Beyond the Frontal Bones: Revisiting the Extent and Efficacy of "Bifrontal" Decompressive Craniectomy in Malignant...

The term bifrontal decompressive craniectomy (DC) is traditionally used to describe bilateral frontal bone removal for diffuse traumatic brain swelling. However, considerable heterogeneity exists in the actual extent of bone removal and dural opening among surgeons, potentially influencing decompressive efficacy. The objective of this study was to quantitatively evaluate the true anatomic extent and radiological effectiveness of bifrontal DC using a reproducible morphometric index.

In this retrospective observational cohort study, we reviewed patients with traumatic brain injury and refractory intracranial hypertension who underwent bifrontal DC between 2013 and 2021 at a single tertiary center. Using 3D Slicer, preoperative and postoperative computed tomography scans were segmented to calculate the Decompressive Craniectomy Index (DCI)-the ratio between the bone-flap area and the total supratentorial cranial area. Basal cisterns were graded as normal, compressed, or obliterated, and the Δ-cistern value (preoperative minus postoperative score) quantified cisternal reopening. Associations between DCI and Δ-cistern categories were analyzed with the Kruskal-Wallis test.

Fifteen patients (10 men, 66.7%) were included. The mean bone-flap area was 20 463 ± 5142 mm 2 , the supratentorial cranial area 56 462 ± 5289 mm 2 , and the mean DCI 0.36 ± 0.09. Higher DCI values correlated significantly with greater postoperative cisternal reopening (H = 8.63; P = .013).

Quantitative morphometric analysis demonstrates that larger decompressive surface areas are associated with greater radiological decompression. The DCI offers an objective measure of operative extent and underscores that the term " bifrontal " may inadequately describe the true scope of decompression achieved. Standardizing the geometric dimensions of the bone flap could enhance reproducibility and outcome interpretation in future studies.