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Groin and anterolateral thigh flaps for hemiglossectomy reconstruction: A comparison based on Japanese speech intelligibility

      Abstract

      Objective

      The differences in speech function between groin flap reconstruction and anterolateral thigh (ALT) flap reconstruction after hemiglossectomy have not been clarified to date. This study aimed to compare Japanese speech intelligibility after hemiglossectomy reconstruction using groin and ALT flaps of similar thickness.

      Methods

      Data of patients who underwent hemiglossectomy reconstruction with groin or ALT flaps between April 2010 and March 2020 were collected from the medical chart database. The ALT flap was the first choice for hemiglossectomy reconstruction, and a groin flap was used when the ALT flap was >10 mm. Cases in which speech intelligibility assessments based on Hirose's 10-point scoring system, the TKR speech test, and the Japanese speech intelligibility test for 100 monosyllables were performed after 6 months postoperatively were extracted. The per-patient scores for each assessment were initially compared between the two flap groups. Then, the results of the Japanese speech intelligibility test for 100 monosyllables were reanalyzed on a syllable-by-syllable basis.

      Results

      Among the 44 hemiglossectomy patients who underwent free-flap reconstruction during the study period, 14 (seven each in the groin flap and ALT flap groups) underwent all three conventional speech intelligibility assessments after 6 months postoperatively. The two groups showed no significant difference in postoperative speech intelligibility in any of the three patient assessment methods. However, in intergroup comparisons based on per-syllable accuracy for each of the 100 monosyllables, the groin flap group showed 19 syllables with a significantly higher accuracy, whereas the ALT flap group showed one such syllable. In particular, five out of the six alveolar consonants (/t/ and /d/) were more accurately articulated in the groin flap group. Per-syllable accuracy was significantly higher in the groin flap group (74.6% vs. 66.7%; 95% confidence interval: 4.6–11.1, p < 0.001).

      Conclusion

      In patients undergoing hemiglossectomy reconstruction, our new analysis method, which compared intelligibility by syllables, showed that the groin flap yielded higher speech intelligibility than the ALT flap. This difference was evident at all four articulation points involving the tongue, whereas there was no significant difference at the two articulation points without tongue involvement.

      Keywords

      Introduction

      The swallowing function after hemiglossectomy has been reported to be better with free radial forearm flap reconstruction than with primary closure; however, the two techniques showed no significant differences in speech function [
      • Hsiao H.T.
      • Leu Y.S.
      • Lin C.C.
      Primary closure versus radial forearm flap reconstruction after hemiglossectomy: functional assessment of swallowing and speech.
      ]. Subsequently, several studies have shown that the speech function after hemiglossectomy with anterolateral thigh (ALT) flap reconstruction was comparable with that after forearm flap reconstruction, making the ALT flap the workhorse for hemiglossectomy reconstruction [
      • Farace F.
      • Fois V.E.
      • Manconi A.
      • Puddu A.
      • Stomeo F.
      • Tullio A.
      • et al.
      Free anterolateral thigh flap versus free forearm flap: functional results in oral reconstruction.
      ,
      • Hsiao H.T.
      • Leu Y.S.
      • Liu C.J.
      • Tung K.Y.
      • Lin C.C.
      Radial forearm versus anterolateral thigh flap reconstruction after hemiglossectomy: functional assessment of swallowing and speech.
      ,
      • de Vicente J.C.
      • de Villalaín L.
      • Torre A.
      • Peña I.
      Microvascular free tissue transfer for tongue reconstruction after hemiglossectomy: a functional assessment of radial forearm versus anterolateral thigh flap.
      ,
      • Tarsitano A.
      • Vietti M.V.
      • Cipriani R.
      • Marchetti C.
      Functional results of microvascular reconstruction after hemiglossectomy: free anterolateral thigh flap versus free forearm flap.
      ,
      • Lu M.
      • Sun G.
      • Hu Q.
      • Tang E.
      • Wang Y.
      Functional assessment: free thin anterolateral thigh flap versus free radial forearm reconstruction for hemiglossectomy defects.
      ,
      • Cai Y.C.
      • Li C.
      • Zeng D.F.
      • Zhou Y.Q.
      • Sun R.H.
      • Shui C.Y.
      • et al.
      Comparative analysis of radial forearm free flap and anterolateral thigh flap in tongue reconstruction after radical resection of tongue cancer.
      ]. This is mainly because the ALT flap causes lower donor site morbidity than the forearm flap [
      • de Vicente J.C.
      • de Villalaín L.
      • Torre A.
      • Peña I.
      Microvascular free tissue transfer for tongue reconstruction after hemiglossectomy: a functional assessment of radial forearm versus anterolateral thigh flap.
      ]. The ALT flap is generally considered to be thin and pliable, but in some cases, it could be thicker, thus limiting the movement of the remaining tongue. Therefore, a groin flap can be chosen for hemiglossectomy reconstruction in cases where the thickness of the ALT flap is greater than 10 mm. In some cases involving groin flap reconstruction, speech is clear and easy to hear. However, no previous report has compared the post-hemiglossectomy speech function between groin and ALT flap reconstructions. This study aimed to compare Japanese speech intelligibility between groin and ALT flaps to determine differences in speech function between the two flaps after hemiglossectomy reconstruction.

