**Acknowledgements**

This work was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS KAKENHI grant no. 18 K09390), and a Special Research Grant on Defense Medicine from the Ministry of Defense of Japan.

## **Conflict of interest**

The authors declare no conflict of interest.

*Transoral Videolaryngoscopic Surgery (TOVS) DOI: http://dx.doi.org/10.5772/intechopen.97473*
