Anterolateral Thigh Free Flap Reconstruction of Parotidectomy Defect

Anterolateral Thigh (ALT) free flap is a widely utilized technique for the reconstruction of head and neck soft tissue defects. Key steps of this procedure include flap design for reconstruction of surgical defect, identification and dissection of perforator vessels and vascular pedicle for harvest of the anterolateral thigh free flap, microvascular anastomosis of the pedicle to head and neck vessels, and flap inset for reconstruction at recipient site. The ALT free flap is a versatile tool that can be utilized for reconstruction throughout the body but is very frequently utilized for reconstruction in oncologic resections of the head and neck. In this case, it was utilized for reconstruction of a soft tissue defect resulting from a parotidectomy with resulting skin and soft tissue defect, performed for removal of a mucoepidermoid carcinoma.    

Anterolateral thigh free flap; free flap reconstruction; parotidectomy; head and neck neoplasms.

Parotidectomy is a complex procedure most commonly performed to remove both benign and malignant neoplasms.¹ Resection of parotid tumors can lead to varying degrees of soft-tissue and skin deficits depending on the depth and extent of tumor invasion. In cases with large soft tissue and/or cutaneous defects, free flap reconstruction is commonly utilized. The size, location, and involved structures of the surgical defect must be considered in flap selection to optimize functional and cosmetic outcomes.
 
The anterolateral thigh (ALT) free flap is a “work horse” flap for reconstruction of large soft-tissue defects.² The ALT free flap can be harvested with varying combinations of skin, fat,  fascia, muscle, and nerve, allowing for customization of the flap to fit the specific defect of each patient.^2,3 Its robust vascular pedicle allows for healthy blood flow to keep the soft-tissue component viable throughout the wound healing process.^2,3 The donor site morbidity is quite low, highlighting the ALT free flap as a reliable choice for large parotidectomy defect reconstruction, as demonstrated in this case.  

The patient is a 43-year-old female who was referred to the otolaryngology clinic for evaluation of a right parotid mass. She reported several months of progressive facial swelling and pain in her right parotid area. Fine-needle aspiration of the parotid mass revealed salivary neoplasm of uncertain malignant potential (SUMP). Repeat FNA of the parotid mass demonstrated low-grade mucoepidermoid carcinoma.

She was recommended to undergo total parotidectomy and neck dissection. Due to the size of the tumor and potential for resection of overlying skin, the option for possible free flap reconstruction was planned to be performed at the time of her oncologic resection.

The patient had stable vital signs and was ASA class II due to a BMI of 31.57. On exam, she had a large mass measuring approximately 6 x 5 cm over her entire right parotid gland that extended to the upper neck. She had symmetrical facial movements bilaterally. The mass was tender to palpation and partially mobile with no involvement of the overlying skin. Otoscopy was normal bilaterally, and there were no other masses in the oral cavity, oropharynx, or neck.

A CT neck with contrast showed a complex, solid, cystic, and heterogeneously enhancing 4.5-cm mass involving the right parotid gland, with the medial aspect adjacent to the carotid sheath. A few prominent but not enlarged lymph nodes were also noted. 

Parotid masses can be classified as benign or malignant. The vast majority of parotid neoplasms are benign, most commonly Warthin’s tumors or pleomorphic adenomas. Various types of primary malignant neoplasms originate in the parotid, namely mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma, or acinic cell carcinoma.^1,4 In this patient’s case, they presented with the most common primary malignancy of the parotid gland, a mucoepidermoid carcinoma.

