[Applications of vascularized pericranial flaps in endoscopic skull base surgeries]

Objective: To study the feasibility and efficacy of pericranial flaps for the repairs of large anterior skull base defects. Methods: The average length of the pericranial flaps needed for skull base repair was determined with computed tomography measurements in 20 adults and anatomical dissections in 5 cadaver specimen. A series of patients who underwent endoscopic skull base surgeries and subsequent reconstructions with pericranial flaps at the Department of Otolaryngology Head and Neck Surgery, Shanghai Jiao Tong University School of Medicine Affiliated Sixth People's Hospital from 2016 to 2022 were retrospectively reviewed. There were 19 males and 6 females, aged from 11 to 59 years, including 13 cases of cerebrospinal fluid (CSF) rhinorrhea (12 traumatic) and 12 cases of sinonasal skull base tumors. Descriptive statistical methods were used. Results: The mean areas of anterior skull base, sellar, and clival defects were 16.13, 14.03 and 13.12 cm², respectively, and the mean pericranial flap lengths were (18.77±3.44)mm, (133.99±5.08)mm, (181.76±6.31)mm, respectively. Among sinonasal skull base neoplasms, the pathologies included olfactory neuroblastoma (n=6), squamous cell carcinoma (n=3), chondrosarcoma (n=1), osteosarcoma (n=1), and invasive schwannoma (n=1), in whom 8 patients underwent adjuvant radiotherapy after surgery. One patient (7.7%) had acoustic neuroma-related CSF leak before radiotherapy. All 25 patients successfully underwent skull base reconstruction without complications such as CSF leak, intracranial infection, forehead wrinkles disappearance, or scalp necrosis. All flaps survived well with no CSF leaks within the follow-up period of 2-4 years. Conclusion: Pericranial flap is a safe choice for large anterior skull base defects following resection of sinonasal skull base neoplasms and complex traumatic CSF leaks when endonasal flaps are not available.