Subarachnoid Hemorhage
Dr. Holly Ryan
Editor: Omar Lopez MS3
Background
1. Headache is a very common complaint in the ED, up to 2% of patients that walk into the emergency department have the CC of HA.
This doesn’t seem like a lot but the most common ED complaint is abdominal pain and that’s about 7%
2. SAH is a stroke
Although it only encompasses 3% of all strokes, it is still a devastating disease.
3. Patient Population has a broad age range
The average age for an ischemic stroke is greater than or equal to 65 while SAH is around 50.
4. Life-threatening and can be fatal.
10% of patients with non-traumatic SAH have sudden death
Untreated SAH leads to one-year mortality up to 65%... thankfully this can be reduced to 18% if patients are appropriately treated and managed
However, there is still a 12% reported rate of missed diagnosis.
Definition
A bleed in the subarachnoid space which is usually filled with CSF, to protect and cushion our brain.
This space is the closest to the actual brain and that is important physiologically because blood that sits on the brain parenchyma can cause irritation, which is why these patients are at increased risk for seizures.
Causes
Primary:
Aneurysmal (85%)
Perimsencephalic (10%)
Vascular Malformations (5%)
Secondary:
Trauma, tumor, SCD
Presentation Work-Up
Buzzwords: thunderclap headache, worst HA of my life
Signs & Symptoms:
Headache
Meningismus
Elevated ICP
Focal neurological signs
Seizure
ABC’s
IV access
Monitor/pulse ox/vitals
POC glucose
Noncontrast CT Head
Labs
Lumbar Puncture
ACEP Clinical Guidelines and Policies
1. Risk stratification for emergent imaging in ED patients with headache?
Level B = Ottawa SAH Rule
2. Further workup necessary in adult ED patient with normal noncon CT Head within 6 hours of HA onset?
Level B = No, if CT scanner is 3rd generation and patient has a NORMAL NEUROLOGIC EXAM
3. Is CTA as effective as LP to r/o SAH?
Level C = Yes but use shared decision making
Lumbar Puncture
CT Angiography
Pros:
Less radiation
No contrast needed
Cons:
Invasive, infection, hematoma
Contraindications
Time
Traumatic LP looks like SAH
85% sensitive and specific
Pros:
95% specific and sensitive
Required if +CTH
Assess other dx
Cons:
Contrast needed
More radiation
No detection of small
Incidental aneurysm
Literature Review
Objective: To measure the sensitivity of modern third generation computed tomography in emergency patients being evaluated for possible subarachnoid haemorrhage, especially when carried out within six hours of headache onset.
Design: Prospective cohort study.
Setting: 11 tertiary care emergency departments across Canada, 2000-9.
Participants: Neurologically intact adults with a new acute headache peaking in intensity within one hour of onset in whom a computed tomography was ordered by the treating physician to rule out subarachnoid haemorrhage.
Main outcome measures: Subarachnoid haemorrhage was defined by any of subarachnoid blood on computed tomography, xanthochromia in cerebrospinal fluid, or any red blood cells in final tube of cerebrospinal fluid collected with positive results on cerebral angiography.
Results: Of the 3132 patients enrolled (mean age 45.1, 2571 (82.1%) with worst headache ever), 240 had subarachnoid haemorrhage (7.7%). The sensitivity of computed tomography overall for subarachnoid haemorrhage was 92.9% (95% confidence interval 89.0% to 95.5%), the specificity was 100% (99.9% to 100%), the negative predictive value was 99.4% (99.1% to 99.6%), and the positive predictive value was 100% (98.3% to 100%). For the 953 patients scanned within six hours of headache onset, all 121 patients with subarachnoid haemorrhage were identified by computed tomography, yielding a sensitivity of 100% (97.0% to 100.0%), specificity of 100% (99.5% to 100%), negative predictive value of 100% (99.5% to 100%), and positive predictive value of 100% (96.9% to 100%).
Conclusion: Modern third generation computed tomography is extremely sensitive in identifying subarachnoid haemorrhage when it is carried out within six hours of headache onset and interpreted by a qualified radiologist.
Results: 91% of cases had a completely negative LP with absolutely no xanthochromia present. Only 4% were positive and 5% were equivocal. Completed CT angiography in the positive or equivicol patient population and found that only 4% had a cerebral aneurysm. Which led to conclude that in suspected SAH cases where CT scan in negative, the rate of detection for cerebral aneurysm with LP is 0.4%.
Management and Disposition
BP Control:
Vasospasm Prevention
Coag Reversal
ICP Control
Seizure PPX??
DISPO = ICU, neurosurgery
Controversies in Care: Seizure PPX
Increased risk:
Coma
More severe disease
Rebleeding
Surgical intervention- craniotomy and surgical aneurysm clipping
Management:
Keppra- EmCrit says Keppra is continued for 3-7 days and can be discontinued if they don’t have a seizure AND the aneurysm has been secured.
Length varies- If patients have seizure they should have longer duration of antiepileptic therapy for at least several months
References
Tintinalli’s
ACEP
Marcolini E, Hine J. Approach to the Diagnosis and Management of Subarachnoid Hemorrhage. West J Emerg Med. 2019 Mar;20(2):203-211. doi: 10.5811/westjem.2019.1.37352. Epub 2019 Feb 28. PMID: 30881537; PMCID: PMC6404699.
Dubosh NM, Bellolio MF, Rabinstein AA, Edlow JA. Sensitivity of Early Brain Computed Tomography to Exclude Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis. Stroke. 2016 Mar;47(3):750-5. doi: 10.1161/STROKEAHA.115.011386. Epub 2016 Jan 21. PMID: 26797666.
Mohan M, Islim AI, Rasul FT, Rominiyi O, deSouza RM, Poon MTC, Jamjoom AAB, Kolias AG, Woodfield J, Patel K, Chari A, Kirollos R; British Neurosurgical Trainee Research Collaborative. Subarachnoid haemorrhage with negative initial neurovascular imaging: a systematic review and meta-analysis. Acta Neurochir (Wien). 2019 Oct;161(10):2013-2026. doi: 10.1007/s00701-019-04025-w. Epub 2019 Aug 13. PMID: 31410556; PMCID: PMC6739283.
Gottlieb M, Morgenstern J. Lumbar Puncture Should Not Be Routinely Performed For Subarachnoid Hemorrhage After A Negative Head Ct. Ann Emerg Med. 2021 Jun;77(6):643-645. doi: 10.1016/j.annemergmed.2020.11.018. PMID: 34030777.
EmCrit