Chapter Temporoparietal Fascia Flap A. Samandar Dowlatshahi, MD 31 Joseph Upton, MD

ince the original description by Monks in the Boston is desired, palmar sensation can be restored by joining the Medical and Surgical Journal in 1898, the vascularized auriculotemporal nerve found within this flap to the palmar Ssuperficial temporal fascia (STF) flap has increased in cutaneous branch of the median nerve (Fig. 31-3). popularity and utility. The tissue that makes up this flap has Finally, the TPF flap offers the advantage of an inconspic- had many names over time, including the superficial layer of uous donor site without functional morbidity. The flap’s lo- the temporal fascia, the superficial cephalic fascia, the pari- cation—away from the upper extremity—allows one team etotemporal fascia and temporoparietal fascia (TPF)—yet all to harvest the flap while the other team prepares the recip- these terms designate the same fascial layer. The flap is based ient site; this two-team approach can considerably reduce on the superficial temporal arterial (STA) system. In hand procedure time. reconstruction, it is commonly used as a thin fascial flap. It is particularly effective for the coverage of digits and the thumb because the flap is thin, mobile and can be precisely RELEVANT ANATOMY fashioned to the shape of the defect (Fig. 31-1). The TPF flap has minimal bulk so late debulking procedures are unnec- Most anatomical textbooks and atlases improperly depict essary. In addition, there is no concern about post-transfer the subtleties of this anatomic region, and this lack of detail volume fluctuations with weight loss and weight gain, as has led to some confusion about flap elevation. Tissue layers can be seen in adipofascial and fasciocutaneous flaps. For have been given many names at various levels. Here we at- digital and web space reconstruction, the flap may be split tempt to clarify the anatomy (Fig. 31-4, Fig. 31-5). longitudinally based on the arborization of the frontal and parietal branches to allow for a more refined reconstruction Fascial Layers (Fig. 31-2). The mechanical stoutness of the fascia can also be harnessed in the reconstruction of pulleys and the exten- • The STF lies immediately deep to the hair follicles and sor retinaculum; the loose areolar plane on the undersurface is continuous with the superficial musculoaponeurotic of the flap provides an ideal gliding surface for reconstruc- system (SMAS) caudal and with the galea aponeurot- tion over tendons. The arterial branching pattern can also be ica cephalic. Fibrous attachments between this fascia utilized for flow-through flap reconstructions that require and skin are looser in the zygomatic region and denser simultaneous soft tissue augmentation. when approaching the vertex of the scalp. In elderly pa- Typically, the TPF flap requires coverage with either a tients, these septa are lax and attenuated, and dissection split-thickness graft or a full-thickness graft. For palmar is easier. The accepted safe flap dimensions are 8 cm × coverage, we prefer to use glabrous skin from the hypothe- 15 cm. Extension in an occipital direction will provide nar eminence or the instep of the foot. Glabrous skin offers a additional tissue (Fig. 31-3, top). Flap reliability is related more durable reconstruction with a lower propensity for hy- to the branching of the STA and distance from the axial perpigmentation. In cases where optimal sensory recovery vessels within the flap.

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• The deep temporal fascia invests the outer surface of the temporalis muscle, which partially originates from this dense fascial layer. The deep temporal fascia is separated from the STF by a loose, and largely avascular, areolar tis- sue plane that is often called the innominate (“no name”) layer. The deep temporal fascia is strictly limited to the temporal fusion line where it is continuous with the peric- ranium, unlike the STF that extends beyond this area and is continuous with the galea. At the level of the temporal fusion line, there can be more dense attachments between these two fascial layers that need to be sharply divided.

