Subarachnoid Haemorrhage

Question 1

Causes of SAH:

Answer 1

TRAUMATIC (most common)

NON-TRAUMATIC
- Aneurysm (85%)
–> 90% berry
- Perimesencephalic (10%)
- Other:
–> AVM, stimulants, vasculitis, dissection, CVT, bleeding diatheses, tumours….

Question 2

SAH risk factors:

Answer 2

MODIFIABLE
- SMOKING
- ETOH
- Stimulants
- HTN

NONMODIFIABLE
- Personal Hx
- FHx aneurysmal SAH (1st degree)
- CT disorders incl polycystic kidneys
- Sickle cell
- Female
- >50

Question 3

What is perimesencephalic SAH?

Answer 3

Blood collects in the basal cisterns anterior to midbrain

**NO ANEURYSM- CTA will be normal.
Source of bleed not clear: possible venous, or small basilar.

Benign, prognosis good.

Question 4

What is a Sentinal Headache? How should it be worked up?

Answer 4

Small leak that occurs in hours/ days before a major SAH bleed.

50% will have

More subtle than thunderclap, but is usually more severe, or different to usual headaches.

Therefore first or worst headache: think ?impending SAH.
–> CT +/- LP

Question 5

SYMPTOMS of SAH:

Answer 5

• Thunderclap headache 95%
• Nausea/ vomiting 75%
• Syncope 60%
• Sentinel headache 50%
• Neck pain/ stiffness
• Diplopia
  –> CN III from growing PCOM

Question 6

EXAMINATION in SAH:

Answer 6

• Low grade fever
• ALOC
• Meningismus 75%
  –> delayed
• Focal neuro
  –> 3rd nerve palsy (PCOM)
  –> Leg weakness (ACOM)
• Intraocular haemorrhage
  –> Vitreous
  –> Retinal
  –> Papilloedema
• ECG changes

Question 7

ECG in SAH:

Answer 7

Raised ICP changes:
- Bradycardia (Cushings)
- Prolonged QT
- Hyperacute OR Cerebral’ T waves (deeply inverted)
- STE or STD

Question 8

DDx for thunderclap headache:

Answer 8

VASCULAR:
-Reversible Cerebral Vasoconstriction Syndrome (RCVS)
- CVT
- Dissection
–> Carotid, vertebral, basilar
- Pituitary apoplexy
- Tumour haemorrhage
- GCA
- HTN crisis (PRES)
- Acute hydrocephalus
- Idiopathic thunderclap (40%)

OTHER HEADACHE:
- Migraine
- Cluster

Question 9

Most common site of aneurysm in SAH:

Answer 9

PCOM 40%
ACOM 35%
MCA 20%
Posterior/vertebrobasilar 5%

Question 10

Fisher Grading:

Answer 10

On imaging (CT)
About vasospasm

I- NO blood
II- Thin, diffuse, <1mm thick
III- Clots, >1mm thick
IV- With intraventricular or intraparenchymal

GRADES 3 and 4 = vasopasm

Question 11

World Federation of Neurological Surgeons (WFNS) Grading:

Answer 11

Is clinical
About survival

I GCS 15
GCS <=14
–> II no neuro
–> III neuro
III GCS <=12
IV GCS <=7

Question 12

Describe sensitivity over time of non-con CT in SAH:

Answer 12

< 6 hours
= About 100%

< 12 hours
= 98%

< 24 hours
= 93%

____________
Sensitivity less for:
- Small bleeds
- Low HCT (<27%)

Question 13

Where is blood seen on CT in SAH?

Answer 13

Basal cisterns –> sulci –> intraventricular –> parenchyma

Question 14

Describe the utility of CTA in SAH:

Answer 14

ONLY once SAH diagnosed- as work up for cause.

= incidentalomas +++ (2.5% of population)

98% sensitive
Will not see anuerysms <3mm

Question 15

Describe the utility of angiography in SAH:

Answer 15

Gold standard
Intervention at same time

BUT:
Less available
Less practical
2% complication rate

Used if CTA neg but still suspicious of aneurysm.

Question 16

Lumbar puncture in SAH: utility and interpretation

Answer 16

Indication:
- Negative CT outside 6 hours
- Negative CT any time but SAH still suspected
AND
- No evidence of raised ICP or mass on CT

Delay LP until 6 - 12 hours to allow breakdown products to occur

Xanthochromia
–> Should be spectro

Red cells <2000 in LAST tube

(95% sensitive)

Question 17

How long does xanthrochromia hang around for?

Answer 17

2 weeks

Question 18

Can an early CTB rule out SAH?

Answer 18

Yes.

If thin, multi-slice, within 6 hours, read by radiologist.

….and no specific ongoing suspicion.

Question 19

Early complications of SAH:

Answer 19

Rebleed
–>15% will, within hours
–> Terrible prognosis, 60% mortality
Vasospasm
–> 20%, Fisher 3,4
Global ischaemia
–> From raised ICP, low CPP
Hydrocephalus
Seizure
Hyponatraemia
–> Cerebral salt-wasting
–> SIADH

Neurogenic APO

Arrythmia
Cardiogenic shock

Question 20

Management of SAH:

Answer 20

• Usual resus/ neuroprotective

TRAUMATIC: nil special. +- anticonvulsant.

SPONTANEOUS: locate aneurysm with angio, intervene, antoconvulsant, antispasmodic.

———————

• Bedrest, no exertion, no valsalva
• BP <140/90
• Nimodipine 60mg 4-hourly
  –> Non-traumatic ONLY
• Tx specific complications:
  –> Hydrocephalus
  –> APO
  –> Arrhythmia
  –> HypoNa
• Neurointervention
  –> Coil/ clip

…..monitor for deterioration = spasm/rebleed.

_________________

CONTROVERSIES
- Seizure prophylaxis
- TXA
- Steroid

Question 21

Sensitivity of LP in SAH:

Answer 21

If correctly done >12 hours to look for xanthochromia (within 10 days)-
95%