Rosen & Barkin's 5-Minute Emergency Medicine Consult (145 page)

Subarachnoid Hemorrhage

CODES

• 430 Subarachnoid hemorrhage
  
• 437.3 Cerebral aneurysm, nonruptured
  
• 747.81 Anomalies of cerebrovascular system
  

BASICS

Interruption of blood flow to a specific brain region:

• Neurologic findings are determined by specific area affected
  
• Onset may be sudden and complete, or stuttering and intermittent
  
• Responsible for 1 in 18 deaths in US
  
• 610,000 new strokes every year in US
  

• Diabetes
  
• Smoking
  
• HTN
  
• Coronary artery disease, dysrhythmias
  
• Peripheral vascular disease
  
• Oral contraceptive use
  
• Polycythemia vera
  
• Sickle cell anemia
  
• Deficiencies of antithrombin III, protein C or S
  

• May be ischemic (thrombotic, embolic, or secondary to dissection/hypoperfusion) or hemorrhagic
  
• Thrombotic stroke is caused by occlusion of blood vessels:
  
  • Clot formation at an ulcerated atherosclerotic plaque is most common
    
  • Sludging (sickle cell anemia, polycythemia vera, protein C deficiency)
    
• Embolic stroke is caused by acute blockage of a cerebral artery by a piece of foreign material from outside the brain, including:
  
  • Cardiac mural thrombi associated with mitral stenosis, atrial fibrillation, cardiomyopathy, CHF, or MI
    
  • Prosthetic or abnormal native valves
    
  • Atherosclerotic plaques in the aortic arch or carotid arteries
    
  • Atrial myxoma
    
  • Ventricular aneurysms with thrombi
    
• Arterial dissection:
  
  • Carotid artery dissection
    
  • Arteritis (giant cell, Takayasu)
    
  • Fibromuscular dysplasia
    
• Global ischemic or hypotensive stroke is caused by an overall decrease in systemic BP: Sepsis, hemorrhage, shock
  
• Hemorrhagic stroke:
  
  • Intracranial hemorrhage
    
  • Subarachnoid hemorrhage
    

• Usually attributable to an underlying disease process, such as sickle cell anemia, leukemia, infection, or a blood dyscrasia
  
• Younger children often present with seizures and/or altered mental status
  

DIAGNOSIS

• Time of onset (or time last seen at baseline)
  
• Trauma/surgery
  
• Medications
  
• Altered mentation/confusion
  
• Headache
  
• Vertigo/dizzy
  
• Focal neurologic deficits
  

• General:
  
  • Cheyne–Stokes breathing, apnea
    
  • HTN
    
  • Cardiac dysrhythmias, murmurs
    
• Anterior cerebral artery:
  
  • Contralateral hemiplegia (lower/upper)
    
  • Hemisensory loss
    
  • Apraxia
    
  • Confusion
    
  • Impaired judgment
    
• Middle cerebral artery:
  
  • Contralateral hemiplegia (upper/lower)
    
  • Hemisensory deficits
    
  • Homonymous hemianopsia
    
  • Dysphasia
    
  • Dysarthria
    
  • Agnosia
    
• Posterior cerebral artery:
  
  • Cortical blindness in half the visual field
    
  • Visual agnosia
    
  • Altered mental status
    
  • Impaired memory
    
  • 3rd-nerve palsy
    
  • Hemiballismus
    
• Vertebrobasilar system:
  
  • Impaired vision, visual field defects, nystagmus, diplopia
    
  • Vertigo, dizziness
    
  • Crossed deficits: Ipsilateral cranial nerve deficits with contralateral motor and sensory deficits
    
• Basilar system:
  
  • Quadriplegia
    
  • Locked-in syndrome
    
  • Coma
    
• Watershed area (boundary zone between anterior, middle, and posterior circulation):
  
  • Cortical blindness
    
  • Weakness of proximal upper and lower extremities with sparing of face, hands, and feet
    

• Detailed neurologic exam; consider calculating National Institutes of Health stroke scale (NIHSS).
  