Vascular Supply • The STA is one of the terminal branches of the external carotid artery. It passes through the parotid gland, travels beneath the facial nerve branches and hereby aids in ana- tomically separating the parotid into superficial and deep lobes. The artery gradually ascends through the sub- FIGURE 31-1 stance of the superficial lobe of the parotid and emerges Precise fashioning of the flap to meet the needs of the recipient at the level of tragus, immediately superficial to the tem- site. In this patient with Dupuytren diathesis, radical fasciectomy poromandibular joint. From this point onward, the ar- and extensive neurolysis were performed, with subsequent tery can be palpated and measures 1.8 mm to 2.7 mm in microvascular transfer of temporoparietal fascia and resurfacing external diameter. The pedicle length when harvested at with a split-thickness skin graft. The 1-year postoperative result is this level is approximately 2.0 cm to 4.0 cm and obviates shown. the need for an intraparotid dissection. Deep dissection is sometimes needed to obtain a vein of adequate caliber.

FIGURE 31-2 Technique of splitting the flap along the arborization of the superficial temporal artery for palmar coverage of 2 adjacent fingers. A precise template and mapping of the superficial temporal system by means of a hand-held Doppler are critical. Digits were separated in a subsequent procedure.

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FIGURE 31-3 Transfer as a thin, sensory flap for palmar coverage. This patient sustained a roller press injury to the palm. The auriculotemporal nerve was raised with the superficial temporal vessels and was joined with the palmar cutaneous branch of the median nerve. The donor site is demonstrated 25 years following surgery. The preauricular incision is inconspicuous; localized alopecia along the scalp closure can occur.

FIGURE 31-4 Fascial layers and relationships in the temporal region.

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Temporal branch of facial n.

Super cial temporal a. and v. 5% 5% Auriculotemporal n. Parotid gland

FIGURE 31-5 Anatomy of the preauricular region relevant to pedicle dissection.

80% • The STA bifurcates into a frontal (anterior) branch and 5% 5% a parietal (posterior) branch, above the zygoma, and there are many variations in the level of branching: FIGURE 31-6 variation may become pertinent to ultimate fl ap design Variable branching pattern of the superfi cial temporal artery. (Fig. 31-6). • Just proximal to or at the zygomatic arch, the STA gives off a branch named the middle temporal artery. This nerve lies along a line drawn from an arbitrary point vessel passes between the zygomatic arch and the su- (nonanatomic) 0.5 cm below the tragus to a point 1.5 perfi cial temporal fascia and eventually reaches the deep cm above the lateral eyebrow. At the level of the arch, temporal fascia, supplying this fascial layer, as well as the fascial planes are thinned and more adherent. This sending branches into the substance of the temporalis makes the nerve vulnerable to injury, especially in a muscle. The dominant blood supply of the temporalis blood-stained fi eld. muscle originates from the deep temporal arteries aris- • The important anatomical pearl to remember during ing from the internal maxillary system. dissection of the fl ap is that the vessels (STA, STV) are • The superficial temporal vein (STV) is usually located superfi cial and nerve VII is deep to the TPF. within 8.0 mm of the artery but can be up to 3.0 cm dis- tant. This vein is anterior and superfi cial to the artery, just beneath the dermis, and can easily be cut while INDICATIONS making a preauricular incision. Above the zygoma, it has an external diameter of 2.1 mm to 3.3 mm. • Being thin and pliable, the TPF fl ap can be used in diffi cult anatomic regions such as the digit, web space, and palm. • For the reconstruction of a gliding surface for tendons, Neural Anatomy such as the dorsum of the hand. • The auriculotemporal nerve (from the V3 mandibu- • In situations where one needs to reconstruct or create lar branch of the trigeminal nerve) is a predominantly tendon pulleys. The entire extensor retinaculum at the sensory nerve that supplies the anterior auricle, the wrist can be reconstructed if necessary. outer surface of the tympanic membrane, the external • Cases where one needs to restore vascularity to a scarred auditory meatus, the temporomandibular joint and the wound bed, or one aff ected by chronic radiation injury. temporal scalp. Over a short distance, it also carries • In burn reconstruction, dorsal defects that are not parasympathetic fibers from the otic ganglion to the amenable to direct grafting (exposed tendons devoid of parotid gland. The auriculotemporal nerve is located be- paratenon) are preferentially treated with a fascial fl ap hind the STA and can be included in the fl ap if sensibil- due to its thinness. This allows for the silhouette of dor- ity is desired. sal veins, metacarpals and tendons to be visible, once • The nerve of greatest concern during TPF flap harvest the reconstructive sequence has been completed, lead- is the temporal branch of the facial nerve. It is a motor ing to a more aesthetic and natural appearance. nerve that innervates the frontalis muscle. The nerve • The STA branching pattern can be incorporated as a obliquely crosses the zygomatic arch at its midpoint and fl ow-through fl ap for digital revascularization or palmar is always deep to the superficial temporal fascia. The arch reconstruction.

