Options for Reconstructive Techniques in Endoscopic Skull Base Surgery

By Brian C. Lobo, MD, and Raj Sindwani, MD

Advances in endoscopic skull base surgery (ESBS) have provided surgeons with greater access to the midline and lateral skull base with far less morbidity than has been the case in the past. As a result, patients exhibit far fewer external signs of surgery. Still, addressing the wound inside the patient is also an essential part of treatment.

Raj Sindwani, MD, PhD

Brian C. Lobo, MD

The extent and robustness of surgical repair required after removal of a lesion is based on several factors. These include the size and complexity of the defect, the specific pathology being treated, the presence and nature of cerebrospinal fluid (CSF) leak and a history of previous radiation or surgery. The Head & Neck Institute’s experienced endoscopic surgeons use the concept of the reconstructive ladder — progressing from local tissue (free or pedicled) through extranasal (regional) vascularized flaps all the way to free tissue transfer from distant sites — to provide superior outcomes for patients who undergo ESBS (Table).

Reconstituting the separation between the intracranial and sinonasal compartments effectively is considered one of the foremost challenges with the endoscopic approach. Moreover, it is an essential part of surgery as it helps decrease the risk of postoperative CSF leak and meningitis, thus allowing most patients to return to a relatively normal quality of life after all the healing is complete.

Although the available reconstructive options are limited by surgical access through the nose itself, progress continues to be made. Newer techniques have been designed and executed to effectively reconstruct the access corridor in the cramped quarters of the sinus and nasal cavities. What follows is a brief description of the various procedures.

Free Autografts

Autografts are some of the most time-tested and reliable means of surgical reconstruction. Graft materials popular in ESBS include fascia lata, abdominal fat, cartilage and bone from the nasal septum and turbinates, and the mucosa overlying the structures inside the nose.

Dural Replacement Grafts

Numerous commercially produced grafting materials are available for use in ESBS, including those obtained from live and cadaveric tissue, as well as totally synthetic materials. The materials that come from live sources are processed such that they are completely decellularized (void of any cells, bacteria, or viruses). These grafts function much like free autografts, but without the need to create another surgical site for graft harvest.

Figure. For a vascular pedicle nasoseptal flap, tissue from the nasal septum (dotted lines) is harvested and placed in the nasopharynx (left) until it can be used to cover a defect (right).

Intranasal Vascularized Flaps

Considered the workhorse of skull base repair, the pedicled nasoseptal flap was introduced by Hadad et al in 2006 (Figure).1 This flap revolutionized endonasal reconstruction, significantly reducing the rates of postoperative CSF leak and meningitis.2 Using a large swath of tissue from the nasal septum (and even part of the nasal cavity floor) pedicled on the posterior septal branch of the sphenopalatine artery provides robust tissue that heals extremely well, especially in the case of significant CSF leak, or when a patient has received radiation therapy in the area.

Intranasal vascularized flaps are an essential part of the reconstructive armamentarium, but other flaps can also provide local tissue coverage. These options include flaps obtained from various parts of the nasal septum, the turbinates and the lateral wall of the nose.3

Extranasal (Regional) Vascularized Flaps

Left: Endoscopic view of the defect shows the optic chiasm (A), the anterior communicating artery (B), the frontal lobe (C) and the dural edges (D). Right: A view of the center (A) and perimeter (yellow line) of the fascia flap.

In cases of extensive or previous surgery, obtaining tissue from other parts of the head and neck is sometimes necessary to provide vascularized coverage for exposed tissues. Two of the extranasal flaps are the pericranial flap and the temporoparietal fascia flap. These flaps have long been widely used in open approaches. It is only in the past decade that minimally invasive skull base surgery techniques have been used to harvest and place these flaps. This has allowed surgeons to avoid the traditional open approaches that extranasal flaps once required, and to procure these through small incisions with low morbidity.

Free Tissue Transfer

In rare cases, free tissue transfer from the forearm, thigh or other parts of the body can be used for very large, refractory and complicated skull base defects. Microvascular techniques can help connect the vascular supply of these grafts to the vessels around the surgical wound, providing a final tier in these unusual cases.

Absorbable Sealants and Fillers

Unfortunately, sewing inside the nasal cavity is all but impossible from an endoscopic approach. Therefore, tissue glues and sealants are typically used to help keep things together. These materials act like mortar to hold the various tissues in place while the grafting materials are healing. To ensure a watertight seal, a multilayered reconstruction is recommended.

References

1. Hadad G, Bassagasteguy L, Carrau RL, et al. A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap. Laryngoscope. 2006;116(10):1882-1886.
2. Zanation AM, Carrau RL, Snyderman CH, et al. Nasoseptal flap reconstruction of high flow intraoperative cerebral spinal fluid leaks during endoscopic skull base surgery. Am J Rhinol Allergy. 2009;23(5):518-521.
3. Hosemann W, Schroeder HW. Comprehensive review on rhino-neurosurgery. GMS Curr Top Otorhinolaryngol Head Neck Surg. 2015;14:Doc01. doi: 10.3205/cto000116.

Dr. Lobo is the Advanced Rhinology and Endoscopic Skull Base Surgery Fellow in the Head & Neck Institute. Dr. Sindwani is Vice Chairman of the Head & Neck Institute and Section Head of Rhinology, Sinus & Skull Base Surgery. He is also Co-Director of the Minimally Invasive Cranial Base and Pituitary Surgery Program, and he has a joint appointment in Cleveland Clinic’s Rose Ella Burkhardt Brain Tumor & Neuro-Oncology Center.