Abstract
Despite the emergence of free tissue transfer, the pectoralis major myocutaneous flap (PMMF) still has a role in anterior base skull reconstruction (when free tissue transfer is not feasible). The aim of this study is to evaluate the results of external PMMF in anterior skull base reconstruction. A retrospective study from 1977 to 2006 was conducted at Yale New Haven Hospital. 16 patients (mean age 64 years), presenting with a malignant tumour of the anterior base skull, were included. The primary pathology was recurrent squamous carcinoma. Tumour resection resulted in orbital exenteration in 60%, and bone resection of the anterior skull base in 81% of patients. The initial skin defect was 49 cm 2 (range 16–100 cm 2 ). The PMMF was the primary reconstructive choice in 87%, and utilized after free flap failure in two cases. Three minor complications were noted. Orbital exenteration and anterior base skull resection is a surgical procedure that leads to significant reconstructive challenges. The PMMF remains a safe and versatile reconstructive tool in anterior skull base tumour resection. The externalized pedicle allows this flap to reach periorbital and anterior skull base.
Resection of malignant skull base disease frequently results in creation of a complex defect. Successful surgical treatment depends on the degree of resection, but also on the reliable reconstruction of the defect. The main reconstructive objective of anterior skull base reconstruction is to seal the dura to prevent cerebrospinal leakage, cerebrospinal fistula and infection of the intracranial contents. The aim of reconstruction is to provide enough tissue to fill the three dimensional cavity reliably and the tissue used for reconstruction of the defect has to be robust enough to withstand postoperative radiotherapy. The postoperative facial appearance should also be considered. Anterior skull base resection and exenteration represents one of the most disturbing facial operations. There is a wide spectrum of treatment modalities in anterior skull base reconstruction: healing by secondary intention, skin graft, local skin flap, local and regional pedicle flap and free flap. Although free tissue transfer has revolutionized reconstruction of the anterior skull base, solving most of the loco-regional flap limitations, it is inappropriate to present it as the only reconstructive option.
Alternative techniques are appropriate for specific circumstances. The pectoralis myocutaneous flap has been considered the mainstay of pedicle flap reconstruction in the head and neck region. This technique fulfils most of the anterior skull base reconstructive objectives. Others have been concerned about whether it can reach and it has the ability to reach the superior end of the defect. Nevertheless, the temporary external pedicle described by Ariyan, has allowed this flap to reach the anterior skull base. The pectoralis major myocutaneous flap (PMMF) still has a role in reconstruction as it provides a readily accessible source of vascularized soft tissue available to the reconstructive surgeon, even as a first choice. The aim of this study is to evaluate the results of external PMMF in anterior skull base reconstruction, in the authors’ institution.
Patients and methods
Surgical technique
After evaluating the extent of the resection, the PMMF size required to fill in the defect is determined ( Fig. 1 A and B ), and marked on the ipsilateral chest. The thoracoacromial vessels are outlined on the chest from the infraclavicular area towards the xiphoid. A skin paddle is outlined, according to the surface of the area to reconstruct ( Fig. 1 C). An incision is made along the lateral portion of the skin paddle down to the pectoralis major muscle. The muscle is then split longitudinally along its fibres and the sub pectoral plane is entered. A retractor is placed and the thoracoacromial vessels and their location are confirmed by direct visualization. At this point, the entire skin incision on the chest wall is made circumferentially, through the skin and the subcutaneous tissue, down to the muscle fascia.
The skin paddle is anchored to the muscle fascia with 3.0 resorbable stitches. Under direct visualization and protecting the thoracoacromial vessels, the muscle and the overlying skin paddle are dissected out. The muscle is dissected up to the infraclavicular space. At this point, the infraclavicular portion of the PMMF, the fibres run transversally across the pedicle ( Fig. 1 D). The muscle is cut so as to maintain the width of this vascular pedicle. After the muscle is separated from the clavicle, the musculo-cutaneous flap is rotated and elevated towards the orbital region the anterior base skull or auricular region, over the clavicle ( Fig. 1 E). The donor site is primary closed ( Fig. 1 F).
Once the flap is in place, the pedicle is protected and wrapped with xeroform gauze impregnated with Silvadene cream 14–21 days later the flap division is performed. An angled DeBakey clamp is placed at the base of the pectoralis major flap in the infraclavicular area. A test dose of 1/4 cm 3 of 10% fluorescein for allergic test is given. Following this, the remainder of the 9–3/4 cm 3 is injected intravenously very slowly. An ultraviolet lamp is used to check if there is a good return flow from the periorbital area to the flap ( Fig. 1 G). If so, the pedicle is transected and the thoracoacromial artery and vein are identified and sutured. The surrounding skin is then excised and undermined and then, the wound is closed ( Fig. 1 H).
Methods
The authors conducted a retrospective analysis between 1979 and 2007, using the clinical record database of Yale New Haven Hospital and the Yale Human Investigation Committee (HIC). All patients who had undergone an anterior skull base resection and external PMMF reconstruction during this period were included. Demographics, tumour characteristics (pathology, localization and recurrences), treatment modalities (radiotherapy, extension of the resection, size of the defect), flap characteristics (size, donor site, time before division) and complications and outcomes were analyzed.
Results
Eighteen patients (11 males, 7 females; mean age 67 years; range 34–89 years) were included. In most cases, pathologic examination showed a squamous carcinoma (10 of 18 patients). The main location was periorbital (10 of 18 patients) or periauricular (8 of 10 patients). In 14 cases, the resection was achieved after tumour recurrences. The characteristics of the tumours are summarized in Table 1 and shown in Figs 2 and 3 . The surgical tumour resection included 11 exenterations, 4 parotidectomies, 4 temporal bone resections, 4 ethmoid and paranasal bone resection, one frontal craniectomy. The defect ranged from 25 to 100 cm 2 (mean 48 cm 2 ). The pedicle size ranged from 25 to 35 cm (mean 29 cm), the skin paddle ranged from 10 cm × 5 cm to 12 cm × 25 cm.
| Gender | Age | Histological diagnosis | Recurrence/primary | Localization |
|---|---|---|---|---|
| Female | 35 | Adenoid cystic carcinoma | Primary | Periorbital |
| Male | 80 | Lacrymal gland carcinoma | Primary | Periorbital |
| Female | 54 | Sebaceous gland carcinoma | Recurrent | Periorbital |
| Female | 55 | SCC | Recurrent | Periorbital |
| Male | 34 | Osteogenic sarcoma | Primary | Periorbital |
| Female | 56 | SCC | Primary | Periorbital |
| Male | 50 | Basal cell | Recurrent | Periorbital |
| Male | 89 | Basal cell | Recurrent | Periorbital |
| Female | 74 | SCC | Recurrent | Periorbital |
| Male | 72 | SCC | Recurrent | Periorbital |
| Male | 85 | SCC | Primary | Pre-auricular |
| Male | 60 | SCC | Recurrent | Pre-auricular |
| Male | 77 | SCC | Recurrent | Pre-auricular |
| Male | 74 | Basal cell | Recurrent | Pre-auricular |
| Female | 72 | Desmoplastic melanoma | Recurrent | Pre-auricular |
| Male | 72 | SCC | Recurrent | Pre-auricular |
| Female | 73 | SCC | Recurrent | Pre-auricular |
| Male | 74 | SCC | Recurrent | Pre-auricular |
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