Normalization of Voice Parameters in Patients with Unilateral Vocal Cord Palsy: Is it Realistic?
Disorders of voice may have an impact on limiting participation, impaired social interaction, reluctance to participate in activities, negative attention of people in the group etc. and all this affect the overall quality of life of an individual. Therefore, the perceptual and objective evaluation enables the clinician to know disorders of voice in depth. Apart from the fibro-optic direct video-laryngoscope examination (provides the physical status of the laryngeal structure), the clinical acoustic voice analysis is performed using classical perturbation measures, including jitter and shimmer. In addition, to measure the normalization of other acoustic vocal parameters, the habitual F0, electroglottography (EGG) and voice range profile (VRP) are also being used.
Need of the study:
Most of the patients remained unable to elevate their pitch and loudness after the voice therapy in spite of regaining of the perceptually normal pitch, quality, and loudness of the voice. Therefore, this study would be suggestive of the termination of the voice therapy by evaluating the pitch and loudness range of voice.
Aim & Objectives:
This study aims to investigate normalization of vocal parameters with voice range profile (VRP) through comparison of qualitative (perceptual) and quantitative measures (acoustic and glottal), in unilateral vocal cord palsy patients following intensive voice therapy.
We included 40 subjects (20 study and 20 controls) of age range between 34-46 years. Subjects included 10 males and 10 females with unilateral vocal cord palsy (UVCP) in the experimental group as well as control group. VHI-30 and GRBAS scale were administered before and after three months period of intensive voice therapy. Computerized Speech Lab (CSL) and Dr. Speech software were used to evaluate the acoustic parameters of voice before and after therapy.
The acoustic voice analysis, EGG and VRP were possible only after intensive regular voice therapy sessions for 3 months as they did not have sufficient phonation for analysis. VHI score and GRBAS scale revealed statistically significant (p<0.05) difference between pre and post-therapy assessment. There was a statistically significant (p<0.05) difference between controls and participants in the study group for EGG and VRP in both males and females.
Significantly greater values of CQ and CQP predispose the greater vocal constriction. It also reflects the symmetry of the contact phase in unilateral vocal cord palsy, is thought to reflect vocal fold tonus and to be particularly sensitive to mucosal dynamics within the vertical plane which may lead to the irregularity of vocal cord contact. In the present study, the voice range profile has shown statistically significant (p<0.05) difference between normal and study in both male and female for the mean F0 range, number of semitones and energy range. The inability to control their laryngeal performances such as the limited F0 range and semitones in unilateral vocal cord palsy may be because the lengthening a string has the effect of lowering pitch where tension must be increased at the same time to counteract the lengthening effect. A stiff vocal ligament within the vocal fold plays an important role to achieve such function that is “increasing pitch by elongating a vocal fold.”
In spite of normalization of vocal parameters both acoustically, perceptually and self-rated VHI score, the EGG and VRP did reveal a statistically significant (p<0.05) difference, after therapy. This recommends that prior to termination of therapy, acoustic measures viz. EGG perturbation, frequency and intensity range of the voice are to be considered as it plays a vital role.