How should I manage a patient with a suspected subdural hematoma (acute and chronic), including imaging, surgical criteria, intensive‑care monitoring, blood pressure targets, intracranial pressure control, seizure prophylaxis, anticoagulation reversal, and follow‑up?

Subdural Hematoma Management

Immediate Imaging and Diagnosis

Obtain non-contrast head CT immediately as the gold standard for detecting subdural hematoma, with imaging completed within 3 hours of symptom onset. 1

• Non-contrast CT is mandatory for initial evaluation due to widespread availability, rapid acquisition, and high sensitivity for acute hemorrhage 1, 2
• CT angiography should be added to identify contrast extravasation, which predicts hematoma expansion risk 1
• MRI with contrast of brain and whole spine is indicated when subdural hematoma occurs without clear trauma history to investigate for spontaneous intracranial hypotension and CSF leak 3, 1
• Repeat CT at 20-24 hours post-initial scan is mandatory for anticoagulated patients, as delayed hemorrhage occurs in 1.4-4.5% despite initially negative imaging 4
• Serial imaging is critical as 28-38% of patients demonstrate hematoma expansion on subsequent scans 1

Surgical Indications

Perform immediate surgical evacuation when subdural hematoma thickness exceeds 5 mm AND midline shift exceeds 5 mm, or when the patient shows neurological deterioration or decreased consciousness. 1

Absolute Surgical Criteria:

• GCS decline of 2 or more points 1, 4
• Hematoma thickness >5 mm with midline shift >5 mm 1
• Symptomatic hematoma with significant mass effect causing neurological deterioration 1
• Development of anisocoria, bilateral mydriasis, or signs of herniation 3, 1

Surgical Technique Selection:

• Burr hole drainage is the preferred first-line approach for chronic subdural hematomas, with subdural drain placement to reduce recurrence 1, 5
• Craniotomy should be considered when diffusion-weighted MRI demonstrates solid clot beneath the dura or when subacute subdural hematoma is diagnosed 5
• Decompressive craniectomy is reserved for refractory intracranial hypertension after multidisciplinary discussion 1

Conservative Management Protocol

Conservative management with close monitoring is appropriate for stable patients without significant neurological deficits, particularly for small or asymptomatic hematomas. 1

Admission and Monitoring Requirements:

• Immediate hospital admission to monitored setting with neurosurgical consultation regardless of GCS score 4
• GCS monitoring every 15 minutes for first 2 hours, then hourly for 12 hours 4
• Document individual GCS components (Eye, Motor, Verbal) rather than sum scores 4
• Assess pupillary size and reactivity at each evaluation 4
• Monitor for focal neurological deficits and level of confusion hourly 4

Risk Factors Requiring Heightened Surveillance:

• Higher Hounsfield unit (hematoma density >67) and greater hematoma depth predict progression from acute to chronic subdural hematoma 6
• Elderly patients (age >60 years) on anticoagulation have 70% risk of deterioration within first 24 hours 4
• Mixed density appearance and concurrent subarachnoid hemorrhage predict hematoma expansion 4, 6

Anticoagulation Reversal

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

Target Coagulation Parameters Before Surgery:

• PT/aPTT <1.5 times normal control prior to any neurosurgical procedure including ICP probe insertion 1
• Platelet count >50,000/mm³ minimum; higher thresholds advisable for neurosurgical operations 1
• Use point-of-care viscoelastic testing (TEG/ROTEM) when available to optimize coagulation status 1
• Anticoagulation interruption typically 7-15 days with low risk of ischemic events during this period 1
• Restart anticoagulation approximately 4 weeks after surgical removal if no ongoing fall risk or alcohol abuse 1

Intracranial Pressure Monitoring

ICP monitoring is NOT indicated if initial CT scan is normal with no evidence of clinical severity or transcranial Doppler abnormalities. 3

Indications for ICP Monitoring After SDH Evacuation (only 1 criterion required):

• Preoperative GCS motor response ≤5 3, 4
• Preoperative anisocoria or bilateral mydriasis 3
• Preoperative hemodynamic instability 3
• Compressed basal cisterns, midline shift >5 mm, or presence of other intracranial lesions 3
• Intraoperative cerebral edema 3
• Postoperative appearance of new intracranial lesions 3

Technical Considerations:

• Intraparenchymal probes preferred over intraventricular drains due to better risk-benefit balance (lower infection rate 2.5% vs 10%, lower hemorrhage risk 0-1% vs 2-4%) 3
• Risk of raised ICP with normal initial CT is only 0-8%, making routine monitoring unnecessary 3

Hemodynamic and Cerebral Perfusion Targets

Maintain cerebral perfusion pressure between 60-70 mmHg in adults without multimodal monitoring. 3

Blood Pressure Management:

• Maintain systolic BP >100 mmHg OR mean arterial pressure >80 mmHg during emergency interventions 1
• Ensure cerebral perfusion pressure ≥60 mmHg when ICP monitoring in place 1
• CPP >70 mmHg not recommended routinely as it increases respiratory distress syndrome 5-fold without improving neurological outcome 3
• CPP <60 mmHg associated with poor outcome 3
• Place MAP reference point at external ear tragus 3

Respiratory Targets:

• PaO₂ between 60-100 mmHg; maintain oxygen saturation >95% 1
• PaCO₂ between 35-40 mmHg throughout all interventions 1
• Continuously monitor end-tidal CO₂ in intubated patients 1

Intracranial Hypertension Treatment

Use mannitol 20% or hypertonic saline at a dose of 250 mOsm, infused over 15-20 minutes, to treat threatened intracranial hypertension or signs of brain herniation after controlling secondary brain insults. 3

Stepwise ICP Management:

• First-line: Osmotherapy (mannitol or hypertonic saline) and/or temporary hypocapnia while awaiting emergency neurosurgery 1
• Second-line: External ventricular drainage for persistent intracranial hypertension not responding to sedation 1
• Follow stepwise escalation, reserving aggressive interventions for non-responders 1

Seizure Prophylaxis

Antiepileptic drugs are NOT recommended for primary prevention of post-traumatic seizures, as they show no benefit and may worsen neurological outcomes. 1

• Consider antiepileptic drugs only if specific risk factors present, such as chronic subdural hematoma or prior epilepsy 1

Transfusion Thresholds

• Transfuse packed red blood cells when hemoglobin falls below 7 g/dL during emergency care 1
• Consider higher hemoglobin threshold for elderly patients or those with cardiovascular disease 1

Critical Pitfalls to Avoid

• Never delay surgical intervention when neurological deterioration occurs (GCS decline ≥2 points), as this leads to poorer outcomes 1, 4
• Never administer long-acting sedatives or paralytics before neurosurgical evaluation, as this masks clinical deterioration 4
• Do not discharge patients based solely on "mild" GCS of 13-14 when elderly, confused, with focal deficits and confirmed subdural hematoma 4
• Avoid hypervolemia as it does not improve outcomes and may cause complications 1
• Do not make irreversible decisions before 72 hours unless brain death criteria met or clear clinical deterioration occurs 4
• Approximately 1 in 4 patients with mild TBI (GCS 13-15) and abnormal findings will require treatment, making premature discharge dangerous 4

Follow-Up Protocol

• Serial neurological assessments provide substantially more valuable information than single determinations 4
• Regular neurological assessments with serial imaging to monitor for progression required during conservative management 1
• Follow-up essential in patients with neural symptoms, particularly for 3 months post-treatment 7