Voice changes and laryngo-video-stroboscopic findings in patients with vocal fold polyps and cysts

Background Vocal fold polyps and cysts are two disorders of the minimal associated pathological lesions of the vocal folds. These disorders may be misdiagnosed by a simple laryngoscopic examination. Laryngo-video-stroboscopic (LVS) assessment is required for proper differentiation. Objectives This study aimed to examine the voice changes and LVS findings of vocal fold polyps and cysts and differentiate between them clearly, and also to determine which stroboscopic signs are correlated to the severity of dysphonia. Patients and methods This study was carried out on 47 patients; 21 of these patients (45%) were diagnosed with vocal fold cysts (group 1) and 26 patients (55%) were diagnosed with vocal fold polyps (group 2). The results of auditory perceptual assessment, LVS evaluation, and acoustic analysis of the voice were compared in both groups. The correlation between the different parameters of LVS and the grade of dysphonia was tested. Results Vocal fold polyps lead to more severe dysphonia than vocal fold cysts, proved by significant differences between both groups in the grade of dysphonia and in acoustic analysis. LVS findings differed significantly between both groups. Irregularity of the edge of the affected vocal fold, phase closure characteristics, and phase symmetry were found to be the most useful parameters for the assessment of the severity of dysphonia in these voice disorders than the amplitude of vibration. Conclusion The results of assessment of voice in vocal fold cysts and polyps are related to the nature and the pathology of the disorder. Irregular vocal fold edges in cases of vocal fold polyps and absent mucosal wave over the lesion in cases of vocal fold cysts enabled clear differentiation between them. Irregularity of the vocal fold edges and symmetry between vocal folds were stroboscopic signs correlated to the severity of dysphonia in cases of vocal fold polyps and cysts.


Introduction
Vocal fold polyps and cysts are among the common lesions of the vocal folds encountered in voice clinics. Th ey are related to the group of minimal associated pathological lesions (MAPLs) of the vocal folds. Th ese disorders result from longstanding permanent changes aff ecting nonorganic voice disorders [1]. Th ey are usually located at the junction of anterior and middle thirds of the vocal folds, the site of maximal vibratory mucosal excursion during phonation [2].
Vocal fold polyps are the most common benign vocal fold lesions removed surgically and are associated with vocal abuse or misuse. It has been proposed that laryngeal polyps represent injury to the basement membrane zone of the vocal fold. Repeated trauma from shearing forces produced by excessive or abusive phonation leads to basement membrane zone disruption and thickening. Th is thickening, along with vascular changes, leads to the characteristic clinical appearance of the vocal polyp [3]. Vocal polyps are benign, round, sessile, or pedunculated lesions, which can be unilateral or bilateral. Th ey are located on the free borders of the vocal fold and are mobile, when pedunculated (Fig. 1). Depending on their size and implantation site, they may compromise vocal quality markedly [4]. Polyps are further classifi ed as translucent polyps (fi lled with edematous-appearing fl uid), hemorrhagic polyps (with vascular changes), hyaline polyps (polyp fi lled with thick, myxoid-appearing fl uid), or fi brotic polyps (fi lled with fi brous tissue) [5].
Cysts are unilateral submucosal masses arising from the Reinke's space at the junction of the anterior and middle third of the vocal fold [5]. Vocal cysts are classifi ed into two subtypes: epidermoid or mucousretention cysts. Epidermoid cysts have caseous content, and are implanted on the subepithelial layers Voice changes and laryngo-video-stroboscopic ndings in patients with vocal fold polyps and cysts Aml S. Quriba a , Mohamed E. Darweesh b

Background
Vocal fold polyps and cysts are two disorders of the minimal associated pathological lesions of the vocal folds. These disorders may be misdiagnosed by a simple laryngoscopic examination. Laryngo-video-stroboscopic (LVS) assessment is required for proper differentiation.