• Emergent noncontrast head CT scan to distinguish ischemic from hemorrhagic events:
  
  • May be normal in 1st 24–48 hr
    
  • GOALS:
    
    • CT completed within 25 min of arrival
      
    • CT read by a radiologist within 45 min
      
    • Thrombolytics administered within 1 hr of presentation
      
• If CT is normal and subarachnoid hemorrhage is suspected, emergent lumbar puncture is indicated
  
• EKG to evaluate for dysrhythmias or presence of MI
  
• Oxygen saturation measurement
  
• Rapid glucose determination
  

• Baseline CBC, electrolytes, renal function tests, liver function test, prothrombin time, partial thromboplastin time
  
• Urinalysis:
  
  • Hematuria can be seen in subacute bacterial endocarditis with embolic stroke.
    
• Sedimentation rate:
  
  • Elevated in subacute bacterial endocarditis, vasculitis, hyperviscosity syndromes
    
• Consider additional tests: Cardiac enzymes, urine pregnancy test, drug screen, alcohol level, ABG, and blood cultures.
  

• Noncontrast head CT
  
• MRI can detect ischemia <2 hr after onset
  
• CXR
  
• Carotid US
  

• EKG to evaluate for arrhythmia
  
• Lumbar puncture if subarachnoid hemorrhage is suspected and head CT nondiagnostic
  

• Intracranial bleeding
  
• Hypoglycemia
  
• Seizure disorder; Todd paralysis
  
• Panic attacks, depression, conversion reaction
  
• Transient global amnesia
  
• Meningoencephalitis
  
• Peripheral neuropathy
  
• Intracranial abscess
  
• Migraine
  
• Air embolism
  
• Transient ischemic attack
  
• Encephalopathy
  
• Neoplasm
  
• Giant cell/Takayasu arteritis
  
• Multiple sclerosis
  
• Compressive myelopathy
  
• Vestibulitis
  
• Medication effect/toxidrome
  

TREATMENT

• Patients may have difficulty moving or communicating after cerebral vascular accident
  
• Neurologic exam in field is helpful:
  
  • Should include assessment of consciousness level, Glasgow coma scale score, gross motor deficits, speech abnormalities, gait disturbance, facial asymmetry, and other focal deficits
    
• Check fingerstick glucose
  

• Manage airway:
  
  • Supplemental oxygen 2–4 L
    
  • Rapid-sequence intubation may be required for airway protection or controlled ventilation to decrease intracranial pressure
    
• For altered mental status, give naloxone and thiamine and check blood glucose
  

• Treat elevated BP with labetalol, nicardipine, nitroprusside, or hydralazine:
  
  • Systolic BP >220 mm Hg or diastolic BP >120 mm Hg on repeated measurements
    
  • If indicated for other concurrent problems (MI, aortic dissection, CHF, hypertensive encephalopathy)
    
  • Initial goal is systolic BP <180 mm Hg, diastolic <110 mm Hg
    
• Control seizures with benzodiazepines, then fosphenytoin/phenytoin
  
• Maintain euvolemia and normothermia.
  
• Thrombolytics:
  
  • Ischemic stroke only; administer within 4.5 hr of symptom onset
    
  • Contraindications:
    
    • Any history of intracranial hemorrhage
      
    • Recent stroke or head trauma <3 mo ago
      
    • Major surgery <14 days ago
      
    • Systolic BP >185 mm Hg; diastolic BP >110 mm Hg
      
    • Bleeding diathesis
      
    • Noncompressible arterial puncture <7 days ago
      
    • MI <3 mo ago
      
    • Anticoagulation: INR >1.7, PT >15 sec, or prolonged PTT; use of heparin within 48 hr
      
    • Platelets <100,000
      
    • Intracranial neoplasm
      
    • Seizure at stroke onset
      
    • Minor or rapidly improving symptoms
      
    • Pregnancy
      
    • Internal bleed (GI/GU) <3 wk ago
      
    • Blood glucose <50
      
    • Age <18 yr
      
  • Avoid anticoagulants and antiplatelet drugs for 24 hr
    
• Treat increased intracranial pressure and cerebral edema:
  
  • Elevate head of bed 30°
    
  • Controlled ventilation to keep partial pressure of carbon dioxide 35–40 mm Hg
    
  • Mannitol
    
• Urgent neurosurgical decompression may be required with brainstem compression in cases of vertebrobasilar stroke or hemorrhage.
  
• In patients with completed or minor strokes, aspirin may prevent recurrence.
  
• For focal embolic/thrombotic strokes:
  
  • Recannulation
    
  • US-enhanced thrombolysis
    
  • Intra-arterial thrombolysis or clot retrieval