The Infrahyoid Musculocutaneous Flap in Head and Neck Reconstruction Supakorn Rojananin,
MD,
Nit Suphaphongs,
MD, Bangkok, Thailand,
The infrahyoid muse&cutaneous flap (IHMF) , as first described by Wang in 1986, is mainly nourished by the superior thyroid vessels through the perforators of the infrahyoid muscles (i.e., sternohyoid muscle, sternothyroid muscle, superior belly of the omohyoid muscle). This thin flap, usually extending from the hyoid bone to the sternal notch at the central part of the anterior neck, provides a skin island of about 4 by 8 cm. After these muscles have been divided from their origins, the flap can be freely transferred on its pedicle of superior thyroid artery to cover the soft tissue defect created after surgical ablation of cancer of the midface, parotid region, oral cavity, oropharnyx, or hypopharynx. From April 1987 to October 1990, our department successfully performed this flap procedure in 22 patients (cancer of the buccal mucosa 8, lower gum 5, floor of mouth 2, tongue 2, lower lip 2, parotid gland 1, skin 1, hemangioma of buccal mucosa 1). Two were treatment failures, three had partial dermal necrosis (distal third of flap surface), and the remainder had no major complications. The donor sites were closed either primarily or by means of a small, local skin flap. Contraindications to the flap are previous thyroid surgery, radical neck dissection, irradiation to the anterior neck, and hairy neck skin. We believe our results indicate that the IHMF is a versatile, reliable flap that may be used in combination with other regional flaps, such as the pectoralis major flap. It obviates the need for a microvascular free flap in many cases.
Alando J. Ballantyne,‘~~, Houston, TEXTS
he infrahyoid muscles have been used to reconstruct T head and neck sites for many decades. In 1965, Bailey [I] popularized the bipedicled sternohyoid muscle flap to reconstruct the larynx after vertical partial laryngectomy. In 1969, Ogura and Biller [2] described a monopedicled inferiorly based sternohyoid muscle flap, and in 1983, Calcaterra [3] employed a superioriy based sternohyoid myofascial flap, for the same purpose. In addition, its use as a sternohyoid myo-osseous flap for the reconstruction of subglottic or tracheal stenosis was described by Finnegan et al [4] in 1975. In 1979, Eliachar and Joachims [5] described their early experience in applying the rotated infrahyoid vascularized myocutaneous flap in laryngotracheal reconstruction and extensively studied the anatomic basis of the blood supply to the strap muscles and overlying skin [6]. It was not until 1986 that the axial infrahyoid musculocutaneous flap was first described by Wang and colleagues [7], with excellent results. The purpose of this study is to confirm the reliability and the application of this flap. SURGICAL
ANATOMY
From the Division of Head-Neck and Breast Surgery (SR, NS), Department of Surgery, Siriraj Hospital Medical School, Faculty of Medicine, Mahidol University, Bangkok, Thailand, and the Department of Head and Neck Surgery, University of Texas, M.D. Anderson Cancer Center (AJB), Houston, Texas. Requests for reprints should be addressed to Supakom Rojananin, MD, Division of Head-Neck and Breast Surgery, Department of Surgery, Sirirah Hospital Medical School, Bangkok 10700, Thailand. Presented at the 37th Annual Meeting of the Society of Head and Neck Surgeons, Maui, Hawaii, May l-4.1991.
