Temporoparietal Fascia Flap

In 1898, the temporoparietal fascia flap was described nearly simultaneously for reconstruction of the external ear (after a horse bite) and for reconstruction of the lower eyelid.[1, 2, 3] Despite these descriptions of its use in head and neck reconstruction, the flap remained an obscure and underused tool until an explosion of new descriptions of its use (as either a pedicled or a microvascular free tissue transfer) resurrected it in recent times.[4, 5]

In 1983, Brent et al reported the successful use of the flap as an axial-pattern fascial flap, a random-pattern fascial flap, and a free fascial flap for secondary ear reconstruction.[6] In 1993, Cheney et al described 21 cases using the flap for a variety of reconstructions in the head and neck.[7] Today, the temporoparietal flaps remain the only single-layered fascia flap that can be used as a pedicled vascular flap in the head and neck. The flap is thin and pliable, and it readily accepts a skin graft. Temporoparietal flaps can drape into concavities and over convexities, such as those present in the external ear, and they are highly vascular and resistant to infection. This reliability and versatility, particularly in the setting of trauma and devascularized tissue beds, make it a flap limited only by the surgeon's imagination.

See the image below.

Temporoparietal fascial flaps have been described for vascularized soft tissue coverage in a remarkable variety of head and neck defects as follows:

• Pedicled fascial flap for auricular reconstruction (primary and secondary)

• Pedicle for vascularized calvarial bone grafts

• Composite skin and cartilage graft from helical root for alar reconstruction

• Composite fascia and hair-bearing skin for scalp and lip reconstruction, soft tissue filler in temporal and parotid defects

• Microvascular free tissue graft - Microvascular anastomosis use with or without a vein interposition graft to obviate the limitation of the pedicle

• Coverage of large scalp defects

• Coverage of contralateral temporal defects

• Double-layered fascial graft - Another description of the temporoparietal flap when it is harvested with temporalis muscular fascia supplied by the middle temporal artery (This flap can accept cartilage and bone grafts placed in the envelope between the 2 layers of fascia.)

• Nasal reconstruction

• Oral reconstruction

In a study of 11 patients who underwent parotidectomy, Movassaghi et al reported that the resulting defect can be successfully filled with a temporoparietal fascia flap to prevent cheek contour deformity, with the tissue barrier possibly also helping to prevent Frey syndrome.[8]

A retrospective study by Pellini et al found that in patients who undergo salvage total laryngectomy, prevention of postoperative pharyngocutaneous fistulas through reinforcement of the pharyngeal suture with a temporoparietal fascia flap is comparable to that achieved when a pectoralis major myocutaneous flap is used. The investigators did find increased surgical time when the temporoparietal fascia flap was employed, but evidence indicates better functional outcomes with this flap in selected patients.[9]

The relevant anatomy of the scalp is emphasized to every medical student with the following mnemonic:

• S - Skin

• C - Subcutaneous tissue

• A - Aponeurosis and occipitofrontalis muscle

• L - Loose subaponeurotic tissue

• P - Pericranium

In the temporoparietal region, this mnemonic is an oversimplification. The literature surrounding this anatomy contains a jumbling of nomenclature describing the various layers of temporal fascia, which can further frustrate surgeons trying to master this flap.

To be accurate, the scalp in the temporoparietal area consists of more than 5 separate layers, and significant creativity would be required to massage the mnemonic SCALP from them (see the image below).

The first layer consists of the skin and subcutaneous tissue. Immediately deep and firmly bound to this layer is the temporoparietal (sometimes called superficial temporal) fascia. This layer is contiguous with the superficial musculoaponeurotic system (SMAS) as it passes over the zygomatic arch into the mid face, and it is contiguous with the galea aponeurotica above the superior temporal line.

Beneath the temporoparietal fascia lies a loose areolar and avascular tissue layer that separates the fascia from the temporalis muscular fascia (sometimes termed the deep temporal fascia). This areolar layer allows the superficial scalp to move freely over the deeper and more fixed temporalis muscular fascia, temporalis muscle, and pericranium.

