|Ahead of print
Infrahyoid flap revisited – A head and neck surgical perspective in the Indian setting
Manikandan Venkatasubramaniyan, Suhas Kodasoge Rajappa, Mudit Agarwal, Anshu Chopra, Abhishek Singh, Rajiv Paul
Department of Head and Neck Surgical Oncology, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi, India
Department of Head and Neck Surgical Oncology, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi
Source of Support: None, Conflict of Interest: None
PURPOSE: In India, head and neck cancer contributes to about 35% of all malignancies. Among head and neck squamous cell cancers, buccal mucosa and tongue are the most common subsites. Reconstruction of defects after resection of primary in these subsites with acceptable cosmetic and functional outcomes remains a challenging task. In the era of free flaps, many pedicled flaps are being overlooked. Infrahyoid flap (IHF) is one among them. This study discusses the feasibility of IHF in reconstruction of small and medium-sized defects in subsites of the oral cavity.
MATERIALS AND METHODS: This study is a retrospective analysis of 23 patients who underwent IHF and reconstruction after excision of primary in a case of oral cavity squamous cell carcinoma from January 2010 till November 2017 with a median follow-up of 15 months. Patients who were diagnosed as a case of squamous cell carcinoma in oral cavity subsites (T1–T3 and N0/N1–N2) and in whom the anticipated defect size was small to medium were included. The evaluation was then done based on the possibility to reach recipient site, vitality after transposition, definitive integration, and clinical outcome.
RESULTS: Out of 23 patients, 5 patients had flap-related complications of which 1 patient had total skin paddle necrosis and 4 patients had partial skin paddle necrosis at distal end. However, no patient developed oro-cutaneous fistula or required corrective surgery. The maximum flap dimension was 9 × 4 cm and average flap dimension was 6 × 4 cm. The postoperative outcome of all patients remained uneventful.
CONCLUSION: The infrahyoid myocutaneous flap is a reliable and convenient flap which can be used as a good alternative for free flaps in small and medium-sized defects of the oral cavity.
Keywords: Head and neck cancer, infrahyoid flap, oral cancer, pedicled flap, reconstruction
|How to cite this URL:|
Venkatasubramaniyan M, Rajappa SK, Agarwal M, Chopra A, Singh A, Paul R. Infrahyoid flap revisited – A head and neck surgical perspective in the Indian setting. Indian J Cancer [Epub ahead of print] [cited 2020 Jan 17]. Available from: http://www.indianjcancer.com/preprintarticle.asp?id=275395
| » Introduction|| |
Oral cancer is the sixth most common cancer worldwide, and in India, head and neck cancer constitutes 35% of all malignancies. Therapeutic strategies in head and neck cancers continue to evolve based on the stage of disease and its subsite.
The surgeon's aim in treating patients with head and neck cancers is not only the complete excision of the tumor but also to reconstruct the defect with minimal morbidity and acceptable functional and cosmetic outcomes. In the era of free flaps (microvascular reconstructions), many reliable, locally available pedicled flaps such as infrahyoid flaps (IHFs) are being less commonly used. This flap has proven to be reliable in reconstruction of small and medium-sized defects in head and neck., Perforators that supply IHF are derived from superior thyroid vessels through infrahyoid muscles (strap muscles). IHF requires less expertise than for free flaps and can be a valuable option of reconstruction for patients who cannot undergo microvascular reconstruction due to factors, such as cost and contraindications for prolonged anesthesia. IHF is economical compared with free flaps, a significant consideration in developing countries. Here, we present our experience of reconstruction of defects with IHF for oral cavity primaries.
| » Surgical Anatomy|| |
The infrahyoid muscle flap consists of skin, subcutaneous tissue, platysma, and the strap muscles, including sternohyoid, sternothyroid, and superior belly of omohyoid. It starts from the midline of neck extending from thyroid cartilage till sternal notch and lateral border is outlined by index finger-thumb pinch test to assess primary closure. This entire pedicled flap is based on superior thyroid artery. Superior thyroid artery arises from the external carotid artery in the anterior aspect and turns downward and medially to enter into the upper pole of the thyroid gland. All the branches of superior thyroid artery except its posterior branch have tiny tributaries supplying the infrahyoid muscles and overlying skin. The venous drainage is through the anterior jugular vein and superior thyroid vein, which, in turn, drains into the internal jugular vein. However, anterior jugular vein needs to be sacrificed during flap harvest for adequate mobilization. The nerve supply to flap is from ansa cervicalis. In selective cases where minimal mobilization of flap needed, the nerve supply can be preserved., This prevents muscle atrophy and flap retraction after radiotherapy.
