Neuro and NSx Flashcards
What is the Canadian CT head injury rule and some exclusion criteria
Rule out tool for intracranial injuries that would require neurosurgical intervention
100% sensitivity for injuries that require NSx and 87-100% for ‘clinically important’ injuries that don’t
Most consistent, validated and effective rule for minor head injuries
70% sensitive for ‘clinically important’ brain injury in ETOH intoxicated pts
CAN ONLY BE APPLIED
GCS 13-15 +
- LOC
- Amnesia to event
- Witnessed disorientation
EXCLUSION
Age<16
Blood thinners
Seizure after injury
HIGH RISK CRITERIA - rules out NSx intervention
GCS<15 2hrs post injury
Suspected open or depressed skull fracture
Signs of basilar skull fracture
>/=2 episodes of vomiting
Age>/=65
MEDIUM RISK - For clinically important brain injury that may require admission
Retrograde amnesia >30minutes from event
Dangerous mechanism (Pedestrian MVA, Ejected from car, fall>3 feet or 5 stairs
What is the NEXUS Head CT rule
Rule out tool to avoid unnecessary CTs in pts of ANY age with blunt head injury within 24hrs
Evidence of skull fracture - basilar or depressed
Scalp hematoma
Neurological deficits
Altered LOC - GCS<15, delayed or inappropriate responses
Abnormal behavior - Agitation, inconsolability etc
Coagulopathy
Presistent vomiting - >1 episode of projectile or forceful emesis
Age>/=65
What is the PECARN head injury algori
PREDICT
What are the modifiable and non-modifiable risk factors for SAH?
Modifiable
- HTN (mild risk increase)
- Smoking (3-10 times risk)
- Alcohol abuse
- Sympathomimetic drugs (cocaine)
Non-modifiable
- Gender (Female 1.6 x men)
- Known aneurysm (either previous rupture or unruptured is greatest risk factor)
- Fatal second degree relative with SAH (4 times risk)
- AVMs
- Associated genetic condition such as Autosomal PCKD, connective tissue disorders (Ehlers Danlos, Marfan), Coarctation of the aorta, hereditary hemorrhagic telangiectasia
Where do aneurysms commonly occur?
85% in carotid system
- 30% AComA
- 25% PComA
- 20% MCA
- 10% other
15% posterior circ
- 10% in Basilar and at bifucation most common
- 5% on vertebral artery, PICA junction most common
25% have multiple
What is the Ottawa SAH Rule for Headache evalutation
Scoring system recommended by the American College of Emergency Physicians to potentially avoid unnecessary scanning.
Has 100% Sensitivity but ~15% specificity so cannot be used to diagnose, only determine need for further imaging.
CAN NOT be used in
- Pts <15 yrs old
- GCS <15
- head trauma or fall within 7 days
- New deficits
- known aneurysms or brain tumors
- Chronic recurrent headaches (>/= 3 headaches of the same character and intensity for >6 months)
IF
Age >/= 40
Neck pain or stiffness
Witnessed LOC
Onset during exercise
Thunderclap headache
Limited neck flexion on exam
Then SAH can NOT be ruled out
What are some causes of a false negative non con CTB for SAH
Time, most sensitive in first few hours (<6hrs)
Anemia
Low volume SAH
Technically poor scan
What is the Modified Fisher Scale (also known as Claasen grading sytem)
Radiological grading system to determine risk of cerebral vasospasm
Grade 0 - Normal CT
Grade 1 - ‘Thin’ focal or diffuse SAH with no Intraventricular hemorrhage (24% incidence DCI)
Grade 2 - ‘Thin’ focal or diffuse SAH WITH IVH (33% DCI)
Grade 3 - ‘Thick’ focal or diffuse SAH with NO IVH (33% DCI)
Grade 4 - ‘Thick’ focal or diffuse SAH WITH IVH (49% DCI)
What is the WFNS scale (World Federation of Neurosurgical Societies)
Clinical grading system based on GCS and neurological deficits. Should be used AFTER Neurological resus (EVD or clot evacuation) and best correlation with outcomes is 12hr post surgery
WFNS 1 - GCS 15 with no deficit
WFNS 2 - GCS 13-14 and NO deficit
WFNS 3 - GCS 13-14 WITH focal deficit
WFNS 4 - GCS 7-12
WFNS 5 - GCS <7
What are the pros and cons of the SAH grading systems?
