|Year : 2015 | Volume
| Issue : 1 | Page : 2-6
Electroglottographic patterns in physiologic and pathologic types of sulcus vocalis
N Sreedevi, Gopi Kishore Pebbili, TK Prakash, Shishira S Bharadwaj
All India Institute Speech and Hearing, Mysore, Karnataka, India
|Date of Web Publication||17-Dec-2015|
Shishira S Bharadwaj
Department of Speech Language Sciences, All India Institute Speech and Hearing, Mysore, Karnataka
Source of Support: The present original research article is an outcome of the project funded by AIISH under AIISH Research Fund (ARF). Further supported by Voice clinic and Department of Speech Language Sciences, AIISH, Mysore, Conflict of Interest: None
| Abstract|| |
Introduction: Sulcus vocalis is a condition of true vocal folds presenting as a linear furrow on the mucosal lining, lengthening toward the entire vibratory surface. Differential diagnosis between physiologic and pathologic sulcus vocalis has traditionally been based upon videostroboscopy that does not conclusively differentiate between the two. Hence, the present study was intended to utilize the electroglottograph (EGG), a routinely utilized voice evaluation tool to track morphological vibratory patterns in these conditions aiding in differential diagnosis. Method: A total of 40 individuals diagnosed as physiologic (17) and pathologic sulcus (23) based on stroboscopic examinations and history details were recruited as the participants for the study and were made to undergo the EGG procedure. Results: The majority of the participants with physiologic sulcus, obtained normal wave morphology barring four participants who demonstrated deviant patterns. In cases of pathologic sulcus, varied wave patterns obtained were prolonged open phase, pit such as undulation in closed phase, abrupt closing phase, and reduced amplitude waveform. Conclusions: The current study enhances the utility of EGG in cases of sulcus and its types (physiologic and pathologic sulcus) by revealing distinct waveform patterns in each and thereby aiding differential diagnosis too. These results from EGG are much relevant to voice clinicians especially in conditions where other evaluation tools are restricted.
Keywords: Electroglottography, pathologic sulcus, physiologic sulcus, videostroboscopy
|How to cite this article:|
Sreedevi N, Pebbili GK, Prakash T K, Bharadwaj SS. Electroglottographic patterns in physiologic and pathologic types of sulcus vocalis. J Laryngol Voice 2015;5:2-6
| Introduction|| |
The sulcus is a general anatomic phrase referring to a serration, groove/furrow. This feature of a groove/furrow as an anatomic deformity in the vocal folds was first observed and described by Giacomini in 1892, which was later termed as sulcus vocalis. Sulcus vocalis in simple terms is a lesion (linear groove) on the mucosal lining of the vocal folds, extending along the vibratory surface. , Research on clinical inspection of sulcus reports it to vary in terms of groove depth and to involve either one or both the vocal folds. In adults, it has been contemplated to occur secondary to unceasing laryngeal inflammatory processes, such as gastroesophageal reflux disorder, chronic laryngitis, iatrogenic complications during vocal cord microsurgeries, or to be of a congenital origin. ,, Bouchayer and Cornut  attribute some of the congenital etiologies of the disorder to defects in development of the 4 th and 6 th brachial arches, consequences of rupture from epidermoid cysts, associated with frequent familial occurrences, and failure of lesions to return following adequate surgical excision of cysts.
Characteristic features and clinical manifestations of sulcus have been observed to vary intensely which has led voice clinicians to classify sulcus into distinct types. Bouchayer and Cornut  classified the condition of sulcus into two types: Sulcus vergeture (linear depression throughout the medial edges of vocal cords) and sulcus vocalis (groove intruding the epithelium of vocal folds and attaching into vocal ligament). Ford et al.  classified sulcus vocalis into three anatomic subtypes. Physiologic (Type I) sulcus as restricted to the superficial lamina propria, pathologic (Types II and III) sulcus as extending into the intermediate, as well as deep lamina propria (vocal ligament). The physiologic sulcus configuration type was evidenced to characterize atrophic vocal folds, presbylaryngis, and paralysis.  Under pathologic sulcus, Type II sulcus or deep sulcus (sulcus vergeture) was reported to portray loss of a functional superficial lamina propria with extension into the vocal ligament, atrophic mucosa (vergeture) and moderate dysphonia. Type III or pouch type/true sulcus was reported in cases of the depression extending to the vocal ligament and penetrating thyroarytenoid muscle and severe dysphonia. Development of spindle-shaped glottal insufficiency because of bowing of the vocal folds, leading to breathy voice was also reported in cases of the pathologic sulcus. A high-pitched effortful voice projection was also evidenced relating to increased stiffness of the vocal folds mucosa. Hence, the above-mentioned features of physiologic and pathologic sulcus from reports of literature reveal certain similarities in their clinical appearance and manifestations and generate ambiguities in differential diagnosis through visualization technique alone.