      Patients and methods

      Patients

      This retrospective study was approved by the Institutional Review Board (approval number: J2021-45). Informed consent was obtained in the form of a posted opt-out form. To compare the postoperative Japanese speech intelligibility between the groin and ALT flaps, the data of patients who underwent hemiglossectomy reconstruction with any one of these two flaps between April 2010 and March 2020 were collected from the medical chart database (Fig. 1). During this period, the authors adopted the ALT flap as the first choice for hemiglossectomy reconstruction, and the groin flap was used when the thickness of the subcutaneous tissue of the lateral thigh was more than 10 mm on ultrasonography. The extent of hemiglossectomy was classified into the following three types (Fig. 2): type 1, oral hemiglossectomy (hemiresection of the oral tongue); type 2, oral hemiglossectomy with partial resection of the base of the tongue; type 3, hemiglossectomy (hemiresection of the whole tongue). Patients who underwent three conventional speech intelligibility assessments after 6 months postoperatively were included in the study. The results of one of these assessments were then reanalyzed using a new method to reveal differences in speech intelligibility between the flap types.
      Fig 1
      Fig. 1Types of flaps used for hemiglossectomy reconstruction in this study. (A) Groin flap. (B) ALT flap. ALT, anterolateral thigh.
      Fig 2
      Fig. 2Classification of the extent of hemiglossectomy. Type 1: oral hemiglossectomy (hemiresection of the oral tongue); type 2: oral hemiglossectomy with partial resection of the base of the tongue; type 3: hemiglossectomy (hemiresection of the whole tongue).

      Speech intelligibility assessment 1: intelligibility per-patient using three conventional methods

      Speech intelligibility of each patient assessed by the following conventional methods was compared between the groin and ALT flap groups.
      • (1)
        Hirose's 10-point scoring system for Japanese speech intelligibility (Hirose's 10-point scoring system): Speech intelligibility was assessed based on the ability to converse daily with family members and unknown people (both on a scale of 1–5) [
        • Hirose H.
        The evaluative criteria for speech intelligibility.
        ,
        • Righini S.
        • Festa B.M.
        • Bonanno M.C.
        • Colombo V.
        • Luca N.
        Dynamic tongue reconstruction with innervated gracilis musculocutaneos flap after total glossectomy.
        ].
      • (2)
        The TKR speech test for Japanese (TKR speech test): Articulation of three different Japanese consonant-vowel (CV) syllable clusters, “ta-chi-tsu-te-to,” “ka-ki-ku-ke-ko,” and “ra-ri-ru-re-ro,” was assessed on a 9-point scoring system (0–3 points for each consonant, 0–9 points in total) [
        • Sarukawa S.
        • Noguchi T.
        • Miyazaki K.
        • Itoh H.
        • Nishino H.
        • Kusama M.
        Development of a tool for speech intelligibility evaluation after glossectomy: the TKR speech test.
        ].
      • (3)
        The Japanese speech intelligibility test for 100 monosyllables (Japanese 100-monosyllable test): Patients were asked to read and record 100 Japanese monosyllables in a random order, which were then played back to five examiners. Speech intelligibility was assessed as the percentage of the 100 syllables that were correctly heard by the examiners, which was expressed as the ratio to the full score of 500 [
        • Furuya G.
        Study on the articulation test in pronunciation in speech disorders.
        ].

