A 3-Dimensional Analysis of Flap Volume Change in Hemi-Tongue Reconstruction.

[BACKGROUND] An adequate volume of the tongue flap is essential to preserve speech and swallowing functions. However, it is generally known that the volume of the free flap tends to decrease over time because of various reasons. Especially in hemi-tongue reconstruction, as half of the normal tongue is retained, some functions are maintained; consequently, there are few studies related to the volume of the flap and function. This study investigated the relationship between flap volume change and function after hemi-tongue reconstruction.

[METHODS] A retrospective chart review of 26 patients who underwent hemi-tongue reconstruction between 2003 and 2020 was performed. Patient demographic data, postoperative radiotherapy (RT), and data on flap types were collected. The volume of the flap was measured by converting the computed tomography and magnetic resonance images into 3 dimensions using the Mimics software. In addition, speech scores and feeding scores were collected.

[RESULTS] The first follow-up computed tomography or magnetic resonance imaging (T1) was performed after an average of 2.09 months, and the second follow-up imaging study (T2) was performed at 16.58 months on average. On average, the T2 volume was 64% of the T1 volume (range, 45.75%-90.54%). Factors including speech and swallowing functions were compared by dividing the group into a group with a more than average decrease in volume (group 1) and a group with a less than average decrease in volume (group 2). In group 1, there were significantly more cases of postoperative RT than in group 2 (85.7%, 50.0%, in group 1 and group 2, respectively; P = 0.049). However, there was no difference in the functional aspects between the 2 groups.

[CONCLUSIONS] The present study revealed that the flap volume decreased more when RT was performed. However, there was no association between the degree of volume loss and speech and swallowing functions. Regardless of the group, the loss of function was not severe, probably because the remaining half of the tongue was functioning.