Ver el código de «Subarachnoid hemorrhage»

==Background==
[[File:Meninges-en.svg|thumb|Anatomy of the meninges]]
Defined as hemorrhage into the subarachnoid space (between the arachnoid membrane and the pia mater). This may occur spontaneously, usually from a ruptured cerebral aneurysm, or may result from head injury.
===Epidemiology===
The prevalence of SAH in patients presenting with true thunderclap headache is estimated at ~10%. <ref>Dubosh NM et al. Sensitivity of Early Brain Computed Tomography to Exclude Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis. Stroke 2016. PMID: 26797666</ref>

===Risk Factors===
*Genetics (polycystic kidney disease, Ehler-Danlos, family history) 
*[[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

===Traumatic Subarachnoid Hemorrhage===
*Differentiate from aneurysmal rupture
*Supportive care with prevention of hypertension, elevated ICP, and vasospasm with PO nimodipine
*Patients with normal neurologic exam NOT on anticoagulation may not need a repeat head CT<ref>Borczuk, et al. Patients with traumatic subarachnoid hemorrhage are at low risk for deterioration or neurosurgical intervention.  J Am Coll Surg.  2014; 219.</ref><ref>Nahmias JT, et al.  Mild Traumatic Brain Injuries Can Be Safely Managed Without Neurosurgical Consultation: The End of a Neurosurgical "Nonsult"? American Association for the Surgery of Trauma.  Annual Meeting.  2016</ref>
**Recommend 6 hour observation

==Clinical Features==
*Sudden, severe [[headache]] that reaches maximal intensity within minutes (97% of cases) 
**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==
{{Intracranial hemorrhage DDX}}

===Other===
*Drug toxicity 
*Ischemic [[Stroke (Main)|Stroke]] 
*[[Meningitis]] 
*[[Encephalitis]]
*[[brain tumor|Intracranial tumor]] 
*Intracranial hypotension 
*[[Metabolic derangements]] 
*[[Cerebral venous thrombosis]] 
*Primary headache syndromes (benign thunderclap headache, [[Migraine]], [[Cluster Headache]])

==Evaluation==
[[File:SubarachnoidP.png|thumb|Noncontrast CT showing subarachnoid hemorrhage (white area in the center stretching into the sulci).]]
[[File:PMC2823144 JETS-03-52-g004.png|thumb|More subtle CT showing subarachnoid hemorrhage (white area in the frontal area 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 onset)
**No limited neck flexion on physical exam 

'''If concerned for SAH and CT normal strongly consider LP, especially if CT obtained >6 hrs after symptom onset'''

===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 does not 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 >20 (60% of patients) 
**Can help differentiate from a traumatic tap (opening pressure expected to be normal) 
**Elevated opening pressure also seen in cerebral venous thrombosis, IIH
*Xanthochromia 
**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>

===CT Angiogram===
*A CT followed by CTA is an acceptable alternative to CT and LP<ref>Walsh B, Vilke GM, Coyne CJ. Clinical Guidelines for the Emergency Department Evaluation of Subarachnoid Hemorrhage. Meurer WJ, JEM. 2016; 50(4) 696-701.</ref>
*CTA has a 98% sensitivity for aneurysms >3mm

==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>80 (CPP of 60 as long as ICP<20)
#*Give [[IVF]] 
#*Give [[pressors]] if IVF ineffective
#Hypertension
#*AHA/ASA has no formal recommendations but states that decreasing to SBP <160 is reasonable<ref>Connolly ES Jr, Rabinstein AA, Carhuapoma JR, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/american Stroke Association. Stroke. 2012; 43(6):1711-1737.</ref>
#*Rapid SBP lowering <140 has been advocated with early research showing improved functional outcome<ref>Anderson CS, Heeley E, Huang Y, et al. Rapid blood-pressure lowering in patients with acute intracerebral hemorrhage. N Engl J Med. 2013; 368:2355-2365.</ref>, but more recent work has found no difference between SBP <140 and <180<ref>Qureshi AI, Palesch YY, Barsan WG, et al. Intensive Blood-Pressure Lowering in Patients with Acute Cerebral Hemorrhage. N Engl J Med. 2016; 1-11. [Epub ahead of print].</ref>
#*Ensure appropriate pain control and sedation before adding antihypertensives
#Discontinue/reverse all anticoagulation 
#*[[Coumadin]] → (Prothrombin complex concentrate (Kcentra) or [[FFP]]) + vitamin K 
#*[[Aspirin]] → [[DDAVP]] 
#*[[Plavix]] → [[Platelets]]
#*[[Dabigatran]] (Pradaxa) → [[Idarucizumab]] (Praxbind): 5 grams IV
#[[Nimodipine]] 
#*Only CCB studied that has been shown improve outcomes (contrary to popular belief, it does not affect large-vessel vasospasm but does decrease incidence of delayed cerebral ischemia)<ref>Francoeur CL, Mayer SA. Management of delayed cerebral ischemia after subarachnoid hemorrhage. Crit Care. 2016;20(1):277.</ref>
#*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
#[[Magnesium sulfate]]
#*Controversial; prevents vasospasm acting as NMDA antagonist and a calcium channel blocker; maintain between 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{{Citation needed|reason=Reliable source needed|date=FEBRUARY 2021}}
#[[Glucocorticoid]] therapy
#*Controversial; evidence suggests is neither beneficial nor harmful
#Glycemic control 
#*Controversial; consider sliding scale if long patient stay in ED while awaiting ICU bed
#Keep head of bed elevated 
#Aneurysm treatment
#*Surgical clipping and endovascular coiling are definitive treatment
#*Antifibrinolytic - Controversial; if delayed aneurysmal treatment, consider short term therapy (<72 hrs) with TXA or aminocaproic acid

{{Intubation with ICH}}

{{AHA SAH BP Guidelines}}

==Disposition==
*Admit

==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
**treatment for symptomatic vasospasm: Triple-H therapy (hemodilution + induced hypertension (pressors) + hypervolemia), balloon angioplasty, or intra-arterial vasodilators{{Citation needed|reason=Reliable source needed|date=February 2016}}
**Studies have not provided strong evidence of benefit Triple-H therapy{{Citation needed|reason=Reliable source needed|date=February 2016}}

===Cardiac abnormalities===
Most likely related to the release of catecholamines due to hypoperfusion of hypothalamus
*[[myocardial ischemia|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 within 24hr

===[[Hyponatremia]]===
*[[Hyponatremia]] is seen in 10%-40% of the patients with subarachnoid hemorrhage who are admitted to the ICU.<ref>Woo, M.H, Kale-Pradhan, P.B. Fludrocortisone in the treatment
of subarachnoid hemorrhage-induced hyponatremia. Annals of Pharmacotherapy. 1997.  31, 637–639.</ref>
*Cerebral Salt Wasting and [[SIADH]] are the two most common causes<ref>Albanese, A. et al. . Management of hyponatremia in patients with acute cerebral insults. Archives of Disease in Childhood, 85. (2001). 246–251.</ref>

==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 (hypertension, 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]]
*[[Lumbar Puncture]]
*[[EBQ:Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage]]

==External Links==
*[http://emcrit.org/podcasts/sah/ EMCrit Podcast - Subarachnoid Hemorrhage]

==References==
<references/>
[[Category:Neurology]]