Introduction
Subtotal glossectomy (STG) and total glossectomy (TG) are surgical options in cases of advanced stage or recurrent carcinomas originating from the floor of mouth (FOM), the oral part of the tongue (OT) or base of the tongue (BOT) [
1]. Despite necessary extensive tumor resections and adjuvant treatment regimens, poor 3- and 5-year disease-specific survival (DSS) rates of 38–51% and 25–41% are reported, respectively [
2‐
4].
Tongue reconstruction remains one of the most challenging problems in head and neck surgery [
1‐
5]. Successful tongue reconstruction includes more than satisfying wound healing, wound closure and survival of free flaps [
5]. Within the past years, an increasing number of studies has focused on functional outcomes after reconstruction, such as sufficient oral nutrition and functional, intelligible speech, and how to optimize these functional outcomes [
5,
6].
The aim of tongue reconstruction differs depending on whether the OT or the BOT is affected. Principally, the OT is essential for speech, mastication, oral hygiene, the oral and oropharyngeal phase of swallowing [
7]. Therefore, thin, pliable flaps, such as the radial forearm free flap (RFFF), are commonly used [
5].
Otherwise, the BOT is crucial for completing the pharyngeal phase of swallowing and for prevention of aspiration [
8]. Subsequently, large, bulky free flaps, such as the anterolateral thigh (ALT) or the rectus abdominis (RA) flap, are necessary to enable oral bolus propulsion into the pharynx and to assist speech articulation [
1,
5,
9].
Numerous studies have already evaluated the impact of free flap reconstruction after glossectomy on oncologic and functional outcomes [
9‐
14]. However, no studies have reported on the use of the myocutaneous serratus anterior free flap (SAFF) for tongue reconstruction after STG and TG. The reliable vascular supply and the branching pattern of the associated vasculature of the SAFF, allow harvesting of up to five muscle digitations with skin islands up to 20 × 20 cm of the same vascular pedicle [
15,
16].
Therefore, the myocutaneous SAFF represents a suitable candidate for tongue rehabilitation that provides the needed versatility for reconstruction of the OT and BOT with one free flap. Hence, it was the main purpose of this study to evaluate the suitability of the myocutaneous SAFF for tongue reconstruction and to evaluate oncologic and functional outcomes.
Discussion
Due to its versatility, ease of harvest, low donor site morbidity, and reliable vascular supply, the SAFF has found many applications in head and neck reconstruction [
16]. Nonetheless, the use of the myocutaneous SAFF for tongue reconstruction after salvage glossectomy has not been previously evaluated in the literature.
Numerous studies have already been published reporting on functional outcomes in patients undergoing glossectomy. Until now, the RFFF was preferred for reconstruction of the tip of the tongue because of its thinness and pliability, while the ALT flap was predominantly used as large and bulky flap for large tongue defects [
10]. Within this prospective study, we could show that the myocutaneous SAFF represents an additional option for tongue reconstruction after salvage STG and TG. Demographic characteristics of our case series were comparable to the literature [
1,
9,
12,
22].
There are several reasons why we believe that the myocutaneous SAFF is an excellent flap for tongue reconstruction that could be equal or even superior to RFFF and ALT. First, it is noteworthy that the SAFF can be harvested with up to five muscle digitations, providing enormous flexibility for reconstruction [
15,
16]. Because of this versatility, it is possible to modify the bulk of the flap as required, ranging from a thin and pliable flap, comparable to a RFFF, to a large and bulky flap, similar to an ALT flap. Empirically, the bulk of the RFFF is frequently too small, while an ALT flap is often too large and, therefore, the SAFF represents a reliable alternative.
Second, there were no significant donor site morbidities and a 100% free flap survival. We used the DASH questionnaire, which evaluates upper limb disabilities, to assess donor side morbidity of free flap harvest. Mean and median DASH scores were 10.8 and 5.0 in our cohort, respectively, which are similar to mean and median DASH scores of 10.4 and 8.0 reported by Miles and Gilbert [
23]. Generally, a mean DASH score of 10.1 was set as norm for representative US population [
21]. Accordingly, harvest of SAFF does not have significant handicaps on upper limb function of patients compared to healthy controls. This finding is in striking contrast with the known donor site morbidity associated with the radial forearm and rectus free flaps, and certainly comparable to the anterior lateral thigh free flap, with the notable advantage of early ambulation which is beneficial in an older at risk population.