| » Materials and Methods|| |
We present our experience of 23 patients who underwent IHF reconstruction after excision of primary in oral cavity squamous cell carcinoma involving different subsites. The time period of study was from January 2010 to November 2017. All the flaps were harvested by a single head and neck surgeon, using the same technique and under 2.5× magnifications (loupe). Prior to flap harvesting, evaluation was done based on the possibility of the flap to reach the recipient site. After harvesting the viability after transposition, definitive integration and clinical outcomes are noted. In this retrospective analysis, patients who were diagnosed as squamous cell carcinoma in oral cavity subsites (T1–T3 and N0/N1–N2) and in whom the anticipated defect size was small to medium were included. The defects were arbitrarily defined as small (3-5 cm), moderate (5-8 cm) and large (>8 cm), since no study has commented upon exact dimensions. Patients who underwent previous neck surgery on the ipsilateral side or in whom the superior thyroid pedicle could not be preserved were excluded from undergoing this flap. Due to retrospective nature of this study, it was granted an exemption in writing by Rajiv Gandhi Cancer Institute Institutional Review Board.
The technique of harvesting flap
After excision of the tumor, dimensions of the defect were measured [Figure 1]. All the specimens were subjected to frozen section study and confirmed for adequacy of margins. The corresponding dimension of the flap was outlined medially in midline, extending superiorly from hyoid bone and inferiorly till suprasternal notch and laterally outlined by index finger-thumb pinch test to assess primary closure in most of the cases  [Figure 2]. The average size of the flap was 6 × 4 cm. However, in our study, the maximum flap size harvested was about 9 × 4 cm. After resection of primary, neck incision was given and subplatysmal flaps were raised to dissect out level I and II lymph nodes following which the flap harvesting was started. Initially, internal jugular vein and superior thyroid pedicle were dissected out. The incision is given in midline vertically and the musculocutaneous flap was raised along the border of sternohyoid muscle till sternal notch. Distally near the sternal notch, sternohyoid and sternothyroid muscles were cut near the origin. The flap was then raised in the avascular plane over thyroid capsule till superior pole of thyroid. Superior belly of omohyoid was included in the flap. Inferior belly was not included, since it does not form the part under skin paddle of the flap. Ansa cervicalis was included if possible. In order to prevent shearing of perforators, stitch was taken from skin paddle to muscle together at the edges of flap. While dissecting near superior pole of thyroid gland, thermal energy source (monopolar/harmonic) was avoided to prevent injury to marginal perforators. Using sharp instruments, anterior and posterior branches of superior thyroid arteries were dissected clipped and cut. At this stage, meticulous dissection was done to preserve the external laryngeal nerve [Figure 3]. After this strap muscles were completely divided from the thyroid cartilage and hyoid bone, at its upper edge. Thyrohyoid muscle was preserved in order to prevent injury to internal laryngeal nerve beneath it. Flap became freely mobile with pedicle as its axis [Figure 4] and was then tunneled through the floor of mouth after partially transecting mylohyoid for tongue and floor of the mouth defect and was placed anterior to mandible for gingivobuccal and retromolar trigone defect, after releasing the stitch [Figure 5] and [Figure 6].