      Speech intelligibility assessment 2: intelligibility per-syllable using a new analysis method

      We hypothesized that differences in speech intelligibility by flap type are more likely to appear in syllables where the tongue is involved in articulation. Therefore, we reanalyzed the results of the Japanese 100-monosyllable test on a syllable-by-syllable basis rather than on a patient-by-patient basis in the following three steps:
      • (1)
        The distribution of correctly and incorrectly heard words for each of the 100 monosyllables was compared between the groin and ALT flap groups.
      • (2)
        For all 100 monosyllables, the percentage of each syllable that was correctly heard by five examiners for all patients was compared between groups. This percentage was defined as “accuracy” in this study, which was the ratio to the full score of 35 when seven patients were included.
      • (3)
        Of the 100 monosyllables, we examined the accuracy of 91 CV syllables with articulation points, excluding five vowels and four semivowels without articulation points. The 91 CV syllables were divided into six articulation points: four articulation points involving the tongue (17 dental, six alveolar, 20 palatal, and 20 velar consonants) and two articulation points without tongue involvement (25 labial and three glottis consonants) (Fig. 3 and Table 1). For each articulation point, the accuracy of each syllable was compared between groups.
        Fig 3
        Fig. 3The six articulation points for Japanese consonant-vowel syllables: (a) bilabial, (b) dental, (c) alveolar, (d) palatal, (e) velar, and (f) glottis.
        Table 1Articulation points and accuracies for 100 Japanese monosyllables.
        Articulation point (N)Consonant (N)Articulation accuracy
        1. Higher with groin flap (p < 0.05)2. No difference (p > 0.05)3. Higher with ALT flap (p < 0.05)
        Bilabial (25)p (8)pa, pi, pu, pe, po, pya, pyu, pyo
        b (8)ba, bi, bu, be, bo, bya, byu, byo
        ɸ (1)hu
        m (8)muma, mi, me, mo, myu, myomya
        Dental (17)s (4)sa, sosu, se
        ts (1)tu
        dz (4)zeza, zu, zo
        n (4)na, nu, ne, no
        ɲ (4)nya, nyuni, nyo
        Alveolar (6)t (3)ta, teto
        d (3)da, de, do
        Palatal (20)ʃ (4)si, sya, syu, syo
        tʃ (4)ti, tya, tyu, tyo
        dʒ (4)zi, zya, zyu, zyo
        r (8)ro, ryura, ri, ru, re, rya, ryo
        Velar (20)k (8)ka, ku, ke, ko, kyuki, kya, kyo
        g (8)ga, gi, gu, ge, go, gya, gyu, gyo
        ç (4)hyohi, hya, hyu
        Glottis (3)h (3)ha, he, ho
        Vowel (5)N/Aa, i, u, e, o
        Semivowel (4)N/Awa, ya, yu, yo
        ALT, anterolateral thigh; N/A, not applicable.