The infrahyoid muscles used in this flap consist of the sternohyoid muscle, the superior belly of the omohyoid muscle, and the sternothyroid muscle. The superior two thirds of these muscles are supplied by the superior thyroid artery and its branches; the inferior one third are supplied by the inferior thyroid artery [a. The superior thyroid artery, the main source of blood supply to the infrahyoid muscles, usually arises from the anterior aspect of the external carotid artery as the first branch. It passes downward and medially to enter the upper pole of the thyroid gland. Throughout its course, it gives off several small arterial twigs: the hyoid, the sternocleidomastoid, the superior laryngeal, the cricothyroid, and some muscular arteries. The sternocleidomastoid branch sends branches to supply the omohyoid, sternohyoid, and sternothyroid muscles. The skin overlying the infrahyoid muscles is nourished by the perforators, which pierce through the omohyoid and sternohyoid muscles, and also by direct cutaneous branches. The inferior portions of the infrahyoid muscles extending between the sternal notch and the level overlying the cricoid cartilage are supplied by the inferior thyroid artery. Usually the inferior thyroid artery originates at the thyrocervical trunk. Just before entering the thyroid gland, it sends an anterior branch, which supplies the sternohyoid muscle, the sternothyroid muscle, and the superior belly of the omohyoid muscle. As demonstrated by Eliachar et al [6 1, the blood supply of these muscles is segmental. However, anastomoses of considerable size within and around the strap muscles, between the branches of superior and inferior thyroid arteries, were also observed.
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THE INFRAHYOID MUSCULOCUTANEOUS FLAP
Thyroid Superior
Thyroid
Sternohyoid
gland
Superior jugular
_-
Stemocletdomastotd M. belly
of omohyoid
External
V.
cartilage
A
M.
I
Anterior
thyroid
M.
Laryngeal nerve
Flguvl.Theflapisreisedfromthedistaltotheproxknalend, ~~3rior jugularvein and the stemahyoidand steme
Figwe 2. The infrahyoidmusculocutaneousflap is dissectedfrom a neurovascularpedicle of superiorthyroidartery and vein and ansa cervicalis.
The venous drainage of the skin overlying the infrahyoid muscles has two systems: First it drains through the superficial system of the anterior jugular vein, which drains to the external jugular vein caudally. Second, blood drains to the superior thyroid vein, which accompanies the corresponding artery to the internal jugular vein. During diiion of the flap, the anterior jugular vein is sacrificed. However, with the considerable anastomosis between the two systems, the flap can survive due to venous drainage by way of the superior thyroid vein and its tributaries. The upper parts of the stemohyoid muscle, the sternothyroid muscle, and the superior belly of the omohyoid muscle are innervated by branches from the superior root of the ansa cervicalis. The lower parts are innervated by branches from the ansa cervicalis.
underwent supraomohyoid neck dissection or functional neck dissection. The infrahyoid musculocutaneous flap was used to cover the defects in every case. Through-andthrough wounds were reconstructed to cover external skin and mucosa by IHMF alone in one patient, by IHMF and an Fstlander flap in one patient, and by IHMF with a pectoralis major musculocutaneous flap in two patients. Technique: After tumor extirpation, the skin island corresponding to the size of the defect is outlined from the midline to the lateral portion of the neck, extending from the thyroid cartilage to the sternal notch. Generally, the island is 4 to 5 by 8 cm. If the defect is somewhat high (midface level), the lower portion can be extended about 2 cm below the sternal notch. The musculocutaneous flap is raised starting from the midline along the border of sternohyoid muscle, then distally the anterior jugular vein and stemohyoid and sternothyroid muscles are divided near their origins. The llap can be raised over an avascular plane of fascia covering the thyroid gland until the superior pole of thyroid gland is reached (Figure 1). The flap is secured by stitching the skin and muscle together at the edges with several sutures. The superior belly of the omohyoid is divided from the inferior segment. The ansa cervicalis may be included. At the upper pole of the thyroid gland, the distal branches of superior thyroid artery and vein that supply the thyroid gland are individually divided and ligated. At this point, every effort should be made to identify and preserve the external branch of the superior laryngeal nerve (Figure 2). The vessels that supply the thyrohyoid and cricothyroid muscles are divided and ligated. After the insertions of the sternothyroid, omohyoid, and sternohyoid muscles are divided from the thyroid cartilage and hyoid bone, respectively, the flap is freely movable, with the soft tissues containing neurovascular pedicles of superior thyroid artery and vein and ansa cervicalis nerve. The flap can then be transferred to cover the defect. The donor site may be closed primarily or by means of