|Figure 2: Marking the outline of flap along with incision line for neck dissection|
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|Figure 3: Delineation of external laryngeal nerve (marked with artery forceps)|
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| » Results|| |
In our case series, out of 23 patients who underwent this flap reconstruction, 5 patients had flap-related complications of which 1 patient had total skin paddle necrosis and 4 patients had partial skin paddle necrosis at distal end as shown in [Table 1]. Patients who had partial skin paddle necrosis had uncontrolled diabetes and poor nutritional status as shown in [Table 2]. Co-morbidities and nutritional status based on serum albumin was taken into account for analysis. Among 23 patients, 9 patients had diabetes mellitus. From [Table 2] it was found that patients who had HBA1c >9.0 and serum albumin <3.0 mg/dL had higher rate of flap-related complications. In one patient, horizontal skin paddle was taken with a dimension of 4.5 × 6 cm in an attempt to prevent vertical scar in the neck. However, patient developed venous congestion and total skin paddle necrosis. The hospital stay for this patient remained same as other patients in the study. Ryle's tube feed was continued for 15 days in this patient in contrast to 1 week in other patients. The necrosed skin paddle was debrided on postoperative day six and found to have healthy muscle underneath. Even though the flap had no intact nerve supply in this case, wound healed with secondary intention in 2 weeks of time as shown in [Figure 7] and [Figure 8]. Patient received adjuvant radiation therapy, and on follow-up, there is no evidence of recurrence and overall satisfaction in terms of function and cosmesis were similar to other patients in the study. None of the patients required corrective surgery or developed oro-cutaneous fistula. The muscle pad of flap remained healthy in all the patients. In our study, the flap dimension exceeded 8 cm in three patients of which complication occurred in one patient. The other two patients in whom there were no flap-related complications are relatively younger ≤40 years. Age and comorbidities can play a significant role in flap-related complications when flap dimension exceeds the average flap size (6 × 4 cm). The postoperative outcome of all patients remained uneventful. Six patients received adjuvant therapy (radiation) as per protocol without any major consequences on the flap (flap retraction). Ansa cervicalis was preserved in three patients in whom the primary was on the floor of the mouth and lower gingival buccal sulcus. Lymph node dissection was done till level IV in all T2 lesions and extending to level V also in five patients. The average dimensions of flap were in the range of 6 × 4 cm in our series. Care was taken such that the width of the flap does not exceed 4 cm in order to prevent difficulty in the primary closure of donor area, except one patient mentioned earlier. In our series, the donor site was closed primarily with adjacent skin mobilization. However, in one patient whom the flaps dimension was 9 × 4 cm, initially before the harvesting of flap, it was planned for primary closure. However, after flap harvest, as the defect size was more than anticipated, we were not able to close the defect primarily. Hence, small deltopectoral flap was used to cover the defect with primary closure of donor area. Since the deltopectoral flap harvested was small in size, this procedure was done as a single-stage procedure and patient had similar post-op recovery as others. This patient received post op adjuvant radiotherapy and developed a contracture at donor site limiting the neck extension as shown in [Figure 9]. Patient was advised for contracture release. However, patient refused for surgery citing that it does not hamper her day-to-day activities. As described by Deganello et al. if the width of the donor site is >5 cm, then usually a deltopectoral flap is required to close the defect. According to author, if operating surgeon feels that a secondary procedure such as deltopectoral flap may be required to close the donor site, free flaps would be a better option to reconstruct defect after excision of oral malignancy, hence avoiding compromise of aesthetics and function of the neck. In our series, all the patients except one are on regular follow-up with no recurrence of disease till date. One patient died 6 years after surgery due to pneumonia and respiratory failure.
|Figure 7: Patient with total skin paddle necrosis (2 weeks postdebridement)|
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|Figure 8: Patient with total skin paddle necrosis – wound look (2-year postsurgery). Arrow indicates flap area|
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|Figure 9: Delto pectoral flap to cover donor site (appearance post radiotherapy). Contracture in neck limiting extension (not hampering day-to-day activities – as said by patient)|
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| » Discussion|| |
Microvascular free flaps, fasciocutaneous flaps, and myocutaneous flaps are the most common methods which are being followed globally for reconstruction of oral cavity defects. Pectoralis major, deltopectoral, nasolabial, supraclavicular, trapezius, and submental flaps form the major chunk under fasciocutaneous and myocutaneous flap category. Ideally, the flaps for reconstruction of defects should be easy to harvest and preferably be a single-stage procedure. Pectoralis major flap which is the workhorse for head and neck reconstruction is too bulky for reconstruction of small to medium-sized defects. Free flaps require expertise and are both time and cost consuming and hence IHF can be the best alternative for this. The first case report of using the infrahyoid system of muscle as a pedicled flap for reconstruction was done by Clarimont et al. in 1977. The first case series of IHF was published by Wang et al. in 1986 in English literature with 112 patients reconstructed with this flap. The shape of flap performed by Wang et al. was rectangular. However, presently we follow a modified incision based on defect dimension to achieve a better cosmetic result and to close the donor site primarily. IHF has been proved to be a very good alternative for reconstruction of defects in the oral cavity, oropharynx, hypopharynx, and lower third of the face., The literature review showed that IHF can also be used to reconstruct defects in parotid region, pharyngolaryngeal tract, and cervical trachea.,,,
