Chapter 36 Anterior and Posterior Pedicle Lateral Nasal Wall Flaps

10.1055/b-0037-143542

Chapter 36 Anterior and Posterior Pedicle Lateral Nasal Wall Flaps

Carlos M. Rivera-Serrano, Ricardo L. Carrau

Introduction

In this chapter, the authors describe the indications and surgical technique to harvest lateral nasal wall pedicle flaps for endoscopic skull base reconstruction. Important anatomic landmarks, technical nuances, and surgical instrumentation are described. In addition, technical tips and tricks, as well as avoidance of possible complications in the surgical technique, are emphasized. Clinical cases and images obtained from cadaveric specimens are shown to illustrate clinical correlation and facilitate understanding of the harvesting process.

36.1 Indications

A successful reconstruction of small skull base defects seems to be independent of which technique or tissues are used.1 Large surgical defects can be repaired using a variety of free grafts; however, vascularized flaps promote faster, more reliable healing, thus decreasing complications resulting from a persistent communication between the sinonasal tract and the cranial cavity.1,2
Rapid and broad expansion of surgical indications, diverse clinical scenarios, and increased size and complexity of surgical defects have triggered the development of new techniques for reconstruction. Various pedicled flaps have been described for endoscopic skull base reconstruction within the last decade including the posterior nasoseptal flap (NSF),3,4 middle5 and inferior turbinate (IT) pedicled flaps,6 anterior and posterior pedicled lateral nasal wall flaps,7,8 facial artery buccinator (FAB) flap,9 transfrontal pericranial flap, transpterygoid temporoparietal fascia flap, occipital galeopericranial flap,10 and others.11
Skull base surgeons must be versatile regarding different techniques for the approach, resection, and reconstruction. Familiarity with diverse reconstructive techniques is important, as not all flaps are always available. The donor site may be compromised during the approach or extirpative phases of the surgery, by prior surgery or radiation therapy or may be involved by tumor. In addition, the defect′s size may require multiple flaps or combination of techniques.
In general, reconstruction with the anterior and posterior pedicle lateral nasal wall flaps should be considered when encountering large cranial base defects and the use of the NSF is not viable, and the defect appears too large to be reconstructed with a middle or IT flap. The advantage of the anterior pedicle lateral nasal wall flap7 and the posterior pedicle nasal wall flap8 over an IT flap, and hence their name, is that these flaps incorporate mucosa of lateral nasal wall in addition to the turbinate itself. These two flaps are not merely slightly extended IT flaps. Their names denote the fundamental concept and principle of harvesting as much of the lateral nasal wall as needed and as possible, even including the nasal floor mucoperiosteum (extended lateral nasal wall flap).
More specifically, the posterior pedicle lateral wall flap is favored in cases where the ipsilateral nasopalatine artery is available and the defect is posterior to the cribriform plate (i.e., planum sphenoidale, sella, and clivus). The anterior pedicle lateral wall flap is favored in cases of defects of the anterior two-thirds of anterior cranial base, or to complement a “short” NSF.
In brief, the IT and lateral nasal wall receive dual blood supply.12–14 The posterior blood supply of the IT is mainly a terminal branch of the posterolateral nasal artery (branch of the sphenopalatine artery).2 The anterior supply originate from the angular artery,2,15,16 anterior ethmoidal artery, and other intranasal vessels.14

36.2 Surgical Steps

Incisions may be made with a monopolar electrocautery fitted with an extended, insulated, needle tip (Arthroscopic electrode; Valley Laboratory, Boulder, CO) or an extended Colorado tip (Stryker Corporation, Kalamazoo, MI). Alternatively, the mucoperiosteum can be incised with a Cottle elevator or any other sharp instrument of preference.

36.2.1 Common Incision for Both Lateral Nasal Wall Flaps

The anterior and posterior lateral nasal wall flaps share some common incisions and therefore there are similarities in the harvesting technique of these flaps. The common incisions are the anteroinferior, superior, and posterior incisions ( Figs. 36.1, 36.4 ). In the posterior pedicle lateral wall flap, an anteroinferior incision is also made, whereas in the anterior pedicle lateral wall flap this tissue is preserved, as it will be the pedicle of the flap. On the other hand, in the anterior pedicle lateral wall flap, a posterior incision is made (area of sphenopalatine vessels), whereas in the posterior pedicle lateral wall flap this area is preserved as its pedicle.

**Fig. 36.1** Anterior pedicle lateral nasal wall flap. Representation of the right lateral nasal wall demonstrating the incisions needed to harvest the *anterior pedicle lateral nasal wall flap*. The three common incisions with the posterior pedicle lateral nasal wall flap are depicted. These are the anteroinferior, superior, and inferior (in magenta intermittent lines). The unique incision in this flap is the posterior incision (pointed with an arrow). The curved arrows point the pedicle/vascular flow of the flap. Please note that the anteroinferior incision is directed laterally (from the head of the inferior turbinate) toward the metal side of the inferior turbinate/nasolacrimal duct opening (correlate with **Fig. 36.2** ), to incorporate the lateral–inferior nasal mucosal wall of the middle meatus. This part of the incision is shown with a lighter color. For additional clarification, the medial aspect of the inferior turbinate is not incised. The white arrow points to the orifice of the nasolacrimal duct (the anteroinferior incision needs to be curved around the orifice of the nasolacrimal duct). The small black arrow points toward the extension of the flap on the nasal floor. IT, inferior turbinate; MT, middle turbinate; ST, superior turbinate.

