OPEN ACCESS ATLAS OF OTOLARYNGOLOGY, HEAD & NECK OPERATIVE SURGERY UPPER & LOWER TRAPEZIUS FLAPS FOR HEAD & NECK RECONSTRUCTION Patrik Pipkorn, Ryan Jackson, Jason Rich Trapezius flaps are a useful reconstructive Lower trapezius island flap option for the head and neck. Because of the popularity of microvascular surgery, as well The lower trapezius island flap is based on as surgeons’ unfamiliarity with back flaps branches of the transverse cervical artery and the need for lateral or prone surgical and provides excellent reconstruction of positioning, trapezius flaps have however posterior occipital and scalp defects. decreased in popularity. But, in a setting without microvascular expertise and with Benefits other reconstructive options exhausted, • “The pectoralis flap of the back” these are robust and reliable flaps with low • Reliable blood supply morbidity. • Provides skin cover up to parietal scalp • Easy to raise once familiar with back There are three types of trapezius flaps i.e. anatomy upper, lower and lateral trapezius island • Up to 9cm of skin width with primary flaps. The lateral trapezius island flap has a closure very variable blood supply and is very • Low donor site morbidity seldom used and is not covered in this • Excellent arc of rotation chapter. Caveats Upper trapezius flap • Requires lateral or prone surgical posi- tion The upper trapezius flap is based on the • Wound prone to seroma paraspinous perforators and branches of the occipital artery and is a good option for • Questionable vascularity after neck carotid cover for skin loss after radical neck dissection if transverse cervical vessels dissection. have been sacrificed Benefits Surgical anatomy • Robust and reliable blood supply As with any surgical procedure a sound un- • Can be raised following prior radical derstanding of the anatomy and good neck dissection judgement are essential. • Can provide up to 10cm width skin and muscle Muscle anatomy (Figure 1) • Can provide skin cover to the midline The trapezius muscle is the most superficial Caveats of the muscles of the upper back and • Limited arc of rotation posterior neck. It is a thin trapezoid-shaped • Often requires skin graft to cover donor muscle with three anatomic and functional site components. The upper portion arises from • Impaired shoulder function (unless XIn the superior nuchal line and the external already sacrificed) occipital protuberance, and it inserts into • Requires slightly rotated surgical posi- the lateral third of the clavicle, defining the tion or a Mayfield headrest for surgical posterior triangle of the neck. This part of exposure the muscle helps to elevate the scapula and the shoulder. The lower two thirds of the muscle originate from the seven cervical variations are important, but only if addi- and six upper thoracic spinal processes and tional pedicle length is required. inserts into the acromion and spine of the scapula. These fibers help to retract the The main blood supply to the muscle origi- scapula. The lower part of the muscle over- nates from branches of the transverse cervi- lies the latissimus dorsi muscle. Deep to the cal artery (TCA) or dorsal scapular artery trapezius muscle are the thin rhomboid (DSA). The muscle has minor blood supply minor and major muscles that originate from perforating paraspinous perforators from C7-T1 and T2-T5 respectively. Supe- from posterior intercostal vessels all along rior to the rhomboid muscles is the levator its origin from C1-T6. The upper portion of scapulae muscle that arises from the the muscle has additional blood supply posterior tubercle of the transverse proces- from branches of the occipital artery ses of C1-C4 and inserts into the superior (Figure 2). and medial borders of the scapula. These muscles retract and elevate the scapula. The transverse cervical artery arises from Superolaterally the trapezius covers the the thyrocervical trunk and crosses laterally supraspinatus muscle. low in the neck, superficial to the preverte- bral fascia and enters the trapezius from its deep surface (Figure 2). Before entering the muscle, it gives off a deep branch, the dor- sal scapular artery which runs deep to levator scapulae, and a superficial branch to the trapezius most commonly between the rhomboid minor and major muscles; However, occasionally this branch runs between the levator scapulae and rhomboid minor muscles. Occipital Transverse cervical Superficial branch Figure 1: Trapezius, latissimus dorsi, leva- Dorsal scapular tor scapulae, and rhomboid muscles Vasculature (Figure 2) The trapezius muscle has a variable blood supply that has been debated over the years. Figure 2: Occipital, transverse cervical and When harvesting upper trapezius flaps its dorsal scapular and superficial branches these variations have no relevance. How- ever, with the lower island flap these 2 Anatomic variations supply to not jeopardize the vascular sup- ply. To preserve the proximal dorsal scapu- It was long believed that the transverse cer- lar artery, the