PATIENTS AND METHODS From April 1987 to October 1990, infrahyoid musculocutaneous flaps (IHMF) were performed in 22 patients (14 females, 8 males). Patient ages ranged from 14 to 93 years (median: 63 years). Eighteen flaps were used to cover oral cavity defects, 2 for parotid defects and 2 for lip reconstruction. Among these 18 patients with oral defects, 1 had recurrent capillary hemangioma of the buccal mucosa and 17 had squamous cell carcinoma of the buccal mucosa (n = 8), lower gum (n = 5), tongue (n = 2), and floor of mouth (n = 2). There were five T2 lesions, two T3 lesions, and seven T4 lesions. Three were recurrences after radiotherapy or surgery. Some of the lesions were so extensive they involved more than one anatomic structure. Two patients had parotid defects secondary to recurrent carcinoma, which required excision of skin and the facial nerve. Two patients had recurrent T3 squamous cell carcinoma of the lower lip after radiotherapy, which required removal of the entire lower lip. All patients who required cervical lymphadenectomy THE AMERICAN
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162 OCTOBER
1991
4-01
COMMENTS Numerous flaps have been available for head and neck reconstruction. These include pectoralis major, lateral trapezius, forehead, deltopectoral, cervical, and platysma flaps. Each has its advantages and disadvantages. However, the ideal flap for an oral defect should be flat, relatively thin, hairless, simple to develop, reliable, versatile, and can be completed in a one-stage procedure. The platysma flap provides a very thin, one-staged flap, but it is unreliable for an oral defect, especially with concurrent neck dissection. Nevertheless, it is excellent for hypopharyngeal reconstruction [8,9]. The lateral trapezius flap is suitable for simultaneous mandibular reconstruction together with internal lining or external skin coverage. However, the donor site defect, its location, and shoulder dysfunction after surgery make it unfavorable for soft tissue coverage only [10,11]. The pectoralis major flap [I.?], the most commonly used, is sometimes too bulky, but it is reliable, versatile, and one- staged. The radial forearm flap requires microvascular expertise [ 131, which is not always available. When compared with the two most common flaps-the pectoralis major flap and the radial forearm flap-the characteristics of the IHMF lie in between.
The IHMF is a musculocutaneous flap but is relatively thin, hairless (i.e., for most Orientals), and, based on our experience thus far, it is reliable, versatile, and one-staged for reconstruction of most oral cavity defects. In addition to oral defect reconstruction, an extensive lower lip defect can also be reconstructed with an excellent result. Since the ansa cervicalis can be preserved with the flap and it is relatively flat, lower lip reconstruction can be performed in one stage without the need for further correction. With its arc of rotation, the IHMF can also be used to reconstruct a facial defect up to the level of the midface and parotid region, as well as the oropharynx and hypopharynx. The donor site can be managed easily without additional scars in the other region. In addition, no change in patient position is required. Among the 22 patients in this study, there were 2 instances of total necrosis of flap skin. Both instances occurred early in our experience, at which time we had designed the flap too low. After further study, we found that the major perforators from the infrahyoid muscles to the skin are usually located between the thyroid and cricoid cartilage. If the flap was outlined below this level, the perforators could have been injured during dissection. Another possible reason for flap failure might have been inadequate venous return. Because the only route for venous drainage remaining in the flap is through the superior thyroid vein, this vein should be protected from injury during neck dissection. The common facial vein should be ligated proximal to the superior thyroid vein as it empties into the internal jugular vein. As described by Eliachar et al [6J, the blood supply to infrahyoid muscles is segmental, and the distal one third of these muscles are supplied by the inferior thyroid artery. With abundant anastomoses of considerable size within the muscle between these two arteries, the distal part can survive when the flap is raised. However, for some reason, three patients in these series developed distal necrosis. When neck dissection is performed concurrently, it should be a functional or supraomohyoid neck dissection that preserves the internal jugular vein and superior thyroid vein. The incision should be curved, extending from the midline to the mastoid area. The anterior curve should not extend beyond the hyoid bone or over the strap muscles. For a large through-and-through wound of the oral cavity or together with segmental loss of mandible, simultaneous two-flap reconstruction is recommended. The IHMF with the pectoralis major flap for oral defect coverage and external skin reconstruction is the best example. For a mandibular defect up to 11 cm, we recommend the lateral trapezius osteomusculocutaneous flap instead of the pectoralis major flap. There are many advantages to this technique. The reconstruction can be performed in one stage with a thin flap, and the donor site can be closed primarily. This minimizes hospitalization time and allows early postoperative irradiation if needed. It also obviates the need for microvascular free flap transfer in many cases.
