Acute Subdural Hematoma

Extravasation of blood into the subdural space between the dura and arachnoid membranes. Most common neurosurgical emergency associated with high morbidity and mortality. A potentially life-threatening condition requiring urgent surgical evacuation for good clinical outcomes

Primary Category
Neurocritical Care
Secondary Category


  • Extravasation of blood into the subdural space between the dura and arachnoid membranes
  • Most common neurosurgical emergency associated with high morbidity and mortality
  • A potentially life-threatening condition requiring urgent surgical evacuation for good clinical outcomes


  • mostly traumatic but can be spontaneous
  • 50-90% death rate in acute traumatic SDH
  • Incidence of traumatic SDH: 11-49%
  • After surgical evacuation, recurrent rates as high as 20% in some cases
  • Most commonly seen in MVAs in the younger population and from falls in the older age group
  • May have a lucid interval in 12-38% of patients
  • 35-80% present with GCS ≤8 with a mortality of 55-70%
  • Death in patients with GCS 3-15: 30-60%


  • Rupture of the bridging veins
  • Mostly traumatic but can be spontaneous
  • Spontaneous causes of acute SDH: anticoagulants/antiplatelet use, intracranial aneurysmal rupture
  • Less common causes: AVMs rupture, cocaine abuse, vascular meningiomas, dural metastases, etc

Figure 1: Acute Subdural Hematoma on CT Brain

notion image
Case courtesy of Dr Andrew Ho,, rID: 23274


  • Parafalcine and tentorial
    • Seen in younger patients with mild traumatic brain injury
    • Managed nonoperatively
  • Posterior fossa
    • Rare
    • Poor outcome
    • 50% death rate
    • Coagulopathy present
    • Associated with low GCS score and occipital fracture
  • Non-traumatic
    • Seen in ruptured intracranial aneurysms, cancers, anticoagulants use, AIDS, bleeding disorders


  • Cerebral blood flow changes
    • Reduces significantly instantly after injury due to a decrease in CPP and an increase in ICP
    • Cerebral vasoconstriction and defect in autoregulation after brain trauma also contribute to a decrease in CBF
    • Hyperemia/hyperperfusion occurs followed by reperfusion injury by oxygen-derived free radicals that are associated with poor clinical outcome
  • Coagulopathy
    • Occur following traumatic brain injury
    • Trigger coagulation pathway increases the likelihood of bleeding
    • Affects hemostasis, intracerebral hematoma formation, and expansion that lead to poor clinical outcomes
  • Delayed deterioration
    • Also known as talk and deteriorate
    • Seen in the elderly
    • Seen within 6 hours after trauma
    • Atrophied brains in the elderly allow more intracranial space to accumulate blood and cerebral edema before clinical deterioration occurs
    • Early identification and evacuation of hematoma are important to avoid this phenomenon

Clinical Features

  • Headache
  • Altered mental status
  • Nausea/vomiting
  • Lethargy
  • Motor weakness
  • Seizures
  • Stupor
  • Coma

Differential Diagnosis

  • Epidural hematoma
  • Subarachnoid hemorrhage
  • Meningitis
  • Encephalitis
  • Intracerebral hemorrhage


  • Non-contrast CT scan of Head: easily available, Crescent shaped mass, sensitivity nearly 100%
  • MRI is superior to CT in identifying small SDH, tentorial, and interhemispheric SDH
  • Additional findings like midline shift, brain herniation, associated brain injuries can be seen in brain imaging
  • Digital subtraction angiography in non-traumatic acute SDH for suspected rupture of a cerebral aneurysm


  • Emergent resuscitation
  • Neurosurgical consultation
  • Maintenance of airway, breathing, and circulation
  • Maintain Pao2> 60mm Hg and MAP> 65mm Hg
  • Intubate patient, if unable to maintain the airway
  • Rapid sequence intubation to facilitate endotracheal intubation
  • Adequate intravenous access
  • Reversal of anticoagulation to avoid hematoma expansion
  • Intracranial pressure monitoring and treatment
    • Elevate head of bed to 300
  • Intracranial pressure Treatment
    • ICP treatment only recommended if the patient is a surgical candidate and on the way to surgical intervention
    • Brief Hyperventilation to maintain PaCO2 of 32-36 mm Hg (max 4 hours)
    • Osmolar therapy with Mannitol 1 to 1.5g/kg and/or 30 to 120ml of 23.4% Hypertonic saline (on the way to surgical suite)
  • Seizure prophylaxis: Phenytoin/fosphenytoin or Levetiracetam
  • Blood pressure and cerebral perfusion pressure management
    • Maintain CPP above 60 mm Hg in adults and 40-65mm Hg in children
  • Analgesia
    • Fentanyl- 25 to 200 mcg/hr
    • Remi-fentanyl- 0.5 to 2 mcg/kg/min
  • Sedation
    • Propofol- 5mcg/kg/min followed by increase in 5-10mcg/kg/min until adequate sedation is achieved
  • Temperature control
    • Maintain normothermia by acetaminophen
  • Glucose control
    • Maintain blood glucose level 120-180 mg/dl
    • Avoid hyperglycemia using insulin sliding scales
  • Stress ulcer prophylaxis
    • PPIs preferred over H2 blockers, sucralfate

Indications for emergent surgery

  • A rapid decline in neurological status Mydriasis: unilateral or bilateral Extensor posture Midline shift in CT Head > 5mmHematoma size in CT Head > 10mm
  • Neurosurgical evacuation under general anesthesia


  • Brain herniation
  • Coma
  • Death


  • Prognosis depends upon age, neurological condition, radiological appearance, the timing of neurosurgery, associated brain injuries, extracranial injuries, and postoperative care
  • 25-50% of cases are comatose after the trauma
  • 12-38% of cases undergo gradual neurological deterioration followed by coma a few hours after the trauma
  • Overall bad prognosis in serious trauma to the brain parenchyma, associated brain edema and/or herniation


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Manish KC

Written by

Manish KC

ECFMG Certified Physician, Clinical Research Coordinator at the Division of Gastroenterology, Hepatology, and Nutrition at the University of Louisville, Remote Researcher at the Larkin Health System, Miami, Florida

Junaid Siddiquie, MD, MRCP

Center for Neuro-Restoration at Cleveland Clinic Main Campus

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