Objective: Endoscopic repair of large anterior skull base (ASB) defects has excellent results when using multilayered repairs with a nasoseptal flap. However, in extensive intranasal tumors, a nasoseptal flap may not always be available. One alternative option is a flexible single-layer ASB repair. Initial studies indicate low cerebrospinal fluid leak rates with a single-layer repair. However, the level of frontal lobe support, particularly the propensity for a significant inferior displacement of the frontal lobe, is not known. The goal of this study is to determine the frontal lobe position after single-layer acellular dermal allograft repair in large ASB defects.
Study design: Retrospective cohort study.
Setting: Tertiary care medical center.
Subjects and methods: This cohort study compares the frontal lobe position in adults who underwent endoscopic endonasal ASB tumor resection and single-layer cadaveric dermal matrix repair (ASB cohort) with control subjects without intracranial abnormalities (control cohort). The ASB cohort includes subjects with an ASB defect of ≥5 cm anterior/posterior and ≥1.5 cm wide and who had imaging at least 2 months after surgery. The frontal lobe position is measured on sagittal CT/MRI using a reference line from the base of the sella to the nasion. A value of zero indicates that the inferior-most aspect of the frontal lobe is at the level of the nasion-sellar line. A positive value indicates that the frontal lobe is inferior to the nasion-sellar line. The ASB cohort frontal lobe position is compared with the control cohort using the Mann-Whitney U test. A priori we set an absolute difference of 5 mm as a clinically significant difference.
Results: The ASB cohort includes 47 subjects who are 57% male with an average age of 60 years (range: 31-89 years). The most common ASB pathology is esthesioneuroblastoma (n = 21) and 81% of the ASB cohort had postoperative radiation. The control cohort includes 20 subjects who are 60% male, with a mean age of 45 years (range: 19-74 years). The majority of controls underwent imaging for head trauma (n = 13). The ASB mean frontal lobe position is -0.2 mm superior to the nasion-sellar line (range: -9.2 to 10.4 mm), while the control's mean frontal lobe position is 1.1 mm inferior to the nasion-sellar line. This difference is not statistically significant (P = 0.13) and does not reach our a priori definition of clinical significance. The frontal lobe position of ASB subjects who had radiation is closer to the nasion-sellar line as compared with those who did not undergo radiation.
Conclusions: Single-layer acellular dermal graft repair maintains frontal lobe support and position in large ASB defects.
Keywords: anterior skull base; cohort study; frontal lobe; skull base repair; skull base tumor.
© 2022 The Authors. World Journal of Otorhinolaryngology ‐ Head and Neck Surgery published by John Wiley & Sons Ltd on behalf of Chinese Medical Association.