British Journal of Plastic Surgery (1991), 44.259-265 0 1991 The Trustees of British Association of Plastic Surgeons

The pedicled extended serratus anterior myocutaneous flap for head and neck reconstruction

T. Inoue, K. Ueda, M. Hatoko and T. Harashina

Department of Plastic and Reconstructive Surgery, Saitama Medical Center, Saitama Medical School, Japan

SUMMARY. A new “extended” myocutaneous flap has been designed by fasciocutaneous extension anteriorly and inferiorly from the 6th to 8th slips of the serratus anterior muscle. This flap has been used as a pedicled flap for various types of head and neck reconstructions and satisfactory results obtained. This article describes the anatomy of the flap, surgical technique and typical cases.

Anatomy

The serratus anterior muscle is situated in the lateral chest, arising from the lateral surfaces of the 1st to, usually, the 10th rib and is attached to the scapula to draw it forward. It is fed by both the lateral thoracic artery and the thoracodorsal artery, and is innervated by the lateral thoracic nerve. To produce the extended myocutaneous (MC) flap, the slips of the serratus anterior muscle attached to the 6th, 7th and 8th ribs are used with the serratus branch of the thoracodorsal artery and vein as the vascular pedicle. The remainder of the serratus anterior remains innervated and intact.

Flap Design and Elevation

The skin portion of this flap should be an elliptical shape so the donor site can be closed easily. It should be designed from the mid-axillary line to the hypo- chondrium so that the major axis of the flap is parallel to the course of the serratus anterior muscle slips, and the center of the flap can be placed on the 7th or 8th slip (Fig. 1). The skin incision is extended from the lateral end of the planned flap toward the axilla for

Serratus ant. MC-flap

thorecodorsal

Fig. 1

Figure l-Diagram of the extended serratus anterior myocutaneous flap.

preparation of the vascular pedicle. This incision does not always have to be sigmoid-it was straight in most of our patients, none of whom showed postoperative problems such as contracture. In designing the flap, attention should be focussed on preoperative confir- mation of the location of the serratus anterior branch with a Doppler flow scope, and also the incision from the flap to the axilla should overlie the latissimus dorsi muscle. Thus, the vascular pedicle can be completely preserved, and the fascial plexus on the serratus anterior muscle remains intact.

When elevating the flap, the patient’s trunk should be slightly rotated in the opposite direction to aid exposure of the anterior margin of the latissimus dorsi muscle and the vascular pedicle.

Once the incision is made along the latissimus dorsi muscle, dissection is advanced in an anterior direction, care being taken not to injure the fascial plexus located above the serratus anterior muscle. The vascular pedicles are fully exposed, and the muscle tissue is freed up to the scapular insertion (Fig. 2). The next step is to elevate the medial end of the skin portion of the flap along with the fascia of the external oblique

Figure 2-After careful dissection at the anterior margin of the latissimus dorsi muscle, the vascular pedicles of the serratus anterior muscle are exposed.

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abdominal muscle until the distal end and lower margin of the 8th or 7th slip of serratus anterior muscle is encountered. Then the incision continues along the posterior surface of the serratus anterior muscle in order to detach the necessary muscle slips from the ribs. The vascular pedicles are prepared as follows: the serratus anterior branch is detached from the more cephalic muscle slips up to the subscapular artery and vein while severing the main thoracodorsal vessels connected to the latissimus dorsi muscle and the circumflex scapular artery and vein. When the 8th

Table 1 The list of reconstructions using extended serratus anterior myocutaneous flap

Case Slips Flap no Age Sex Reconstruction used size (cm)

1 62 f 2 16 m 3 56 m 4 25 f 5 50 m 6 14 m I 56 m 8 42 m 9 50 m

10 45 m 11 68 m

oral cavity 6, I, 8th lx 14 cervical oesophagus I, 8th 10x20 tempo-auricular skin 6, I, 8th lx 14 cheek soft tissue 8th 1x14 temporal skin none 6x11 oral cavity 6, I, 8th lx 14 cervical oesophagus 6, I, 8th 1x15 cervical oesophagus 6, I, 8th 1x15 oral cavity 6, I, 8th 6x12 oral cavity 6, I, 8th 1x15 cervical oesophagus 6, I, 8th 10x22

muscle slip alone is used, there are many short muscular branches to the 6th and 7th slips, calling for careful and skilful detachment. The vascular pedicle is longer than 15 cm in length.

We have used extended serratus anterior MC flaps in head and neck reconstruction for 11 patients (Table 1). Some of these are described here.