WFNS Pros
- Fast and easy to calculate
- Does not require imaging
- High interobserver reliability
- Step wise increase in likelihood of poor outcome with increasing grades
WFNS Cons
- Relies on accurate examination
- Significant increase in likelihood for poor outcome in between steps 2 and 3
- Groups wide range of pts in grade 4 (GCS 7-12 +/- deficit) so possible to have widely differing outcomes
MFS Pro
- Very high inter-reliability
-Validates prognostic tool for radiological vasospasm
- Risk of vasospasm increased with each grade (previously peaked at 3 and then decreased slightly at 4)
MFS Cons
- Doesnt prognostic overall outcome, only radiological vasospasm
- Clot density in not a feature of the system
What is the Hunt and Hess grading system?
- Measure of perioperative mortality risk based on intensity of meningeal inflammation, severity of neurological deficit, level of arousal and presence of associated disease.
- Uses ambiguous terms in grading system decreasing inter-reliability.
- Predates the GCS by 5 yrs and still one of the most widely recognized scoring systems
H&H 1 - Asymptomatic or minimal headache and slight nuchal rigidity
H&H 2 - Moderate to severe headaches, CN palsies, Nuchal rigidity but no other neurological deficits
H&H 3 - Drowsy and confused or mild focal deficit
H&H 4 - Stupour, moderate to severe hemiparesis, early decerate rigidity and ‘vegetative disturbance’
H&H 5 - Deep coma, decerebrate rigidity, ‘moribund appearance’
What are the CSF findings in SAH
Some RBCs
<5WBC
WBC:RBC ratio 1:700
Xanthochromia
Minimal clearing of RBCs between tubes 1 and 4
If Xanthochromia present, SAH confirmed.
Can be absent early but always present 12hrs after bleed
False positive potential if CSF protein >100mg/dL or bloody taps
What are the common cause of ICH?
Hypertensive Vasculopathy (1/3 of all ICH)
Most commonly in deep structures
- Basal Ganglia (especially putamen)
- Thalamus
- Pons
- Cerebellum
Cerebral amyloid angiopathy (1/5 of all ICH and second most common)
- Risk increase with age and typically peripheral lobar haemorrhages
20% undetermined
Medication related (15%)
- Warfarin, heparin, DOACs, Thrombolysis
Vascular structural lesions
- Tumors, AVM, AVF (dural arteriovenous fistula)
Systemic Disease
Rarer causes
- Moya moya disease (basal ganglia typically)
- Pregnancy and puerperium ( up to 6 weeks post partum and usually with pre/eclampsia
- CN infections (fungal, herpes)
- Vasculitis
- CVS thrombosis
What are some methods of decreasing intracranial pressure in head injury
Ensure head elevation and no tube ties/collars are on the neck
Deep sedation and analgesia with propofol and fentanyl +/- barbiturates
Aim Sats ~95% and paO2 80-120
Hyperventilation aim paCO2 35-38
and avoid unnecessary PEEP
Osmotic agents - Hypertonic saline 3% 3ml/kg or mannitol 0.5-1g/kg
Surgical correction - decompressive craniectomy, burr holes, EVD
Deepening sedation with barbiturates
Theraputic hypothermia
What are the complications of cervical spine immobilisation
- Raised ICP
- Reduced access to the neck
- Pain and discomfort - pressure areas
- Airway compromise added difficulty with airway interventions
- Aspiration risk
- Impaired ventilation
- Impaired head movement
- Potential worsening of spinal cord injury
- Unnecessary distraction from important resuscitation issues
- Unnecessary additional radiology esp in children
- Requirement for log-rolling, increased nursing requirements, staff distraction from other duties
Risk factors for intracerebral hemorrhage expansion/deterioration and some signs on CT
Most expansion occurs in first 3hrs to 24hrs
RISK
- Shorter time from symptom onset to initial imaging
- Antiplatelet/anticoagulant use
- Contrast extravasation (spot sign is 90% specific and 50% sensitive, leakage sign between initial and delayed phase has 90% sensitivity and specificitiy and associated with poor prognosis)
Non con CT signs:
- Irregular hematoma shape
- Island sign (>3 scattered hematoma separate from main hematoma)
- Swirl sign (unclotted fresh blood has lower attenuation that clotted blood)
- Black hole sign (dark area within hematoma that is not connected to adjacent brain tissue is 94% specific and 32% sensitive)
- Blend sign (hemorrhage that contains hyperdense and hypodense regions)
Intraventricular extension has worse neurological complications and outcomes
Edema takes hours to develop, and extensive or irregular edema suggests underlying
- CVT
- Ischemic stroke with hemorrhagic transformation
- Tumor