MEC presents more commonly in females, and the mean age of onset is 55 years old. MEC can present as painless swelling of the parotid gland or in combination with other symptoms indicative of malignancy, such as pain/tenderness, rapid growth, facial nerve palsy, cervical lymphadenopathy, overlying skin ulceration, and tumor fixation to surrounding structures.^1,5-7 In the case of MEC, tumors can vary from low- to intermediate- to high-grade, depending on the degree of dedifferentiation of the tumor cells, and grade correlates to prognosis with higher-grade tumors being more aggressive. Five-year survival for MEC ranges from up to 90% for low-grade tumors to 30–42% for high grade ones.⁷ Low grade MECs have a 3.3% risk of spread to regional lymph nodes followed by 8.1% for intermediate grade and 34% for high grade MECs.⁸ Distant metastases are rarely seen, but locations include lungs, bone, and liver.⁹

Surgery is the mainstay of treatment for primary parotid malignancies with potential for adjuvant radiation with or without systemic treatment in advanced cases. The focus of this article is on the reconstructive aspect following surgical resection of the tumor. While reconstruction is not always necessary, a variety of options are available for reconstruction of the soft-tissue deficits left behind following parotidectomy. Appropriate selection of the reconstruction depends on the size and location of the primary tumor, as well as the structures that are resected. 

For small deficits resulting from superficial or partial parotidectomy, reconstruction is not focused on contour. However, surgeons may elect to utilize techniques to prevent the development of gustatory sweating (Frey’s syndrome) or first-bite syndrome with use of commercially available allografts.² For instance, acellular human dermis (ACD) is a common allogenic option that is positioned and secured within the parotid bed to prevent aberrant nerve regeneration.^2,10 Benefits of ACD include the lack of a donor site, minimal addition to operative time, and reduction of Frey Syndrome by 82%.^2,10 

In cases where notable contour deformity is anticipated, autogenic free fat or dermal fat grafts can be utilized to restore facial symmetry. These techniques involve harvesting abdominal fat or fat along with the overlying dermis for volume restoration of the parotidectomy defect.² Overcorrection of the defect is needed for this technique as postoperative fat resorption occurs.¹⁰ Fat resorption occurs at different rates for each patient, leading to ambiguity in the volume of fat required during harvesting.^2,10 Donor site morbidity is low but can involve hematoma, infection, hyperesthesia, itching, and pain.²

Additional vascularized soft tissue options for small to moderate deficits employ the use of local or regional tissue flaps, including the sternocleidomastoid (SCM) muscle flap, superficial musculoaponeurotic system (SMAS) flap, and submental flap.² The SCM muscle flap involves transection and rotation of the SCM muscle, superiorly or inferiorly, to fill the parotidectomy defect.^2,10 The SCM flap has been shown to reduce Frey syndrome and aid in facial symmetry.² However, it is rarely used presently due to significant risks including potential injury to the accessory spinal nerve, atrophy of the muscle, and contour deformity in the neck.^2,10 The SMAS flap involves separation of the SMAS from the superficial subcutaneous fat and deep parotidomasseteric fascia.¹⁰ The separated SMAS is then plicated onto itself to fill the parotidectomy defect.¹⁰ For the SMAS flap, the defect cannot involve the SMAS layer, making it unsuitable for larger or invading parotid tumors.¹⁰ The submental flap is also an option for parotidectomy defects and involves harvesting a myocutaneous pedicle that contains the platysma, anterior digastric, and mylohyoid muscles.¹¹ The submental artery and vein are utilized as the vascular supply for the pedicle, which is subsequently rotated superiorly and secured to the parotidectomy defect after de-epithelialization.¹¹ All of the local flaps described above reduce the need for a second incision, reducing morbidity as well as operative time.^2,10,11 

For larger defects, free tissue transfer, or free flaps, can be considered. Free flap options can include the anterolateral thigh flap (ALT), radial forearm free flap (RFFF), or lateral arm flap. The ALT free flap reconstructive option will be discussed in further detail below and was the reconstructive option of choice for this patient.

The goals of reconstruction for parotidectomy defects are to restore adequate contour and facial symmetry, prevent Frey syndrome, and reduce morbidity for both donor and recipient sites. The rationale for choosing which reconstructive option is appropriate depends largely on the size and complexity of the defect as well as patient preference, identified through shared decision making.  

