What are the clinical presentation, imaging findings, and management recommendations for subdural hematoma?

Subdural Hematoma: Clinical Presentation, Imaging, and Management

Clinical Presentation

Subdural hematoma presents with a spectrum of symptoms ranging from headache and altered consciousness to focal neurological deficits and coma, with the severity depending on hematoma size, acuity, and patient age. 1

Key Clinical Features to Assess:

• Glasgow Coma Scale (GCS) score, particularly motor response, as this determines surgical urgency and predicts outcomes 2
• Pupillary examination for anisocoria or bilateral mydriasis, which indicates herniation risk and constitutes an absolute indication for immediate surgery 2
• Focal neurological deficits including motor weakness, sensory changes, or speech disturbances 1
• Symptoms of increased intracranial pressure: severe headache, vomiting, progressive deterioration over minutes to hours 1
• Level of consciousness changes, including disorientation and confusion 3

High-Risk Populations:

• Elderly patients (≥65 years) are at significantly higher risk, with ground-level falls accounting for 34.6% of deaths in this age group 4
• Anticoagulated patients have dramatically increased risk, with 30% of fatal cases involving aspirin, warfarin, clopidogrel, or heparin use 4
• Patients on clopidogrel have particularly high mortality (OR = 14.7) after traumatic intracranial hemorrhage 4

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Imaging Findings

Non-contrast CT is the mandatory gold-standard for detecting acute subdural hematoma and must be obtained emergently. 1, 2

CT Imaging Protocol:

• Obtain initial CT within 3 hours of symptom onset, as 28-38% of patients demonstrate hematoma expansion on subsequent imaging 1, 2
• Measure maximal hematoma thickness and degree of midline shift, as these determine surgical urgency 2
• Assess for mass effect indicators: compressed basal cisterns, midline shift >5mm, ventricular collapse 2

Acute Subdural Hematoma Appearance:

• Homogenous, crescent-shaped hyperdense extra-axial collection 5
• Located between dura mater and arachnoid membrane 6

Advanced Imaging Indications:

• CT angiography can identify patients at high risk for hematoma expansion by revealing contrast extravasation within the hematoma 1, 2
• MRI of brain with contrast and whole spine should be performed when subdural hematoma occurs without clear trauma history to investigate for spontaneous intracranial hypotension and CSF leak 2, 7
• MRI provides better characterization of subacute and chronic subdural collections and can detect smaller hematomas missed on CT 4

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Management Recommendations

Immediate Surgical Indications

Perform immediate surgical evacuation when subdural hematoma thickness exceeds 5mm AND midline shift exceeds 5mm, or when the patient shows neurological deterioration or decreased consciousness. 2

The appearance of anisocoria, bilateral mydriasis, or other signs of brain herniation constitutes an absolute indication for immediate surgical evacuation. 2

Additional surgical triggers include:

• GCS decline of 2 points or more 2
• Symptomatic hematoma with significant mass effect 2
• Progressive neurological deterioration 2

Surgical Approach

Burr hole drainage is the preferred first-line surgical approach for chronic subdural hematomas, with subdural drain placement to reduce recurrence rates. 2

• Burr-hole drainage with irrigation and closed-system drainage is recommended as initial treatment, with reoperation rates of approximately 16% 8
• Extended craniotomy with membranectomy is reserved for acute rebleeding with solid hematoma, as it offers no advantages regarding reoperation rates or outcomes 8
• Decompressive craniectomy should be considered for patients with refractory intracranial hypertension after multidisciplinary discussion 2

Conservative Management

Conservative management with close monitoring is appropriate for stable patients without significant neurological deficits, particularly for small or asymptomatic hematomas. 2

Conservative management requires:

• Regular neurological assessments 2
• Maintaining euvolemia (avoiding hypervolemia, which does not improve outcomes) 2
• Serial imaging to monitor for progression 2

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Anticoagulation Management

Rapidly reverse anticoagulation using prothrombin complex concentrate plus vitamin K for patients on anticoagulation who develop subdural hematoma. 1, 2

Pre-Surgical Coagulation Targets:

