Visual assessment of voice disorders in patients with occupational dysphonia

In a group of persons using the voice occupationally, the frequent symptoms are hoarseness, voice fatigability and aphonia. Pathological changes in the larynx may have organic or functional character which require different methods of treatment and rehabilitation. Visualization of vibrations of the vocal folds is an essential condition for an appropriate assessment of the causes of dysphonia.

The purpose of the study is assessment of the usefulness of a high-speed imaging (HSI) system in the diagnosis of functional and organic dysphonia of occupational character, compared with digital kymography (DKG) and digital stroboscopy (DS) with a high resolution module.

The study group consisted of 64 patients with voice quality disorders with features of occupational dysphonia. The control group consisted of 15 patients with euphonic voice. Analysis of the voice quality parameters during phonation of the 'e' vowel was performed using HSI, DKG and stroboscopy of high resolution, by means of a digital HS camera (HRES Endocam, Richard Wolf GmbH, Knittlingen, Germany). Vocal folds vibrations were registered at the rate of 4,000 frames per second.

HSI is the most reliable diagnostic tool giving the possibility of an analysis of the true vibrations of the vocal folds. It also enables an observation of the aperiodicity of vibrations of the vocal folds, while DS with high resolution allows diagnosis of the periodicity of the vibrations.

HSI is particularly useful in the diagnosis of neurologically-based pathology of the voice (paralytic dysphonia) and organic dysphonia. The quickest method of diagnosing the phonatory paresis of the glottis is DKG. The advantage of both HSI and DKG is the non-invasiveness of examinations; however, their limitations are time-consuming and the high cost of equipment.