Chapter 35 Middle and Inferior Turbinate Flaps

10.1055/b-0037-143541

Chapter 35 Middle and Inferior Turbinate Flaps

Raewyn G. Campbell, Bradley A. Otto, Daniel M. Prevedello, Ricardo L. Carrau

Introduction

The aim of skull base repair is to provide a watertight layer that separates the sinonasal and intracranial spaces to avoid complications, such as meningitis, intracranial abscesses, encephaloceles, cerebrospinal fluid (CSF) leaks, and tension pneumocephalus. Successful reconstruction of small skull base defects (generally <1 cm) appears to be independent of the reconstruction technique.1–3 These defects can be successfully repaired using a variety of free grafts and other techniques and the repair does not require a vascularized flap.1 However, free tissue grafting is not as dependable when reconstructing larger, more complex skull base defects (>3 cm).1,4–8 Currently, pedicled flaps provide the most reliable technique when used as a critical component of a multilayer reconstruction for the repair of these large skull base defects.4,8 Pedicled flaps do not require a wide base (as do rotation or advancement flaps); therefore, they have greater reach and mobilize easier to the defects. Their mobility also helps in conforming well to irregular surfaces, which are common at the skull base.

The posteriorly pedicled nasoseptal flap (also known as the Hadad–Bassagaisteguy flap) is widely used and could be considered the workhorse flap for skull base repair after endonasal skull base surgery. However, in patients with prior septectomy, wide sphenoidotomies, or tumor involving the septum or sphenoid rostrum, a pedicled nasoseptal flap may not be feasible. Other reconstructive options using intranasal flaps include the inferior turbinate or a middle turbinate posteriorly based flaps. This chapter will discuss the indications, contraindications, and surgical technique for each of these flaps.

35.1 Reconstruction Technique

Our preparation is identical for both flaps. Cottonoids impregnated with a solution of 1:10,000 epinephrine are placed in the nasal cavity bilaterally during the surgical setup. At the beginning of surgery, the lateral nasal wall is infiltrated with lidocaine 1% with epinephrine 1:100,000. The sites corresponding to the planned incisions are also injected; however, one must avoid injecting the area adjacent to the flap′s vascular pedicle (i.e., causes vasospasm of the pedicle potentially impairing its viability), and the interior turbinate (i.e., it may be equivalent to an intravascular injection).

Any mucosa, bony spicule, or foreign body at the defect and its surrounding areas should be removed to allow the taking of the flap. Multiple techniques (i.e., inlay, onlay, inlay/onlay) and materials may be used to stop the flow of CSF before the flap is placed. We use an inlay graft of collagen matrix (e.g., DuraGen Dural Regeneration Matrix, Integra Life Sciences Corporation, Plainsboro, NJ) or fascia lata in the subdural or epidural space to stop the flow of CSF and, to some degree, obliterate the intracranial dead space.

35.2 Inferior Turbinate Flap

35.2.1 Indications

An inferior turbinate flap can be used to cover small clival and sellar defects. It may also be combined with free abdominal fat (filling the defect or obliterating the sphenoid sinus) to compensate for the limited reach of the flap.4 One significant consequence of the inferior turbinate flap is donor site crusting, which can last for up to 4 weeks until remucosalization is complete.4

35.2.2 Contraindications

The inferior turbinate flap is contraindicated in any patient who has undergone a sphenopalatine artery ligation on the ipsilateral side. Previous inferior turbinectomy or inferior turbinate surgery may reduce the flap′s pliability, limit its ability to mold to the shape of the defect, and compromise its blood supply.

35.2.3 Anatomy

The inferior turbinate flap is based on the inferior turbinate artery, a branch of the posterior lateral nasal artery, which is a branch of the sphenopalatine artery. The posterior lateral nasal artery runs inferolaterally along the perpendicular plate of the ascending process of the palatine bone and gives a branch to the middle turbinate medially. The inferior turbinate branch enters the inferior turbinate on the anterior aspect of its lateral attachment, 1.0 to 1.5 cm from its posterior border.9 It runs through bone in 50% ( Fig. 35.1 ), through soft tissue in 14%, and following a mixed pattern in 36%.10 The artery runs through soft tissue on the medial aspect of the bone for approximately 1.2 cm before entering the bone and dividing into up to six branches ( Fig. 35.2 ).10 As it travels anteriorly, the artery becomes larger, probably due to contributions from the angular artery (branch of the facial artery), which constitutes the anterior blood supply to the inferior turbinate.11 However, the dominant blood supply is the inferior turbinate artery.12 The posterior pedicled inferior turbinate flap provides a surface area of approximately 4.97 cm2; thus, larger defects may require harvesting bilateral inferior turbinate flaps.11

**Fig. 35.1** Endoscopic photograph of the inferior turbinate artery traveling intraosseously. White lines delineate the path of the artery.

**Fig. 35.2** Cadaveric dissection demonstrating the inferior turbinate artery dividing into two branches (white arrows).

35.2.4 Surgical Steps4,13

The nasal cavity is decongested and prepared as previously described (see Reconstruction Technique).
It is important to avoid disrupting the nasolacrimal orifice by sharply dissecting the mucoperiosteum around it during the flap harvest.
Next, the inferior turbinate is medialized so that the medial surface of the inferior turbinate is well visualized. (Steps 4–6 identify and preserve the pedicle of the inferior turbinate flap.)
An uncinectomy allows the identification of the natural ostium of the maxillary sinus.
Enlarge the maxillary sinus ostium posteriorly toward the posterior maxillary sinus (antral) wall.
Elevate the mucosa from the anterior aspect of the ascending process of the palatine bone in a submucoperiosteal plane and proceed posteriorly to identify the crista ethmoidalis, the sphenopalatine foramen, and the sphenopalatine artery and its terminal branches. There is significant anatomic variation of the sphenopalatine artery branches and, accordingly, the sphenopalatine foramen or foramina. In fact, the posterolateral nasal artery may extend anterior to the posterior wall of the maxillary antrum.14,15 Recognizing this anatomic variation during the maxillary antrostomy and mucoperiosteal elevation is vital to avoid injury to the vascular pedicle.
Once the vascular pedicle is well defined ( Fig. 35.3 ), make two sagittal incisions to define the superior and inferior limits of the flap ( Fig. 35.4 ).
Make a posterior to anterior incision along the superior sagittal plane of the inferior turbinate.
Then make an inferior sagittal incision along the caudal margin of the inferior turbinate.
Next, make a vertical incision at the head of the inferior turbinate at its attachment at the piriform aperture joining the two sagittal incisions ( Fig. 35.5 ).
Use a periosteal elevator (freer dissector or Cottle elevator) to raise the mucoperiosteum off the inferior turbinate from anterior to posterior both medial and lateral to the inferior turbinate bone.
Elevate in a submucoperiosteal plane to prevent injury to the vasculature.
The inferior turbinate bone is kept in situ until the flap is elevated. The bone is then removed once the flap is elevated using through-cutting forceps.
The flap is then rotated into the skull base defect and bolstered in place ( Fig. 35.6 ).