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CONTRAINDICATIONS SURGICAL TECHNIQUE

• Inadequately debrided wound or infected wound bed. Recipient Site Preparation (Fig. 31-7) • Osteomyelitis. Despite more recent literature support- • The recipient wound bed is meticulously debrided and ing the use of fascial flaps for coverage of wounds after wound edges are freshened to allow a clean and uniform debridement of osteomyelitis, the TPF is not our first inset. choice in this situation, unless the surface area of ex- • A precise template of the defect is made. posed and decorticated bone is limited. • The path of the pedicle is prepared carefully to avoid • When flap bulk is needed. kinking of the vessels and account for anticipated post- • Caution should be exercised in patients who have un- operative swelling. Target vessels can be digital or com- dergone previous parotid surgery with dissection of the mon digital vessels, the palmar arch, the ulnar or radial vessels, facelift (rhytidectomy) with SMAS suspension su- vessels. The typical configuration is an end-to-side tures in the temporal region or inadvertent cautery injury. arterial anastomosis and an end-to-end venous anas- • The flap is contraindicated in patients where no STA tomosis. Venous outflow should be generous; a vena pulse is palpable; thus, preoperative Doppler is manda- comitans is available in most circumstances. tory to identify the vessel. • When reconstructing finger wounds, we liberally use • Temporal fascia and vessels may be present but abnor- K-wire fixation to hold interphalangeal and metacarpo- mal in facial lipodystrophy, hemifacial atrophy or hemi- phalangeal joints in the protected position to prevent facial microsomia. the development of joint contractures. Often, the distal • The flap is relatively contraindicated in the patient with interphalangeal joint is not immobilized to allow flexor total alopecia due to prominence of the scar on the digitorum profundus gliding and avoid tendon adhesion. scalp.

FIGURE 31-7 Young patient with avulsion injury to the dorsum of the hand with extensor tendon laceration and traumatic metacarpophalangeal joint arthrotomy. Recipient site preparation by means of wound debridement followed by fashioning of a template and dissection of the recipient vessels in the anatomic snuffbox. The 2-year postoperative result is shown (bottom right).

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FIGURE 31-8 A T-shaped incision is marked out and the temporal vessels are evaluated with a Doppler. The dissection on top of the superficial temporal fascia is initially carried out. The template allows harvest of only what is needed. Finally, the pedicle is dissected up to the parotid gland.

Flap Harvest (Fig. 31-8) plane and STV much easier. The STV is first identified. • Hair should be clipped at the site of the incisions to al- The STA will be within 2 cm of it but may not be pulsa- low for a clean closure at the end of the case. tile if epinephrine has been used. The anterior skin flap • The course of the superficial temporal artery and its bi- is raised and the dissection extends cephalad. Continued furcation is outlined using a hand-held Doppler, as is the upward traction and meticulous hemostasis is the key anticipated location of the temporal branch of the facial to this dissection. Skin flaps are raised only as much as nerve. Marking the temporal ridge will give an approxi- needed to accommodate the size of the fascial flap. mate idea of flap dimensions readily available for harvest. • A T-extension of the incision may be needed in the tem- • The patient’s head is positioned in 30-degree elevation poral region. Appropriate modification may be required to decrease venous bleeding. A solution containing epi- in male pattern baldness. With upward dissection into the nephrine is routinely instilled into the subcutaneous temporal region, the fascia is much closer to the overlying space for hemostasis. scalp and at the crest of the temporal fossa is directly ad- • A preauricular, retrotragal rhytidectomy incision herent to it and at the same level as the hair follicles. This is made, extending into the temporal scalp. In the denotes the safe superior extent of the TPF flap. hair-bearing region, the knife should be beveled parallel • The template is centered over the axial vessels. Transillu- to the long axis of the hair follicles. mination will facilitate identification of the vessels and • The skin incision is made through the dermal layer. their branching pattern. A unique characteristic of this Upward traction will make identification of the areolar flap is the ability to split it along the vessel arborization