Case reports

1. Oral reconstruction

Case 1 A 62-year-old female had an extended resection including half of the tongue and right radical neck dissection at the Department of Oral Surgery, for cancer of the tongue. Reconstruction with a 7 x 14 cm right extended serratus anterior MC flap was performed for repair of the defect. The flap consisted primarily of the 8th muscle slip, and the 6th and 7th slips were partly used to ensure preservation of the vascular pedicle. The resulting pedicle was about 20 cm in length and was smoothly passed to the oral cavity through a tunnel dissected in the subclavicular area. Primary closure of the donor site was easily obtained. The flap healed without complications. The transferred flap was slightly bulky soon after operation, but the volume decreased after the third postoperative month. Preparation of dentures is being considered at present, eight months postoperative (Fig. 3).

Figure 3-Case 1. (A) 62-year-old female underwent extended resection including right half of the tongue and right radical neck dissection. (B) Right extended SA-MC flap I x 14 cm in size was used for reconstruction. The flap consisted primarily of the 8th muscle slip, and the 6th and 7th slips were partly used. (C)Transferred flap 6 months after operation.

The Pedicled Extended Serratus Anterior Myocutaneous Flap for Head and Neck Reconstruction 261

2. Cervical oesophagus reconstruction

Case 2 The patient was a 76-year-old male with cancer of the hypo- pharynx. Radiotherapy was followed by bilateral radical neck dissection and total resection of the pharynx from the root of the tongue to the oesophagus resulting in a defect 10 cm in length. A left serratus anterior MC flap 10 x 20 cm in size was used for this reconstruction. The 7th and 8th muscle slips were used and the vascular pedicle was 18 cm in length. The flap was transferred to the neck through a subclavicular tunnel and was rolled into a cylindrical form for use in reconstruction of the cervical oesophagus. The donor site was partially closed, leaving the central area covered with meshed skin graft. The postoperative course was uneventful. The patient began to ingest orally from the second postoperative week and was discharged in the second month. Unfortunately he died of heart disease one month later, up to which time oral intake was possible, according to his family (Fig. 4).

3. Facial reconstruction

Case 3

A 56-year-old patient had undergone total parotidectomy about one year previously for left parotid cancer. Due to regional recurrence of the cancer, left radical neck dissection was performed together with extensive resection of locally recurrent tumour. The defect involved the cheek up to the temporal region. A left extended serratus anterior MC flap 7 x 14 cm in size was used for reconstruction. The flap, including the 7th and 8th muscle slips, had a 20 cm long pedicle, and was transferred to the defect through a subclavicular tunnel. The muscle tissue was used for covering the carotid artery and for augmentation of the neck. The donor site was closed primarily. The flap was slightly

congested in the distal area postoperatively, but survived completely with slight hyperpigmentation. The patient was discharged without complications in the second postopera- tive month after treatment with chemotherapy (Fig. 5).

Fig. 4

Figure &Case 2. Barium swallow of case 2 at the second postoperative week shows good passage down the reconstructed oesophagus.

Figure 5-Case 3. (A) A Xi-year-old male underwent extensive resection of the left lateral face with left radical neck dissection for recurrent parotid cancer. (B) The flap completely survived with slight pigmentation.

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Case 4 Discussion

This patient was a 25-year-old female with hemifacial atrophy associated with systemic lupus erythematosus. A dermal-fat augmentation of the cheek using a right extended serratus anterior MC flap was performed. The flap was I x 4 cm in size and used only the 8th muscle slip, with the cutaneous portion located as distally as possible. The vascular pedicle was 22 cm in length. The flap was transferred to the cheek through a tunnel created in the subclavicular area and the sub-platysmal area of neck using an auxiliary incision in the supraclavicular skin. The proximal part of the flap skin was exposed in the submandibular area as an indicator of vascularity, and the remainder was buried subcutaneously in the cheek with its epidermis removed. The flap took completely with little shrinkage, and augmentation of the cheek was nearly perfect. Resection of the 8th muscle slip remaining in the neck and the indicator flap, and partial correction of the surgical scar on the lateral chest was carried out in the 6th postoperative month (Fig. 6).

The first serratus anterior MC flap was reported by Takayanagi and Tsukie (1982). Those authors de- signed gaps on the muscle body in the lateral chest, where the largest flap possible was 12 x 7 cm because the flaps were not extended. Our “extended” serratus anterior MC flaps were extended mainly in the anterior direction, primarily from the 8th muscle slip, and the largest flap possible is 10 x 22 cm. As the area of the skin island is located distally to the serratus anterior muscle, a long vascular pedicle can be obtained, the longest being 22 cm in our experience in the cases with muscle slips. If a small flap without any muscle slip is needed, a pedicle longer than 25 cm can be obtained. This permits a pedicled flap to reach as far as the temporal area of the face, so that it can be readily used for head and neck reconstruction in most cases (Fig. 8).