• Prothrombin time/aPTT should be <1.5 times normal control prior to any neurosurgical procedure 2
• Platelet count >50,000/mm³ is the minimum required; higher thresholds are advisable for neurosurgical operations 2
• Use point-of-care viscoelastic testing (TEG/ROTEM) when available to optimize coagulation status before intervention 2

Anticoagulation Resumption:

• Restart anticoagulation approximately 4 weeks after surgical removal of traumatic subdural hematoma if no ongoing fall risk or alcohol abuse is present 2
• The duration of anticoagulation interruption is typically 7-15 days, with low risk of ischemic events during this period 2

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Hemodynamic and ICP Management

Blood Pressure Targets:

• Maintain systolic blood pressure >100 mmHg OR mean arterial pressure >80 mmHg during emergency interventions 2
• In adults without multimodal neuromonitoring, maintain cerebral perfusion pressure (CPP) between 60-70 mmHg 2
• CPP >70 mmHg is not recommended as it increases respiratory distress syndrome risk five-fold without neurological benefit 2
• CPP <60 mmHg is associated with poorer neurological outcomes 2
• Reference MAP at the level of the external ear tragus for CPP calculation 2

Respiratory Targets:

• Target PaO₂ between 60-100 mmHg throughout all interventions 2
• Target PaCO₂ between 35-40 mmHg throughout all interventions 2
• Continuously monitor end-tidal CO₂ in intubated patients 2

ICP Monitoring Indications:

ICP monitoring is not required when the initial non-contrast CT scan is normal and there are no clinical severity indicators. 2

ICP monitoring after subdural hematoma evacuation is indicated if any one of the following is present: 2

• Pre-operative motor response on GCS ≤5
• Pre-operative anisocoria or bilateral mydriasis
• Pre-operative hemodynamic instability
• Compressed basal cisterns, midline shift >5mm, or other intracranial lesions
• Intra-operative cerebral edema
• Post-operative emergence of new intracranial lesions

Intraparenchymal ICP probes are preferred over intraventricular drains because they have lower infection rates (≈2.5% vs 10%) and lower hemorrhage risk (0-1% vs 2-4%) 2

ICP Treatment:

• For impending cerebral herniation, employ osmotherapy and/or temporary hypocapnia while awaiting emergency neurosurgery 2
• Apply external ventricular drainage for persistent intracranial hypertension unresponsive to sedation 2

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Transfusion Thresholds

• Transfuse packed red blood cells when hemoglobin falls below 7 g/dL during emergency care 2
• Consider higher hemoglobin threshold for transfusion in elderly patients or those with cardiovascular disease 2

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Special Considerations

Spontaneous Intracranial Hypotension:

When subdural hematoma occurs without clear trauma history, perform MRI of brain with contrast and whole spine to investigate for spinal CSF leak. 2, 7

• Treat the underlying CSF leak as the primary management strategy 7
• Epidural blood patch should be prioritized as initial treatment 7
• Small or asymptomatic hematomas should be managed conservatively while treating the CSF leak 7
• Symptomatic hematomas with significant mass effect may need burr hole drainage in conjunction with treating the leak 7

Elderly Patients:

• Triage set points should be lower, with systolic blood pressure <110 mmHg considered significant 4
• Brain atrophy creates more space for brain movement during impact, increasing strain on bridging veins 4
• Mortality risk increases further after age 74 (1.67 higher odds of death) 4

Recurrence Risk:

• Recurrence remains the principal complication (9-33%), occurring more commonly with older age, bilateral subdural hematomas, and coagulopathy 3
• In patients with coagulopathy, the reoperation rate is 41%, significantly higher than 12% in non-coagulopathic patients 8

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Critical Pitfalls to Avoid

• Do not delay surgical intervention when neurological deterioration occurs, as this leads to poorer outcomes 2
• Avoid hypervolemia, as it does not improve outcomes and may cause complications 2
• Do not routinely use antiepileptic drugs for primary prevention of post-traumatic seizures, as they show no benefit and may worsen neurological outcomes 2
• Do not attempt to determine the age of subdural hematomas by imaging alone, as care should be taken with this assessment 4
• Do not discharge anticoagulated patients with head trauma without appropriate imaging and observation, as delayed hemorrhage can occur 2