CNS Flashcards
What is a traumatic brain injury?
A traumatic insult to the brain possibly producing physical, intellectual, emotional, social, and vocational changes
What organizations use theGlasgow Coma scale
used to describe injury severity by the international and United States National Traumatic Coma Data Banks
TBI classifications: Mild
GCS 13-15 - associated with a mild concussion
TBI classification: Moderate
GCS 9-12 - associated with structural injury such as hemorrhage or contusion
TBI classification: Severe
GCS 3-8 - associated with cognitive and/or physical disability or death
**loss of consciousness for 6hours or more
What populations are at risk for TBI?
Infants 6 months to 2 years School-age children Adolescents and young adults 15-35 years of age People more than 70 years of age Men 1.5 times as likely to sustain a TBI Persons living in high-crime areas
Blunt Trauma
- closed, nonmissile
- Head strikes hard surface or a rapidly moving object strikes the head
- The dura remains intact; brain tissues not exposed to the environment
- Causes focal (local) or diffuse (general) brain injuries
Open Trauma
- penetrating, missile)
- Injury breaks the dura and exposes the cranial contents to the environment
- Causes primarily focal injuries
What are the most common type of brain injury?
mild concussion and classic cerebral concussion
Focal brain injury
- accounts for more than 2/3 of head injuries
- specific and involves observable brain lesions
- contusions
- intracranial bleeding that displaces brain tissue
- cerebral edema
- coup-contrecoup
Diffuse axonal injury (DAI)
accounts for less than 1/3 however accounts for the greatest number of severely disabled survivors
What are some causes of brain trauma?
- Falls 28%
- Motor vehicle crashes 20%
- Moving objects or moving against stationary objects 19%
- Assault 11%
- Sports-related events
- Blasts (military active duty personnel)
Compound fractures
caused by objects striking the head with great force or by the head striking an object forcefully
Basilar skull fracture
- occipital blow- fracture of occipital bone and across the petrous pyramid
- the cervical vertebrae upwardly impacting the base of the skull can produce a posterior fossa basilar skull fracture
Coup
- directly below the point of impact against object
- shearing of subdural veins
- trauma to base of brain
Contrecoup
- on the pole opposite the site of impact (within the skull)
- shearing forces through brain
Coup-Contrecoup
- injuries happen in one continuous motion
- coup - wall
- contrecoup - rebounds
Where are contusions commonly found?
- frontal lobes, particularly at the poles along the inferior orbital surfaces
- temporal lobes, especially in the anterior poles and along the inferior surface
- frontotemporal junctions
The ______ the area of the impact, the greater the severity of injury because the force is _____ into a _____ area.
smaller; concentrated; smaller
Contusions result in what type of changes?
- attention
- memory
- executive attentional function (motivation, planning,)
- affect
- emotion
- behavior
What is the difference between focal contusions and hemorrhagic contusions?
focal contusions are superficial, involving just the gyri whereas hemorrhagic contusions may coalesce into a large, confluent intracranial hematoma
What are the clinical manifestations of a contusion?
- immediate loss of consciousness (no longer than 5 mins)
- loss of reflexes
- transient cessation of respiration
- brief period of bradycardia
- decreased blood pressure (30secs - a few mins)
- a momentary increase in CSF pressure
- ECG and EEG changes on impact
What evaluations do you want to do on someone with a contusion?
- complete history and physical exam
- skull and spinal xray
- CT
- MRI
How is treatment directed with a patient who has a contusions?
controlling ICP and managing symtoms
What can contusions cause?
Extradural (epidural) hemorrhage or hematoma
Subdural hematoma
Intracerebral hematoma
Extradural Hematoma
- 85% arterial bleeding
- 15% meningeal vein or dural sinus injury
- 90% have a skull fracture
- The temporal fossa is the most common site of extradural hematoma caused by injury to the middle meningeal artery or vein
What is the common cause of an extradural hematoma?
-MVAs
occasionally minor falls and sporting accidents
Posterior extradural hematomas are caused by what?
a fracture across the transverse sinus from an occipital blow
What are some clinical manifestations with a classic temporal extradural hematomas?
- LOC followed by a lucid period that lasts for a few hours to a few days
- headache of increasing severity
- vomiting
- drowsiness
- confusion
- seizure
- hemiparesis
- ipsilateral pupillary dilation and contralateral hemiparesis
Subdural Hematoma
- 10% to 20% of persons with traumatic brain injury
- MVAs are the most common cause
- 50% of subdural hematomas associated with skull fractures
- Falls (older adults, substance abuse)
Acute Subdural hematoma
- Develops within 48 hours
- Often located at the top of the skull
- As ICP rises the bleeding veins are compressed and thus bleeding is self-limited
What are some clinical manifestations of an acute subdural hematoma?
-headache
-drowsiness
-restlessness
-agitation
-slowed cognition
-confusion
progressing to..
LOC
respiratory pattern changes
pupillary dilation
homonymous hemianpia
Chronic Subdural hematoma
Develops over weeks to months
Older adults
Alcohol abuse
80% complain of chronic headaches and have tenderness at site of injury
What is the difference in the treatment of an acute vs chronic hematoma?
acute- clot evac through burr hole
chronic- craniotomy and then perc drain
Subdural hematoma forms after head trauma that severs the ______ _____ from dura to brain.
bridging veins
What are intracerebral hematomas associated with?
MVAs, falls and contusions
Where do intracerebral hematomas commonly occur?
frontal and temporal lobes but may also occur in the hemispheric deep white matter
The intracerebral hematoma acts as an _____ _____. Resulting in _______ ICP and compreesion of brain tissues with ____ ____.
expanding mass; increased; resultant edema
What are some clinical manifestations of an intracerebral hematoma?