Moreover, the SAFF derives its vascular supply from the thoracodorsal artery, a branch of the subscapular and axillary artery. This central position in the vascular system provides a relative protection from peripheral vascular disease [
16]. Hence, free flaps of the thoracodorsal system are particularly useful in patients with peripheral vascular disease, which could comprise the use of lower limb free flaps [
24].
Though some case series reported of improved flap sensibility, speech and swallowing recovery of neurotized free flaps, systematic reviews failed to demonstrate that sensory reinnervation of neo-tongues is associated with benefits regarding functional outcomes [
10,
25]. However, SAFF can be also harvested with a long thoracic nerve for potential sensory reinnervation of neo-tongue or for anastomosis with hypoglossal nerve if the surgeon feels this is warranted.
Regarding functional outcomes, 57.1% of patients remained gastrostomy tube dependent 12 months after salvage surgery, which is comparable to the literature, where gastrostomy tube dependence rates of 24–75% are reported [
12‐
14]. Further, successful decannulation rates of 84–100% were reported in patients undergoing TG with laryngeal preservation, which equals the decannulation rate of 85.7% in our patient cohort [
9,
12,
13,
26]. Altogether, there were no significant differences regarding functional outcomes, in our case series compared with other free flaps reported in previous studies.
However, we found a significantly higher rate of gastrostomy tube dependence in those patients with SCCs of the BOT and in patients who were operated via transcervical approach. It is already known that a greater extent of glossectomy results in a poorer functional outcome [
5]. Particularly, quality of life regarding speech and swallowing function correlates with the extent of tongue base resection [
27]. The following reasons may be at least a partial explanation for the significantly worse swallowing function after transcervical salvage glossectomy and resection of BOT. First, it was postulated that damaging or cutting the muscles of the FOM could result in poor swallowing function due to impaired, uncoordinated elevation of the hyoid and the larynx [
28,
29]. Second, since we knew that large, bulky neo-tongues assist in oral bolus protrusion and completion of the pharyngeal phase of swallowing, it seems logical that preservation of a functional BOT should have a more favorable prognosis than resection and reconstruction [
5,
26]. Third, significantly worse dysphagia in patients after transcervical tumor resection might be also caused by selection bias. Patients with larger carcinomas causing trismus due to tumor infiltration or fibrosis of the pterygoid muscles, which makes oral tumor resection impossible, have to undergo more invasive transcervical tumor resection. Accordingly, worse swallowing function after transcervical tumor resection can either result from surgical approach or by already preoperatively existing impaired swallowing function due to tumor extent.
Despite radical tumor resection and successful reconstruction, the oncologic outcome is principally poor in patients suffering from tongue carcinomas with tumor recurrences in 50–58% of patients. Recurrences mainly occur within the first 2 years of follow-up and the majority of these patients died of recurrent disease [
9,
30,
31]. Similarly, we observed tumor recurrences in four patients (57.1%) occurring with an average time to recurrence of 17.6 months. Among those four patients, two died of extensive local recurrence within the first 2 years after glossectomy.
Overall 2-year DSS was 55.6% in our cohort, which was remarkably worse in younger adults. Popovtzer et al. [
31] already reported on this extraordinary tumor behavior in young adults. Accordingly, he described two different tumor types. On the one hand, there are patients with aggressive tumor behavior and 40% mortality within the first 2 years after surgery, and on the other hand, there are patients with almost indolent course and freedom from recurrence for 20 years [
31].
Although we have demonstrated for the first time that myocutaneous SAFF can be successfully used for tongue reconstruction after salvage glossectomy, there are limitations with our study. The main limitation is the small sample size of our case series and that patients with TG and STG were included and compared. This is a reflection of the low incidence of patients with extensive and resectable tongue carcinoma who are surgical candidates. Moreover, T3 and T4 tongue carcinomas are characterized by high recurrence rates and poor outcomes, as already discussed by numerous studies [
2‐
4]. Due to these issues, robust data regarding long-term outcomes in this population remain elusive. Therefore, in our study we could provide only 12 months of follow-up of oncologic and functional outcomes, which is another limitation of the study.