What are the indications for performing a decompressive craniectomy in patients with life‑threatening intracranial hypertension?

Decompressive Craniectomy Indications

Decompressive craniectomy is indicated for life-threatening intracranial hypertension when ICP remains refractory to maximal medical management, with specific thresholds and clinical scenarios varying by underlying pathology. 1, 2

Primary Indications by Etiology

Traumatic Brain Injury

• Perform decompressive craniectomy when ICP remains >20-25 mmHg despite maximal medical therapy (sedation, osmotic agents, external ventricular drainage) and CPP falls below 60-70 mmHg. 1, 3
• Symptomatic extradural hematoma regardless of location requires surgical removal in severe head injury. 1
• Acute subdural hematoma with thickness >5mm and midline shift >5mm requires evacuation. 1
• Brain contusions with mass effect after failure of first-line intracranial hypertension treatment warrant decompressive craniectomy. 1
• Early intervention within 72 hours is crucial for optimal outcomes—mortality reduces from 48.9% to 26.9% with surgery, though severe disability increases (8.5% vs 2.1%). 1, 4

Malignant MCA Infarction

• Perform hemicraniectomy in patients with impaired consciousness and >50% MCA territory edema with midline shift. 2
• Age is critical: patients <60 years show both reduced mortality and improved functional outcomes, while those >60 years have reduced mortality but higher rates of severe disability. 4, 2
• Fronto-parieto-temporo-occipital craniectomy with diameter ≥12 cm plus durotomy and enlargement duroplasty is the standard technique. 5
• Do not remove ischemic brain tissue—only evacuate concomitant hematomas if present. 5

Cerebellar Infarction

• Perform craniectomy when neurological signs of brainstem compression develop. 2
• Extend craniectomy to the transverse sinus with foramen magnum opening. 5
• Unlike supratentorial strokes, removal of ischemic cerebellar tissue should be performed along with durotomy and duroplasty. 5
• Place external ventricular drainage with ICP monitoring if concomitant hydrocephalus exists—shunt placement alone without craniectomy is contraindicated. 5

Absolute Contraindications

Do not perform decompressive craniectomy in the following scenarios: 2

• Bilateral nonreactive, non-drug-induced pupillary dilation with coma 1, 2
• Clinical or radiological signs of severe, irreversible brainstem ischemia 1, 2
• Severe comorbidities such as severe heart failure or incurable neoplasia 2

Stepwise Treatment Algorithm

First-Line Management

• Sedation and correction of secondary brain insults (hypoxia, hypotension, hyperthermia) 1
• Maintain CPP >60 mmHg using volume replacement and/or catecholamines 5, 2
• Osmotic therapy (mannitol 20% or hypertonic saline targeting serum osmolality 300-310 mOsmol/kg) 6

Second-Line Management

• External ventricular drainage for persistent intracranial hypertension despite sedation 1
• Brief moderate hyperventilation (target PaCO₂ 35 mmHg) as bridge to definitive therapy 2, 6

Third-Line Management (Refractory Intracranial Hypertension)

• Decompressive craniectomy when ICP remains elevated despite above measures 1, 2
• Multidisciplinary discussion required before proceeding 1, 2
• Large temporal craniectomy (>100 cm²) with enlarged dura mater plasty is the most commonly used technique 1, 2

Technical Specifications

• Craniectomy diameter must be ≥12 cm for adequate decompression. 5
• Dural expansion with large augmentation graft is essential for ICP reduction. 2, 6
• ICP monitor placement is recommended intraoperatively. 5
• Both unilateral and bifrontal approaches are acceptable, with choice depending on pathology location. 2

Critical Timing Considerations

• Early decompressive craniectomy (within 48-72 hours) yields significantly better outcomes than delayed intervention. 1, 7
• In subarachnoid hemorrhage, early craniectomy within 48 hours resulted in 75% good outcomes versus 12.5% with late decompression. 7
• Intervention before clinical signs of brainstem compression develop is associated with improved survival and functional outcomes. 2

Monitoring Requirements

• ICP monitoring is indicated after severe TBI in patients with signs of high ICP on CT, when neurological evaluation is not feasible, or with abnormal initial CT (>50% will develop intracranial hypertension). 1, 2
• Continuous CPP monitoring with target >60 mmHg 5, 2
• Control CT after 24 hours or earlier if signs of intracranial hypertension present 5

Common Pitfalls to Avoid

• Inadequate craniectomy size (<12 cm diameter) leads to insufficient decompression and persistent brain herniation. 5, 6
• Delaying surgery beyond 72 hours significantly worsens outcomes. 1, 7
• Performing craniectomy after irreversible brainstem injury has occurred provides no benefit. 1, 2
• Correcting coagulation disorders before surgery is essential—fibrinogen must be in normal range, and platelet transfusion should be considered if antiplatelet drugs were used. 5
• Shunt placement without craniectomy for cerebellar infarction with hydrocephalus is ineffective and contraindicated. 5

Expected Outcomes

• Good outcome (GOS 4-5 at 6 months) occurs in 40-57% with unilateral craniectomy versus 28-32% in controls. 1
• At 12 months post-TBI, 45.4% of decompressive craniectomy patients have favorable outcomes versus 32.4% with medical management alone. 2
• Number needed to treat is approximately 2 to prevent one death. 2
• The trade-off is clear: decompressive craniectomy reduces mortality by approximately 50% but increases the proportion of survivors with severe disability. 2, 4