The superior incision starts somewhat vertically and follows the posterior aspect of the lacrimal bone (i.e., unguis) or nasomaxillary line, just anterior to the uncinate process. This incision is then curved posteriorly at the superior aspect of the inferior turbinate, continuing posteriorly along the superior aspect of the turbinate until reaching the sphenopalatine area. Posterior to the uncinate process, the incision can migrate cephalad to incorporate the fontanelle of the maxillary sinus. Alternatively, a maxillary antrostomy can be made to facilitate the previously described incision. Resection of the middle turbinate is not necessary, but it greatly facilitates the incisions and harvesting process. At the most posterior aspect of this incision, the sphenopalatine foramen and some of its arteries will be encountered.

The anteroinferior incision starts at the caudal edge of the nasal bones and then travels inferiorly and posteriorly toward the head of the inferior turbinate. Once it reaches the lowest point of the head of the inferior turbinate, it curves laterally to travel in a posterior direction (sagittal direction), now in the inferior meatus, until reaching the nasolacrimal duct opening ( Fig. 36.2 ). The orifice of the nasolacrimal duct is preserved by continuing the incision in the most medial/cephalic aspect to the orifice. After sparing the opening of the duct, the incision continues inferiorly on the lateral wall of the inferior meatus, eventually reaching the nasal floor. The incision can potentially continue medially (across the nasal floor; coronal plane) until reaching the septum. Alternatively, the incision can go straight down from the axilla of the middle turbinate to incorporate additional meatal mucosa and nasal floor into the flap ( Fig. 36.3 ); however, the mucosa around the lacrimal duct should be preserved, with the disadvantage of having to create a perforation (“button hole”) to elevate the flap off the duct opening. Frequently, a small incision needs to be carried slightly into the first few millimeters of the turbinate (head) itself, to facilitate later turbinate “unfolding” and bone removal ( Fig. 36.2 ).

**Fig. 36.2** Anterior pedicled lateral nasal wall flap. (a) Anteroinferior incision = red intermittent line. Superior incision = white intermittent line. Note how the most inferior aspect of the anteroinferior incision is continued (curved white arrow) on the meatal side to incorporate the lateral–inferior nasal mucosal wall of the middle meatus. (b) The turbinate bone has been removed with Kerrison rongeurs (not shown), and the incision is continued on the metal side toward the nasolacrimal duct opening (smaller red intermittent line). If the turbinate head hangs lower than the nasal wall, an incision over the head of the inferior turbinate is made and connected to the main anteroinferior incision. This additional incision should be extended as inferiorly as possible to facilitate later turbinate “unfolding” and bone removal; this area is pointed with an elevator. Otherwise, the turbinate mucoperiosteum will not unfold, thus retaining the shape of the turbinate. (c) The incision shown in (b) is completed with endoscopic scissors. (d) The incision (red intermittent line) is curved around the opening of the lacrimal duct (white arrow) and then continued inferiorly. Alternatively, the incision can go straight down from the axilla of the middle turbinate to incorporate additional meatal mucosa and nasal floor into the flap; however, the mucosa around the nasolacrimal duct should be preserved, with the potential disadvantage of creating a perforation (“button hole”) in the flap.

**Fig. 36.3** Anterior pedicled lateral nasal wall flap. (a) Intermitted red line = continuation of the anteroinferior incision into the lateral nasal wall (inferior meatus) and then into the nasal floor. (b) The inferior (sagittal) incision (black intermitted arrow) is made along the nasal floor and joins the anteroinferior incision (red intermittent line). (c) The flap is elevated posteriorly. The intermitted red line represents the location of the anteroinferior incision, which is extending into the nasal floor. (d) The flap is further elevated all the way to the area of the sphenopalatine vessels. The red intermittent line represents the anteroinferior incision. Note how this incision curves first into the meatal side and then around the opening of the lacrimal duct (white arrow), finally continuing inferiorly into the nasal floor. The green intermittent line represents an alternative incision that goes straight down from the axilla of the middle turbinate to incorporate additional meatal mucosa and nasal floor into the flap; however, the mucosa around the lacrimal duct should be preserved, with the potential disadvantage of creating a perforation (“button hole”) in the flap. (e) The flap is almost completely elevated. The black arrow points at the pedicle. (f) The flap is transposed superiorly into the anterior cranial base. In the figure, a wide septectomy was performed. The black arrow represents the superior aspect of the nasal septum at the skull base.

The inferior incision connects the most inferior (or inferomedial if the incision is extended to the nasal floor) aspect of the anteroinferior incision and the most inferior (or inferomedial) aspect of the posterior incision in the anterior pedicle lateral wall flap, or the most inferior (or inferomedial) aspect of the anteroinferior incision and pedicle of the posterior pedicle lateral wall flap.

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