Neurosurgery Flashcards
What are the most common cervical spinal levels involved after trauma?
- Vertebral fracture: C2 (1/3 = odontoid fractures)
- C6
- C7
What is the most common level of subluxation injury and why?
C5-C6 because its the greatest area of flexion and extension in cervical spine
Which dermatome level is the shoulders?
C4
Which dermatome is the first in the chest?
T2
How do we grade DTRs?
2+ normal 0= no response 1+ sluggish tone 3+ more brisk 4+ clonus
Clinical difference: complete vs. incomplete spinal cord injury?
Complete: no motor/sensory below level
Incomplete: some residual function below level of injury
What are devastating clinical exam findings in complete spinal cord injury in high cervical cord (C3 or above)?
Diphragmatic paralysis - cannot breathe
Paralysis of all 4 limbs
What is myelopathy?
sensory or motor dysfunction caused by pathology of spinal cord
When is Babinski normal?
Infants up to age 2
What is spinal shock?
temporary, concussive like syndrome associated with flaccid paralysis below level of injury with loss of all reflexes, plus loss of urinary/rectal tone
Why are thoracic spinal injuries less common than cervical in trauma?
1 Thoracic vertebrae are more stable due to high facets and ribs that decrease motion
2 More canal space because no anterior enlargements in the spinal cord (vs. cervical/lumbar)
What is sacral sparing?
Sparing of function at sacral nerve level
Why is sacral sparing important?
It signifies better chance of functional neurological recovery
What are common mechanisms of neck injuries?
Flexion
Extension
Axial loading (vertebral compression)
rotational injuries
What is atlanto-occipital dislocation?
Superior facets of atlas lose articulation with occipital condyles at the base of the skull: due to ligamentous disruption between occiput and cervical spine
What is most dangerous injury of cervical spine?
atlanto-occipital dislocation: higher risk of severe high cervical cord injury.
Who is at increased risk of atlanto-occipital dislocation?
Down syndrome patients: screen before sports participation
What is the typical cause of Brown Sequard syndrome?
Penetrating trauma
What is the typical cause of anterior cord syndrome?
Severe flexion injury
What is the typical cause of central cord syndrome?
Severe extension injury in an elderly patient with pre-existing cervical stenosis
Why are the distal lower extremities spared in central cord syndrome?
Topographical organization: lower extremity motor function is at the lateral aspects of the cord = spared
Which incomplete cord syndrome carries best prognosis of recovery?
Brown Squared
Which incomplete cord syndrome carries worst prognosis of recovery?
Anterior cord: 10% recover ambulation
How do we diagnosed spinal cord injuries and cervical vertebral fractures?
- History
- Neuro exam
- imaging if needed to confirm
What is NEXUS criteria?
Determines if adult patients need spinal radiographs. Indicated for trauma UNLESS: patient meets NSAID Neuro deficit Spinal tenderness AMS Intoxicated Distracting injury
What radiographs do we obtain of the cervical spine in trauma?
1 AP
2 Lateral
3 Open mouth (odontoid)
What is indication for ordering CT scan of cervical spine?
Detecting vertebral fractures
identify hematomas / disk fragment in spinal cord
clearance of cervical spine in comatose/obtunded patients
What is indication for ordering MRI scan of cervical spine?
- Detect injury to spinal cord itself in patients with neurological deficits
- Areas of edema, ruptured disks, ligamentous injury
- Sees hematoma well
- Detects abnormalities in patients with SCIWORA
What is SCIWORA?
Spinal Cord Injury Without Radiographic Abnormalities
Who is susceptible to SCIWORA?
Children/young adults due to tearing or contusion of spinal cord from overstitching and spinal column subluxation due to ligamentous laxity/flexibility of developing spine
Where is more common SCIWORA injury? Who gets it?
C2, patients < 3 years
How may SCIWORA present?
after brief episodes of UE weakness or paresthesias –> delayed development of near deficits
How can we identify spinal cord abnormalities in patients with SCIWORA?
MRI
What are general treatment principles for patients with cervical spine injury?
Rigid cervical collar on spine board early closed reduction with tongs or halo traction for awake patients with obvious subluxation on imaging: causing spinal cord compression - IV fluids - Vasopressors if neurogenic shock - Foley - stool softener - VTE prophylaxis
What is neurogenic shock?
Hemodynamic state: SNS outflow through spinal cord disrupted: vasodilation, bradycardia and dangerous hypotension
How do we treat neurogenic shock?
1 Normal saline
2 Dopamine or phenylephrine if needed
3 Treat bradycardia with atropine or dopamine
What are goals of management for patients with complete spinal cord injuries or high cervical cord injuries?
Facilitate nursing and rehab
Prevent decubitus ulcers, bowel/bladder management, avoid DVT, avoid pneumonia
What are general indications of emergent surgery with spinal cord injury? (3)
1 Unstable vertebral fracture
2 Non reducible spinal cord compression with deficit
3 Ligamentous injury with facet instability
Why is restoration of spinal stability so important?