Objectives
This study aimed to examine the voice changes and LVS ndings of vocal fold polyps and cysts and differentiate between them clearly, and also to determine which stroboscopic signs are correlated to the severity of dysphonia.
of the vocal folds. Th e vocal fold aff ected is bulged, congested, and shows a vascular ectasia on top of the lesion (Fig. 2). An epidermoid cyst may be acquired, secondary to vocal abuse or congenital, because of remaining epithelium trapped inside the lamina propria. Th e histological analysis of the epidermioid cyst shows that the lesion is covered by a stratifi ed squamous and keratinized epithelium, making it resistant to manipulation. Mucous-retention cysts develop from the obstruction of the glandular ducts caused by voice overuse, laryngitis secondary to gastroesophageal refl ux, or upper-airway infections. Th ey are more common in adults, especially those with high vocal demand. Th e histological analysis of the mucous cyst shows that the cavity is covered by ciliated cylindrical epithelium [6].
Laryngo-video-stroboscopy (LVS), the imaging technique of choice, has received considerable attention over the last 20 years and has become a standard procedure in voice centers and even for the general otolaryngologist. Pathology of the vocal fold may produce changes in the appearance and vibratory characteristics observed during stroboscopic examination [7]. Interpretation of the stroboscopic examination typically involves systematic judgments of a series of parameters or 'signs'. Th ese signs, identifi ed by Hirano and Bless [8], included vocal fold edge, periodicity, amplitude, mucosal wave, glottal closure, vibratory behavior, and phase symmetry.
Th e aim of this work was to study the voice changes and LVS fi ndings of vocal fold polyps and cysts diff erentiate between them clearly. Another objective was to determine which stroboscopic signs are correlated to the severity of dysphonia. Th ese signs must have more importance during assessment of these disorders.

Patients and methods
Th is study was carried out in Outpatient Units of Phoniatrics, ENT Departments of Zagazig and Tanta Universities. It was initiated in January 2010 and ended in December 2010. Patients in this study were examined and diagnosis was confi rmed by three experienced phoniatricians and by a pathological examination.
Forty-seven patients with a diagnosis of a vocal fold cyst (group 1) or a vocal fold polyp (group 2) were included in this study. Each patient was subjected to an examination using the voice assessment protocol used in Ain-Shams University Hospitals. Th is protocol passes through the following levels.

Elementary diagnostic procedures
Th is includes the patient's interview, the preliminary auditory perceptual assessment (APA) of the patient's voice, and careful laryngeal examination. Documentation of the APA was performed by highfi delity voice recording. Patients' voices were recorded with a high-fi delity FM audio tape system (Akai system-Electronics Tokyo, Japan "Headquarters Singapore" ) using a cardioid dynamic microphone (Khaldi 4-2100, German, used a metallic strip attached to a vibrating membrane that would produce intermittent current). Th e speech material recorded included reading a standardized text, counting task and sustained vowel prolongation including /a/, /i/ and /u/ vowels. Th e recordings were performed in a sound-treated room to minimize environmental noise. Th e recorded materials for all patients were rated for APA by three experienced phoniatricians using a modifi ed GRBAS scale [9]. Th e APA sheet comprised a four-point scale (0-3) to determine the Right-sided vocal fold polyp .

Figure 1
Left-sided vocal fold cyst .  In this level, acoustic analysis was carried out using the multidimensional voice program (MDVP model 4305) from Kay Elemetric Corporation (Lincoln Park, New Jersey, USA). Th e sampling rate was set to 50 000 Hz. In a quiet room, the patient was asked to sustain a vowel/ /for 3-4 s at a comfortable pitch and loudness after he/she was instructed to clear the throat. A dynamic microphone was positioned at a constant mouth-to-microphone distance of 10-15 cm. A 2 s mid-vowel segment was selected and analyzed ( Fig. 3).
Th e following parameters were measured and automatically calculated: (1) Average fundamental frequency (F 0 ): this represents the average fundamental frequency for all extracted pitch periods. (2) Jitter percent (jitt%): this represents the relative period-to-period (very short term) variability in frequency [10]. (3) Shimmer percent: this represents the relative period-to-period (very short term) variability of the peak-to-peak amplitude [10]. (4) Noise to harmonic ratio: this is the ratio of the energy of the aperiodic component in the speech signal to the energy in the speech signal [11]. (5) Relative average perturbation (RAP): this enables an evaluation of the variability of the pitch period within the voice sample analyzed at a smoothing factor of three periods [10]. (6) Amplitude perturbation quotient: this enables an evaluation of the variability of the peak-to-peak amplitude within the voice sample analyzed at a smoothing factor of 11 periods [10].
Data was analyzed using SPSS (Statistical Package for Social Sciences) version 17 (predictive business intelligence "PBI" company in South Africa and items: overall grade of dysphonia and character of voice including strained, leaky, breathy, and irregular (0 for normal, 3 for severe).