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a small rotational flap taken from the adjacent skin. With the 4 to 5 by 8 cm flap, we could reconstruct defects in the oral cavity, the entire lower lip, the oropharyngeal defect, and the skin defects of the parotid and midface regions. However, if the cheek defect is full thickness, it may be beyond the ability of the flap to cover both sides. We prefer to use the IHMF with a pectoralis major flap for this type of defect. Contraindications for IHMF reconstruction include previous thyroid surgery, surgical scar at the anterior neck of the same side, radical neck dissection that sacrificed the internal jugular vein, injury of the superior thyroid artery and vein during neck dissection, atherosclerosis of the superior thyroid artery, radiation treatment to the anterior neck, and hairy anterior neck skin. RESULTS Fifteen patients healed uneventfully, including three with simultaneous two-flap reconstruction. There were two instances of complete skin necrosis of the flap: one in a patient with floor of mouth cancer and the other in a patient with cancer of the buccal mucosa. Three patients developed necrosis of the distal third of the skin. Wound infections in the neck occurred in two patients without loss of flap. No patient developed an orocutaneous fistula. In the 15 uncomplicated cases, the hospital stay was 7 to 15 days (mean: 11 days); in the 7 cases with complications, the hospital stay was 12 to 30 days (mean: 20 days). The average time required to raise the flap was about 1l/z hours. One elderly woman had atherosclerotic changes at the distal branch of the superior thyroid artery before it enters the upper pole of the thyroid gland, but the proximal part appeared normal. She had no surgical complications. All IHMF donor sites were closed primarily or by means of small rotatational skin flap at the distal portion.
THE AMERICAN
JOURNAL
OF SURGERY
VOLUME
OCTOBER
1991
THE INFRAHYOID MUSCULOCUTANEOUS FLAP
REFERENCES
7. Wang H, Shen J, Dongbai, Wang J, Tian A. The infrahyoid
1. Bailey BJ. Partial laryngectomy and laryngoplasty: a technique
myocutaneous flap for reconstruction after resection of head and neck cancer. Cancer 1986; 57: 663-8. 8. Coleman JJ III, Jurkiewicz MJ, Nahai F, Matheo SJ. The platysma myocutaneous flap: experience with 24 cases. Plast Reconstr Surg 1983; 72: 315-21. 9. Metheetrairut C, Rojananin S, Chongkolwatana C. Platysma myocutaneous flap for hypopharyngeal reconstruction. Siriraj Hospital Gaz 1990; 42: 44-9. 10. Demergasso F, Piazza M. Trapezius myocutaneous flap in reconstructive surgery for head and neck cancer. An original technique. Am J Surg 1979; 138: 533-6. 11. Guillamondegui OM, Larson DL. The lateral trapezius musculocutaneous flap, its use in head and neck reconstruction. Plast Reconstr Surg 1981; 67: 143-50. 12. Ariyan S. The pectoralis major myocutaneous flap. Plast Reconstr Surg 1979; 63: 73-81. 13. Song R, Gao Y, Song Y, et al. The forearm flap. Clin Plast Surg 1982; 9: 21-6.
