[Contemporary postural and segmental modification of forced voice]

Abstract

The forced voice corresponds with increased peri-laryngeal tension during phonation caused by inappropriate muscle action. It is usually accompanied by a characteristic posture (the face thrust forwards, tension in the neck muscles etc...). This posture may cause dysfunction of the cords themselves, leading to dysphonia, and perhaps requiring laryngeal microsurgery. Our project aimed to put forward and validate a system of objective, non-invasive measurements of the postural features of the forced voice, in order to improve the management of these patients. The study was prospective, comparing a control group with no previous vocal problems with a group of patients with problems of laryngeal dysfunction. We carried out a number of simultaneous measurements of postural and segmental activity during phonation, using in parallel an accelerometer, a method of cine-analysis, and a postural platform. Recordings were made during phonation, but only analysed during the resting phase. It turned out that the speed of displacement of the centre of gravity was the most useful discriminating factor. The mean value was 0.07 (displacement type 0.126) for the control group, and 0.32 (displacement type 0.211) for the patient group. The discrimination between these two groups was significant (p < 0.001, Mann-Whitney test). The reliability of this measurement allows us to envisage the inclusion into the clinical investigation package of measurements of the postural and segmental changes in the forced voice.