What is the role of decompressive craniectomy in preserving brain function for patients with severe increased intracranial pressure due to traumatic brain injury or other conditions?

Decompressive Craniectomy for Preservation of Brain Function

Decompressive craniectomy should be performed for refractory intracranial hypertension in severe traumatic brain injury and malignant cerebral edema when medical management fails, as it reduces mortality by approximately 50% (from 48.9% to 26.9%), though survivors face increased risk of severe disability. 1

Primary Indications by Clinical Scenario

Traumatic Brain Injury

• Perform decompressive craniectomy as third-line treatment when intracranial pressure remains elevated despite sedation, correction of secondary brain insults, and external ventricular drainage. 2
• The procedure is indicated for control of refractory intracranial pressure in the early phase of TBI (within first 72 hours) through multidisciplinary discussion. 1, 2
• Specific surgical indications include removal of symptomatic extradural hematoma regardless of location, and removal of significant acute subdural hematoma (>5mm thickness with >5mm midline shift). 1, 2

Stroke-Related Indications

• Decompressive hemicraniectomy with dural expansion is indicated for malignant MCA infarction when patients have impaired consciousness and >50% MCA territory edema with midline shift (Class I, Level A Evidence). 1
• The procedure should be considered for swollen supratentorial hemispheric ischemic stroke when patients continue to deteriorate neurologically despite medical management. 1
• For cerebellar infarction with neurological signs of brainstem compression, decompressive craniectomy may be considered (Class III, Level C Evidence). 1

Technical Requirements for Optimal Outcomes

Surgical Technique

• A large temporal craniectomy (>100 cm², approximately 15 cm in diameter) with enlarged dura mater plasty is the most commonly used and effective technique. 1, 2, 3
• A sufficiently large frontotemporoparietal craniectomy increases effectiveness and reduces chances of external cerebral herniation. 3
• Wide craniectomy with dural expansion is crucial for adequate ICP reduction. 1

Timing Considerations

• Early intervention before clinical signs of brainstem compression develop yields better outcomes. 1
• Early decompressive craniectomy (within 72 hours) is crucial for optimal outcomes in severe head injury. 2
• The procedure immediately reduces ICP (mean decrease of 7.86 mm Hg) and reduces therapeutic intensity levels within 12 hours post-surgery. 4

Absolute Contraindications

Do not perform decompressive craniectomy in the following situations:

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

Expected Outcomes and Prognostic Data

Mortality Benefit

• The number needed to treat is approximately 2 to prevent one death. 1
• Mortality is reduced from 48.9% with medical management alone to 26.9% with decompressive craniectomy. 1, 2

Functional Outcomes

• At 12 months post-injury, 45.4% of decompressive craniectomy patients had favorable outcomes versus 32.4% with medical management alone. 1
• Good outcome (GOS 4-5 at 6 months) occurs in 40-57% of patients with unilateral craniectomy, compared to 28-32% in controls. 2
• The trade-off is increased severe disability: 8.5% versus 2.1% with medical management alone. 2

Mechanism of Benefit

• Decompressive craniectomy reduces the cumulative ischemic burden of the brain by improving brain oxygen levels (PbtO2) and reducing time spent with compromised cerebral oxygenation. 4

Post-Operative Management

Monitoring Requirements

• ICP monitoring is suggested after severe TBI in patients with signs of high ICP on brain CT scan or when neurological evaluation is not feasible. 1, 5
• Close monitoring for signs of neurological worsening is essential. 1
• Systemic anticoagulation monitoring and resumption are necessary post-operatively, particularly in ECMO patients. 6

Cranioplasty Timing

• Early cranioplasty, as soon as the brain is lax, appears reasonable to mitigate many late complications. 3

Critical Pitfalls and Complications

Early Complications (Days)

• New or expanding hematomas within the first few days can be life-threatening; obtain CT scans at 24 and 48 hours postoperatively to detect them. 3
• External ventricular drain insertion carries high risk of intra- and post-procedural bleeding, particularly in anticoagulated patients. 6

Late Complications (Months)

• Syndrome of the trephined and paradoxical herniation may occur many months after decompression. 3
• Overall complication risk is estimated around 40%, with brain swelling being the main cause of mortality. 7

Special Population: ECMO Patients

• In ECMO patients with acute intracranial hypertension from space-occupying lesions, decompressive craniectomy may be indicated with successful outcomes reported, though evidence is limited and risks versus benefits should be discussed in multidisciplinary manner. 6
• Hyperosmolar therapy is indicated for cerebral edema management. 6

Medical Management Limitations

Recognize when medical therapy has failed:

• Controlled hyperventilation and/or mannitol or hypertonic saline have little value once a decision against craniectomy is made, showing only transitory effects with rebound phenomena after discontinuation. 1
• Corticosteroids, hypotonic fluids, and sedatives (except benzodiazepines for alcohol withdrawal) are not recommended for increased intracranial pressure. 1