II. Epidemiology
- Represents 30% of Traumatic Intracranial Hemorrhage causes
- Six times more common than Epidural Hematoma
III. Risk Factors
- Anticoagulation (e.g. Warfarin)
- Brain atrophy predisposes to sudural Hematoma (even with minor Head Trauma)
- Elderly
- Alcoholism
IV. Pathophysiology
- Cranial Trauma results in Subdural Hemorrhage
- Tear of bridging veins between Dura Mater and the arachnoid membrane on the surface of the brain
- Sudden acceleration-deceleration is typical cause
- Subdural Hematoma accumulation exerts pressure on the brain
- Results in neurologic tissue ischemia
- May progress to Cerebral Herniation (esp. acute Subdural Hematoma)
V. Precautions: Acute Subdural Hematoma
- Acute Subdural Hematomas are vastly different than chronic Subdural Hematoma
- Acute Subdural Hematoma has a 60-80% mortality rate
- Requires rapid assessment and management (surgical decompression)
VI. Causes: Acute Subdural Hematoma
- Severe Closed Head Injury
- Rapid Deceleration Injury
VII. Associated Conditions: Acute Subdural Hematoma
- Comorbid Brain Contusion
VIII. Symptoms
- Acute Subdural Hematoma (Rapid progression of symptoms)
- Headache
- Irritability
- Chronic Subdural Hematoma (Insidious symptom progression)
- Intermittent Headache
- Variable levels of Decreased Level of Consciousness
IX. Signs
- Acute Subdural Hematoma (<24 hours)
- Fluctuating levels of consciousness
- Dilated pupils
- Hemiplegia
- Hyperreflexia
- Babinski's Sign
- Convulsions
- Subacute (24 hours to 2 weeks)
- Chronic Subdural Hematoma (>2 weeks)
- Progressively impaired intellect
- Agitation
- Impulsive behavior
- Hemiparesis
- Stupor
- Variable Level of Consciousness
X. Imaging: CT Head
- Subdural Hematoma appears as crescent-shaped Hematoma
- As this is below the dura, the Subdural Hematoma follows the surface of the brain
- Gyri are absent in region of Subdural Hematoma
- Helps identify subacute Subdural Hematoma which is isodense and more difficult to distinguish
- Appearance varies based on timing
- Acute: White blood collection
- Subacute: Isodense blood collection (may be subtle)
- Chronic: Dark blood collection
XI. Labs: Cerebrospinal fluid
- Increased CSF Opening Pressure
- CSF Protein increased
- CSF Bloody or xanthochromic fluid
XII. Diagnostic Testing: EEG
- Localized disturbance
XIII. Management
- Admit all patients with chronic or acute Subdural Hematoma (SDH)
- Anticoagulation and antiplatelet agent use predisposes to subdural expansion
- Manage systolic Blood Pressure, targets per neurosurgery, but typically <180 mmHg
- Surgical decompression
- Indications
- Subdural thickness >10 mm
- Midline shift >5 mm
- Glasgow Coma Scale decreases >2 points from initial injury
- Cerebral Herniation findings (e.g. acute Anisocoria)
- Over age 65 years old, are unlikely to need surgical intervention if
- Midline shift <=1 mm
- Width <= 10 mm
- Evans (2015) Injury 46(91): 76-9 [PubMed]
- Emergency surgical decompression if acute Subdural Hematoma with signs of Herniation
- Indications
XIV. Prognosis
- Worse prognosis than Epidural Hematoma (given decompression)
- Subdural Hematomas are associated with greater brain parenchymal injury than Epidural Hematomas
- Predictors of worse prognosis
- Loss of consciousness at time of Closed Head Injury (associated with Diffuse Axonal Injury)
- Low initial glasgow coma score (GCS score)
- Increased Intracranial Pressure
- High injury mechanism
XV. References
- Abuguyan (2024) Crit Dec Emerg Med 38(7): 4-11
- Dreis (2020) Crit Dec Emerg Med 34(7):3-21
- Marcolini and Swaminathan in Swadron (2023) EM:Rap 23(5): 13-14