Catastrophies Flashcards
Causes of Cauda Equina Syndrome?
Disc herniation (most common)
Infection (discitis, epidural abscess)
Cancer (mets vs primary)
Haem (spontaneous bleed, spinal artery thrombosis)
Trauma (fracture, haematoma)
Systemic (GBS, MS, progressive neurological disease, diabetes)
Iatrogenic (post LP/spinal/epidural or surgery)
What are the typical intracranial sites of hypertensive bleeds?
Cerebellar hemispheres
Basal Ganglia (most common)
Pontine
What are some of the characteristics of a lobar haemorrhage
Located more peripherally near the gray-white matter junction
Associated with subarachnoid and subdural blood, often goes to the edge of the brain
Usually 70+, associated with cerebral angiopathy
Where is aneurysmal rupture subarachnoid blood usually located?
Usually centrally near the circle of willis (95% of aneurysms), often gravity dependent and blood will pool in the basal cisterns
Where is traumatic subarachnoid blood usually located
Usually peripherally near the site of impact or in the contrecoup distribution
Blood will extend into the sulci
How do Extra(Epi)dural haematomas usually appear
Convex (lentiform) in shape
Do not cross suture lines
Usually directly under skull fracture
Most common cause is fracture through the pterion rupturing the middle meningeal artery
Also occurs with fracture rupturing a dural venous sinus
How do Subdural haematomas usually appear?
Concave (crescent, sickle) in shape
Can cross suture lines and may not be directly under a fracture
Blood between dura and arachnoid, can track into the falx cerebri
Do not extend into the sulci
In trraumatic pneumocephalus, where does the air come from?
Externally from a laceration overlying a fracture
Internally from fracture extending to the mastoid air cells
What are the sites of normal calcification on CT Brain
The pineal gland in the midline (approx 30yo)
The choroid plexes bilaterally
What is the chemical cause of Xanthochromia?
Blood breakdown products
- Bilirubin, oxyhaemoglobin and methaemoglobin
How useful is the Ottawa SAH rule?
Almost 100% sensitive but only 15% specific, hence it is a SnOut
How useful is a CT scan in suspected SAH?
- Within 6hrs approx 98.5% sensitive and 99.5% specific
- Still very sensitive at 86% after this, and the baseline rate of people presenting with SAH after 6hrs is lower leading to a combined post test probability of 0.8%
- Small volume bleed, severe anaemia, non-neuro radiologist and increased time all decrease sensitivity
CT angio COW is 99% sensitive/specific
How useful is LP in SAH?
Essentially 100% sensitive but poorly specific with high false positive rate
What are the criteria for clot retrieval in ischaemic stroke?
- Proximal large vessel clot (M1, prox M2, internal carotid, basilar)
- Pre-morbid state good (modified Rankin </= 2)
- NIHSS >/=5
- Within 6hrs of onset, or 6-24hrs but large area of salvageable penumbra
How should a deteriorating SAH patient generally be managed?
- Urgent NSx referral
- Intubate, avoid hypoxia, hypercapnoea and hypotension during the intubation
- Aim lower end of normal CO2 (ie 35mmHg)
- Neuroprotective strategies such as head up 30 degrees, avoid pressure on neck, cough and straining
- Aim SBP <140mmHg, can use labetalol 20mg, hydralazine 5mg etc
- Consider mannitol/3% saline
- Consider repeat CTB for re-bleed or vasospasm
- Seizure prophylaxis 20-60mg/kg Keppra or 20mg/kg Phenytoin
In a previously stable non-intubated SAH patient, what may cause a deterioration?
- Seizures
- Rising ICP ie re-bleed
- Vasospasm
- Hypercapnoeic resp failure
- Iatrogenic (ie opioids)
What is the dosing of 3% Saline in raised ICP?
3mls-5/kg of 3% saline
210-350mls for a 70kg man
Aiming for Na+ 145-150
Contraindicated with hypervolaemia and Na+ >160
What is the dosing of Mannitol in raised ICP?
2ml/kg - 5mls/kg of 20% mannitol
or 0.25gm/kg - 1gm/kg
Can repeat to 5ml/kg or 1gm
50kg patient would receive 100mls of 20% which is 20gm
Contraindicated with intravascular volume depletion
What are the different neuroprotective blood pressure targets?