and review. Tram Am Acad Ophthalmol Otolaryngol 1966; 70: 559-74. 2. Ogura JH, Biller HF. Glottic reconstruction following extended frontolateral hemilaryngectomy. Laryngoscope 1969; 79: 2181-4. 3. Calcaterra TC. Stemohyoid myofascial flap reconstruction of the larynx for vertical partial laryngectomy. Larynogoscope 1983; 93: 422-4. 4. Finnegan DA, Wong ML, Kashima HK. Hyoid autograft repair of chronic subglottic stenosis. Ann Otol Rhino1 Laryngol 1975; 84: 643-9. 5. Eliachar I, Joachims HZ. Reconstruction of the larynx and trachea with hyoid transposition. In: Bernstein L, editor. Plastic and reconstructive surgery of the head and neck. New York: Grune 8c Stratton, 1981; 259-65. 6. Eliachar I, Marcovich A, Harshai Y, Lindenbaum E. Arterial blood supply to the infrahyoid muscle: an anatomical study. Head Neck Surg 1984; 7: 8-14.
THE AMERICAN JOURNAL OF SURGERY
VOLUME 162 OCTOBER 1991
403
MD,
Nit Suphaphongs,
MD, Bangkok, Thailand,
The infrahyoid muse&cutaneous flap (IHMF) , as first described by Wang in 1986, is mainly nourished by the superior thyroid vessels through the perforators of the infrahyoid muscles (i.e., sternohyoid muscle, sternothyroid muscle, superior belly of the omohyoid muscle). This thin flap, usually extending from the hyoid bone to the sternal notch at the central part of the anterior neck, provides a skin island of about 4 by 8 cm. After these muscles have been divided from their origins, the flap can be freely transferred on its pedicle of superior thyroid artery to cover the soft tissue defect created after surgical ablation of cancer of the midface, parotid region, oral cavity, oropharnyx, or hypopharynx. From April 1987 to October 1990, our department successfully performed this flap procedure in 22 patients (cancer of the buccal mucosa 8, lower gum 5, floor of mouth 2, tongue 2, lower lip 2, parotid gland 1, skin 1, hemangioma of buccal mucosa 1). Two were treatment failures, three had partial dermal necrosis (distal third of flap surface), and the remainder had no major complications. The donor sites were closed either primarily or by means of a small, local skin flap. Contraindications to the flap are previous thyroid surgery, radical neck dissection, irradiation to the anterior neck, and hairy neck skin. We believe our results indicate that the IHMF is a versatile, reliable flap that may be used in combination with other regional flaps, such as the pectoralis major flap. It obviates the need for a microvascular free flap in many cases.
Alando J. Ballantyne,‘~~, Houston, TEXTS
he infrahyoid muscles have been used to reconstruct T head and neck sites for many decades. In 1965, Bailey [I] popularized the bipedicled sternohyoid muscle flap to reconstruct the larynx after vertical partial laryngectomy. In 1969, Ogura and Biller [2] described a monopedicled inferiorly based sternohyoid muscle flap, and in 1983, Calcaterra [3] employed a superioriy based sternohyoid myofascial flap, for the same purpose. In addition, its use as a sternohyoid myo-osseous flap for the reconstruction of subglottic or tracheal stenosis was described by Finnegan et al [4] in 1975. In 1979, Eliachar and Joachims [5] described their early experience in applying the rotated infrahyoid vascularized myocutaneous flap in laryngotracheal reconstruction and extensively studied the anatomic basis of the blood supply to the strap muscles and overlying skin [6]. It was not until 1986 that the axial infrahyoid musculocutaneous flap was first described by Wang and colleagues [7], with excellent results. The purpose of this study is to confirm the reliability and the application of this flap. SURGICAL
ANATOMY
From the Division of Head-Neck and Breast Surgery (SR, NS), Department of Surgery, Siriraj Hospital Medical School, Faculty of Medicine, Mahidol University, Bangkok, Thailand, and the Department of Head and Neck Surgery, University of Texas, M.D. Anderson Cancer Center (AJB), Houston, Texas. Requests for reprints should be addressed to Supakom Rojananin, MD, Division of Head-Neck and Breast Surgery, Department of Surgery, Sirirah Hospital Medical School, Bangkok 10700, Thailand. Presented at the 37th Annual Meeting of the Society of Head and Neck Surgeons, Maui, Hawaii, May l-4.1991.
