Subarachnoid hemorrhage: Difference between revisions

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==Background==
''Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space. Clinical approach differs by etiology — see the appropriate page below:''
===Pearls===
*Obtain neuro exam before intubation
*If intubate prevent HTN (rebleeding)  
**Pretreatment
***Lidocaine 1-1.5mg/kg (100mg) (blunts incr in BP)
***Fentanyl 2-3mcg/kg (sympatholytic)
**Induction
***If pt has high BP - use propofol
***If pt has adequate BP - use etomidate
**Treat pain
***Prevents incr catacholamines / incr BP
===Epidemiology===
*Of All pts in ED who p/w HA:
**1% will have SAH
**10% will have SAH if c/o worst HA of life
**25% will have SAH if c/o worst HA of life + any neuro deficit
===Risk Factors===
*Genetics (polycystic kidney disease, Ehler-Danlos, family hx)
*Hypertension
*Atherosclerosis
*Cigarette smoking
*Alcohol
*Age >50
*Cocaine use
*Estrogen deficiency
===Etiology of Spontaneous SAH===
*Ruptured aneurysm (85%)
*Nonaneurysmal (15%)
**Perimesencephalic hemorrhage (10%) - lower risk of complications
**Other: tumor, coagulopathy, dissection, vasculitis, SCD, venous sinus thrombosis


==Clinical Features==
*[[Aneurysmal subarachnoid hemorrhage]] — spontaneous/non-traumatic SAH (most commonly ruptured cerebral aneurysm)
*Sudden, severe [[headache]] that reaches maximal intensity within minutes (97% of cases)
*[[Traumatic subarachnoid hemorrhage]] — SAH due to blunt or penetrating head trauma
**Sudden onset is more important finding than worst [[headache]]
*May be associated with [[syncope]], [[seizure]], [[nausea/vomiting]], meningismus
**Meningismus may not develop until hrs after bleed (blood breakdown -> aseptic meningitis)
*[[Retinal hemorrhage]]
**May be the only clue in comatose patients
*Sentinel bleed headache 6-20 days before serious SAH in 30-50% of patients


== Differential Diagnosis ==
[[Category:Neurology]]
{{Intracranial hemorrhage DDX}}
[[Category:Critical Care]]
 
===Other===
*Drug toxicity
*Ischemic [[Stroke (Main)|Stroke]]
*[[Meningitis]]
*[[Encephalitis]]
*Intracranial tumor
*Intracranial hypotension
*Metabolic derangements
*[[Cerebral venous thrombosis]]
*Primary headache syndromes (benign thunderclap headache, [[Migraine]], [[Cluster Headache]])
 
== Diagnosis  ==
[[File:SubarachnoidP.png|thumb|Noncontrast CT showing subarachnoid hemorrhage (white area in the center stretching into the sulci).]]
===Ottawa SAH Rules<ref>Ottawa SAH Rule JAMA. 2013 Sep 25;310(12):1248-55. doi: 10.1001/jama.2013.278018</ref>===
''Never has been externally and prospectively validated, authors caution implementation into routine use''
*100% sensitive to rule out SAH (97.1%-100%)
*Can exclude SAH if all of the following are true
**Age < 40
**No Neck pain or stiffness
**No Witnessed LOC
**No onset during exertion
**No Thunderclap symptomatology (max intensity at honest)
**No limited neck flexion on physical exam
 
'''If concerned for SAH and CT normal strongly consider LP'''
 
===Non-Contrast Head CT ===
{| class="wikitable"
| align="center" style="background:#f0f0f0;"|'''Time from onset of symptoms'''
| align="center" style="background:#f0f0f0;"|'''Sensitivity of CT'''
|-
| <6 hours||~100%<ref>Perry JJ, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ. 2011; 343:d4277.
</ref>
|-
| 6-12 hours||98%
|-
| 12-24 hours||93%<ref>van Gijn J and van Dongen KJ. The time course of aneurysmal haemorrhage on computed tomograms. Neuroradiology. 1982; 23:153–156.</ref>
|-
| 24 hours - 5 days||<60%
|}
 
*SAH due to aneurysm - look in cisterns (esp. suprasellar cistern)
*SAH due to trauma - look at convexities of frontal and temporal cortices
 
===Lumbar Puncture===
*Elevated RBC count that doesn't decrease from tube one to four
**Note: decreasing RBCs in later tubes can occur in SAH; only reliable if RBC count in final tube is nl
*Opening pressure &gt;20 (60% of pts)
**Can help differentiate from a traumatic tap (opening pressure expected to be normal)
**Elevated opening pressure also seen in cerebral venous thrombosis, IIH
*Xanthrochromia
**May help differentiate between SAH and a traumatic tap
**Takes at least 2hr after bleed to develop (beware of false negative if measure early)
**Sn (93%) / Sp (95%) highest after 12hr
*If unable to obtain CSF consider CTA
**CTA also highly sensitive for predicting delayed cerebral ischemia
*If traumatic tap is suspected
**Tube 4 RBC count <500 has negative predictive value of 100% for SAH. Tube 4 RBC decrease of 70% compared to tube 1 excludes a radiographically detectable SAH.<ref>Gorchynski J, Oman J, and Newton T. Interpretation of traumatic lumbar punctures in the setting of possible subarachnoid hemorrhage: who can be safely discharged? Cal J Emerg Med. 2007; 8(1): 3–7.</ref>
**One study found that >2000 RBCs had a sensitivity of 93% and specificity of 93% for SAH, sensitivity increased to 100% when xanthochromia added.<ref>Perry JJ, Alyahya B, Sivilotti MLA, et al. Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study. BMJ : British Medical Journal. 2015;350:h568.</ref>
 
==Management==
Physiologic derangements, such as hypoxemia, metabolic acidosis, hyperglycemia, BP instability, and fever, can worsen brain injury and has been independently associated with increased M&M, but no studies showing benefit of corrections.
 