Non-traumatic ICH
- Safe to aim for <140
Non-traumatic SAH
- <140 associated with lower risk of rebleeding
- However <140 gives often inadequate CPP if evidence of RICP
- Consensus guidelines say <160mmHg, but if no evidence of RICP can aim for 140mmHg
Mannitol vs HTS
HTS
- Volume expander (good in trauma, sepsis etc)
- Aiming Na+ 145-155
- Less likely to leak into brain tissue via damaged BBB
- Indications are raised ICP, hyponatremia and volume expansion
- Tissue necrosis if extravasates
- Hyperchloraemic acidosis
- Peaks at 10mins, lasts 1hr
Mannitol
- Osmotic diuretic
- Causes hypovolaemia
- electrolyte shifts (HypoK + Na)
- Risk of rebound raised ICP with repeated doses in damaged BBB (absorption into brain tissue)
- Can cause AKI
- Effects within minutes, peak at 4hrs)
When should patients with GBS and MG be intubated based on PFT’s?
- PFT with the most evidence is forced vital capacity
- Normal FVC in 70kg male is 5L, or >50ml/kg
- Patients with FVC <20ml/kg (<1.5L in adults) are at risk of resp failure
- Generally patients with FVC <15ml/kg (ie <1L) need to be intubated, although clinical judgement should be used
What are the differentials for thunderclap headache (TCH)?
A severe headache that begins abruptly and peaks within 1min
Most common
- SAH (50% have TCH)
- Reversible cerebral vasoconstriction syndrome (RCVS, 95% have TCH)
Less common
- PRES/hypertensive crisis
- Pre-eclampsia
- Cerebral venous sinus thrombosis
- Spontaneous intracranial hypotension
- Cervical/vertebral artery dissection
- ICH
- Ischaemic stroke
Uncommon
- Meningoencephalitis
- Complicated sinusitis
- Pituitary apoplexy
- Aortic dissection
- Phaeocrhomocytoma
- brain tumour
What are clinical situations in which differentials for thubnderclap headache are more common?
Intra/post partum
- RCVS, cerebral venous sinus thrombosis
Recurrent over days/weeks
- RCVS
- Sentinel bleed (controversial)
Orthostatic in nature
- Spontaneous, traumatic or iatrogenic intracranial hypotension (ie post LP)
Minor trauma
- intracranial hypotension, vertebral artery dissection
Horner syndrome/Pulsatile tinnitus
- Ipsilateral carotid artery dissection
Facial/ear/nose pain
- complicated sinusitis
Fevers and meningism
- Meningoencephalitis
Visual/eye symptoms
- Cavernous sinus thrombosis
What are the inclusion criteria for endovascular clot retrieval?
- Ischaemic stroke with proven large vessel occlusion on CTA (ICA, M1, prox M2, basilar)
- Independent pre-morbid function ie Modified Rankin score 0-2 (3 is grey zone for treatment)
- Up to 24hrs post symptom onset
- Accessible to clot retrieval based on anatomy
- NIHSS score >6
- Thrombolysis started if applicable
What is the dosing and adverse effects of Alteplase for ischaemic stroke thrombolysis?
- 0.9mg/kg max 90mg
- 10% as bolus then 90% over 1hr
Adverse effects
- 2-5% significant bleeding
- 1% angioedema
What are the exclusion criteria for endovascular clot retrieval?
- Modified Rankin score >3
- NIHSS score <6
- Presence of large hypodensity on CT head beyond ischaemic changes
- No ischaemic penumbra present
- Presence of large core infarct >50mls in patient with pre-existing severe co-morbidities
- > 24hrs since symptoms started (relative)
What are the inclusion and exclusion criteria for thrombolysis in stroke?
Inclusion
- Ischaemic stroke with measurable neurological deficit (NIHSS >6)
- Age >18yrs
- Symptoms started <4.5hrs ago
Exclusion
- Typical thrombolysis contraindications
- Evidence of haemorrhage
- Extensive regions of irreversible injury
- No ischaemic penumbra
- Consistent with endocarditis as cause
- Known or high possibility of dissection
What is ACEM’s position on the use of thrombolysis in ischaemic stroke?
What are the advantages and disadvantages of LP vs CTA
CT
- Non-invasive
+
- IV contrast risks
- incidental aneurysms
- radiation
LP
- Can identify other non-SAH causes ie meningitis
+
- Invasive
- Painful and complications
- Time consuming
- Needs appropriate skill set and can be challenging (ie obesity)
- Needs to be performed 12hrs post the onset of headache
- possible equivocal results
What are the criteria on LP to exclude an SAH?
- Absence of xanthochromia
+ - Absence or very few (<5) RBC’s
