration injuries
- rupture of bridging veins in subdural space
- associated with brain contusions
- high mortality rate
Characteristics of Coup/contrecoup injury
- often caused by translational acceleration injury
- brain contusions + shearing forces on brain/veins in both the rostral and caudal directions due to impact and rebound
Common consequences of rotational acceleration injury
- diffuse axonal injury ==> microscopic tearing of nerve cells in brain
- under a microscope = “axonal spheroids”
- patients are usually in chronic vegetative state
Goal of treatment in head injuries
- save any neurons that have reversible damage
- minimize secondary effects/mitigate symptoms
Importance of controlling ICP
- increased ICP ==> CSF in spinal subarachnoid space OR venoconstriction @ CNS capacitance vessels ==> blood displacement into jugular venous system
- ==> herniation of brain (which is non-compressible) ==> brain damage
- also: if ICP > MAP, then there will not be blood flow to brain ==> syncope & eventaully cell death
Common signs/symptoms of increased ICP
- sudden change in neurological condition
- headache, nausea, vomiting ==> progressive lethargy and LOC
Herniation syndromes (4)
- subfalcine herniation
- central herniation
- uncal transtentorial herniation
- tonsillar herniation
Characteristics of subfalcine herniation
- cingulate gyrus is pushed away from the expanding mass and herniates beneath the falx cerebri.
- The anterior cerebral artery is often kinked, which may result in a stroke in distribution of this vessel.
Characteristics of central herniation
- Occurs when there is downward pressure centrally
- can result in bilateral uncal herniation
- results in loss of consciousness.
Characteristics of uncal transtentorial herniation
- the uncus herniates across the tentorial edge, and downward into the posterior fossa
- herniation compresses the midbrain and its ipsilateral cerebral peduncle
- ==> ipsilateral third nerve palsy (test pupillary light reaction, could be fixed and dilated)
- ==> contralateral hemiparesis (paralysis of one side of body)
- Rarely, uncal herniation can compress the opposite cerebral peduncle against the tentorial edge, resulting in a hemiparesis that is ipsilateral to the mass lesion and herniated uncus.
Characteristics of tonsillar herniation
- cerebellar tonsils herniate downward into the foramen magnum (coning)
- medulla is compressed → abnormal cardiac and respiratory responses, including Cushing’s reflex (bradycardia and hypertension) in the setting of high intracranial pressure.
- Tonsillar herniation most commonly is encountered in the setting of a mass lesion in the posterior fossa.
Critical avoidance in context of intracranial mass lesion
- DO NOT PERFORM A LUMBAR PUNCTURE
- lumbar punctures can precipate herniation syndromes due to pressure differentials created during the procedure
Categories included in the GCS
- Eye opening
- Best verbal response
- Best motor response to pain/verbal command
GCS: Eye opening grading
None - 1
To pain - 2
To loud speech - 3
Spontaneous - 4
GCS: Verbal response grading
None - 1
Incomprehensible sounds - 2
Inappropriate words - 3
Confused/Disoriented - 4
Oriented - 5
GCS: Motor response grading
None - 1
Extension to pain - 2
Abnormal flexion to pain - 3
Withdraws from pain - 4
Localizes pain - 5
Obeys command - 6
Scoring guidelines & utility of GCS
- < 8 ==> intubation
- GCS = good predictor of mortality
- correlates w/likelihood of good outcome vs. moderate to sever disability vs. death
- correlates w/likelihood of intracranial mass lesion
Concussion: GCS definition
GCS = 13-15 ==> mild traumatic brain injury
Most common symptoms of concussion (5)
- Headache
- Dizziness
- Lack of awareness of surroundings
- Muddled thinking
- Nausea and Vomiting
Common signs of concussion
- Vacant stare
- delayed responses
- inattention
- disorientation
- loss of consciousness.