Clinical diagnostic aids
Th is includes augmentation and documentation of the glottic picture and high-fi delity voice recording. Augmentation of the glottic picture was performed with LVS using either the rigid oral 70 telescope or a fl exible nasofi broscope, connected to a camera in association with stroboscopic light. Videostroboscopic recording was done by using a computer integrated Rhino-laryngeal Stroboscope from Xion medicals (Berlin, Germany). Th e following stroboscopic signs were evaluated in all patients: (1) Edge of the vocal fold: irregularity of each vocal fold, rated individually. Saharan Africa). Qualitative data of both groups (grade of dysphonia and LVS signs) were presented as number and percent. Comparison between both groups was carried out using the 2 -test. Th e Mann-Whitney test for independent samples, which is a nonparametric test, was used to compare quantitative data (acoustic parameters) of both groups. For this comparison, both groups were further divided into subgroups according to sex; comparison between the same sexes of the two groups was performed. Th is was done because of the normal variation of fundamental frequencies between men and women, which may lead to errors during comparison of acoustic parameters. Th e Pearson correlation coeffi cient was used to test the correlation between diff erent LVS signs and the grade of dysphonia.

Results
Of the 47 patients in the study, 21 were diagnosed with a vocal cyst (group 1) and 26 were diagnosed with vocal fold polyps (group 2 Evaluation of the 47 patients who participated in this study using the voice assessment protocol yielded the following fi ndings. Table 1 and Fig. 4 show very highly signifi cant diff erences between grades of dysphonia in the group of patients with vocal cysts and vocal fold polyps. Comparison between the group of patients with vocal cysts and vocal fold polyps in the male and female subgroups in terms of acoustic parameters showed signifi cant diff erences in the following: average fundamental frequency (F 0 ) (in the male subgroup), jitt% (in both subgroups), and the RAP (in both subgroups) ( Table 2).  Distribution of the overall grade of dysphonia in both groups .  Comparison between the group of patients with cysts (group 1) and the group of patients with polyps (group 2) in LVS indicated highly signifi cant diff erences in irregularity of the vocal fold edge and absence of the mucosal wave, and signifi cant diff erences in decreased amplitude of vibration and predominant closed phase (Table 3 and Fig. 5).
Th e results of the correlation between the rated LVS signs and the grade of dysphonia indicated that irregularity of the vocal fold edges and symmetry between vocal folds showed a highly signifi cant correlation to the grade of dysphonia, whereas phase closure was signifi cantly correlated to the grade of dysphonia (Table 4).