- decreased level of consciousness
- coma or a confusional state
- contralateral hemiplagia
- temporal lobe herniation
What is the treatment for intracerebral hematoma?
- evacuation or
- reducing ICP and allowing the hematoma to absorb slowly
What are the two types of open trauma head wounds?
compound fracture and missile injuries
What is a compound fracture?
open communication between the cranial contents and the environment
When should a compound fracture be investigated?
whenever there are lacerations of the scalp, tympanic membrane, a sinus, an eye, or mucus membranes.
What can be injured with a basilar skull fracture?
cranial nerves
What are the two mechanisms of injury with missile trauma?
crush and stretch injury
What is a crush injury?
the laceration and crushing of whatever tissue the missile touches,
What is the amount of crush related to?
degree of fragmentation, deformity, size and shape
What is a tangential injury?
injury to the coverings of the brain (scalp)
What is a stretch injury?
involves blood vessels and nerves that are damaged without direct contact due to the amount of tissue stretched secondary to shape deformation and striking velocity
What causes primary increase in ICP with a stretch injury?
air compressed in front of a bullet exerts an explosive effect on entry, producing extreme distant tissue damage and an immediate primary increase in ICP
What causes secondary increase in ICP with a stretch injury?
edema
What are some clinical manifestations with an open head injury?
-LOC
How is a diagnosis of a compound fracture made?
- physical exam
- xrays
What is a diffuse axonal brain injury?
-results from a shaking effect
What is the primary mechanism of injury with a DAI?
rotational acceleration but can also be acceleration/deceleration and shaking, inertial effect
What does the severity of a DAI correspond with?
Severity corresponds to the amount of shearing force applied to the brain and brainstem (mild, moderate, severe)
What is axonal damage?
Shearing, tearing, or stretching of nerve fibers
What is the definition of a mild concussion
Temporary axonal disturbances causing attention and memory deficits but no loss of consciousness
Mild concussion: grade I
I—confusion, disorientation, and momentary amnesia
Mild concussion: grade II
II—momentary confusion and retrograde amnesia
Mild concussion: grade III
III—confusion with retrograde and anterograde amnesia
Classic cerebral concussion: grade IV
- Disconnection of cerebral systems from the brainstem and reticular activating system
- Physiologic and neurologic dysfunction without substantial anatomic disruption
- Loss of consciousness (<6 hours)
- Anterograde and retrograde amnesia
- Uncomplicated (no focal injury)
- Complicated (focal injury)
What is postconcussive syndrome?
Headache, cognitive impairments, psychologic and somatic complaints, cranial nerve signs and symptoms
How is postconcussive treated?
- Reassurance and symptomatic relief
- Close observation for 24 hours by a reliable individual so immediate intervention can be obtained if delayed effects become severe
DAI can further be categorized into..
mild DAI
moderate DAI
severe DAI
Mild DAI
- coma 6-24hours
- death uncommon, but cognitive, psychological and sensorimotor deficit
- 30% display decerebrate or decorticate posturing
Moderate DAI
- widespread physiologic impairment
- actual tearing of some axons in both hemispheres
- basal skull fracture, a focal injury, commonly associated
- last more than 24 hours
- recovery incomplete
- GCS 4-8 then 6-8 by 24hours
Severe DAI
- involves severe mechanical disruption of many axons in both cerebral hemispheres
- initial GCS of 3 - 78% mortality
- initial GCS of 3-8 - 36% mortality
- immediate autonomic dysfunction
- increased ICP
Treatment for TBI
- CT and MRI
- seizure meds
Spinal cord trauma most commonly occurs from what vertebral fractures?
simple fracture, compressed fracture, and comminuted fracture
Where are the most common vertebral injuries?
-C1-C2 (cervical)
-C4-C7
-T1-L1 (thoracic-lumbar)
these are the most mobile parts of the vertebral column
How does a primary spinal cord injury occur?
occurs if an injured spine is not adequately immobilized
What are some examples of a primary spinal cord injury?
- cord concussion
- cord contusion
- cord compression
- laceration
- transection - complete and incomplete, preserved sensation only,motor nonfunctional,motor functional
- hemorrhage
- damage or obstruction of spinal blood supply
How does a secondary spinal cord injury occur?
begins within mins after injury, microscopic hemorrhages appear in central gray matter and pia arachnoid that increase in size within 2 hours - edema in the white matter occurs impairing microcirculation
Hyperextension injury of the spine
- fracture and dislocation of posterior elements such as spinous processes, transverse processes, laminae, pedicles, or posterior ligaments
- results from forces of acceleration-deceleration and the sudden reduction in the anteroposterior diameter of the spinal cord
Where is the location of injury from hyperextension?
cervical area
Hyperflexion injury if the spine
- fracture or dislocation of the vertebral bodies, disks, or ligaments
- causes subluxation of vertebrae
- results from sudden and excessive force that propels the neck forward or causes an exaggerated lateral movement of the neck to one side
Where is the location of injury from hyperflexion?
cervical area
Vertical compression (axonal loading)
- shattering fractures
- spinal cord is contused directly by retropulsion of bone or disk material into the spinal cord
- results from a force applied along an axis from top of the cranium through the vertebral body
Where is the location of injury from vertical compression?
T12-L2
Rotational forces
- ruptures support ligaments in addition to producing fractures
- adds shearing force to acceleration-acceleration forces
Where is the location of injury from rotational forces?
cervical areas