      Statistical analysis

      Descriptive statistics for continuous variables are presented as mean (standard deviation [SD], range). Fisher's exact probability test, Mann-Whitney U test, and Student's t-test were used to test for differences in patient characteristics between groups. Intergroup differences were analyzed using Student's t-test for the three conventional speech intelligibility assessments. Fisher's exact probability test was also employed to analyze the differences between groups in the distribution of correctly and incorrectly heard syllables. A paired t-test was employed to analyze the differences between groups in the accuracy for each monosyllable. Repeated measures analysis of variance (ANOVA) was applied to determine the overall difference in the scores for each syllable (14-point scale when both groups together included 14 patients) among five examiners. When the results of ANOVA were significant, the differences between individual methods were estimated using Bonferroni's multiple comparison as a post hoc test.
      All p values were two-sided. Statistical significance was set at p < 0.05. All statistical analyses were conducted using the SPSS PASW Statistics version 26.0 software (IBM Inc., Armonk, NY, USA).

      Results

      Patient characteristics

      During the study period, 44 patients underwent hemiglossectomy with reconstruction using a free flap, of which 14 underwent all three conventional speech intelligibility assessments after six months postoperatively: seven each in the groin flap and ALT flap groups. The cohort details are summarized in Table 2. In two cases in the ALT flap group, the cut surface of the tongue tip was directly sutured without insetting the flap to simplify the flap design and inset. In one case in the ALT flap group, a small triangular flap was created in the flap to bilobe the tip of the skin paddle, which was then inserted into the floor of the mouth to prevent scar contracture.
      Table 2Patient characteristics.
      VariableGroin flap (n = 7)ALT flap (n = 7)p Value
      Patient number0.27
      Female41
      Male36
      Age (y, mean [SD, range])51.1 (20.4, 21-78)62.0 (12.5, 37-73)0.25
      BMI (kg/m2, mean [SD, range])21.3 (4.1,16.4-27.1)21.7 (3.5,15.7-26.4)0.87
      Pathological type1
      SCC77
      Tumor stage0.95
      T121
      T223
      T323
      T410
      Clinical stage0.69
      I20
      II14
      III31
      IV12
      Tongue defect type0.88
      1: Oral hemiglossectomy32
      2: Oral hemiglossectomy with partial base of tongue resection35
      3: Hemiglossectomy10
      SOND1
      Bilateral12
      Ipsilateral65
      Flap thickness (mm, mean [SD, range])7.2 (2.5, 5-10)7.6 (2.5, 5-10)0.78
      Direct suture of the tongue tip defect020.46
      Bilobed skin paddle011
      Arterial thrombosis011
      Partial flap necrosis011
      Postoperative RT140.27
      Timing of postoperative assessment (d, mean [SD, range])1219 (585, 381-1965)1078 (1062, 227-3397)0.76
      Residual dentition0.32
      1: No denture needed67
      2: Denture needed10
      3: Unable to fit dentures due to flap interference00
      ALT, anterolateral thigh; BMI, body mass index; RT, radiation therapy; SCC, squamous cell carcinoma; SD, standard deviation; SOND, supraomohyoid neck dissection.
      The two groups showed no remarkable differences in relation to patient characteristics, including sex, age, body mass index, pathological type, tumor (T) staging, clinical staging, tongue defect type, neck dissection, flap thickness, direct suture of the tongue tip defect, bilobed skin paddle, arterial thrombosis, partial flap necrosis, postoperative radiotherapy, the timing of postoperative assessment, and residual dentition at the time of postoperative assessment.

      Speech intelligibility assessment using the three conventional methods

      When the per-patient scores were compared, the groin and ALT flap groups showed no significant differences in any of the three conventional assessment methods: Hirose's 10-point scoring system (9.4 vs. 9.0; 95% confidence interval [CI]: -1.0 to 1.8, p = 0.52), the TKR speech test (7.6 vs. 7.7; 95% CI: -2.4 to 2.1, p = 0.89), and the Japanese 100-monosyllable test (74.6% vs. 66.7%; 95% CI: -11.4 to 27.2, p = 0.39) (Fig. 4).
      Fig 4
      Fig. 4Speech intelligibility assessment using the three conventional methods. (A) Hirose's 10-point scoring system for Japanese speech intelligibility. (B) The TKR speech test for Japanese. (C) The Japanese speech intelligibility test for 100 monosyllables analyzed by the conventional method. Boxes contain the lower to upper quartiles of the dataset, while the center line in each box denotes the median. In Hirose's 10-point scoring system, the median was 10 points for both groups, and in the TKR speech test, the median was 9 points for both groups, so these medians overlapped at the upper edge of the box. The whiskers mark the largest and smallest observed values within 1.5 times the interquartile range from the box. The X marks indicate the mean. ALT, anterolateral thigh.