Case 5

The patient was a 50-year-old female with a neurofibroma of the left temporal region. Since resection of the entire area was difficult, only the area that she was most worried about was resected at her request. An extended serratus anterior MC flap 6 x 17 cm in size with no muscle slip attached, a fascia-cutaneous flap to be exact, was used for reconstruction. Due to the very long pedicle (25 cm), the flap reached the defect in the temporal region. Postoperatively, the flap became slightly congested, but improved without any treatment. Ultimately, a major portion of the flap survived, with only a distal area becoming necrotic. The necrotic area required correction in the second postoperative month; otherwise, the results were satisfactory (Fig. 7).

Unlike other muscles, the serratus anterior muscle is characterized by an inflow of nutrient vessels from its surface, allowing safe preservation of the vascular pedicle under direct vision. The vascular pedicle of this flap is the serratus anterior branch of the thoracodorsal artery, which is the more laterally located of the two nutrient arteries of the serratus anterior muscle.

The fascia over the serratus anterior muscle is the main carrier of blood flow, and the flap is extended anteriorly because this fascia is in continuity with the fascia of the external oblique muscle of the abdomen. As shown in Case 5, if a flap is not too large, blood flow through the fascia alone permits vascularisation

Fig. 6

Figure &Case 4. (A) Preoperative view of 25-year-old female with right hemifacial atrophy. (B) The final view of the augmented cheek 1 year after surgery.

The Pedicled Extended Serratus Anterior Myocutaneous Flap for Head and Neck Reconstruction 263

Fig. 7

Figure 7-Cuse 5. A SO-year-old female with neurofibroma of the left temporal region underwent a resection of the area that she was most worried about. (B) Left extended serratus anterior fasciocutaneous flap (with no muscle slip) was used for reconstruction. (C) After slight correction the result was satisfactory in the 7th postoperative month.

without any muscle tissue attached. However, our experience indicates that detachment of the fascia from the serratus anterior muscle is very difficult. There are many short muscular branches from the fascia, and it is a time-consuming, delicate process to ligate these without disturbing blood flow in the fascia. These muscular branches tend to be shorter and thinner in the lower muscle slips. In our earlier cases, we made an effort to preserve more of the muscle but we now elevate the 7th and 8th muscle slips together. In reconstruction following tumour resection in the head and neck involving radical neck dissection, these slips are used to cover important structures in the neck such as the carotid artery, and also to augment the

ant.

dotation Ar'c MC flap

Fig. 8

Every type of myocutaneous flap poses a risk of functional loss at the donor site, and using a myocuta- neous flap to ensure transfer of a sufficient amount of tissue behoves us as reconstructive surgeons to select a flap likely to produce minimum loss of function. The flap described here causes little postoperative func- tional loss, because it involves the use of only a small amount of the serratus anterior muscle and permits preservation of the long thoracic nerve. In this respect, the flap is superior to the conventional pectoralis major and latissimus dorsi MC flaps used for head and neck reconstruction (Ariyan, 1979; Barton er al., 1983).

Figure S-The arc of rotation of the extended serratus anterior MC Microsurgical development has stimulated the use flap. of free flaps for reconstruction and these have become

dissected neck. However, the presence of muscle bulk should be avoided as far as possible in patients who require no volume in the neck, as in Case 5. In this case, designing a flap with no muscle slip and a long pedicle (25 cm) permitted reconstruction of the tem- poral region. However, the flap became congested postoperatively, ultimately becoming partly necrotic. This was due to the fact that the vascular pedicle located in the fascia superficial to the serratus anterior muscle could not be preserved adequately in prepara- tion of the flap. If detached carefully, we think that flaps about 5 x 10 cm in size can survive, but it requires such meticulous technique that we now use the 8th muscle slip and resect it later in patients who do not need volume in the neck, as we did in Case 4. The use of one or two slips of the serratus anterior muscle does not’result in functional loss. Moreover, the use of a safer flap with muscle slips attached for reconstruction is satisfactory in such cases as case 4, because secondary operation is necessary for correction of the flap in most patients undergoing reconstruction for hemifacial atrophy.

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commonplace in head and neck reconstruction. A flap obtained from a remote area allows a shorter operative time and transplantation of a sufficient volume of tissue, but the main disadvantage is the requirement of a special technique, microvascular anastomosis, which needs to be performed by an experienced operator. The long pedicle of our flap, its greatest merit, allows reconstruction using a pedicled flap without microvascular anastomosis in nearly all cases of head and neck reconstruction.

