Lateral nasal wall flap for endoscopic reconstruction of the skull base: anatomical study and clinical series

Expert Strategies: Skull Base Reconstruction-Global Perspectives, Insights, and Algorithms through a MixedMethods Approach

OBJECTIVE

There is limited consensus on endoscopic skull base surgery (ESBS) reconstruction principles. This study aims to generate comprehensive themes regarding ESBS reconstruction by pooling the experiences of ESBS experts, with comparison to a literature review of current published evidence.

METHODS

Structured qualitative interviews of ESBS experts regarding postoperative management and reconstruction of various defect locations were conducted.

RESULTS

A total of 68 experts comprising 40 academic teams across 13 countries with an average of 18 years of ESBS experience were included. We propose 10 stepwise algorithms for common skull base reconstruction scenarios based on these expert interviews. When available, the nasoseptal flap is used for all high_flow cerebrospinal leak defects. Multilayered reconstruction is favored at all anatomical subsites with increasing number of layers for increasing defect size and complexity. Heterogeneity exists in terms of inlay technique and materials, free grafting versus various pedicled flap options for low-flow defects or in the absence of a nasal septum, nasal packing, tissue sealant, lumbar drain use, and postoperative management. Commonalities and discrepancies between experts were summarized.

CONCLUSION

Skull base reconstruction and post-ESBS management is highly complex with a wide variety of practice patterns and expert strategies. Further research of higher quality evidence is warranted to identify optimal management patterns, though the current work aims to inform surgeons on these controversial areas by drawing from numerous experiences.

The Nasopharyngo-Septal Butterfly Flap: A Novel Adjunct for Reconstructing Large Skull Base Defects

Objective

Skull base defects can be challenging to reconstruct. The nasoseptal flap (NSF) remains the first-line option for reconstruction. However, it can be inadequate to cover wide defects or compromised by tumor invasion or prior surgery requiring additional reconstructive options. The goal of the study is to describe a novel flap for clival and craniovertebral junction (CVJ) reconstruction.

Study Design

Cadaveric study with an illustrative clinical case.

Setting

Cadaver dissection laboratory and tertiary university hospital.

Methods

Endoscopic endonasal dissection was performed in 15 cadavers. A modification of the inferior incision of the NSF was carried out. The inferior incision was performed at a more cranial location, sparing the mucosa of the posterior septum. Two lateral longitudinal incisions were carried out at the pterygo-sphenoidal junction freeing the nasopharyngeal mucosa. A third incision was performed separating the rostral mucosa from the nasal floor. The resulting flap was rotated postero-superiorly covering the clivus and CVJ.

Results

An inferiorly based butterfly-shaped nasopharyngo-septal flap, consisting of nasopharyngeal and posterior septal mucosa and receiving blood supply from the bilateral ascending pharyngeal arteries, was formulated. The lower wings comprised nasopharyngeal mucosa while the upper wings comprised posterior septal mucosa. The mean surface area of the flap was 12.35 ± 0.21 cm2 covering the clivus and CVJ in all cadavers.

Conclusion

The nasopharyngo-septal flap is a novel vascularized flap that is well-suited for reconstructing clival and CVJ defects where the NSF is insufficient and can also be used as a salvage flap in cases where the NSF is unobtainable.

Special Considerations in Pediatric Endoscopic Skull Base Surgery

Originally pioneered in adults, endoscopic endonasal approaches for skull base pathology are being increasingly applied as a minimally invasive alternative for young children. Intrinsic anatomic differences between these patient populations have sparked discussions on the feasibility, safety, and efficacy of these techniques in pediatric patients. This work aims to serve as a primer for clinicians engaged in the rapidly evolving field of pediatric endoscopic skull base surgery. A succinct overview of relevant embryology, sinonasal anatomy, and diagnostic workup is presented to emphasize key differences and unique technical considerations. Additional discussions regarding select skull base lesions, reconstructive paradigms, potential surgical complications, and postoperative care are also highlighted in the setting of multidisciplinary teams.

Skull Base Reconstruction following Surgical Treatment of Sinonasal Malignancies

Skull base defects following resection of anterior cranial fossa and sinonasal tumors are not uncommon. Advances in endoscopic techniques have allowed for entirely endonasal resection and reconstruction of these tumors. This article discusses techniques in the evaluation and management of anterior skull base defects.