Discussion
Accurate history taking, clinical examination and upto-date investigations allow for the accurate diagnosis and documentation of various voice disorders. Benign vocal fold lesions such as polyps and cysts impair patient's quality of life and need dealing with urgently.
Proper diff erentiation between vocal fold cysts and vocal fold polyps cannot be achieved, except by a careful detailed assessment. Th e results of this assessment can be well understood when associated with the pathology or the nature of the voice disorder.
Th e results of the present study showed a signifi cant diff erence in the grade of dysphonia between groups of patients with vocal fold cysts and those with vocal fold polyps. Th is could be attributed to the diff erent histopathological origin and the hyperfunctional vocal behavior of the patients.
As is known, there are two common types of vocal fold cysts: mucus-retention cysts, which result from obstruction of a glandular duct, and epidermoid cysts (congenital and acquired), in which epithelial cells are buried in the superfi cial layer of the lamina propria. Th us, both types arise from the superfi cial layer of the lamina propria (Reinke's space) [8], leaving mucosa over them usually intact or just stretched. Th is can Distribution of LVS signs in both groups. LVS, laryngo-videostroboscopic .   explain the mild or the moderate degree of dysphonia that usually accompanies vocal fold cysts. Th e reverse occurs in case of vocal fold polyps that arise from the vocal fold mucosa itself, leading to more severe mucosal changes and more severe degrees of dysphonia [12].
Acoustic analysis is an objective tool for the assessment of voice, whereas APA is a subjective tool. Th e results of comparison between the group of patients with vocal fold cysts and the group of patients with vocal fold polyps in terms of acoustic parameters confi rmed the results of comparison of the grade of dysphonia, which is an item from APA. Th ere were signifi cant diff erences in some acoustic parameters, especially those related to frequency such as fundamental frequency (F 0 ) (in the male subgroup), jitt% (in both male and female subgroups), which refers to a very short period-to-period variability in frequency, and the RAP (in both male and female subgroups), that enables an evaluation of the variability of the pitch period within the voice sample analyzed at a smoothing factor of three periods. Th erefore, in this study, both subjective and objective tools for voice assessment showed signifi cant diff erences between both groups of patients with voice disorders. Th ese diff erences can also be attributed to the diff erent histopathological origin of the disorder. Jitter is one of the main measures for microinstability in vocal fold vibrations. Even very small growths on vocal folds, such as small polyps, may infl uence frequency perturbation, which increases as control and is related to perceived vocal eff ort and the hyperfunctional vocal behavior of the patient [13,14].
Although LVS assessment has been an important feature of the assessment of voice disorders for more than 100 years, it is still used routinely. Common stroboscopic signs are assessed in all cases without deciding which stroboscopic signs are more clinically relevant to certain types of voice disorders [12,15] Th e rest of the signs cannot be used for diff erentiation as they have the same common fi ndings in both groups.
Finally, in this study, the results of the correlation between the rated LVS signs and the grade of dysphonia showed that not all LVS were correlated to the degree of dysphonia. Irregularity of the vocal fold edges and symmetry between vocal folds showed a highly signifi cant correlation to the grade of dysphonia, whereas phase closure was correlated signifi cantly to the grade of dysphonia. Th ese results are useful for identifi cation of the factors responsible for dysphonia and its severity in cases of vocal fold cysts and polyps and any voice disorder with the same or a similar nature, for example other MAPLs. It appears that ratings of amplitude of vibration, mucosal wave, vibratory characteristics, and periodicity were not important. Th is is a surprising fi nding, especially as ratings of the mucosal wave have always been reported to be useful in the assessment of vocal fold function and dysfunction. Th is can explain the fact that, although the mucosal wave over the lesion is usually absent in vocal fold cysts, the degree of dysphonia is usually mild or moderate.
Although these signs are not important in this type of voice disorders (MAPLs), they may be more useful for other kinds of voice disorders including paralysis, functional voice problems, or neurological problems of the voice [12].
On the basis of these results, it is clear that some of the LVS signs are related to vibrations and some are related to edge (vibration and edge). Th is classifi cation can be used to diff erentiate between diff erent categories of vocal fold pathology [7]. Vibration factors may be more responsible for the severity of dysphonia in cases of vocal fold paralysis, functional voice problems, and neurological problems, whereas edge factors may be more responsible for the severity of dysphonia in cases of MAPLs.

Conclusion
Th e results of assessment of voice in vocal fold cysts and polyps are related to the nature and the pathology of the disorder. Irregular vocal fold edges observed in cases of vocal fold polyps and absent mucosal wave over the lesion in cases of vocal fold cysts were highly signifi cantly diff erent between the two groups. Stroboscopic signs correlated to the severity of dysphonia in cases of vocal fold polyps and cysts were irregularity of the vocal fold edges and symmetry between vocal folds. However, vibration factors may be more responsible for the severity of dysphonia in other cases not included in the present study such as cases of vocal fold paralysis, functional voice problems, and neurological problems.

Recommendation
On the basis of this study, we can recommend classifi cation of LVS into fewer signs that can eff ectively describe the dysphonia of diff erent MAPLs. Further studies on other types of voice disorders are required to clarify this possibility.