Laser laryngeal microsurgery is currently the primary method of treatment of various laryngeal diseases. The development of laryngeal microsurgery came from the introduction of a small spot $CO_2$ laser micromanipulator and more precise microlaryngeal instruments. $CO_2$ laser laryngeal microsurgery has enabled very precise surgery because it has small focus size and hemostatic effect. There are some limitations to the use of the $CO_2$ Laser such as adjacent tissue damage and vocal fold scarring. These problems can be minimized through understanding the mechanisms by which lasers function and correctly manipulating the parameters under a surgeon's control. We should also recognize the safety of $CO_2$ laser for the surgeon to precisely perform the procedure.

The population of professional voice users is increasing in Korea, nowadays. Voice problems in professional voice users cause more negative impact to have their ability to work and maintain their well-being life. In this article, the authors reviewed the characteristics of professional voice users and described the evaluation methods, treatment option and managements in professional voice users.

Because the human voice is produced through vibration of the vocal cords during the exhalation of airflow, it is important to observe the vibration pattern of the vocal cords in patients complaining of voice changes. However, it is not easy to observe the actual vibration pattern of the vocal cord because it vibrates so fast that it cannot be observed by the naked eye and it is located deep in the throat. Recently, with advances in instruments, including laryngoscopes and video camera systems, the vibration pattern of the vocal cords can now be observed. However, considering that present video camera systems can detect 30-60 images per second and the vocal cord vibrates at 100-200 and 200-300 times per second in men and women, respectively, it is not possible to record the whole mucosal wave of the vocal cord in real time. To overcome this limitation, a stroboscope, which converts fast movements of the vocal cord into slower images, has been developed. Since then, several instruments were developed to examine vocal vibration pattern. However, each instruments have advantages and disadvantages. Therefore, we should know about these things to apply them in patients with voice problem.

Background and Objectives:This study is to objectively compare and analyze the acoustic changes in the patients with total thyroidectomy before and after RI therapy. Subjects and Methods:For this study, a total of 50 patients with total thyroidectomy were participated as subjects. Voice samples were obtained at the time of post-operation (Post-OP), before high-dose radioactive iodine therapy (Pre-RIT), and after high-dose radioactive iodine therapy (Post-RIT). Acoustic analysis, the maximum phonation time and K-VHI (Korea-Voice handicap index) were used for subjective evaluation. Results:According to the comparison analysis of the three periods, mFo (Hz) was significantly reduced in all of the vowels /a/ and /i/ as the hormone was discontinued. This can be related to the reduction in vocal range. As thyroid hormone was discontinued, Shim (%) and APQ (%) values, which are the parameters related to the degree of aggressiveness, showed a significant increase in the middle vowel /a/. As thyroid hormone was discontinued, emotional index was significantly decreased in VHI (voice handicap index). Conclusion:These results can be assumed that thyroid hormone suspension is related to the increased changes in the vocal intensity, the increase in noise and the reduction in vocal range. Emotionally, these data can be assumed that the responsive factors of one's own voice disorders were significantly decreased in the patients with vocal handicap.

Background & Objectives : The Speech Handicap Index (SHI) is used to assess speech problem of head and neck cancer patients. The aim of this preliminary study was to evaluate the reliability and validity the Korean version SHI. Materials and Methods : Sixteen patients with oral cavity cancer and 26 normal control were participated in the study. Test-retest reliability of the Korean version of SHI was completed by 20 out of 42 subjects after 2weeks. Mann-Whitney U test was used to compare the Korean version of SHI scores between normal population and patients group. The relationship between the Korean version of SHI and diadochokinesis (DDK) was investigated using Spearman correlation coefficients. Results : The Korean version of SHI provided a high internal consistency (${\alpha}$=0.99) and test-retest reliability (Spearman rho 0.98). The mean SHI scores [total (T), speech (S), and psychosocial (P)] in normal population were 0.8 (T), 0.2 (S) and 0.4 (P), whereas those in patients group were 58.1 (T), 27.9 (S) and 27.0 (P) respectively. There were significant differences in total SHI score as well as in all of the sub-SHI scores between two groups. Moreover, significant correlation between the Korean version of SHI parameters (T, S, P) and sequential motion rate (SMR) were yielded in patients group. Conclusion : The Korean version of SHIwas reliable and valid. It can be useful as a supplementary clinical tool for diagnosing and measuring treatment efficacy of speech problems related to oral cavity cancer.

Background and Objectives:The purpose of this study is to find features in acoustics and to learn useful features of parameters in order to distinguish laryngeal diseases through many acoustic variables. Materials and Methods:The subjects of this study were 125-male patients who had been diagnosed with vocal nodule, vocal polyp, vocal cyst, Reinke's edema, leukoplakia. To research the features of each disease in acoustics, they are measured 34 parameters by using MDVP. Results:It is clear that in order to see a meaning result when distinguishing laryngeal diseases, $F_0$, $MF_0$, $T_0$, Fhi, Flo, PER variables are significant (p<.05). It means that variables related to fundamental frequency are important to anticipate which group will be diagnosed with Reinke's edema and leukoplakia. vAm had an effect on getting a significant result in terms of amplitude perturbation parameters, which is useful to distinguish between laryngeal polyp/cyst and other laryngeal disease (p<.05). ATRI made a significant result in related to tremor parameters, which is useful to distinguish between laryngeal polyp and other laryngeal disease (p<.05). Conclusion:$F_0$, $MF_0$, $T_0$, Fhi, Flo, PER, vAm, ATRI might be meaningful parameters distinguishing pathologic from benign laryngeal diseases. Especially, the vAm and ATRI are an important factor when forecasting which group would be diagnosed with vocal polyp.

False vocal fold hypertrophy caused by diverse pathologic lesion, such as laryngeal amyloidosis, laryngeal lipidosis, laryngocele, saccular cyst and sulcus vocalis. False vocal fold hypertrophy, however, is also caused laryngeal structure deformity, irrespective of pathologic lesions. In this article, we report some cases of false vocal fold hypertrophy caused by inward bowing of thyroid cartilage. At the clinic of the department of otorhinolaryngology in Gangnam Severance Hospital, with 3 male complained of hoarseness as subjects, and comfirmed of false vocal fold hypertrophy using the stroboscopy and larynx CT we checked vocal fold and laryngeal structure. Three patients with apparent hypertrophy of false vocal fold were investigated with computerized tomography (CT). In all patients, marked concavity of thyroid cartilage was revealed in CT scan at the level of the false vocal fold, and this deformity of the thyroid cartilage seemed to cause a protrusion of false vocal fold which taken as hypertrophy in stroboscopy. Careful palpation of the larynx and a CT scan taken at the level of the false vocal fold should be useful in determining whether hypertrophy of the false vocal fold is pathologic. For the next articles, It is necessary to discuss for the cause, diagnosis, treatment and prevention of inward bowing of thyroid cartilage.