Quantitative determination of the optimal temporoparietal fascia flap necessary to repair skull-base defects.

BACKGROUND: The ability to reconstruct large cranial base defects has greatly improved with the development of pedicled vascularized flaps. The temporoparietal fascia flap (TPFF) is a viable alternative to the Hadad-Bassagasteguy nasoseptal flap for large ventral skull-base defects. This study aims to characterize the size of the TPFF necessary for optimal ventral skull-base reconstruction. METHODS: Eleven formaldehyde-fixed cadaveric heads were used to harvest TPFF of varying heights on each side (total = 22). TPFF was passed through the pterygomaxillary fissure (PMF) to the ventral skull base to assess its coverage. For a subgroup of 12 sides, the TPFF was trimmed to determine the minimum height necessary for coverage. RESULTS: The TPFF height was (mean ± standard deviation [SD]) 14.72 ± 1.02 cm (range, 12.5 to 16.5 cm) and width was 8.43 ± 1.05 cm (range, 6 to 10.5 cm). The distance from the TPFF pedicle through the PMF was 5.8 ± 0.5 cm (range, 5 to 6.5 cm). All TPFF flaps provided complete ipsilateral coverage of clival defects, and all but 1 covered the entire clivus. All TPFF flaps, when rotated anteriorly, provided coverage up to the cribriform plate. The minimum TPFF height necessary for complete coverage of cribriform defects and ventral defects up to the planum sphenoidale was 12 cm. TPFF height for specimens with and without complete ventral skull-base coverage was significantly different (p < 0.0001). CONCLUSION: The TPFF is a versatile alternative to the nasoseptal flap and a height of at least 12 cm can provide enough coverage for all ventral skull base defects.

Rate of rhinosinusitis and sinus surgery following a minimally destructive approach to endoscopic transsphenoidal hypophysectomy.

BACKGROUND: There remains considerable variation in the extent of sinonasal preservation during the approach for endoscopic transsphenoidal hypophysectomy (TSH). We advocate for a minimally destructive approach utilizing turbinate lateralization, small posterior septectomy, no ethmoidectomy, and preservation of nasoseptal flap (NSF) pedicles bilaterally. Due to these factors, this approach may affect the rates of postoperative rhinosinusitis. The objective of this study is to define the rates of postoperative rhinosinusitis in patients undergoing this approach. METHODS: Single institution, retrospective chart review of patients undergoing TSH from 2005 to 2018. RESULTS: A total of 415 patients were identified and 14% developed an episode of postoperative rhinosinusitis within 3 months. These patients were significantly more likely to have had a history of recurrent acute or chronic rhinosinusitis. Most cases were sphenoethmoidal sinusitis managed with 1 to 2 courses of antibiotics. Of patients with postoperative rhinosinusitis, most did not undergo NSF. Average follow-up was 38 months. Six patients (1.4%) underwent post-TSH functional endoscopic sinus surgery (FESS). Average time from TSH to FESS was 26.3 months. Two of these patients had a history of prior chronic rhinosinusitis without polyposis. Two patients underwent revision TSH for recurrent tumor as the primary indication for surgery at time of FESS. Twenty-two-item Sino-Nasal Outcome Test (SNOT-22) scores generally increased immediately postoperatively, but frequently decreased below preoperative level by the time of last follow-up, regardless of whether patients developed rhinosinusitis. CONCLUSION: Sinonasal preservation during TSH is associated with a low rate of postoperative rhinosinusitis requiring FESS and excellent long-term patient reported outcomes. We continue to advocate for sinonasal preservation during pituitary surgery.

Evaluation of cranial base repair techniques utilizing a novel cadaveric CPAP model.

BACKGROUND: Although recent guidelines for obstructive sleep apnea recommend early postoperative use of continuous positive airway pressure (CPAP) after endonasal skull base surgery, the time of initiation of CPAP is unclear. In this study we used a novel, previously validated cadaveric model to analyze the pressures delivered to the cranial base and evaluate the effectiveness of various repair techniques to withstand positive pressure. METHODS: Skull base defects were surgically created in 3 fresh human cadaver heads and repaired using 3 commonly used repair techniques: (1) Surgicel™ onlay; (2) dural substitute underlay with dural sealant onlay; and (3) dural substitute underlay with nasoseptal flap onlay with dural sealant. Pressure microsensors were placed in the sphenoid sinus and sella, both proximal and distal to the repair, respectively. The effectiveness of each repair technique against various CPAP pressure settings (5-20 cm H2 O) was analyzed. RESULTS: Approximately 79%-95% of positive pressure administered reached the sphenoid sinus. Sellar pressure levels varied significantly across the 3 repair techniques and were lowest after the third technique. "Breach" points (CPAP settings at which sellar repair was violated) were lowest for the first group. All 3 specimens showed a breach after the first repair technique. For the second repair technique, only a single breach was created in 1 specimen at 20 cm H2 O. No breaches were created in the third group. CONCLUSION: Different skull base repair techniques have varying ability to withstand CPAP. Both second and third repair techniques performed in a nearly similar fashion with regard to their ability to withstand positive pressure ventilation.

A cadaveric model for measuring sinonasal continuous positive airway pressure-a proof-of-concept study.

BACKGROUND: Obstructive sleep apnea is a common respiratory disorder that can have negative effects on health and quality of life. Positive pressure therapy (CPAP) is the primary treatment. There is a lack of consensus on the risk of postoperative CPAP after endoscopic sinus or skull base surgery. We present a proof-of-concept cadaver model for measuring sinonasal pressure delivered by CPAP. METHODS: Three fresh cadaver heads were prepared by removing the calvaria and brain. Sphenoidotomies were made and sellar bone was removed. Pressure sensors were placed in the midnasal cavity, sphenoid sinus, and sella. CPAP was applied and the delivered pressure was recorded at increasing levels of positive pressure. Paired t tests and intraclass correlation coefficients were used to analyze results. RESULTS: Increases in positive pressure led to increased pressure recordings for all locations. Nasal cavity pressure was, on average, 81% of delivered CPAP. Pressure was highest in the sphenoid sinus. The effect of middle turbinate medialization on intrasphenoid pressure was not statistically significant in 2 heads. Intrasellar pressure was 80% of delivered CPAP with lateralized turbinates and 84% with medialized turbinates. Pressure recordings demonstrated excellent reliability for all locations. All heads developed non-sellar-based cranial base leaks at higher pressures. Cribriform region leaks were successfully sealed with DuraSeal®. CONCLUSION: Our proof-of-concept cadaver model represents a novel approach to measure pressures delivered to the nasal cavity and anterior skull base by CPAP. With further study, it may have broader clinical application to guide the safe postoperative use of CPAP in this population.