Step Ladder Expansive Cranioplasty: Feasibility Study on Computed Tomographic Scan Images

Abstract

Background A novel technique of step ladder expansive cranioplasty was suggested, in a recent study, as a credible alternative to decompressive hemicraniectomy and found feasible on evaluation on a mathematical model, where human cranium was represented by a hemisphere of 9 cm radius. The findings on the mathematical model required to be validated in clinical setting before planning any clinical trial. Methods A retrospective analysis of cases of decompressive craniectomy performed at a single neurosurgery center over past 18 months was done. Cases in which an NCCT head was repeated on the first postoperative day, due to evidence of intractable raised ICP postoperatively, were included in the study. The pre- and postoperative films were evaluated to determine various parameters, namely the thickness of skull bone at the craniectomy margins, projection of dural outpouching beyond the craniectomy defect, and the height required to be gained by an expansive cranioplasty to accommodate the augmented volume of the dural sac. Results Six cases that satisfied all criteria were included. The mean surface area of craniectomy defects were 66.89 cm 2 in size. The maximum projection of the dural outpouching, as measured from the craniectomy margin, was 2.7 cm, necessitating construction of an expansive cranioplasty achieving 1.6 cm of gain in height in the cranium with minimum calvarial convexity. Conclusion The results of this study indicate that a two-step expansive cranioplasty can accommodate adequate volume expansion in individuals whose average calvarial thickness at the craniectomy defect is 0.8 cm.