      Speech intelligibility assessment using the new method

      In an intergroup comparison of the per-syllable accuracy for each of the 100 monosyllables, the groin flap group showed significantly higher accuracy for 19 syllables, whereas the ALT flap group showed a significantly higher accuracy for one syllable (Fig. 5A and Table 1). In particular, the alveolar consonants (/t/ and /d/) were more accurately articulated with the groin flap. Per-syllable accuracy was significantly higher in the groin flap group (74.6% vs. 66.7%; 95% CI: 4.6 to 11.1, p < 0.001) (Fig. 5B). The same five examiners in this study (Examiners 1–5) assessed the speech intelligibility of all 14 patients. Repeated measures ANOVA assuming sphericity indicated that the scores for each syllable differed significantly among the five examiners (F [4, 396] = 3.308, p < 0.05) (Fig. 5C). The difference between Examiner 1, with the lowest score, and Examiner 2, with the highest score, was significant (9.6 vs. 10.3, 95% CI: 0.12–1.14, p = 0.006).
      Fig 5
      Fig. 5A new analysis method for the Japanese speech intelligibility test for 100 monosyllables. (A) Accuracy for each of the 100 monosyllables. (B) Result of paired t-test. (C) Repeated measures ANOVA in the accuracy of each syllable among five 5 examiners. Error bar: mean ± 1 SD. ALT, anterolateral thigh; ANOVA, analysis of variance; Exam, examiner; SD, standard deviation.
      At all four articulation points involving the tongue, the accuracy was significantly higher in the groin flap group, including 17 dental consonants (82.7% vs. 68.1%; 95% CI: 6.6–22.7, p = 0.0014), 6 alveolar consonants (69.5% vs. 31.4%; 95% CI: 23.0–53.2, p = 0.0013), 20 palatal consonants (73.6% vs. 62.7%; 95% CI: 5.8–15.9, p < 0.001), and 20 velar consonants (60.9% vs. 51.3%; 95% CI: 1.9–17.2, p = 0.017) (Fig. 6). The two groups showed no significant difference in accuracy at the two articulatory points without tongue involvement, which included 25 bilabial consonants (76.8% vs. 79.8%; 95% CI: -8.2 to 2.3, p = 0.26) and three glottis consonants (92.4% vs. 90.4%; 95% CI: -19.5 to 23.3, p = 0.74). The two groups also showed no differences in accuracy for the five vowels and four semivowels (84.4% vs. 86.7%; 95% CI: -7.0 to 2.6, p = 0.31).
      Fig 6
      Fig. 6Accuracy of 91 consonant-vowel syllables at six articulation points. At all four articulation points involving the tongue, the accuracy was significantly higher for the groin flap group. *p < 0.05. ALT, anterolateral thigh; n.s., not significant.

