How to manage a subdural hematoma (SDH) in a comatose patient?

Management of Subdural Hematoma in a Comatose Patient

A comatose patient with acute subdural hematoma requires immediate urgent neurosurgical consultation and surgical evacuation if the hematoma is ≥10 mm thick or causes midline shift ≥5 mm, with surgery performed as soon as possible to reduce mortality. 1, 2

Initial Assessment and Stabilization

Immediate Priorities

• Control life-threatening hemorrhage first if polytrauma is present, followed by urgent neurological evaluation including pupils, Glasgow Coma Scale motor score, and brain CT scan 1
• Maintain systolic blood pressure >100 mmHg or mean arterial pressure >80 mmHg during resuscitation and any surgical intervention 1
• Maintain PaO2 between 60-100 mmHg and PaCO2 between 35-40 mmHg to optimize cerebral perfusion while avoiding secondary brain injury 1

Hemodynamic Management

• Avoid hypotension (systolic <110 mmHg) which worsens outcomes in brain-injured patients 1
• Transfuse red blood cells if hemoglobin <7 g/dL, with higher thresholds considered for elderly patients or those with cardiovascular disease 1
• Maintain euvolemia; patients may become dehydrated if diabetes insipidus develops 1

Surgical Decision-Making

Absolute Indications for Emergency Surgery

Surgical evacuation via craniotomy is mandatory for: 2

• SDH thickness >10 mm on CT scan, regardless of GCS score
• Midline shift >5 mm on CT scan, regardless of GCS score
• GCS decline of ≥2 points from injury to admission
• Asymmetric or fixed dilated pupils
• Intracranial pressure >20 mmHg (once monitoring established)

Surgical Approach

• Perform craniotomy with or without bone flap removal and duraplasty as the standard surgical technique for comatose patients 2
• Surgery should be performed as soon as possible after indication is established, as timing affects mortality 1, 2, 3
• Recent evidence shows trauma centers with higher surgical intervention rates have 30% lower mortality (adjusted OR 0.7) and better functional outcomes 3

Special Considerations

• Acute SDH with mass effect requires time-critical transfer to neurosurgical center, even by local team if specialized transport unavailable 1
• Surgical evacuation rates vary dramatically between centers (7-52%), but higher intervention rates correlate with improved survival 1, 3

Intracranial Pressure Management

ICP Monitoring

• All comatose patients (GCS <9) with acute SDH require ICP monitoring, particularly those with radiological signs of intracranial hypertension 1
• Insert ICP monitor after correcting coagulopathy (platelets >50,000/mm³ for systemic hemorrhage; higher values advisable for neurosurgery) 1
• Maintain cerebral perfusion pressure ≥60 mmHg once ICP monitoring available, individualized based on autoregulation status 1

Medical Management of Elevated ICP

• For impending cerebral herniation, use osmotherapy (mannitol) and/or temporary hypocapnia while awaiting emergency neurosurgery 1
• Mannitol dosing: 0.25-2 g/kg as 15-25% solution over 30-60 minutes for adults 4
• Use stepwise escalation approach for persistent intracranial hypertension, reserving aggressive interventions for refractory cases 1

Coagulation Management

Preoperative Optimization

• Maintain prothrombin time/aPTT <1.5 times normal control before neurosurgery 1
• Platelet count should exceed 50,000/mm³ minimum; higher values advisable for neurosurgical procedures including ICP probe insertion 1
• Use point-of-care testing (TEG/ROTEM) if available to guide coagulation optimization 1
• During massive transfusion, use RBC:plasma:platelet ratio of 1:1:1, then adjust based on laboratory values 1

Post-Evacuation Management

Monitoring for Complications

• Persistent coma after SDH evacuation may result from cerebral hyperperfusion, which can cause delayed recovery lasting several weeks 5
• Exclude other causes of persistent coma: residual midline shift, cerebral infarction, nonconvulsive seizures, metabolic derangements, and infection 5
• Serial neurological examinations (GCS motor score and pupillary reactions) after achieving physiological stability are essential 1

Prognostic Considerations

• Pupil reactivity is a critical prognostic indicator: mortality rates are 44.4% for reactive pupils, 57.1% for unilaterally unreactive, and 85.9% for bilaterally unreactive pupils 6
• Patients with GCS 3 have 80.7% mortality overall, but surgical intervention reduces this to 64.3% compared to 91.0% with conservative management 6
• Allow 24-72 hours of physiological stabilization before definitive prognostication, as some patients show delayed but meaningful recovery 1, 5

Critical Pitfalls to Avoid

• Do not delay surgery in patients meeting surgical criteria; earlier intervention correlates with better outcomes 2, 3
• Avoid hypotension and hypoxia during resuscitation and transfer, as these worsen secondary brain injury 1
• Do not use mannitol in patients with severe dehydration, anuria, or pulmonary edema, as it may cause renal failure and fluid overload 4
• Mannitol may increase cerebral blood flow and worsen intracranial hypertension in children during first 24-48 hours post-injury 4
• Do not perform external ventricular drain alone for posterior fossa hemorrhage with compressed basal cisterns, as this may be harmful 1