#Avoid hypotension
#*Maintain MAP &gt;80
#*Give [[IVF]]
#*Give [[pressors]] if IVF ineffective
#Discontinue/reverse all anticoagulation
#*[[Coumadin]] --> (Prothrombin complex conc or [[FFP]]) + vitamin K
#*[[Aspirin]] --> [[DDAVP]]  
#*[[Plavix]] --> [[Platelets]]
#[[Nimodipine]]
#*Prevents vasospasm (associated with improved neuro outcomes and decreased cerebral infarction)
#*Give 60mg q4hr PO or NGT only (never IV) within 96hr of symptom onset. NNT 13 to prevent one poor outcome
#*Keep an eye on BP for fluctuations
#[[Magneisum sulfate]]
#*Controversial; prevents vasospasm acting as NMDA antagonist and a calcium channel blocker; maintain b/w 2-2.5 mmol/L
#Seizure prophylaxis
#*Controversial; 3 day course may be preferable
#*[[Phenytoin]], [[levetiracetam]], [[carbamazepine]] and [[phenobarb]]. Phenytoin can be associated with worse neurologic & cognitive outcome
#Glucocorticoid therapy
#*Controversial; evidence suggests is neither beneficial nor harmful
#Glycemic control
#*Controversial; consider sliding scale if long pt stay in ED while awaiting ICU bed
#Keep head of bed elevated
#Aneurysm treatment
#*Surgical clipping and endovascular coiling are definitive tx
#*Antifibrinolytic - Controversial; if delayed aneurysmal tx, consider short term therapy (<72 hrs) with TXA or aminocaproic acid
 
{{AHA SAH BP Guidelines}}
 
== Complications  ==
*Rebleeding
**Risk is highest within first 24 hours (2.5-4%), particularly within first 6 hours
**Usually diagnosed by CT after acute deterioration in neuro status
**Only aneurysm treatment is effective in preventing rebleeding
*Vasospasm
**Leading cause of death and disability after rupture
**Typically begins no earlier than day three after hemorrhage
**Characterized by decline in neuro status
**Aggressive treatment can only be started after aneurysm has been treated
***Tx for symptomatic vasospasm: Triple-H therapy (hemodilution + induced hypertension (pressors) + hypervolemia), ballon angioplasty, or intra-arterial vasodilators.
****Studies have not provided strong evidence of benefit Triple-H therapy
*Cardiac abnormalities (?2/2 release of catecholamines due to hypoperfusion of hypothalamus)
**Ischemia
***Elevated troponin (20-40% of cases)
***ST segment depression
**Rhythm disturbances
***[[Torsades]], [[A-fib]]/flutter
**[[QT prolongation]]
**Deep, symmetric TWI
**Prominent U waves
*Hydrocephalus
**Consider ventricular drain placement for deteriorating LOC + no improvement w/in 24hr
*[[Hyponatremia]]
**Usually due to [[SIADH]]
***Treat via isotonic, or if necessary, hypertonic saline (do not treat via H2O restriction)
**Rarely due to cerebral salt-wasting
***Volume depleted, so treat with isotonic saline
 
== Prognosis  ==
=== Hunt and Hess  ===
Subjective terminology, but good interobserver variability
{| class="wikitable"
| align="center" style="background:#f0f0f0;"|'''Grade'''
| align="center" style="background:#f0f0f0;"|'''Description'''
| align="center" style="background:#f0f0f0;"|'''Survival Rate'''
|-
|0 ||Unruptured aneurysm||-
|-
|1 ||Asymptomatic or mild HA and slight nuchal rigidity||70%
|-
|1a ||No acute meningeal/brain reaction, with fixed neurological def||-
|-
|2 ||Moderate to severe HA, stiff neck, no neurologic deficit except CN palsy||60%
|-
|3 ||Mild mental status change (drowsy or confused), mild focal neurologic deficit||50%
|-
|4 ||Stupor or moderate to severe hemiparesis||20%
|-
|5 ||Coma or decerebrate rigidity||10%
|}
 
:Grade 1 or 2 have curable disease
 
:Add one grade for serious systemic disease (HTN, DM, severe atherosclerosis, COPD)
 
=== World Federation of Neurosurgical Societies (WFNS)  ===
Objective terminology, and fair interobserver variability
{| class="wikitable"
|-
!width="50"| Grade
! GCS
! Focal neurological deficit
|-
! 1
| 15 || Absent
|-
! 2
| 13–14 || Absent
|-
! 3
| 13–14 || Present
|-
! 4
| 7–12 || Present or absent
|-
! 5
| <7 || Present or absent
|}
 
Other scales are also available, including the Ogilvy and Carter scale (comprehensive, yet complex), and the Fisher scale or Claassen grading system (vasospasm index risk).
 
Note: First-degree relatives are at 2-5 fold increase in SAH, so screening is considered on individual basis.
 
== See Also  ==
*[[Intracranial Hemorrhage (Main)]]
*[[Head Trauma]]
 
== Source  ==
<references/>
[[Category:Neuro]]

Latest revision as of 04:22, 28 April 2026

Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space. Clinical approach differs by etiology — see the appropriate page below:

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