The infrahyoid muscles used in this flap consist of the sternohyoid muscle, the superior belly of the omohyoid muscle, and the sternothyroid muscle. The superior two thirds of these muscles are supplied by the superior thyroid artery and its branches; the inferior one third are supplied by the inferior thyroid artery [a. The superior thyroid artery, the main source of blood supply to the infrahyoid muscles, usually arises from the anterior aspect of the external carotid artery as the first branch. It passes downward and medially to enter the upper pole of the thyroid gland. Throughout its course, it gives off several small arterial twigs: the hyoid, the sternocleidomastoid, the superior laryngeal, the cricothyroid, and some muscular arteries. The sternocleidomastoid branch sends branches to supply the omohyoid, sternohyoid, and sternothyroid muscles. The skin overlying the infrahyoid muscles is nourished by the perforators, which pierce through the omohyoid and sternohyoid muscles, and also by direct cutaneous branches. The inferior portions of the infrahyoid muscles extending between the sternal notch and the level overlying the cricoid cartilage are supplied by the inferior thyroid artery. Usually the inferior thyroid artery originates at the thyrocervical trunk. Just before entering the thyroid gland, it sends an anterior branch, which supplies the sternohyoid muscle, the sternothyroid muscle, and the superior belly of the omohyoid muscle. As demonstrated by Eliachar et al [6 1, the blood supply of these muscles is segmental. However, anastomoses of considerable size within and around the strap muscles, between the branches of superior and inferior thyroid arteries, were also observed.
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1991
THE INFRAHYOID MUSCULOCUTANEOUS FLAP
Thyroid Superior
Thyroid
Sternohyoid
gland
Superior jugular
_-
Stemocletdomastotd M. belly
of omohyoid
External
V.
cartilage
A
M.
I
Anterior
thyroid
M.
Laryngeal nerve
Flguvl.Theflapisreisedfromthedistaltotheproxknalend, ~~3rior jugularvein and the stemahyoidand steme
Figwe 2. The infrahyoidmusculocutaneousflap is dissectedfrom a neurovascularpedicle of superiorthyroidartery and vein and ansa cervicalis.
The venous drainage of the skin overlying the infrahyoid muscles has two systems: First it drains through the superficial system of the anterior jugular vein, which drains to the external jugular vein caudally. Second, blood drains to the superior thyroid vein, which accompanies the corresponding artery to the internal jugular vein. During diiion of the flap, the anterior jugular vein is sacrificed. However, with the considerable anastomosis between the two systems, the flap can survive due to venous drainage by way of the superior thyroid vein and its tributaries. The upper parts of the stemohyoid muscle, the sternothyroid muscle, and the superior belly of the omohyoid muscle are innervated by branches from the superior root of the ansa cervicalis. The lower parts are innervated by branches from the ansa cervicalis.
