Neuro and NSx

Question 1

What is the Canadian CT head injury rule

Question 2

What are the modifiable and non-modifiable risk factors for SAH?

Answer 2

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

Question 3

Where do aneurysms commonly occur?

Answer 3

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

Question 4

What is the Ottawa SAH Rule for Headache evalutation

Answer 4

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

Question 5

What are some causes of a false negative non con CTB for SAH

Answer 5

Time, most sensitive in first few hours (<6hrs)
Anemia
Low volume SAH
Technically poor scan

Question 6

What is the Modified Fisher Scale (also known as Claasen grading sytem)

Answer 6

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)

Question 7

What is the WFNS scale (World Federation of Neurosurgical Societies)

Answer 7

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

Question 8

What are the pros and cons of these grading systems?

Answer 8

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

Question 9

What is the Hunt and Hess grading system?

Answer 9

• 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’

Question 10

What are the CSF findings in SAH

Answer 10

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

Question 11

What are the common cause of ICH?

Answer 11

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

Question 12

What are some methods of decreasing intracranial pressure in head injury

Answer 12

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

Question 13

What are the complications of cervical spine immobilisation

Answer 13

• 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

Question 14

What is the Canadian C Spine Rule and its exclusion criteria?

Answer 14

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

Question 15

What is the nexus rule for C spine imaging and some differences to the CCSR

Answer 15

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

Question 16

spinal chord lesions

Question 17

types of intracranial herniation