Pericranial flap for endoscopic reconstruction of skull base defects ("money box approach"): Experience at our center and literature review.

Introduction: One of the main challenges in the development of endoscopic surgical techniques for the treatment of nasosinusal neoplasms and skull base pathology is the reconstruction of the defects resulting from these procedures. Endonasal flaps (with the nasoseptal flap as the primary option) are typically the first-line choice for managing such defects. Unfortunately, in some cases, these flaps are either unavailable or insufficient to adequately repair the defect. In such scenarios, the pericranial flap can be employed with excellent outcomes. However, large case series describing the endoscopic use of the pericranial flap for skull base reconstruction are lacking in the literature, and its reconstructive limits, indications, and outcomes remain to be clearly defined.

Materials and methods: We present a descriptive observational study involving a sample of 7 patients who, between 2019 and 2025, underwent surgery at our center in which a pericranial flap was used for skull base defect reconstruction. The surgical technique employed includes an endonasal approach with a Draf III procedure, combined with an external approach allowing flap harvesting and frontal sinus opening for its insertion into the nasal cavity. A bicoronal incision is made in the scalp, the skin and galea aponeurotica are elevated anteriorly up to 1 cm above the orbital rim. The flap is then elevated from the calvarium and introduced through an external osteotomy in the superior region of the frontal sinus, identified via endoscopic transillumination ("money box approach"). This allows the flap to be guided into the nasal cavity and positioned to cover the existing defect, with both intracranial and extracranial coverage.

Results: Eighty-five percent of patients were male, with a mean age at surgery of 62.5 years. In 85% of cases, the flap was required for primary reconstruction of a defect following extensive oncologic resection, with adenocarcinoma being the most frequent histology and the transcribriform approach the most commonly used. The mean anteroposterior diameter of the defect was 4.06 ± 1.8 cm, and the mean latero-lateral diameter was 1.86 ± 0.44 cm, resulting in a mean defect area of 7.53 cm². The median postoperative hospital stay was 10 days. Postoperative complications occurred in two cases, but only one required surgical revision due to a cerebrospinal fluid leak, which was resolved by repositioning the flap.

Conclusion: When endonasal flaps are not viable, the pericranial flap, due to its size, robustness, and versatility, is a highly effective surgical tool for the reconstruction of complex defects throughout the entire ventral skull base. Although most experience to date relates to anterior approaches, its use can also be considered for posterior approaches (such as transclival) with favorable outcomes. For this reason, it is recommended as the reconstructive option of choice when pedicled endonasal flaps are either unavailable or insufficient.