      Discussion

      Our new analysis method, which compared intelligibility by syllable, showed that the groin flap yielded higher speech intelligibility than the ALT flap in hemiglossectomy reconstruction. This difference was evident at all four articulation points involving the tongue, whereas the two flaps showed no significant difference at the two articulation points without tongue involvement. No significant differences were found between any of the three conventional assessment methods. Our hypothesis which stated that differences in speech intelligibility by flap type are more likely to appear in syllables where the tongue is involved in articulation was validated by the findings. To the best of our knowledge, this is the first report to compare the speech function of the groin flap with that of another flap in hemiglossectomy reconstruction.
      Only a few previous studies, including this one, have shown that speech intelligibility after hemiglossectomy reconstruction differs depending on the types of flaps used [
      • Su W.F.
      • Chen S.G.
      • Sheng H.
      Speech and swallowing function after reconstruction with a radial forearm free flap or a pectoralis major flap for tongue cancer.
      ,
      • Matsui Y.
      • Shirota T.
      • Yamashita Y.
      • Ohno K.
      Analyses of speech intelligibility in patients after glossectomy and reconstruction with fasciocutaneous/myocutaneous flaps.
      ,
      • Zhang P.P.
      • Meng L.
      • Shen J.
      • Liu H.
      • Zhang J.
      • Xiang X.
      • et al.
      Free radial forearm flap and anterolateral thigh flap for reconstruction of hemiglossectomy defects: a comparison of quality of life.
      ]. This is probably because speech intelligibility after hemiglossectomy is not originally poor, and differences due to skin flaps are unlikely to appear. In fact, in this study, the median scores in both Hirose's 10-point scoring system and the TKR speech test were the highest possible for both groups (Fig. 4A, B), and these two methods could not clarify the difference in speech intelligibility between the groin and ALT flap groups. Only the Japanese 100-monosyllable test showed some difference in the mean score (74.6% vs. 66.7%, Fig. 4C); therefore, we reanalyzed the results by using a new method. By comparing the results of the test on a syllable-by-syllable basis rather than a patient-by-patient basis, we were able to reveal differences between the two flap groups.
      Because patients with good and poor speech function are averaged out, per-patient speech intelligibility assessments, such as the three conventional methods used in this study, may not show any differences between flap types. On the other hand, our per-syllable assessment emphasizes the difference between pronounceable and unpronounceable syllables depending on the flap type. Indeed, the differences in speech intelligibility between the two flap groups were particularly evident at articulation points involving the tongue, rather than at those without tongue involvement. We believe that a syllable-by-syllable comparison, rather than a patient-by-patient comparison, is more appropriate when comparing speech intelligibility after tongue reconstruction using two or more different operative procedures.
      Tongue reconstruction using a groin flap or a superficial circumflex iliac artery perforator (SCIP) flap harvested from the groin region has been reported previously [
      • Murakami R.
      • Tanaka K.
      • Kobayashi K.
      • Fujii T.
      • Sakito T.
      • Furukawa M.
      • et al.
      Free groin flap for reconstruction of the tongue and oral floor.
      ,
      • Green R.
      • Rahman K.M.
      • Owen S.
      • Paleri V.
      • Adams J.
      • Ahmed O.A.
      • et al.
      The superficial circumflex iliac artery perforator flap in intra-oral reconstruction.
      ,
      • Goh T.L.H.
      • Park S.W.
      • Cho J.Y.
      • Choi J.W.
      • Hong J.P.
      The search for the ideal thin skin flap: superficial circumflex iliac artery perforator flap–a review of 210 cases.
      ,
      • Strobbe S.
      • Van Landuyt K.
      • Delaere P.
      • Vander Poorten V.
      • Vanclooster C.
      Superficial circumflex iliac artery perforator flap for reconstruction of oral defects after tumor resection.
      ,
      • Iida T.
      • Mihara M.
      • Yoshimatsu H.
      • Narushima M.
      • Koshima I.
      Versatility of the superficial circumflex iliac artery perforator flap in head and neck reconstruction.
      ,
      • Ma C.
      • Tian Z.
      • Kalfarentzos E.
      • Zhang Y.
      • Zhang Z.
      • Lam D.
      • et al.
      Superficial circumflex iliac artery perforator flap for tongue reconstruction.