underwent supraomohyoid neck dissection or functional neck dissection. The infrahyoid musculocutaneous flap was used to cover the defects in every case. Through-andthrough wounds were reconstructed to cover external skin and mucosa by IHMF alone in one patient, by IHMF and an Fstlander flap in one patient, and by IHMF with a pectoralis major musculocutaneous flap in two patients. Technique: After tumor extirpation, the skin island corresponding to the size of the defect is outlined from the midline to the lateral portion of the neck, extending from the thyroid cartilage to the sternal notch. Generally, the island is 4 to 5 by 8 cm. If the defect is somewhat high (midface level), the lower portion can be extended about 2 cm below the sternal notch. The musculocutaneous flap is raised starting from the midline along the border of sternohyoid muscle, then distally the anterior jugular vein and stemohyoid and sternothyroid muscles are divided near their origins. The llap can be raised over an avascular plane of fascia covering the thyroid gland until the superior pole of thyroid gland is reached (Figure 1). The flap is secured by stitching the skin and muscle together at the edges with several sutures. The superior belly of the omohyoid is divided from the inferior segment. The ansa cervicalis may be included. At the upper pole of the thyroid gland, the distal branches of superior thyroid artery and vein that supply the thyroid gland are individually divided and ligated. At this point, every effort should be made to identify and preserve the external branch of the superior laryngeal nerve (Figure 2). The vessels that supply the thyrohyoid and cricothyroid muscles are divided and ligated. After the insertions of the sternothyroid, omohyoid, and sternohyoid muscles are divided from the thyroid cartilage and hyoid bone, respectively, the flap is freely movable, with the soft tissues containing neurovascular pedicles of superior thyroid artery and vein and ansa cervicalis nerve. The flap can then be transferred to cover the defect. The donor site may be closed primarily or by means of
PATIENTS AND METHODS From April 1987 to October 1990, infrahyoid musculocutaneous flaps (IHMF) were performed in 22 patients (14 females, 8 males). Patient ages ranged from 14 to 93 years (median: 63 years). Eighteen flaps were used to cover oral cavity defects, 2 for parotid defects and 2 for lip reconstruction. Among these 18 patients with oral defects, 1 had recurrent capillary hemangioma of the buccal mucosa and 17 had squamous cell carcinoma of the buccal mucosa (n = 8), lower gum (n = 5), tongue (n = 2), and floor of mouth (n = 2). There were five T2 lesions, two T3 lesions, and seven T4 lesions. Three were recurrences after radiotherapy or surgery. Some of the lesions were so extensive they involved more than one anatomic structure. Two patients had parotid defects secondary to recurrent carcinoma, which required excision of skin and the facial nerve. Two patients had recurrent T3 squamous cell carcinoma of the lower lip after radiotherapy, which required removal of the entire lower lip. All patients who required cervical lymphadenectomy THE AMERICAN
JOURNAL
OF SURGERY
VOLUME
162 OCTOBER
1991
4-01
COMMENTS Numerous flaps have been available for head and neck reconstruction. These include pectoralis major, lateral trapezius, forehead, deltopectoral, cervical, and platysma flaps. Each has its advantages and disadvantages. However, the ideal flap for an oral defect should be flat, relatively thin, hairless, simple to develop, reliable, versatile, and can be completed in a one-stage procedure. The platysma flap provides a very thin, one-staged flap, but it is unreliable for an oral defect, especially with concurrent neck dissection. Nevertheless, it is excellent for hypopharyngeal reconstruction [8,9]. The lateral trapezius flap is suitable for simultaneous mandibular reconstruction together with internal lining or external skin coverage. However, the donor site defect, its location, and shoulder dysfunction after surgery make it unfavorable for soft tissue coverage only [10,11]. The pectoralis major flap [I.?], the most commonly used, is sometimes too bulky, but it is reliable, versatile, and one- staged. The radial forearm flap requires microvascular expertise [ 131, which is not always available. When compared with the two most common flaps-the pectoralis major flap and the radial forearm flap-the characteristics of the IHMF lie in between.
