What is the difference between a craniotomy and a craniectomy?

Craniotomy vs. Craniectomy: Key Surgical Differences

A craniotomy involves removing a bone flap that is replaced at the end of surgery, while a craniectomy involves removing bone that is not immediately replaced, leaving the brain covered only by soft tissue until later reconstruction.

Fundamental Technical Distinction

The core difference lies in bone flap management:

• Craniotomy: The skull bone is removed as a flap and secured back in place with plates, screws, or sutures at the conclusion of the procedure 1, 2
• Craniectomy: The bone flap is removed and either discarded or stored (in a bone bank or subcutaneous abdominal pocket) for later replacement through a separate cranioplasty procedure 1, 2

Clinical Context and Indications

When Craniectomy is Preferred

Decompressive craniectomy is specifically indicated when brain swelling is present or anticipated, as leaving the bone off allows the swollen brain to expand outward rather than herniate downward 1.

Key scenarios include:

• Malignant cerebral edema from stroke: Particularly in massive MCA territory infarction with midline shift in patients typically under 60 years old 1
• Refractory intracranial hypertension: When elevated ICP does not respond to medical management after traumatic brain injury 1, 3
• Large cerebellar hemorrhage or infarction: With brainstem compression or hydrocephalus 1
• Acute subdural hematoma with severe brain swelling: When the brain is bulging after clot evacuation 3, 4

When Craniotomy is Preferred

Craniotomy is the standard approach when mass effect can be relieved without concern for subsequent brain swelling 1.

Typical indications:

• Brain tumor resection: Especially metastases >3 cm or surgically accessible lesions without significant edema 1
• Intracerebral hemorrhage evacuation: In stable patients without massive edema 1
• Vascular malformations: Where definitive treatment eliminates the pathology 1
• Posterior fossa surgery: When adequate decompression is achieved and postoperative swelling is not anticipated 5, 6

Complication Profiles

Craniotomy Complications

• Lower overall complication rates in posterior fossa surgery (7% vs 32.6% for craniectomy) 5
• Pseudomeningocele: 4% (vs 19.2% for craniectomy) 5
• CSF leak: 2% (vs 11.5% for craniectomy) 5
• Shorter hospital stays (mean 9.3 vs 11.8 days) 5

Craniectomy-Specific Complications

Craniectomy creates unique complications related to the skull defect 2:

• Syndrome of the trephined: Neurological deterioration from atmospheric pressure on unprotected brain 2
• External brain tamponade: Scalp pressing on brain surface 2
• Paradoxical herniation: Brain shifting toward the craniectomy defect 2
• Wound complications: Higher infection rates and dehiscence 1, 7
• Hydrocephalus: May develop requiring ventriculoperitoneal shunt before cranioplasty 7, 8, 9

Mortality and Functional Outcomes

Traumatic Brain Injury Context

In acute subdural hematoma, craniotomy is performed 10 times more frequently than craniectomy in the United States 4. However, craniectomy patients have:

• Higher in-hospital mortality (35.0% vs 10.9%) 4
• Longer hospital stays (median 14.3 vs 10.9 days) 4
• More frequent discharge to skilled nursing facilities (79.1% vs 63.9%) 4

These differences reflect patient selection bias—craniectomy is reserved for more severely injured patients with refractory brain swelling 3, 4.

Stroke Context

For refractory intracranial hypertension after stroke, decompressive craniectomy reduces mortality but increases survival with severe disability 1. The 2022 AHA/ASA guidelines note that while craniectomy may reduce mortality in comatose patients with large hematomas and midline shift, its effectiveness for improving functional outcomes remains uncertain 1.

Reconstruction Considerations

After craniectomy, cranioplasty should be performed 12-16 weeks later to minimize complications 8. Early cranioplasty (within 10 weeks) is associated with:

• Higher infection rates 8
• Increased hydrocephalus development 8
• Elevated complication rates in patients with ventriculoperitoneal shunts (22.4% overall) 8

During the waiting period, patients require protective helmets to prevent injury to the unprotected brain 8.

Critical Pitfall

The most common error is performing craniotomy when significant brain swelling is present or anticipated. If the brain is bulging at the time of surgery or edema is expected to worsen over subsequent days, the bone flap must be left off 1, 3. Replacing the bone in this scenario can lead to catastrophic intracranial hypertension, herniation, and death 1.