1. Hunt Hess grades for SAH: 
- 0: unruptured aneurysm
- 1: asymptomatic, or mild headache, and slight nuchal rigidity
- 1a: any neurological deficit, but no acute meningeal/brain reaction
- 2: CN palsy, mod-severe headache, nuchal rigidity
- 3: Mild focal neuro deficit, lethargy, confusion
- 4: Stupor, moderate-severe hemiparesis, early decerebrate posturing
- 5: Rigidity, deep coma, decerebrate rigidity, moribund appearance
2. Risk of vasospasm based on Hunt Hess grade 
- 1: 22%
- 2: 33%
- 3: 52%
- 4: 53%
- 5: 74%
3. Modified Fisher grade for SAH {source} 
- 0: No SAH, no IVH on CT
- 1: Thin focal/diffuse SAH, no IVH
- 2: Thin focal/diffuse SAH, + IVH
- 3: Thick focal/diffuse SAH, no IVH
- 4: Thick focal/diffuse SAH, + IVH
4. Risk of vasospasm based on modified fisher scale {source} 
- 0-1: 24%
- 2: 33%
- 3: 33%
- 4: 40%
5. More on the modified Fisher grade; from the {original study} "Explicit criteria for classifying blood as thick or thin, or focal or diffuse, were not applied."

1, 2, 3, and 4 correlate to modified fisher grades 1, 2, 3, and 4.
6. Modified fisher scale vs original fisher scale: 

7. Segments of MCA

There are a few different classification systems for the segments of the MCA; the surgical approach names the following: 

- M1 (sphenoidal): the straight part of the MCA, shown above in blue

- M2 (insular): the rising part of the MCA, inside the insula

- M3 (opercular): where the MCA once again turns straight as it runs along the parietal and temporal operculae.

- M4 (cortical/terminal): where the MCA turns out into the cortex. 

Some systems lump the insular and opercular segments together as M2, and call the cortical branches M3. 

The radiographic system names M1 as the MCA before bifurcation, and M2 as the MCA after bifurcation (seen below): 

8. Branches of the internal carotid: from a paper in {neurosurgical focus} 

9. Branches of ICA:

C1: cervical: no branches

C2: Petrous: has 3 parts (see below for best image - source)

- vertical segment 

- posterior loop (antero-interior to cochlea)

- horizontal segment (deep and medial to greater/lesser superficial petrosal nerves) 

C3: lacerum: passes over foramen lacerum, passes petrolingual ligament 

C4: cavernous: passes anteriorly, then supero-medially, then bends anteriorly to anterior clinoid. Ends at proximal dural ring (see below for best image- source) 

Branches in C4: 

- MHT (meningiohypophyseal trunk) - prominent MHT may indicate petroclival meningioma or dural AVM

- Tentorial artery (prominent may indicate petroclival/tentorial meningoma) 

- Inferior hypophyseal artery (supplies posterior lobe of pituitary) 

C5: clinoid: labelled as "C" in above image, between proximal and distal dural rings; distal dural ring completely encircles carotid-- it is at this point that the carotid becomes intradural. 

C6: Opthalmic: distal dural ring to just proximal to p-comm origin. 

- Opthalmic artery - origin distal to cavernous sinus in 89%, in cav sinus in 8%, absent in 3%. 

- Superior hypophyseal artery: supplies anterior lobe of pituitary and the stalk! 

C7: communicating: from just before p-comm origin to just below anterior perforated substance (where it bifurcates into ACA/MCA) 

- p-comm: gives off few anterior thalamoperforators (supplies optic tract, chiasm, posterior hypothalamus)

- anterior choroidal: supplies optic tract, medial globus pallidus, genu of internal capsule, inferior half of posterior limb of internal capsule, uncus, optic radiation, lateral geniculate body. 

10. Branches of the ICA (angiographic) {source}