      ]. The advantages of both flaps are that they are thin and pliable, and thin flaps can be safely harvested even in patients with a body mass index greater than 25 kg/m2 [
      • Goh T.L.H.
      • Park S.W.
      • Cho J.Y.
      • Choi J.W.
      • Hong J.P.
      The search for the ideal thin skin flap: superficial circumflex iliac artery perforator flap–a review of 210 cases.
      ]. In addition, good speech and swallowing functions have been reported in partial and hemiglossectomy reconstructions with an SCIP flap [
      • Ma C.
      • Tian Z.
      • Kalfarentzos E.
      • Zhang Y.
      • Zhang Z.
      • Lam D.
      • et al.
      Superficial circumflex iliac artery perforator flap for tongue reconstruction.
      ]. However, if thinness is the reason for the higher speech intelligibility of the groin flap, then it cannot explain the difference in speech function between the groin and ALT flap groups shown in this study, since there was no difference in the flap thickness between the two flap groups.
      Therefore, why was the groin flap better in this study comparing speech function between groin and ALT flaps of similar thickness? We focused on the structural differences between the two flaps. The groin and lateral thigh have the same subcutaneous tissue structure, consisting of two adipofascial layers of the protective adipofascial system and the lubricant adipofascial system without evident superficial fascia [
      • Nakajima H.
      • Imanishi N.
      • Minabe T.
      • Kishi K.
      • Aiso S.
      Anatomical study of subcutaneous adipofascial tissue: a concept of the protective adipofascial system (PAFS) and lubricant adipofascial system (LAFS).
      ]. However, with respect to the structure of the dermis, the dermis of the groin is less than half as thin as that of the lateral thigh [
      • Lee Y.
      • Hwang K.
      Skin thickness of Korean adults.
      ]. Therefore, we speculate that the thinness of the dermis in the groin flap contributed to its higher speech intelligibility. Since the dermis becomes thicker in the groin, forearm, and lateral thigh in that order [
      • Lee Y.
      • Hwang K.
      Skin thickness of Korean adults.
      ], previous studies that reported comparable speech function between the forearm and ALT flaps in hemiglossectomy reconstruction might also have to be re-examined [
      • Farace F.
      • Fois V.E.
      • Manconi A.
      • Puddu A.
      • Stomeo F.
      • Tullio A.
      • et al.
      Free anterolateral thigh flap versus free forearm flap: functional results in oral reconstruction.
      ,
      • Hsiao H.T.
      • Leu Y.S.
      • Liu C.J.
      • Tung K.Y.
      • Lin C.C.
      Radial forearm versus anterolateral thigh flap reconstruction after hemiglossectomy: functional assessment of swallowing and speech.
      ,
      • de Vicente J.C.
      • de Villalaín L.
      • Torre A.
      • Peña I.
      Microvascular free tissue transfer for tongue reconstruction after hemiglossectomy: a functional assessment of radial forearm versus anterolateral thigh flap.
      ,
      • Tarsitano A.
      • Vietti M.V.
      • Cipriani R.
      • Marchetti C.
      Functional results of microvascular reconstruction after hemiglossectomy: free anterolateral thigh flap versus free forearm flap.
      ,
      • Lu M.
      • Sun G.
      • Hu Q.
      • Tang E.
      • Wang Y.
      Functional assessment: free thin anterolateral thigh flap versus free radial forearm reconstruction for hemiglossectomy defects.
      ,
      • Cai Y.C.
      • Li C.
      • Zeng D.F.
      • Zhou Y.Q.
      • Sun R.H.
      • Shui C.Y.
      • et al.
      Comparative analysis of radial forearm free flap and anterolateral thigh flap in tongue reconstruction after radical resection of tongue cancer.
      ]. This is because syllable-based comparisons of speech intelligibility between the forearm and ALT flaps, as in this study, may show that the forearm flap is superior in speech function because the dermis is thinner.
      Our results showed that the groin flap yielded better postoperative speech intelligibility than the ALT flap, but the groin flap also shows some disadvantages for hemiglossectomy reconstruction. The groin flap has a short and thin vascular pedicle, making it difficult to use for head and neck reconstruction [
      • Murakami R.
      • Tanaka K.
      • Kobayashi K.
      • Fujii T.
      • Sakito T.
      • Furukawa M.
      • et al.
      Free groin flap for reconstruction of the tongue and oral floor.
      ,
      • Goh T.L.H.
      • Park S.W.
      • Cho J.Y.
      • Choi J.W.
      • Hong J.P.
      The search for the ideal thin skin flap: superficial circumflex iliac artery perforator flap–a review of 210 cases.
      ,
      • Ma C.
      • Tian Z.
