Neuro and NSx Flashcards
What is the Canadian CT head injury rule
What are the modifiable and non-modifiable risk factors for SAH?
Modifiable
- HTN
- Smoking
- Alcohol abuse
- Sympathomimetic drugs (cocaine)
Non-modifiable
- Gender (Female 1.6 x men)
- Known aneurysm (either previous rupture or unruptured)
- 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 these 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
What is the Canadian C Spine Rule and its exclusion criteria?
Well validated rule to avoid unnecessary imaging.
Highly sensitive 99-100%
Can be used on any alert and cooperative pt, despite blood alcohol content
Exclusion criteria
- non trauma pts
- GCS<15
- Unstable vitals
- <16 yrs old
- Acute paralysis
- Known vertebral disease
- Previous C spine surgery
CT indicated if
Age>65, extremity paresthesia or dangerous mechanism
No low risk factors (sitting in ED, ambultory at the time, delayed neck pain, no midline tenderness, simple rearend MVA)
Pt unable to actively rotate neck 45 degrees
What is the nexus rule for C spine imaging and some differences to the CCSR
Well validated rule to help elliminate unnecessary CTs
Highly sensitive but marginally less so then CCSR.
Does not have age limitation so can be used in paediatric population and elderly but needs caution when used over 65 as sensitivity drops to between 66-84%
Also does NOT include mechanism
Unlike CCSR also includes intoxication