Residency · Residency · Neurosurgery

Decompressive Craniectomy for TBI

Introduction

Decompressive craniectomy involves removal of a large bone flap with expansile duraplasty to accommodate brain swelling and reduce intracranial pressure. It is a last-resort surgical intervention for refractory intracranial hypertension in severe TBI when medical management fails. Two landmark randomized controlled trials, DECRA and RESCUEicp, have fundamentally shaped current practice and the informed consent conversation with families.

Indications

Decompressive craniectomy is indicated for refractory intracranial hypertension with ICP above 22 mmHg despite maximal Tier 1 and Tier 2 medical management. Primary DC is performed at the time of mass lesion evacuation when the brain is diffusely swollen and fails to re-expand after clot removal. Secondary DC is performed as a separate procedure for medically refractory ICP elevation. The procedure should be considered in patients with a salvageable prognosis and absent signs of irreversible brainstem injury. DC within 48 hours is also indicated for malignant middle cerebral artery infarction in patients under 60 years, though this represents a separate indication from TBI.

Surgical Technique

Bone Flap Size and Design

The minimum bone flap diameter should be 12 by 15 centimeters or 15 centimeters in the anteroposterior dimension. Undersized flaps lead to brain herniation through the defect and venous infarction at the bone edges, potentially worsening the situation. Frontotemporoparietal hemicraniectomy is most common for unilateral pathology. The bone flap must extend to the floor of the middle cranial fossa to allow adequate temporal lobe decompression. Bifrontal craniectomy is used for diffuse bilateral swelling, with bone removal across the midline and preservation of a sagittal sinus bridge.

Key Operative Steps

A large reverse question mark or trauma flap incision provides access. The free bone flap is removed and preserved for later reimplantation, stored either in a subcutaneous abdominal pocket or in a bone bank at minus 80 degrees Celsius. Expansile duraplasty is a critical component, using augmented closure with pericranium, fascia lata, or synthetic dural substitute. The durotomy must be generous to allow brain expansion. Meticulous hemostasis is achieved with inspection for cortical bleeding. The temporalis muscle and scalp are loosely approximated and closed without tension.

Bilateral Technique

The bifrontal approach uses a bicoronal incision with bilateral frontal bone flap removal extending posteriorly past the coronal suture. The superior sagittal sinus is preserved. Bilateral frontal duraplasty completes the decompression.

Evidence from Landmark Trials

DECRA Trial (2011)

The DECRA trial randomized patients with diffuse TBI and ICP above 20 mmHg for more than 15 minutes to early bifrontotemporoparietal DC versus standard care. DC reduced ICP and ICU stay but was associated with worse functional outcomes on the GOS-E. The trial has been criticized for using a low ICP threshold of 20 mmHg, early randomization before maximal medical therapy was exhausted, and inclusion of patients with relatively modest ICP elevations.

RESCUEicp Trial (2016)

The RESCUEicp trial randomized patients with refractory ICP above 25 mmHg for 1 to 12 hours to DC versus continued medical therapy including barbiturates. DC reduced mortality from 48.9 percent to 26.9 percent but increased rates of vegetative state and severe disability. More survivors in the DC group achieved moderate disability or good recovery at 12 months. The conclusion is that DC reduces mortality but increases survival with disability, making informed family counseling essential.

RESCUE-ASDH

This ongoing or recently completed trial evaluates primary DC versus craniotomy for acute SDH evacuation, addressing whether leaving the bone flap off during initial surgery improves outcomes.

Postoperative Management

ICP monitoring continues contralaterally or via an intraparenchymal monitor. The patient is positioned with the operated side up or in neutral position, and the unprotected brain is safeguarded with a helmet. Medical ICP management continues as needed. Monitoring for complications includes external cerebral herniation through the defect and hydrocephalus. Cranioplasty, the bone flap replacement, is typically performed at 6 to 12 weeks after resolution of swelling. Custom titanium or PEEK implants are used if autologous bone is unavailable or has resorbed.

Complications

Early Complications

Hemorrhagic complications include contralateral epidural or subdural hematoma in up to 10 percent and contusion expansion. External cerebral herniation with brain protrusion through the craniectomy defect indicates persistent swelling. CSF leak and wound breakdown occur especially with large defects and tight closures. Infection includes wound infection and empyema.

Delayed Complications

Hydrocephalus occurs in 10 to 40 percent of patients and may require ventriculoperitoneal shunting. Syndrome of the trephined, also called sinking skin flap syndrome, causes neurological deterioration from atmospheric pressure transmitted to the brain surface and improves dramatically after cranioplasty. Subdural hygroma is common and usually resolves spontaneously or after cranioplasty. Bone flap resorption occurs in 20 to 50 percent of autologous flaps, especially in younger patients. Seizures are at increased risk at craniectomy margins.

Cranioplasty

Timing has traditionally been 3 to 6 months, but evidence suggests earlier cranioplasty at 6 to 12 weeks may improve neurological recovery. Materials include autologous bone, custom titanium mesh, PEEK, PMMA, and hydroxyapatite. Autologous bone resorption is higher in children, with larger defects and fragmented flaps. Concurrent VP shunt placement may be needed if hydrocephalus has developed.

Clinical Pearls

The bone flap must be sufficiently large, at least 12 by 15 centimeters, and must extend to the middle fossa floor; a small craniectomy can worsen outcomes by causing brain strangulation at the bony edges. RESCUEicp demonstrated that DC saves lives but at the cost of increased severe disability; this trade-off must be discussed explicitly with families during shared decision-making. Syndrome of the trephined is an underrecognized cause of neurological plateau or decline after DC; cranioplasty often produces dramatic improvement and should not be unduly delayed. Monitor for contralateral hemorrhagic complications after DC, as the rapid ICP reduction can precipitate bleeding on the opposite side.

References

1. Cooper DJ, Rosenfeld JV, Murray L, et al. Decompressive craniectomy in diffuse traumatic brain injury (DECRA). N Engl J Med. 2011;364(16):1493-1502.
2. Hutchinson PJ, Kolias AG, Timofeev IS, et al. Trial of decompressive craniectomy for traumatic intracranial hypertension (RESCUEicp). N Engl J Med. 2016;375(12):1119-1130.
3. Stiver SI. Complications of decompressive craniectomy for traumatic brain injury. Neurosurg Focus. 2009;26(6):E7.
4. Kolias AG, Kirkpatrick PJ, Hutchinson PJ. Decompressive craniectomy: past, present and future. Nat Rev Neurol. 2013;9(7):405-415.

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