      • Kalfarentzos E.
      • Zhang Y.
      • Zhang Z.
      • Lam D.
      • et al.
      Superficial circumflex iliac artery perforator flap for tongue reconstruction.
      ]. In addition, the volume of the sartorius muscle included in the groin flap is limited, whereas the ALT flap can be adjusted to fill the submandibular dead space with the lateral vastus lateralis muscle [
      • Strobbe S.
      • Van Landuyt K.
      • Delaere P.
      • Vander Poorten V.
      • Vanclooster C.
      Superficial circumflex iliac artery perforator flap for reconstruction of oral defects after tumor resection.
      ]. Therefore, we consider the following indications for hemiglossectomy reconstruction using a groin flap: (1) the ALT flap is more than 10 mm thick; (2) patients desire high speech intelligibility; (3) the patients’ upper neck arteries, such as the superior thyroid, lingual, and facial arteries, are available for anastomosis; and (4) the patients’ suprahyoid muscles are relatively preserved and there is no need to fill the submandibular dead space.
      The strength of this study is that we did not create a new speech intelligibility assessment; instead, we used the results of the well-known Japanese 100-monosyllable test and revealed the differences in speech intelligibility due to flap types simply by adapting a new analysis method to the results. Because of the small number of patients requiring tongue reconstruction, it was not easy to compare speech function in a large number of patients with similar defects reconstructed with different types of flaps. While a patient-by-patient comparison involves comparing the mean values of two small-sized independent samples (seven patients in each sample of this study), a syllable-by-syllable comparison has the advantage of comparing the mean values of as many as 100 corresponding samples, which is more likely to produce significant differences. In fact, we found a significant difference between the two flap groups only in the new analysis, even though the accuracy rates of the groin and ALT flaps were 74.6% and 66.7%, respectively, in both analyses (Figs. 4C and 5B).
      This study had several limitations. First, it had a small sample size. However, the groin flap showed significantly higher speech intelligibility at all four articulation points involving the tongue (Fig. 6), suggesting that it is more suitable for hemiglossectomy reconstruction in terms of Japanese syllable articulation. Second, this study only assessed speech function after hemiglossectomy reconstruction and not swallowing function. Swallowing function after hemiglossectomy has been reported to be better with free radial forearm flap reconstruction than primary closure [
      • Hsiao H.T.
      • Leu Y.S.
      • Lin C.C.
      Primary closure versus radial forearm flap reconstruction after hemiglossectomy: functional assessment of swallowing and speech.
      ]. In addition, swallowing function after hemiglossectomy reconstruction has been reported to be good enough to be compared with that in normal individuals, regardless of the type of flap used [
      • Hsiao H.T.
      • Leu Y.S.
      • Liu C.J.
      • Tung K.Y.
      • Lin C.C.
      Radial forearm versus anterolateral thigh flap reconstruction after hemiglossectomy: functional assessment of swallowing and speech.
      ]. Third, speech function assessments in this study were objective assessments of speech intelligibility by medical personnel, and not subjective assessment by patients themselves using patient-reported outcome measures. Fourth, inter-rater variability might have existed in our new method of analysis. To minimize the effect of this variability, it is preferable that all patients' speech intelligibility be assessed by the same five examiners. Fifth, the patients in this study were evaluated for speech function only once postoperatively. Therefore, the changes in postoperative speech function over time are unknown. Finally, speech intelligibility was assessed only for daily conversations and monosyllables, not for words or sentences.

      Conclusions

      The groin flap yielded higher speech intelligibility than the ALT flap in hemiglossectomy reconstruction using our new analysis method, which compared intelligibility by syllable. The difference was evident at all four articulation points involving the tongue, although no significant difference was observed at the two articulation points without tongue involvement.

      Declaration of Competing Interest

      None declared.

      Acknowledgements

      We would like to thank Editage (www.editage.com) for English language editing.

      Financial disclosure

      The authors have nothing to disclose.

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