Confusing the issue further is the division of the temporalis muscular fascia as it splits into a superficial and deep layer (of the deep temporal fascia) surrounding a fatty tissue pad at the temporal line of fusion, approximately 2 cm above the zygomatic arch. The temporalis muscular fascia is contiguous with the pericranium above the superior temporal line and is contiguous with the masseter muscle fascia below the arch.

The superficial temporal artery supplies the temporoparietal fascia flap. The artery emerges from the parotid tissue, gives off the middle temporal artery, and traverses a tortuous course in the preauricular area. Approximately 3 cm above the zygomatic arch, it divides into the terminal frontal and parietal branches. The superficial temporal vein generally runs superficial to and with the artery, but variability, including branching or a posterior course, may be encountered.

The auriculotemporal nerve, a sensory branch of the mandibular nerve, lies posterior to the superficial temporal artery within the temporoparietal fascia. The frontal branch of the facial nerve traverses an oblique course over the zygomatic arch, which can be estimated by a line connecting a point 0.5 cm inferior to the tragus to a point 1.5 cm lateral to the superior brow. This nerve also lies within the temporoparietal fascia, and flap elevation anterior to the frontal branch of the superficial temporal artery should proceed with caution to avoid injuring this nerve.

Although the temporoparietal fascia flap is highly vascular and reliable, prior injury to the temporal field could result in flap necrosis. Radiation therapy, trauma, or previous surgery around the superficial temporal arteriovenous supply may increase the risk of flap necrosis and should be considered relative contraindications. Preoperative Doppler assessment of the superficial temporal artery and its branches can confirm vascular flow to the flap. Significantly, in a 1985 report, Brent has described successful elevation and skin grafting of a random temporoparietal flap in a secondary microtia reconstruction when no axial vessels could be identified by Doppler assessment or surgical dissection.[10]

Prior trauma to the area may also increase the risk of postoperative alopecia, which is always a risk anytime this flap is harvested.

Trauma, previous surgery, irradiation, or carotid occlusion may jeopardize the integrity of the temporoparietal fascia flap. Doppler ultrasonography should be used preoperatively to determine the reliability of the superficial temporal artery and to map the course of the main pedicle, frontal branch, and parietal branch.

The face and scalp are prepared and draped. The flap can usually be harvested without shaving hair if the hair is carefully prepped out of the field with ointment and tape or rubber bands.

The important topography of the temporoparietal flap to mark on the scalp includes the superior temporal line, the course of the superficial temporal artery trunk and the frontal and parietal branches, and the approximate course of the frontal branch of the facial nerve (see the image below). The incision is marked as a vertical incision from the root of the helix to the superior temporal line. This incision can be extended as a V superiorly to gain additional access to the galea. The preauricular portion of the incision is extended as a face-lift incision around the tragus as necessary.

The anterior and posterior scalp flaps are elevated in the subcutaneous plane immediately deep to the hair follicles. The temporoparietal fascia adheres to this subcutaneous tissue, and meticulous sharp dissection is necessary to avoid injuring either the vascular supply of the flap or the hair follicles.

The frontal branch of the superficial temporal artery and the anterior edge of the flap are ligated. As with any frontal dissection in the superficial planes, care should be taken anterior to this point to avoid injury to the frontal branch of the facial nerve. If dissection becomes necessary anterior to this point, then the frontal branch should be identified and carefully preserved.

After elevation of the skin flaps, the superior, posterior, and anterior edges of the flap are divided (see the image below). A flap measuring up to 17 X 14 cm can be harvested without extensive scalp undermining. The dissection then proceeds from superior to inferior by dissecting the loose areolar tissue between the 2 layers of fascia. This plane is avascular and easily identified, and dissection can proceed quickly during this portion of the operation.

