1. Subarachnoid hemorrhage
extravasation of blood into the subarachnoid space between the pial and arachnoid membranes

2. Etiologies Trauma Spontaneous MOST COMMON cause of SAH
Ruptured aneurysms (75-80%)
Cerebral AVMs
CNS vasculitides
Cerebral artery dissection
Coagulation disorders
Dural sinus thrombosis
No cause determined

3. Risk Factors Hypertension OCPs
Substance abuse—cigarette smoking, cocaine abuse, alcohol consumption
Diurnal variation ins BP
Pregnancy and parturition
During LT or cerebral angiography in those with aneurysms
Advancing age

4. Cerebral Aneurysms Cerebral VS extracranial blood vessels
Less elasticity of tunica media and adventitia
Tunica media has less muscle
Adventitia is thinner
More prominent internal elastic lamina
Subarachnoid space has very little supportive tissue

5. Cerebral Aneurysms
Early precursors of aneurysms are small outpouchings through defects in the media of the arteries
These defects are thought to expand as a result of hydrostatic pressure from pulsatile blood flow and blood turbulence, which is greatest at the arterial bifurcations

6. Cerebral Aneurysms Etiology
Congenital (Medial gap: defect in muscular layer of arterial wall)
Atherosclerotic or hypertensive
Embolic (atrial myxoma)
Infectious (mycotic aneurysms)
Traumatic
Associated with other conditions

7. Cerebral Aneurysms LOCATION Saccular aneurysms (berry aneurysms)
Located on major arteries at the apex of branch points (site of maximum hemodynamic stress on a vessel)
Fusiform aneurysms
More common in the vertebrobasilar system

9. Cerebral Aneurysms Saccular aneurysms location
85-95% in carotid system, with the ff most common locations
ACoA: 30%
P-comm: 25%
MCA: 20%
5-15% in the posterior circulation (vertebro-basilar)
20-30% would have multiple aneurysms

11. Clinical Features SYMPTOMS Headache Vomiting Syncope Photophobia
MAJOR RUPTURE IS THE MOST FREQUENT PRESENTATION
SYMPTOMS
Headache
Most common, present in 97% of cases
“Worst headache of my life”
Severe and sudden
Vomiting
Syncope
Photophobia
Neck pain
Focal cranial nerve deficits (diplopia, ptosis)

12. Clinical Features SIGNS (+) Kernig’s or Brudzinksi’s Coma
Increased ICP
Damage to brain tissue
Hydrocpehalus
Diffuse ischemia
Seizure
Low blood flow
Ocular hemorrhage
Due to compression of the central retinal vein and the retinochoroidal anastomoses by elevated CSF pressure causing venoud HPN and disruption of retinal veins

13. Aneurysmal Rupture
The probability of rupture is related to the tension on the aneurysm wall
Law of La Place: tension is determined by the radius of the aneurysm and the pressure gradient across the wall of the aneurysm
The rate of rupture is directly related to the size of the aneurysm
< 5 mm: 2% risk of rupture
6-10 mm: 40% have already ruptured upon diagnosis

14. Aneurysmal Rupture
Blood extravasates under arterial pressure into the subarachnoid space and quickly spreads through the CSF around the brain and spinal cord
Direct damage to local tissues
Increased ICP
Meningeal irritation

15. Hunt and Hess Classification of SAH
Grading SAH
Hunt and Hess Classification of SAH
Grade
Description 1
Asymptomatic or mild H/A and slight nuchal rigidity 2
CN palsy (III, VI), moderate to severe H/A, nuchal rigidity 3
Mild focal deficit, lethargy, confusion 4
Stupor, moderate to severe hemiparesis, early decerebrate rigidity 5
Deep coma, decerebrate rigidity, moribund appearance
Add one grade for serious systemic disease (HPN, DM, severe atherosclerosis, COPD), or severe vasospasm on arteriography.

16. Grading SAH
Grades 1 & 2: operated ASAP as soon as an aneurysm is diagnosed
Grade > 3 managed until condition improved to grade 2 or 1
Exception: life threatening hematoma or multiple bleeds (operated on regardless of grade)

17. Grading SAH MORTALITY Admission Grade 1 or 2: 20% OR Grade 1 or 2: 14%
Rebleed: major cause of death for Grade 1 or 2
Signs of meningeal irritation increases surgical risk

18. Grading SAH WFNS SAH Grade WFNS Grade GCS Score Major Focal Deficit
0** 1 15 - 2
13-14 3 + 4
7-12
+ or - 5
3-6
*aphasia, hemiparesis or hemiplegia
** intact anseurysm

19. Grading SAH Fischer Scale (CT scan appearance) Grade Description 1
No blood detected 2
Diffuse deposition of subarachnoid blood, no clots, and no layers of blood greater than 1 mm 3
Localized clots and/or vertical layers of blood 1 mm or greater in thickness 4
Diffuse or no subarachnoid blood, but intracerebral or intraventricular clots are present

20. SAH Grading
The Hunt and Hess and the WFNS grading systems correlate well with patient outcome
The Fischer classification predicts the likelihood of symptomatic cerebral vasospasm, one of the most feared complications of SAH
All 3 grading systems are useful in determining the indications for and timing of surgical management

21. Outcome of Aneurysmal SAH
10-15% die before reaching medical care
45% overall mortality rate
NO SURGERY: Rebleeding is the major cause of M&M in 15%
SURGERY: Vasospasm kills 7%
66% who underwent clipping never return to the same QoL