What is the management of extraaxial collections in the brain, such as epidural, subdural, or subarachnoid hematomas or effusions?

Management of Extraaxial Collections in the Brain

For acute traumatic extraaxial collections (epidural, subdural, subarachnoid hematomas), immediate non-contrast CT is the gold standard for diagnosis, with surgical evacuation indicated for symptomatic patients or those with mass effect, while small asymptomatic collections can be managed conservatively with close neurological monitoring and repeat imaging. 1, 2

Initial Diagnostic Approach

Imaging Selection

• Non-contrast CT is the primary imaging modality for acute extraaxial collections, providing rapid identification of epidural hematomas, subdural hematomas, and subarachnoid hemorrhage 1
• CT demonstrates high sensitivity for acute blood and allows assessment of mass effect, midline shift, and cisternal compression 1
• MRI with T2-weighted and FLAIR sequences is more sensitive than CT for detecting small subdural hematomas, subacute subarachnoid hemorrhage, and brain stem injuries, but is reserved for patients with persistent unexplained neurological findings despite normal CT 1
• Gradient echo (GRE) and susceptibility-weighted imaging (SWI) sequences are equivalent to CT for acute hemorrhage detection and superior for identifying chronic blood products 1

Critical Radiologic Features to Assess

• Compression of basal cisterns (the best radiologic sign of intracranial hypertension) 1, 3
• Midline shift >5 mm 1, 3
• Ventricular effacement 3
• Hematoma volume (>25 mL for intracerebral, >30 cm³ for epidural) 3, 4
• Presence of skull fracture overlying meningeal vessels or major sinuses 5

Management Strategy by Collection Type

Subdural Hematoma

Conservative Management Criteria:

• Small subdural hematomas ≤3 mm never require surgery and can be managed with outpatient monitoring, though 11% may enlarge to a maximum of 10 mm 6
• Asymptomatic patients with Glasgow Coma Scale (GCS) 15 and no mass effect can be observed with close neurological monitoring 7
• Maintain euvolemia to optimize cerebral perfusion 7

Surgical Intervention Indications:

• Development of altered consciousness 7
• New or worsening focal neurological deficits 7
• Initial subdural hematoma size >8.5 mm is the optimal threshold for predicting need for surgical intervention (AUC 0.81) 6

Risk Factors for Expansion:

• Larger initial hematoma size 6
• Concurrent subarachnoid hemorrhage 6
• Hypertension 6
• Convexity location 6
• Initial midline shift 6

Monitoring Requirements for Severe Cases (GCS ≤8):

• Intracranial pressure (ICP) monitoring with intraparenchymal probes preferred over ventricular catheters 2, 3
• Maintain cerebral perfusion pressure (CPP) 60-70 mmHg 2, 3
• Maintain systolic blood pressure >100 mmHg or mean arterial pressure >80 mmHg 2
• Maintain PaO₂ 60-100 mmHg and PaCO₂ 35-40 mmHg 2

Epidural Hematoma

Conservative Management Criteria:

• Asymptomatic patients with small epidural hematomas (<30 cm³) and GCS 15 can be managed non-operatively with serial CT and neurological observation 4, 5
• Large volume epidural hematomas (>30 cm³) can be managed conservatively if GCS remains stable with symptomatic improvement 4

High-Risk Features Requiring Close Monitoring:

• Skull fracture transversing meningeal artery, vein, or major sinus (55% deterioration rate) 5
• CT diagnosis within 6 hours of trauma (43% deterioration rate) 5
• Patients with both risk factors have 71% chance of requiring evacuation 5

Surgical Indications:

• Declining GCS despite conservative management 4
• Posterior fossa epidural hematoma with obstructive hydrocephalus 4
• Progressive neurological deterioration 5

Subarachnoid Hemorrhage

Imaging Evaluation:

• CT angiography (CTA) and MR angiography are useful for identifying underlying vascular malformations, arteriovenous malformations, tumors, or cerebral vein thrombosis 1
• Catheter angiography should be considered if non-invasive studies suggest vascular cause or clinical suspicion is high 1

Special Consideration - Spontaneous Intracranial Hypotension:

• When subdural collections occur with diffuse pachymeningeal enhancement and postural headache, consider spontaneous intracranial hypotension (SIH) 1
• Surgical drainage of subdural collections in SIH can precipitate catastrophic brain herniation and should be avoided 8
• Treatment requires epidural blood patch at the site of CSF leak, not cranial surgery 1
• Spinal imaging (MRI or CT myelography) is essential to identify CSF leak location 1

Follow-Up Protocol

Repeat Imaging Timing

• Repeat CT at 4-6 weeks to ensure resolution or stability for conservatively managed collections 7
• Serial imaging during hospitalization for patients with risk factors for expansion 5, 6

Hematologic Management

• Transfuse red blood cells for hemoglobin <7 g/dL 2
• Maintain platelet count >50,000/mm³ 2
• Maintain PT/aPTT <1.5 times normal control 2
• Special consideration required for patients on anticoagulants or antiplatelet therapy 7

Critical Pitfalls to Avoid

• Do not perform burr hole drainage of subdural collections in suspected spontaneous intracranial hypotension, as this can cause fatal downward herniation 8
• Do not rely solely on hematoma density on CT to date subdural collections, as CSF admixture can create misleading appearances 1
• Do not assume all subdural fluid collections after subarachnoid hemorrhage are hygromas; differentiate from external hydrocephalus as management differs 9
• Avoid maintaining CPP >70 mmHg routinely, as CPP >90 mmHg worsens outcomes due to vasogenic edema 2, 3
• Do not delay neurosurgical consultation for posterior fossa epidural hematomas, even if small, due to risk of obstructive hydrocephalus 4