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into frontal and parietal branches. Five vessel branching • Doppler checks are performed hourly for the first 48 patterns exist, the most common being a bifurcation 2 hours, every 2 hours for 24 hours, then every 4 hours cm above the zygomatic arch (Fig. 31-6). until discharge. • Next, the location and approximate course of the tem- • In general, the hand is immobilized and elevated for 2 poral branch of the facial nerve is once again verified weeks. K-wires are then removed; tendon gliding and and marked. The nerve lies deep to the superficial tem- hand therapy are begun. poral fascia. • The flap margins are then incised, and the STF is elevated in a retrograde fashion. This is relatively facile since this COMPLICATIONS is a loose areolar plane that is avascular until the middle temporal artery to the deep temporal fascia is encoun- • The vast majority of early complications are technical and pre- tered. This is ligated if only the STF is used. ventable. They are related to either inadequate donor site • The flap should be kept moist during flap elevation as it preparation and debridement, or microvascular difficul- has a tendency to desiccate. ties that often correlate with traumatic flap dissection • If both superficial and deep fascia are needed, elevate the and poor microvascular technique. The only exception STF first and the deep temporal fascia separately. is an unrecognized bleeding diathesis, or coagulopathy • When approaching the location of the facial nerve, it is such as homocysteinemia. critical to slow the pace of the operation and make an ef- • Postoperative edema. This may compress pedicle blood fort to find the temporal branch. In our experience, per- flow. manent frontalis weakness has only been encountered • Hematoma. This can impair graft survival. when the branch was not clearly visualized intraoper- • Alopecia. It can occur if the dissection between fascia and atively or when the surgeon was working in a blood- skin is carried out too close to the hair follicles during stained field. Meticulous hemostasis with the bipolar flap elevation, or if scalp flap handling is excessively electrocautery is key. traumatic. The use of epinephrine has also been associ- • Once the flap is raised as a vascular island on the su- ated with temporary hair loss in the scalp. perficial temporal vessels, it can either be harvested or • Nerve injury. The most dreaded complication is injury the pedicle dissected into the parotid to acquire further to the temporal branch of the facial nerve. In our ex- length. This is often necessary to reach a level where the perience, careful visualization of the nerve prevents in- vein is one large conduit. advertent injury. A nerve stimulator can be helpful at the very least. Another option is the use of continuous nerve intraoperative monitoring. The necessary devices Flap Inset are commercially available and hospitals typically carry • The flap is transferred and inset beneath the surround- them for use in thyroidectomy and parotidectomy. ing skin. The anastomoses are then completed under the • Parotid injury. Other potential complications are a sialo- microscope. cele from intraparotid dissection, gustatory hyperhidro- • The auriculotemporal nerve can be joined to a local sen- sis from injury to the auriculotemporal nerve during sory nerve if sensation is needed (eg, auriculotemporal its intraparotid course (Frey syndrome), and a neuroma nerve to the palmar cutaneous nerve). of the auriculotemporal nerve. In patients who wear • The skin graft of intermediate thickness (0.016 inches) is glasses, a section of the auriculotemporal nerve (if har- then placed over the flap. Glabrous skin is preferred for vested with the flap) should be carried out so that a po- the palmar surfaces and nonglabrous skin for the dor- tential neuroma would not be immediately beneath the sal surfaces. Split-thickness skin grafts or full-thickness temple of the eyeglass frame. skin grafts are normally used. • A petroleum gauze and cotton bolster dressing is applied. OUTCOMES • The dressings are fenestrated to allow postoperative Doppler monitoring of the flap pedicle. • With proper planning and execution, the TPF flap is a re- liable method for soft tissue reconstruction in the hand. The donor site scar is well concealed and heals well; Aftercare scalp flap alopecia has not occurred except in the imme- • Aspirin (81 mg) is administered daily for 3 months. diate vicinity of the incision and can be minimized by • During hospitalization, chemical deep vein thrombosis incision beveling. prophylaxis is administered in the form of heparin or low • It is particularly useful for small defects when local tis- molecular weight heparin, starting the day of surgery. sue is not available.