British Journal of Plastic Surgery

There are several routes for the transfer of a flap produced in the lateral thoracic area to the head and neck area. The first is the subcutaneous tunnel, which is rather long, but can be used for reconstruction in the lower neck. The second route is created by dividing the muscle tissue directly below the clavicle and then tunnelling over the clavicle from behind the pectoralis major muscle to reach the area of the head and neck. While this route is technically simple and is fairly short, the pedicle is likely to be compressed by the clavicle, leading to vascular occlusion. Our experience shows that the subclavicular tunnel is the best route. This tunnel is created by dissecting between the clavicle and subclavian vein, starting deep to the pectoralis major muscle. It is the most physiologic and shortest route. However the technique is rather difficult, and the subclavian vein may be tom unless it is carefully performed. A space of 5 x 3 cm is possible between the clavicle and the subclavian vein, and an extended serratus anterior MC flap of about 10 x 20 cm, wrapped in a vinyl sheet, can be smoothly passed through the tunnel (Fig. 9). We have passed flaps wrapped in vinyl sheets to remote regions in other cases (Inoue and Fujino, 1986 ; Inoue et al., 1990). It is simple and does not injure the surrounding tissues.

Fig. 10

Figure l&A donor site up to 7 cm in width can be easily closed primarily.

In using a large flap, the scar at the donor site may be as serious a problem as functional loss. Our flap is obtained from a fairly low area of the lateral chest, which is far less conspicuous than the donor sites of deltopectoral (Bakamjian et al., 1971) and pectoralis major MC flaps. Furthermore, defects up to about 10 cm in width can be primarily closed. Nevertheless, the maximum width for easy closure is about 7 cm

(Fig. 10). We perform free skin grafting to avoid very tight closure in most cases in consideration of postoperative respiratory function, because most of the patients undergoing reconstruction are elderly, and the operation takes a long time.

Conclusions

We have devised a new myocutaneous flap by fasciocutaneous extension from the 6th-8th slips of the serratus anterior muscle anteriorly and inferiorly, and have used it for various types of head and neck reconstruction. This flap seems to be superior to conventional flaps used for reconstruction because it :

1. 2. 3.

4.

5.

Fig. 9

Figure %-Wrapping the flap in a vinyl sheet facilitates passing it through the subclavicular tunnel.

Requires no microvascular anastomosis. Has a long pedicle, 15-20 cm in length. Preserves the upper serratus muscle slips and the long thoracic nerve. Has a donor site such that flaps about 10 cm in width can be primarily closed, and is located in a covered area. Requires no postural change while operating.

References

Ariyan, S. (1979). The pectoralis major myocutaneous flap. A versatile flap for reconstruction in the head and neck. Plastic and Reconstructive Surgery, 63,73.

The Pedicled Extended Serratus Anterior Mvocutaneous Flap for Head and Neck Reconstruction 265

Baknmjian, V. Y., Lmg, M. awl Rigg, B. (1971). Experience with the medially based deltopectoral flap in reconstructive surgery of the head and neck. British Journal of Plastic Surgery, 24,174.

Barton, F. R., Jr., Spicer, T. E. and Byrd, H. S. (1983). Head and neck reconstruction with the latissimus dorsi myocutaneous flap: Anatomical observations and report of 60 cases. Pfastic and Reconstructive Surgery, 71, 199.

Inoue, T. and Fq+o, T. (1986). An upper arm flap, pedicled on the cephalic vein with arterial anastomosis, for head and neck reconstruction. British Journal ofPlastic Surgery, 39,451.

Inoae, T., Taaaka, I. and Harasbiaa, T. (1990). Reconstruction of ischial pressure sore using an inferior rectus abdominis myocuta- neous gap. European Journal of Plastic Surgery, 13,22.

Takrymagi, S. aad Tsukie, T. (1982). Free serratus anterior muscle and myocutaneous flaps. Am&s ofPlastic Surgery, 8,277.

The Authors

Tnkeo Inone, MD, Assistant Professor Koicki Ueda, MD, Instructor Mitsuo Hatoko, MD, Instructor Takao Ha&ha, MD, Professor G, Department of Plastic and

Reconstructive Surgery, Saitama Medical Center, Saitama Med- ical School, 1981 Tsujido Kamoda, Kawagoe, 350 Japan.

Requests for reprints to Dr Inoue at the above address.

Paper received 6 October 1990.

Accepted 23 November 1990.