Skull base repair following endonasal pituitary and skull base tumour resection: a systematic review

PURPOSE

Postoperative cerebrospinal fluid rhinorrhoea (CSFR) remains a frequent complication of endonasal approaches to pituitary and skull base tumours. Watertight skull base reconstruction is important in preventing CSFR. We sought to systematically review the current literature of available skull base repair techniques.

METHODS

Pubmed and Embase databases were searched for studies (2000-2020) that (a) reported on the endonasal resection of pituitary and skull base tumours, (b) focussed on skull base repair techniques and/or postoperative CSFR risk factors, and (c) included CSFR data. Roles, advantages and disadvantages of each repair method were detailed. Random-effects meta-analyses were performed where possible.

RESULTS

193 studies were included. Repair methods were categorised based on function and anatomical level. There was absolute heterogeneity in repair methods used, with no independent studies sharing the same repair protocol. Techniques most commonly used for low CSFR risk cases were fat grafts, fascia lata grafts and synthetic grafts. For cases with higher CSFR risk, multilayer regimes were utilized with vascularized flaps, gasket sealing and lumbar drains. Lumbar drain use for high CSFR risk cases was supported by a randomised study (Oxford CEBM: Grade B recommendation), but otherwise there was limited high-level evidence. Pooled CSFR incidence by approach was 3.7% (CI 3-4.5%) for transsphenoidal, 9% (CI 7.2-11.3%) for expanded endonasal, and 5.3% (CI 3.4-7%) for studies describing both. Further meaningful meta-analyses of repair methods were not performed due to significant repair protocol heterogeneity.

CONCLUSIONS

Modern reconstructive protocols are heterogeneous and there is limited evidence to suggest the optimal repair technique after pituitary and skull base tumour resection. Further studies are needed to guide practice.

Vascular pedicled flaps for skull base defect reconstruction

OBJECTIVE

Techniques for reconstruction of skull base defects have advanced greatly since the introduction of the vascular pedicled nasoseptal flap in 2006. The objective of this review is to assess the current state of the field by examining both intranasal and extranasal techniques of vascular pedicled skull base defect repair, their indications and success rates, and novel techniques that are currently under investigation.

METHODS

A review of the literature describing the use of vascular pedicled flaps in skull base defect reconstruction was conducted using PubMed and Google Scholar.

RESULTS

The nasoseptal flap remains the most widely used vascular pedicled flap for endoscopic repair of skull base defects. Its ease of harvest, wide arch of rotation, and high success rates make it a popular choice among surgeons. Several variations including a "rescue" nasopseptal flap have been developed. Other less commonly used pedicled intranasal flaps include the middle turbinate flap and the posterior pedicled inferior turbinate flap. Additionally, several novel vascular pedicled flaps have been developed and tested in small cohorts of patients. Extranasal flaps such as the pericranial flap and the temporoparietal fascia flap are used less frequently than intranasal flaps. However, they remain valuable options for reconstruction in certain situations.

CONCLUSION

Advancements continue to be made in the field of skull base defect reconstruction using vascular pedicled flaps. Though the nasoseptal flap remains the most widely utilized option, additional intranasal techniques continue to be developed and tested to optimize surgical outcomes and patient care.

LEVEL OF EVIDENCE

NA.

Methods of Skull Base Repair Following Endoscopic Endonasal Tumor Resection: A Review

Following the introduction of fully endoscopic techniques for the resection of pituitary tumors, there was a rapid expansion of the indications for endonasal endoscopic surgery to include extrasellar tumors of the skull base. These techniques offer significant advantages over traditional open surgical approaches to the skull base, including improved tumor resection, and better post-operative neurological outcomes. Following their introduction, however, the initial rate of post-operative CSF leak was unacceptably high. Post-operative CSF leak following skull base surgery is a major source of morbidity, and can lead to the development of life-threatening intracranial infection. The use of vascularized naso-septal flaps transformed the management of these patients, significantly reducing the rate of post-operative CSF leak and increasing the number of patients that could benefit from this less invasive treatment modality. Adequate repair of iatrogenic defects in the skull base is of crucial importance for patients with skull base tumors, as the development of a post-operative CSF leak, and the associated complications can significantly delay the administration of the adjunctive oncological therapies these patients require. In this review, we provide an overview of the latest evidence regarding skull base reconstruction following endoscopic skull base surgery, and describe the skull base repair technique in use at our institution.