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• For the coverage of extensive defects after radical de- PEARLS AND PITFALLS bridement of osteomyelitis or osteoradionecrosis, we prefer to use a muscle flap, which is better suited to de- • Meticulous microsurgical planning and execution are liver a rich blood supply to an infected area and even- critical since postoperative flap monitoring can be chal- tually atrophies and contours satisfactorily in most lenging in the absence of a skin paddle. instances. For web space defects, there are few other flap • During flap harvest, start by dissecting out the vascular options that allow a precise reconstruction in a single pedicle and ensuring the presence of a reliable venous stage. As in any elective free tissue transfer, the micro- anatomy. surgical success rate should exceed 95%. • Continued upward traction and meticulous hemostasis • This flap requires meticulous technique and careful he- is the key to skin flap elevation during flap harvest. Skin mostasis. In a bloodstained field, nerve injuries can and flaps are raised only as much as needed to accommodate do occur. For this reason, we have restricted its use as a the size of the fascial flap required. free flap in cases where other pedicled fascial flaps such • Dissection of the fascia from caudad to cephalad as the radial forearm, first dorsal metacarpal artery flaps, allows it to enter the tissue plane between fascia and and local digital fascia are unavailable. hair-­bearing scalp more readily.

FIGURE 31-9 Variable anatomy of the superficial temporal vessels. A: The superficial temporal vein was not accompanying the artery but was found to be draining toward the occipital system. B, C: The artery is running anterior to the vein. D: The vein starts anterior to the artery, crosses over the artery and then runs posterior to it in a cephalic direction. E: One artery accompanied by two superficial temporal veins of similar caliber.

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• The important anatomical pearl is that the vessels (STA, SUGGESTED READINGS STV) are superficial and nerve VII is deep to the TPF. • The anatomy of the superficial temporal vessels can be Brent B, Upton J, Acland RD, et al. Experience with the tem- variable. Methodical dissection prevents frustration (Fig. poroparietal fascial free flap. Plast Reconstr Surg. 1985 31-9). These vessels are very tortuous in elderly patients, Aug;76(2):177-188. which can be misleading. Carty MJ, Taghinia A, Upton J. Fascial flap reconstruction of the • Venous anatomy, and arterial branching pattern, can be hand: A single surgeon’s 30-year experience. Plast Reconstr Surg. 2010 Mar;125(3):953-962. variable. • The pedicle is shorter than other fascial flaps, such as the Monks G. Restoration of a lower eyelid by a new method. Boston Med Surg J. 1898;139:385-387. radial forearm. Hence, careful planning of pedicle ori- entation and target vessel configuration is critical. Use a Serafin D. The temporal fascia flap: Discussion by J. Upton. In: Ser- afin D, ed. Atlas of Microsurgical Composite Tissue Transplantation. precise template and a suture or laparotomy sponge to W.B. Saunders Company; 1996: 323-338. simulate pedicle orientation. Upton J, Rogers C, Durham-Smith G, Swartz WM. Clinical applica- • When using the auriculotemporal nerve for sensory tions of free temporoparietal flaps in hand reconstruction. J transfer, do not skeletonize the nerve along its entire in- Hand Surg Am. 1986 Jul;11(4):475-483. traparotid course since it carries important parasympa- thetic fibers from the otic ganglion to the parotid gland. Injury can lead to gustatory sweating (Frey syndrome) and can be quite bothersome to patients. • Long-term outcomes are superior to the results ob- tained with dermal substitutes covered with split grafts.

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