Patients with large head and neck soft tissue defects benefit most from the ALT free flap reconstructive procedure. The ALT flap is a feasible alternative for patients whose low BMI makes the radial forearm free flap inadequate.¹² Those with high BMI and abundance of subcutaneous adipose tissue benefit from the increased tissue and its ability to fill deeper defects.¹²

There are no absolute contraindications to the ALT free flap, but patients who are morbidly obese, have peripheral artery disease, or previous trauma or scarring to the ALT skin may be unsuitable for the procedure.¹² Patients with medical comorbidities that prevent long surgeries or anesthesia are also relatively contraindicated.¹²

This case video details the ALT free flap reconstruction of a 43-year-old female with a soft tissue defect resulting from a subtotal parotidectomy for a mucoepidermoid carcinoma. While initially scheduled for a total parotidectomy, the choice to preserve the facial nerve and perform a subtotal parotidectomy makes this case noteworthy. The reconstruction of the subtotal parotidectomy defect through an ALT free flap offers an educational example regarding the surgical techniques, benefits, and uses of the ALT free flap.  

The ALT free flap was first described by Song et. al in 1984.¹³ It was subsequently used widely in Asia for reconstruction with a landmark study by Wei et al. in 2002 showing its effectiveness in a large cohort of 672 patients.¹⁴ It was introduced in western practice in the early 2000s with some hesitancy due to difficulty of perforator dissection, anatomic variations, and increased thickness of the flap in the western population.¹⁵ However, with development of the ultra-thin flap through suprafascial dissection and advancements in microvascular surgery techniques, the ALT flap has become a mainstay in reconstruction of head and neck defects globally. 

For extensive and complex defects that may require skin coverage, free tissue transfers are the gold standard option, of which the ALT free flap is the most versatile.² The ALT free flap involves a vascular pedicle derived from the descending branch of the lateral circumflex femoral artery which commonly gives off 2–4 perforating arteries to the overlying skin.^2,3 The overlying vastus lateralis muscle, fascia lata, subcutaneous fat, and skin can be harvested to fill a large parotidectomy defect.^2,3 Innervated flap harvest and inset utilizing the lateral femoral cutaneous nerve of the thigh is not commonly employed; however, the option for obtaining free nerve grafts from the harvest site for cable grafting in facial nerve reconstruction is often utilized in cases where facial nerve sacrifice is required during oncologic resection.² A relative drawback in the use of the ALT flap includes variable vascular anatomy of each patient,³ specifically the variability in perforator artery location. This variability can increase the time in the operating room, requires meticulous and careful dissection of small perforators, and can lead to partial flap necrosis if a perforator is damaged during harvest.³ Donor site morbidity is minimal but includes: hematoma or seroma (2%), wound dehiscence (4.1%), and infection (3.6%).³ Overall, the ALT flap offers a versatile and reliable option for reconstruction of large parotidectomy and other head and neck defects. 

For the patient in this case, an ALT flap with a 12 x 4 cm skin paddle was harvested from the left thigh. The pedicled artery and vein were anastomosed to the right facial artery and vein, respectively. The flap was then de-epithelialized and contoured to fill the defect and sutured into place (Figure 1). Drains were placed in the donor and recipient sites. Total operating time was 8 hours and 51 minutes for the parotidectomy and reconstruction with estimated blood loss being approximately 100 ml. Postoperatively, the patient experienced increased pain at the site of parotidectomy, which was managed effectively with opioid pain medications, and had some expected postoperative fullness and edema as well. In follow-up, she had a small dehiscence posterior to the right auricle, which was managed conservatively and resolved. No long-term complications were noted, and an overall successful ALT free flap resulting in restoration of facial volume symmetry was performed. The patient continues to follow up with the Otolaryngology clinic for her cancer care. The patient underwent radiation therapy and has been doing well in surveillance.

Figure 1. Postoperative wound photograph.

• Handheld doppler.
• Microvascular tools (atraumatic vascular clamps, jewelers, venous coupler device).

The authors of this article have nothing to disclose.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.