As the surgeon approaches the root of the helix, dissection must proceed carefully to avoid injury to the vascular pedicle. The pedicle is identified, and the flap base is narrowed to 2.0-2.5 cm, if necessary, to improve rotation. Dissection inferior to the root of the helix is limited by the parotid gland and the risk of injury to the main trunk of the facial nerve. As mentioned previously, 2 layers of vascularized fascia can be harvested by identifying and carefully dissecting the temporalis muscular fascia with its nutrient middle temporal artery. The artery can be followed to its origin from the superficial temporal artery in the region of the zygomatic arch.

The flap is draped carefully into the recipient site and fastened to the surrounding skin and soft tissue (see the image below). The pliability of the flap makes it uniquely suited to draping over irregular surfaces. A skin graft may be applied to the flap and held in place with sutures and suction drainage. The wound is dried carefully with cautery and then irrigated. Suction drainage is placed in the superior donor site away from the pedicle, and the wound is closed in layers. A pressure dressing is applied to the scalp for 12-24 hours.

Alopecia

Alopecia is more common in the setting of scalp tissue previously compromised by trauma, irradiation, or surgery. The surgeon can reduce the incidence of this complication by meticulous elevation of the scalp flaps in the proper plane immediately deep to the hair follicles. Cauterization of the skin edges and hair follicles should be minimized.

Hematoma

Meticulous attention to hemostasis should occur prior to closure. Injury to the frontal branch of the facial nerve can occur if the dissection proceeds anterior to the frontal branch of the superficial temporal artery.

Flap necrosis

Complete failure of this flap is rare, even in the presence of poor wound vascularity and contamination.

The temporoparietal flap is a very hearty flap with excellent survivability and low incidence of necrosis and infection. The donor site normally heals well, and the incisions are usually camouflaged well by hair and rhytids. Even when skin grafts over the flap are unsuccessful, the flap has the vascularity to survive and re-epithelialize or remucosalize.

A study by Schrötzlmair et al, using a patient questionnaire, found that among adults and children who underwent auricular reconstruction with a porous polyethylene framework and temporoparietal fascia flap, approximately 80% expressed satisfaction with the surgery’s results. Complaints primarily concerned scars and shape. Compared with adults, children in the study reported that the reconstruction had greater benefit to their health-related quality of life.[11]

Even though microvascular reattachment of the severed auricle has been described many times in the literature, the difficulty in performing this technique reliably has led some authors to propose implantation of the de-epithelialized cartilaginous framework under a temporoparietal fascial flap as the standard therapy for this traumatic deformity.

Helal et al reported good results from reconstruction of full-thickness defects of the upper one third of the auricle using a combination of an autologous contralateral conchal cartilage graft and a superficial temporoparietal fascia flap. The procedure was performed on 14 patients, 13 of whom found the cosmetic appearance to be acceptable.[12]

In a report on ear reconstruction in young children, using a porous, high-density polyethylene implant, Reinisch and Tahiri stressed the importance of employing a meticulously harvested, well-vascularized, superficial temporoparietal fascia flap and appropriate color-matched skin grafts.[13, 14]

The versatility and reliability of the temporoparietal fascia flap will no doubt result in future descriptions as reconstructive surgeons imagine new ways to employ it in difficult wounds.[15]

For example, a retrospective study by Altındaş et al reported that in selected patients, a two-stage prelaminated temporoparietal fascia flap with skin graft can successfully be used to reconstruct partial facial defects, without the need for tissue expansion or microsurgery.[16]

A study by Lesta-Compagnucci et al suggested that in patients with microtia, random occipito-temporal fascia flaps in association with a dermal regeneration template can serve as an alternative to temporoparietal fascia flaps in ear construction surgery. Operations took an average of 177 minutes in the 46 temporoparietal fascia flap patients, compared with 84.5 minutes in the eight patients in whom the random occipito-temporal fascia flap/dermal regeneration template was employed. Moreover, the complication rate was similar in both groups.[17]