OBJECTIVE: To provide the normative values for laryngeal stroboscopy (LS) concerning amplitude, open quotient, asymmetry and phase difference in healthy, young subjects. STUDY DESIGN: Prospective case-control study. SETTING: Patients treated at a single institute. METHODS: A total of 68 healthy subjects were included in the study (35 women, 33 men), aged 18-35 years. After obtaining LS recordings, image processing was performed to attain parameters of vocal fold vibration. RESULTS: In women, the location of the maximum vibration amplitude is approximately in the 1/3 posterior part of the glottis, while in men, the location is moved to the glottis centre. In males, the relative amplitude vibration of the vocal folds in the 1/3 anterior part of the glottis was significantly higher than in females (P = 0.029). Women showed significantly higher open quotients (OQ) at the posterior part of the glottis than the male subjects (P < 0.001) and men presented significantly higher OQ at the anterior part of the glottis than the females (P < 0.001). The average OQ values for both sexes were almost the same. Females showed significantly higher relative glottal gap area (P = 0.044). Women presented a significantly lower amplitude asymmetry than men (P = 0.002). The weighted absolute left-right phase difference reached up to 24° and remained insignificantly higher in the men than the women (P = 0.142). CONCLUSIONS: The study provides normative values for LS in young adults for the measurement of therapy outcomes in patients with voice disorders and realisation of evidence-based medicine. The LS parametrisation is easy to perform in clinical practice.
OBJECTIVE: To provide the normative values for laryngeal stroboscopy (LS) concerning amplitude, open quotient, asymmetry and phase difference in healthy, young subjects. STUDY DESIGN: Prospective case-control study. SETTING:Patients treated at a single institute. METHODS: A total of 68 healthy subjects were included in the study (35 women, 33 men), aged 18-35 years. After obtaining LS recordings, image processing was performed to attain parameters of vocal fold vibration. RESULTS: In women, the location of the maximum vibration amplitude is approximately in the 1/3 posterior part of the glottis, while in men, the location is moved to the glottis centre. In males, the relative amplitude vibration of the vocal folds in the 1/3 anterior part of the glottis was significantly higher than in females (P = 0.029). Women showed significantly higher open quotients (OQ) at the posterior part of the glottis than the male subjects (P < 0.001) and men presented significantly higher OQ at the anterior part of the glottis than the females (P < 0.001). The average OQ values for both sexes were almost the same. Females showed significantly higher relative glottal gap area (P = 0.044). Women presented a significantly lower amplitude asymmetry than men (P = 0.002). The weighted absolute left-right phase difference reached up to 24° and remained insignificantly higher in the men than the women (P = 0.142). CONCLUSIONS: The study provides normative values for LS in young adults for the measurement of therapy outcomes in patients with voice disorders and realisation of evidence-based medicine. The LS parametrisation is easy to perform in clinical practice.