Minimize risk for secondary injury and allow for early mobilization of patient to minimize risk
Do we treat acute spinal cord injury with IV steroids?
NO: no evidence for it
What is the most common complication of exposure of the anterior cervical spine?
Recurrent laryngeal nerve injury: paralyze vocal cords, risk of dyspnea with bilateral injury, transient dysphagia, rarely esophageal perforation (high risk of infection)
What is diffuse axonal injury due to and what happens?
Rotational acceleration and deceleration causes stretching of axons between grey and white matter
What is common cause of DAI?
Shaken baby syndrome
What is the definition of TBI?
Criteria:
- Period of LOC
- Loss of memory for events immediately before/after accident
- Alteration in mental state at time of accident
- And/or FND
What are components of GCS?
Eye opening (1-4)
Best verbal response (1-5)
Best motor response (1-6)
What GCS scores encompass severe vs. moderate vs. mild TBI?
Severe: 3-8
Moderate 9-12
Mild 13-15
What do we do with patient with GCS < 8?
Considered to be in coma
mandates establishment of airway
What non-head trauma factors can affect GCS?
ETOH/drug intox, sedatives, severe hypoxia, shock, severe hypothermia
What are Raccoon eyes?
bilateral periorbital ecchymosis
What is Battle’s sign?
Retroauricular ecchymosis
What makes us think of basilar skull fracture?
raccoon eyes and Battle’s sign: bilateral periorbital ecchymosis, Retroauricular ecchymosis
How do we use hemiparesis and blown pupil to localize lesion in uncal herniation?
Hemiparesis: C/L to lesion
Pupil: ipsilateral to lesion
Which has better prognosis: decorticate or decerebrate posturing?
Decorticate
What is decorticate posturing?
Flexion in UE, Extension in LE in response to painful stimuli
What is decerebrate posturing?
Extension in UE and LE in response to painful stimuli
How to distinguish between acute and chronic SDH?
Acute: W/in 72 hours head injury
Chronic: delayed onset in elderly usually: presentation often insidious: gait abnormalities, decreased consciousness, aphasia, cognitive dysfunction, memory loss and/or personality changes
Who is particularly susceptible to SDH?
Alcoholics, elderly, patients on anti-coagulation
Why are elderly patients more susceptible to SDH?
Relatively atrophic brain increases tension on bridging veins: making them more susceptible to head trauma
What is the formula for cerebral perfusion pressure?
= mean arterial pressure - intracranial pressure
What affects ICP? (3)
Brain tissue, CSF and blood
What is the most powerful intracranial vasodilator?
Co2
Can TBI cause hypotension?
NO - look for other factors
What is Cushing’s triad and the pathophys behind it?
Hypertension, bradycardia, irregular RR
- Increased ICP –> systemic BP rise to maintain CPP –> increased BP to carotid sinus biofeedback causes bradycardia
- Respiratory center in medulla: will become impaired as result of elevated ICP
What is coup vs. contrecoup injury?
Coup: injury to brain tissue just below skull at point of impact
Force of impact may thrust brain tissue against skull to opposite side and cause injury = contrecoup
What is initial management of GCS patient <= 8?
1 Intubation: protect airway, can help facilitate ICP management
2 Neurologic exam
3 Noncon CT STAT
Key thing to keep in mind in patient with GCS < 8 after trauma?
Cannot use PE to identify other injuries! Need to assess for other injuries to chest abdomen, pelvis
What are indications for head CT with TBI?
1 Moderate or severe GCS: scores 3-12
2 Mild GCS with anticoagulation, alcohol abuse, elderly
Which drugs can increase ICP and are C/I in TBI?
Succinylcholine, ketamine
Use rocuronium/etomidate instead
How can we decrease intracranial hypertension?
1 Hyperventilation 2 Bed elevation to 30-45 degrees 3 Mannitol 4 Paralyze patient --> hypothermia 5 Barbituate coma or decompressive craniotomy
What is the role of hyperventilation?
CT findings or clinical signs of Intracranial HTN
- Initiate hyperventilation to PaCO2 of 30-35 –> temporarily reduce ICP via vasoconstriction
Who should NOT receive mannitol?
Hypotensive/hypovolemic patients due to effects of volume depletion
What is role of corticosteroids in TBI?
None
What is craniotomy?
Removing skull flap to evacuate hematoma
When do we use craniotomy?
Indicated for acute subdural and epidural hematomas:
- Midline shift > 10mm
- Hematoma thickness > 5mm
- ICP > 20mm Hg (despite medical management)
What is craniectomy?
Removal of skull flap without replacing bone flap, allowing the brain to swell beyond the skull
When do we repeat imaging for TBI patients who are being medically managed?
Use urgent followup CT for:
- New neurologic signs
- Continued vomiting
- Worsening HA
- Loss of > 2 points on GCS
- Any signs of increase ICP
What are criteria for brain death?
GCS of 3 while not hypoxic, normotensive, euthermic, non on sedatives/paralytics
- No CN reflexes
- No respiratory effort during apnea test
How do we define concussion?
Disruption of inflow and outflow tracts from reticular activating system