The advantage of IHF compared with free flap includes simultaneous neck dissection can be done through the same incision, less time consuming, better tolerated among elderly and debilitated patients, and economically more feasible. The approximate expenditure of performing a free flap is about 1.5 times the locoregional flap at our institute. In comparison to other myocutaneous flaps, IHF gives aesthetically good results at the defect site. Even though the skin paddle necrosis of IHF ranges from 3% to 47%, the necrosis of muscles is rare., The probable cause of skin necrosis is the damage of perforators supplying the skin paddle and inadequate venous drainage. Preoperative radiotherapy is not an absolute contraindication to IHF. In such cases, one should be vigilant about lack of pliability over the skin and radiation-induced fibrosis. If these features are present, then the flap is contraindicated., Few studies do not recommend IHF when modified radical neck dissection (MRND) has been done. In our opinion, MRND is not a contraindication for IHF, unless or until there is ENE (extranodal extension) with the involvement of strap muscles and the internal jugular vein is sacrificed. However, the IHF has its own limitations that preclude its routine use in all the patients. There is a limit to the maximum dimension of skin paddle. It is difficult to reconstruct the defects of the upper half of face and there is an additional risk of injury to the external laryngeal nerve.
Even though few studies in literature recommend only till level III if the patient was planned for IHF, Gangloff et al. do not consider this as a contraindication. In our series, we have performed flap harvesting after lymph node dissection till level IV without compromising the blood supply of flap. On follow-up (median = 15 months), we had no locoregional recurrence in any of the patients. Functional outcomes in terms of swallowing were excellent in patients who did not undergo adjuvant radiation. Patients who underwent radiation were able to take liquid and semisolid diet without any difficulty. According to Remmert et al. in cases of a short pedicle, one can attempt microvascular reconstruction with this flap after harvesting. However, neither we nor any other series had used it., On reviewing the larger case series in IHF reconstruction,,,, this flap has been proven to be a very good alternative to microvascular free flaps in small and medium-sized defects. The factors analyzed in the larger case series were adequate venous drainage, skin paddle necrosis, need for secondary surgical intervention, and functional aspects. Functional aspects of the flap are important in oro-pharyngeal reconstruction., In our study, we found out that, even though IHF is one of the options available for locoregional reconstruction, HBA1c >9.0 and serum albumin <3.0 mg/dL may lead to flap related complications. However, this cannot be a contraindication, since these factors should be evaluated using larger case series. Our experience over 7 years has made this flap as a viable reconstructive option following head and neck cancer surgery. This flap can be done by surgeon who is well versed in neck dissection and thyroid surgeries, because of anatomical familiarity. According to us IHF can be a viable option for medium sized defects which usually requires free flap for reconstruction [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]. Patients with hypoalbuminemia and uncontrolled diabetes should be optimized as much as possible for better outcomes of the flap. In our study, author became comfortable with flap harvesting and insetting after doing five cases.
|Figure 11: Carcinoma lower alveolus – 2-week post-op with flap integration. (Dental rehabilitation is being planned at a later date)|
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|>Figure 12: Patient in Figure 10 and 11 – post-op cosmetic appearance at 2 months|
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|Figure 13: Carcinoma retromolar trigone – appearance after flap insetting postresection of primary|
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|Figure 14: Patient in Figure 13 - post-op with flap integration at 2 weeks|
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| » Conclusion|| |
The infrahyoid myocutaneous flap is a reliable and convenient flap, which can be used safely even in patients undergoing lymph node dissection extending till level IV and V and to reconstruct the small and medium-sized defects of oral cavity. The probable indications for IHF include lack of expertise for the free flap, high-risk patients, and financial concerns. Even though free flap reconstruction in head and neck is considered as ideal one, IHF is an important locoregional flap in the armamentarium of head and neck surgeons encountered with small to medium-sized defects of oral cavity.
Human subject protection
Due to retrospective nature of this study, it was granted an exemption in writing by Rajiv Gandhi Cancer Institute IRB.
The guidelines in the Declaration of Helsinki were followed at all points during this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]
[Table 1], [Table 2]