The IHMF is a musculocutaneous flap but is relatively thin, hairless (i.e., for most Orientals), and, based on our experience thus far, it is reliable, versatile, and one-staged for reconstruction of most oral cavity defects. In addition to oral defect reconstruction, an extensive lower lip defect can also be reconstructed with an excellent result. Since the ansa cervicalis can be preserved with the flap and it is relatively flat, lower lip reconstruction can be performed in one stage without the need for further correction. With its arc of rotation, the IHMF can also be used to reconstruct a facial defect up to the level of the midface and parotid region, as well as the oropharynx and hypopharynx. The donor site can be managed easily without additional scars in the other region. In addition, no change in patient position is required. Among the 22 patients in this study, there were 2 instances of total necrosis of flap skin. Both instances occurred early in our experience, at which time we had designed the flap too low. After further study, we found that the major perforators from the infrahyoid muscles to the skin are usually located between the thyroid and cricoid cartilage. If the flap was outlined below this level, the perforators could have been injured during dissection. Another possible reason for flap failure might have been inadequate venous return. Because the only route for venous drainage remaining in the flap is through the superior thyroid vein, this vein should be protected from injury during neck dissection. The common facial vein should be ligated proximal to the superior thyroid vein as it empties into the internal jugular vein. As described by Eliachar et al [6J, the blood supply to infrahyoid muscles is segmental, and the distal one third of these muscles are supplied by the inferior thyroid artery. With abundant anastomoses of considerable size within the muscle between these two arteries, the distal part can survive when the flap is raised. However, for some reason, three patients in these series developed distal necrosis. When neck dissection is performed concurrently, it should be a functional or supraomohyoid neck dissection that preserves the internal jugular vein and superior thyroid vein. The incision should be curved, extending from the midline to the mastoid area. The anterior curve should not extend beyond the hyoid bone or over the strap muscles. For a large through-and-through wound of the oral cavity or together with segmental loss of mandible, simultaneous two-flap reconstruction is recommended. The IHMF with the pectoralis major flap for oral defect coverage and external skin reconstruction is the best example. For a mandibular defect up to 11 cm, we recommend the lateral trapezius osteomusculocutaneous flap instead of the pectoralis major flap. There are many advantages to this technique. The reconstruction can be performed in one stage with a thin flap, and the donor site can be closed primarily. This minimizes hospitalization time and allows early postoperative irradiation if needed. It also obviates the need for microvascular free flap transfer in many cases.
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162
a small rotational flap taken from the adjacent skin. With the 4 to 5 by 8 cm flap, we could reconstruct defects in the oral cavity, the entire lower lip, the oropharyngeal defect, and the skin defects of the parotid and midface regions. However, if the cheek defect is full thickness, it may be beyond the ability of the flap to cover both sides. We prefer to use the IHMF with a pectoralis major flap for this type of defect. Contraindications for IHMF reconstruction include previous thyroid surgery, surgical scar at the anterior neck of the same side, radical neck dissection that sacrificed the internal jugular vein, injury of the superior thyroid artery and vein during neck dissection, atherosclerosis of the superior thyroid artery, radiation treatment to the anterior neck, and hairy anterior neck skin. RESULTS Fifteen patients healed uneventfully, including three with simultaneous two-flap reconstruction. There were two instances of complete skin necrosis of the flap: one in a patient with floor of mouth cancer and the other in a patient with cancer of the buccal mucosa. Three patients developed necrosis of the distal third of the skin. Wound infections in the neck occurred in two patients without loss of flap. No patient developed an orocutaneous fistula. In the 15 uncomplicated cases, the hospital stay was 7 to 15 days (mean: 11 days); in the 7 cases with complications, the hospital stay was 12 to 30 days (mean: 20 days). The average time required to raise the flap was about 1l/z hours. One elderly woman had atherosclerotic changes at the distal branch of the superior thyroid artery before it enters the upper pole of the thyroid gland, but the proximal part appeared normal. She had no surgical complications. All IHMF donor sites were closed primarily or by means of small rotatational skin flap at the distal portion.
THE AMERICAN
JOURNAL
OF SURGERY
VOLUME
OCTOBER
1991
THE INFRAHYOID MUSCULOCUTANEOUS FLAP
REFERENCES
7. Wang H, Shen J, Dongbai, Wang J, Tian A. The infrahyoid
1. Bailey BJ. Partial laryngectomy and laryngoplasty: a technique
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