Ch78 Special Aneurysms and Non-Aneurysmal SAH

Question 1

Prevalence of incidental aneurysms?

Answer 1

5-10%

Question 2

What are the main methodological limitations of ISUIA?

Answer 2

Patients were not randomized to surgery (vs. no surgery), and there were substantial differences between treated and untreated groups Follow-up was < 5 years in 50% of patients Selection bias: low recruitment numbers from each center

Question 3

What is the PHASES score?

Answer 3

Predicts risk of rupture of intracranial unruptured aneurysm in 5 years. Population (European/N.American 0, Japanese 3, Finnish 5) Hypertension (No 0 Yes 1) Age (<70 =0, >70=1) Size: <7mm = 0 7-9mm = 3 10-19.9mm =6 >20mm = 10 Earlier SAH from another aneurysm (No 0 Yes 1) The score is used to calculate the 5 year rupture rate which goes up by 0.5% until score of 10 (=5%). Score 11 = 7.2% and score 12 = 17.8%.

Question 4

Which unruptured aneurysms would you offer treatment to?

Answer 4

If large or symptomatic then treat. If: <60 yo with <7mm aneurysm treat only if posterior circulation + risk factors <60 yo with >7mm aneurysm >60 yo with <7mm aneurysm +risk factors >60 yo with 7-12mm aneurysm if posterior circulation >12mm treat Any aneurysm growing on surveillance

Question 5

How do unruptured cavernous carotid artery aneurysms present?

Answer 5

1. incidentally When symptomatic; 2. headache 3. Cavernous sinus syndrome 4. monocular blindness 5. CCF

Question 6

What proportion of SAH have multiple aneurysms?

Answer 6

15-30%

Question 7

How would you identify the correct aneurysm that has bled if multiple?

Answer 7

Look for epicentre of blood localised vasospasm irregular aneurysm (Murphy’s teat) If none of the above help, suspect the largest aneurysm

Question 8

What genes are associated with aneurysm formation?

Answer 8

CDKN2B (Ch9) SOX17 (Ch 8) EDNRA (Ch4)

Question 9

When would you screen family for aneurysms?

Answer 9

If 2 or more first degree relatives have been diagnosed with intracranial aneurysms or aSAH. Modality should be MRA for screening and DSA if something is picked up. Patients with coarctation of the aorta screening is recommended.

Question 10

What are the ISUIA rupture rates?

Answer 10

5 year rupture rates! Anterior circulation: <7 mm = 0%, 7-12 mm = 2.5%, 13-24 mm = 14.5%, >25 mm = 40%; Posterior circulation: <7 mm = 2.5%, 7-12 mm = 14.5, 13-24 mm = 18.4%, >25 mm = 50%

Question 11

How do you treat traumatic aneurysms?

Answer 11

Require occlusion (surgical or endovascular) as rarely resolve on their own

Question 12

What are the risk factors for unruptured aneurysms to grow?

Answer 12

Size, location (MCA / Basilar tip), multiple aneurysms, FHx of SAh and smoking.

Question 13

Where do cavernous ICA aneurysms occur?

Answer 13

On the horizontal portion

Question 14

What are the segments of the cavernous ICA?

Answer 14

Posterior vertical, posterior bend, horizontal, anterior bend and anterior vertical.

Note the MHT comes from the posterior bend and the inferior lateral trunk comes from the horizontal segment.

Question 15

What is cavernous sinus syndrome?

Answer 15

CN3 palsy without dilated pupil (because the sympathetics which cause pupillary dilation are also affected!)

Question 16

Which carotico-cavernous fistulas need urgent treatment?

Answer 16

Eye pain or threat to vision due to venous engorgement. Treat with endovascular occlusion of the fistula

Question 17

Which genetic conditions predispose to aneurysms?

Answer 17

AD Polycystic kidney disease

Ehlers Danlos type 4

Marfan’s

Pseudoxanthoma elasticum

MEN1

HHT

NF-1

Fibromuscular dysplasia

(Note these aneurysms rupture at a smaller size and earlier age)

Question 18

What type of aneurysms are traumatic aneurysms?

Answer 18

False aneurysms - i.e. do not contain all 3 layers.

Treat endovascularly!

Question 19

What proportion of patients with bacterial endocarditis develop mycotic aneurysms?

Answer 19

10%. Most occur on distal MCA branches. Highest incidence with Strep Viridians

Question 20

How do you treat mycotic aneurysms?

Answer 20

IV abx. Treatment needed with SAH or aneurysm fails to shrink with 6 weeks abx.

Question 21

What are the treatment options for giant aneurysms?

Answer 21

Direct surgical clipping

Bypass

Trapping

Hunterian ligation

Endovascular stenting

Question 22

What are the causes of cortical SAH?

Answer 22

AVMs

dAVF

Cortical venous thrombosis

RCVS

PRES

Amyloid angiopathy

Anticoagulaion

Cortical brain tumours

Question 23

How do you investigate SAH that have a negative DSA?

Answer 23

Repeat angio @ 14 days

MRI

Spinal angiography

Question 24

Where do traumatic aneurysms occur?

Answer 24

At the skull base (petrous or cavernous part of ICA - both associated with skull base fractures) Peripherally - distal ACA

Question 25

How do you treat traumatic aneurysms?

Answer 25

Require occlusion as rarely resolve on their own

Question 26

What are the perimesencephalic cisterns?

Answer 26

Interpeduncular, crural, ambient and quadrigeminal

Question 27

What separates the interpeduncular cistern from the chiasmatic cistern?

Answer 27

Lillequist's membrane superior leaflet. Note the inferior leaflet separates the

Question 28

What are the diagnostic criteria for a perimesencephalic SAH?

Answer 28

CT within 48h has blood confined to the perimesencephalic cisterns (not chiasmatic cistern!). Allowed to have some in the medial sylvian fissure. No intraparenchymal blood DSA negative SAH grade 1/2

Question 29

Where do mycotic aneurysms occur?

Answer 29

Distal MCA (75-80%)

Question 30

How do you treat mycotic aneurysms?

Answer 30

Antibiotics Surgical management difficult as often friable and fusiform morphology Serial angiograms to assess size of aneurysm

Question 31

What is a giant aneurysm?

Answer 31

\>2.5cm