rhomboid minor muscle must vical artery was the main blood supply to be divided. Additionally, it is important to the trapezius flap after reports of distal flap consider the status of the transverse necrosis when the superficial branch of the cervical vessels as they may have been dorsal scapular artery was ligated to obtain sacrificed during the neck dissection. additional length. However, cadaveric stu- dies in the early 1990’s shed further light on Innervation anatomic variations, and showed that the dorsal scapular and transverse cervical The trapezius is innervated mainly by the artery (superficial branch) had a reciprocal XIn. It enters the deep surface of the relationship. In 50% of cases the dorsal sca- superior edge of the muscle in the lower pular artery was dominant and was a branch posterior triangle of the neck after passing of transverse cervical artery. In 30% the through the upper third of the sternocleido- transverse cervical artery was the main sup- mastoid muscle (Figure 4). It receives add- ply with the dorsal scapular artery being a itional innervation from branches of C3 and branch from the transverse cervical artery. C4 although the clinical importance of these In 20 % the blood supply was equal, but had fibers is unclear. separate takeoffs from the subclavian artery. This differed slightly from earlier cadaveric studies with a higher proportion of the dorsal scapular artery having a separate takeoff directly from subclavian artery (Figure 3). TCA XIn 30% DSA 34% 33% TM Figure 4: Accessory (XIn) fully exposed in right neck dissection, passing deep to anterior border of trapezius muscle (TM) Figure 3: Origin of dorsal scapular artery (DSA) Upper Trapezius Flap: Surgical steps Variations of how the vessels are inter- The upper trapezius flap is based on the twined with the brachial plexus have also paraspinous perforators and branches of the been described. These variations are impor- occipital artery. tant to understand if additional pedicle length is required when harvesting a lower Informed consent trapezius island flap. Since it is difficult to know which artery is dominant, it may be Preoperative counselling includes risk of safer to not divide the distal dorsal scapular seroma or haematoma, as well as unsightly artery to preserve this additional blood scars. The patient needs to be informed 3 about shoulder dysfunction (especially if • The lateral extension of the trapezius at the XIn is still functioning) and the possible the acromion generally marks the lateral need for a skin graft to the donor site. extent of the flap • Skin over the deltoid can be raised if ad- Surgical preparation and positioning (Fig- ditional length is needed, but any skin ure 5) beyond the trapezius is supplied ran- domly through the dermal plexus and is The patient’s neck and upper back are prep- not reliable ped and draped. Exposure needs to include • The defect size will dictate the width of the upper back, just beyond the thoracic the flap, although the wider the flap the spinal processes. This exposure is obtained more reliable it is by slightly tilting the patient away from the • Up to about 6cm can be raised without side of the flap, especially if the patient’s a need for skin grafting; a simple pinch head is supported in a Mayfield headrest. test will give guidance Alternatively, the patient is positioned in a lateral decubitus position, al-though this Raising the flap makes the oncologic resection in the neck more challenging. • Start by making the anterior incision through skin, fascia and fat to the level of the trapezius muscle (Figure 6) Figure 5: Patient slightly tilted away from the side of the flap to expose the upper back, just beyond thoracic spinal processes Flap design (Figure 5) Before raising the flap, the surgeon needs to Figure 6: Start by identifying the anterior have a good understanding of the surgical edge of the trapezius muscle defect. • The superior edge of the trapezius mus- • By making this incision anteriorly, cle denotes the anterior edge of the flap adjustments can still be made should it • Pre- or intraoperative ultrasound can be turn out that the edge of the muscle is in used to better define the superolateral a different position than was anticipated border of the trapezius muscle to plan • Once the anterior edge of the trapezius the incisions is identified, the remainder of the skin incision is made 4 • Continue with the posterior skin inci- • If possible, close the defect primarily sion (Figure 9) • Divide the trapezius from its attachment • Otherwise close the defect with a skin from the spine of the scapula graft • Anteriorly the transverse cervical ves- sels will be encountered and need to be divided to enable rotation of the flap (Figure 7) Figure 9: Primary closure of door site Lower Trapezius Island Flap: Surgical Figure 7: Anteriorly the transverse cervical steps vessels are encountered The lower trapezius island flap is based on • Continue with blunt dissection between branches of the transverse cervical artery.