FACTS
- peak age 55-60 yo --> although 20% between 15-45 yrs
- 10-15% die before getting care
- Risk of re-rupture is greatest in first 24 hours
HPI
- Smoker
- HTN
- Etoh use
- Family Hx of ruptured aneurysms
- Known syndromes or connective tissue diseases (PCKD, Marfan, EDS)
- seizures - this matters, because not all SAH are started on AEDs
- Drug use (specifically, cocaine)
- Neurologic baseline - pertinent in old people to know baseline level of confusion because confusion alone is a HH3 and indication for EVD
- recent myelography (very rare mimic - see below)
Labs: ensure Cr reasonable for CTA/DSA and CBC/Coags ready for EVD
IMAGING
CTH non-con
impossible to use this to diagnose aneurysm location, however there are some patterns:
- Acomm = anterior interhemispheric fissures or gyrus rectus
- MCA / Pcomm = unilateral sylvian fissure
- Basilar apex / SCA = prepontine pr peduncular cistern
- Lower posterior fossa (PICA/VA dissection) = predominantly within ventricles
CTA H&N:
- look for the neck wideness (narrower <5mm = better for coiling)
CT C-spine - should be included on CTA H&N, but this is necessary to clear a C-collar which is often placed when a person is found down after rupture
MRA will not be more useful than CTA, however can be done if patient has a real and serious allergy to contrast or whatever contraindication. Pretty poor sensitivity for aneurysms < 3mm in diameter
A/P
I. Acute management
- HOB > 30
- Clear C-collar ASAP with CT C-spine or MRI C-spine: many of these patients are found down and treated as traumas. C-collars can reduce jugular venous outflow if applied correctly and tightly.
- Ventriculostomy as indicated: EVD at 20AMB, cannot drain too aggressively, you actually want the high ICP to "tamponade" the bleeding, SBP CAP at 140
- Ask CCM to place a Left radial a-line while you do the EVD to get ready for DSA
II. Secure the aneurysm
DSA vs. OR
After securing aneurysm, EVD to 5 or 10, CAP liberalized3
III. Managing Spasm / Neuro ICU admission orders
- Euvolemia: avoid hypotension, check IOs at 4am and 4pm, place foley if needed
- SAH precautions: minimize stimulations
- HA management: can be very intractable, steroids often the only thing that help if not other contraindications
- HOB > 30 degrees
- Nimotop 30q2 or 60q4 (more frequent = to avoid periodic dips in BP)
- TCDs to monitor MCA, ACA, ICA velocities and Lindegaard ratio if available at your institution
Angio negative SAH: repeat DSA or MRI Brain and pan-spine in about a week
Spasm watch (Days 4-14)
HHH Therapy: Hypervolemia, Hypertension, Hemodilution
- Euvolemia: (Hypervolemia/Hypertension)
- Daily TCDs
- Electrolyte repletion: preserve cerebral perfusion, maintain vascular tone, and reduce the risk and severity of vasospasm
- Na+
- K+: low K+ causes hyperexcitability of vascular smooth muscle
- Mg2+: has direct vasodilatory effects (acts as Ca2+ channel blocker)
Table 1: Electrolyte Targets in Vasospasm
Electrolyte | Target Range (Post-SAH) | Rationale | Notes |
Sodium (Na⁺) | 140–150 mmol/L (high-normal) | Prevents hyponatremia-induced cerebral edema and hypovolemia; maintains osmotic gradient to limit ICP spikes. | Avoid rapid correction (>8–10 mmol/L/24h) to prevent osmotic demyelination. Often managed with hypertonic saline in salt-wasting. |
Magnesium (Mg²⁺) | ≥2.0 mg/dL (0.82 mmol/L) | Vasodilatory effect via calcium channel antagonism; neuroprotective in ischemia. | Check daily; replete IV if low—monitor for hypotension with rapid infusion. |
Potassium (K⁺) | 4.0–4.5 mmol/L | Stabilizes vascular and neuronal membrane potentials; prevents arrhythmia that could reduce cerebral perfusion. | Prefer central line for high-dose IV repletion; avoid hypokalemia in nimodipine therapy. |
Calcium (Ca²⁺) | Ionized Ca²⁺ >1.1 mmol/L | Needed for cardiac contractility and vascular tone regulation; hypocalcemia can worsen hypotension. | Correct Mg first if refractory hypocalcemia. |
Phosphate (PO₄³⁻) | ≥2.5 mg/dL | Supports ATP production for neuronal and vascular smooth muscle function. | Often drops during aggressive repletion of other electrolytes—replace enterally if possible. |
Figure 1: Saccular aneurysms and locations
most commonly at branch points. Fusiform aneurysms more common in vertebrobasilar system.
Sentinel Bleed workup without SAH
sometimes people have a thunderclap HA w/o clear SAH on a low-quality CT. These are managed as SAH until proven otherwise, especially if the patient has a known aneurysm
How to prove otherwise
1) MRI Brain w/wo contrast - higher definition picture to evaluate for presence of blood however this is not sensitive until 2-3 days post-bleed
+/- MRI pan-spine to evaluate for gravity dependent blood
2) Lumbar puncture: send CSF in 4 tubes, very important to be as atraumatic as possible
- if RBCs stable or downtrending from tubes 1-4 --> unlikely SAH
- if RBCs uptrending or xanthochromic supernatant --> more likely SAH
- if this is traumatic, its a useless test
- this is not without risk, if there is an actual ruptured aneurysm can precipitate rebleeding
- if a person is jaundiced, this can be false-positive
Specific Aneurysms
Cavernous Sinus Carotid Aneurysms
- For unruptured, most likely symptom is a CN6 palsy (closest proximity to abducens nerve in cavernous sinus)
- facial pain syndromes in the maxillary nerve distribution
Mycotic Aneurysms
Opthalmic Aneurysms
- may present with chiasmal syndrome
Acomm Aneurysms
- may present with chiasmal syndrome
Basilar Apex Aneurysms
- may present with chiasmal syndrome
P-comm Aneurysms
- 10% of these aneurysms p/w non-pupil sparing CN 3 palsy
Infundibulum vs Aneurysms
infundibulum = funnel shaped initial artery segment, most commonly at Pcomm origin
Associated Syndromes
PCKD
- PCKD is associated with intracranial aneurysms, cervical arterial dissections, intracranial dolichoectasia, spinal meningeal diverticula
- general mechanism is abnormal collagen/proteoglycans produced --> weaken
Marfan Syndrome
Subarachnoid hemorrhage mimic
This is a very rare mimic of subarachnoid hemorrhage - if you see someone who is wide awake with what looks like a modified fisher 7 subarachnoid hemorrhage, ask them if they recently got a myelogram!
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