CNS Injury I-III

Question 1

Types of forces resulting in cerebral trauma

Answer 1

• contact phenomena
• acceleration
  
  • translational
  • rotation
• penetrating
• secondary injury

Question 2

Contact phenomenon

Question 3

Layers of Scalp

Answer 3

• S = skin
• C = subcutaneous tissue
• A = galea
• L = loose connective tissue
• P = periosteum

Question 4

Common causes of brain injury

Answer 4

• Motor vehicle accidents
• Violence
• Recreation
• Falls (elderly)

Question 5

Populations @ risk for head injury

Answer 5

• economically disadvantaged populations in major cities
• males: females = 2:1
• peak ages:
  
  • 24-35 yrs
  • 0-4 yrs (child abuse)
  • 65+ (falls)

Question 6

Contact phenomena head injuries cause & effects

Answer 6

• result from an object striking the head
• ==> lacerations of the scalp
• ==> fractures of skull
• ==> epidural hematomas
• ==> cerebral contusions

Question 7

Skull fracture types

Answer 7

• 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

Question 8

Concussion definition

Answer 8

• =”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

Question 9

Common concussion symptoms

Answer 9

• headache
• dizziness
• poor attention, inability to concentrate
• fatigue, sleep disturbance
• irritability, depressed mood
• intolerance of bright light or loud noise

Question 10

Contact phenomena examples

Answer 10

• clubs, pool cues
• baseball bats
• rocks
• bottles

Question 11

Types of acceleration injuries

Answer 11

• transalational: head movement in single plane after impact
• rotational: head movement in multiple planes

Question 12

Signs of basilar skull fracture

Answer 12

•CSF rhinorrhoea •Bilateral periorbital haematomas (Racoon eyes) •Subconjunctival haemorrhage •Bleeding from external auditory meatus •CSF otorrhoea •Battle’s sign •Facial nerve palsy

Question 13

Consequences of transalation acceleration injuries

Answer 13

• stretching/tearing of veins between brain and dura ==> subdural hematoma
• brain contusion
• coup/contrecoup injuries

Question 14

Characteristics of brain contusion

Answer 14

• often due to transalational acceleration injuries
• often occurs @ frontal/temporal
• can lead to swelling, brain shift, increase in intracranial pressure, herniation
• low mortality alone

Question 15

Examples of rotational acceleration injuries

Answer 15

• MVA ejection
• motorcycle accident
• auto-pedestrian accident

Question 16

Consequences of rotational acceleration injury

Answer 16

• ==> microscopic tearing of nerve cells @ brain

Question 17

Characteristics of epidural hematomas

Answer 17

• Caused by contact phenomena
• extradural arterial hemorrhage
• Associated with skull fractures
• Classic “lucid interval” after trauma occurs
• Low mortality rate

Question 18

Characteristics of subdural hematoma

Answer 18

• caused by translational acceleration injuries
• rupture of bridging veins in subdural space
• associated with brain contusions
• high mortality rate

Question 19

Characteristics of Coup/contrecoup injury

Answer 19

• 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

Question 20

Common consequences of rotational acceleration injury

Answer 20

• diffuse axonal injury ==> microscopic tearing of nerve cells in brain
• under a microscope = “axonal spheroids”
• patients are usually in chronic vegetative state

Question 21

Goal of treatment in head injuries

Answer 21

• save any neurons that have reversible damage
• minimize secondary effects/mitigate symptoms

Question 22

Importance of controlling ICP

Answer 22

• 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

Question 23

Common signs/symptoms of increased ICP

Answer 23

• sudden change in neurological condition
• headache, nausea, vomiting ==> progressive lethargy and LOC

Question 24

Herniation syndromes (4)

Answer 24

• subfalcine herniation
• central herniation
• uncal transtentorial herniation
• tonsillar herniation

Question 25

Characteristics of subfalcine herniation

Answer 25

* 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.

Question 26

Characteristics of central herniation

Answer 26

* Occurs when there is downward pressure centrally * can result in bilateral uncal herniation * results in loss of consciousness.

Question 27

Characteristics of uncal transtentorial herniation

Answer 27

* 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.

Question 28

Characteristics of tonsillar herniation

Answer 28

* _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_.

Question 29

Critical avoidance in context of intracranial mass lesion

Answer 29

* DO NOT PERFORM A LUMBAR PUNCTURE * lumbar punctures can precipate herniation syndromes due to pressure differentials created during the procedure

Question 30

Categories included in the GCS

Answer 30

* Eye opening * Best verbal response * Best motor response to pain/verbal command

Question 31

GCS: Eye opening grading

Answer 31

None - 1 To pain - 2 To loud speech - 3 Spontaneous - 4

Question 32

GCS: Verbal response grading

Answer 32

None - 1 Incomprehensible sounds - 2 Inappropriate words - 3 Confused/Disoriented - 4 Oriented - 5

Question 33

GCS: Motor response grading

Answer 33

None - 1 Extension to pain - 2 Abnormal flexion to pain - 3 Withdraws from pain - 4 Localizes pain - 5 Obeys command - 6

Question 34

Scoring guidelines & utility of GCS

Answer 34

* \< 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

Question 35

Concussion: GCS definition

Answer 35

GCS = 13-15 ==\> mild traumatic brain injury

Question 36

Most common symptoms of concussion (5)

Answer 36

1. Headache 2. Dizziness 3. Lack of awareness of surroundings 4. Muddled thinking 5. Nausea and Vomiting

Question 37

Common signs of concussion

Answer 37

* Vacant stare * delayed responses * inattention * disorientation * loss of consciousness.