Lim et al.,  studied the features of sulcus and its types through certain acoustic and perceptual measures. Their results are as follows: Perceptual judgment for all sulcus types was rated with significantly varied roughness. The authors reported that the roughness was a significant factor when differentiating physiologic and pathologic sulcus and grade, breathiness and roughness were all noteworthy when differentiating Types II and III pathologic sulcus. Increased Jitter percent and decreased HNR with an increase in sulcus severity was evidenced. Electroglottograph (EGG) findings revealed more severe irregularity in frequency (CFx) than amplitude (CAx). Wide patterns of the vocal cords contact were observed in Type III sulcus and were attributed to the asymmetrical vibration of rigid vocal cord mucosa, erratic glottal closure, and false vocal fold contact through functional reparation.
Literature in this purview reveals studies exploring vital attributes of sulcus phenomenon through mainly invasive imaging techniques and a few noninvasive acoustic measures. In the Voice Clinic, All India Institute of Speech and Hearing (AIISH), Mysore, India, there was a spurt in the overall incidence of sulcus cases from 1.5% to 8% in a span of 1-year (2013-2014). The boost in the frequency of sulcus cases was evidenced with the advent and use of the visualization technique (videostroboscopy) alone. This triggers speculations whether detection of sulcus condition was being unnoticed through other techniques till the utilization of stroboscopy in the recent past. Hence, further emphasis is laid on the need to explore outcomes of other evaluation measures in the sulcus and its types thereby aiding in apt differential diagnosis, as well as preventing false positive errors in diagnosis.
In this context, the need to probe into the vibratory patterns of vocal folds in the sulcus and its types through noninvasive viable procedures to voice clinicians becomes vital. The procured data on vibratory patterns can further be used to validate associated emblematic features of the condition and can provide auxiliary data to comprehend sulcus phenomenon in the larger facet. One such edifying objective noninvasive electrophysiological tool that facilitates observation of vocal fold vibratory properties is the EGG. By measuring the electrical resistance/conductance between two electrodes positioned approximately over the thyroid cartilages, EGG theoretically reflects vocal fold contact area variations. It is an entirely innocuous and easy to handle method of monitoring laryngeal vibrations, impervious to ambient noise. EGG has been in clinical vogue since decades for the purpose of phonatory analysis. Hence, it is essential to obtain glottal vibratory patterns through EGG in cases of sulcus and its types, providing vital attributes of vocal folds vibratory qualities, and validating the diagnosis made. In cases of dearth for other evaluation measures such as jitter, shimmer, and quality measures, EGG can provide legitimate information during differential diagnosis. Hence, the present study was intended to obtain qualitative EGG data in two types of the sulcus, the physiologic type, and the pathologic type and thereby identify morphological wave patterns associated with them.
| Method|| |
Forty individuals diagnosed as having bilateral sulcus vocalis through the procedure of videostroboscopy and in the age range of 20-35 years were recruited as participants for the study. All participants were ensured to be devoid of respiratory abnormalities and communicable diseases at the time of testing. It was also ensured that EGG could be carried out with ease in all the participants by observing for certain characteristics to control extrinsic variables. These being: Colossal head-neck circumference, excess fat tissues around the neck, having maximum phonation time <5-6 s. Participants in whom these features were not seen were alone included for the study.
A detailed case history was obtained from voice disordered individuals visiting AIISH; prior to the videostroboscopic recording procedure. During this, the presence/absence of vocally abusive behaviors, voice characteristics, and the breathing patterns were also observed.
In phase 2, videostroboscopic examination was executed by an experienced otolaryngologist on these voice disordered individuals. The digital video archive software version 2.5 (Xion medical GmbH company at the Xion headquarters in Berlin, Germany) from Xion Medical was used to video record. The stroboscope effect was obtained from the hardware, Xion Endo Strobe-D, and the LED light source from the hardware, Xion Xenon R-180 was utilized. During this procedure, the rigid scope was inserted into the back of the participant's oropharynx. Following this, a video recording was compiled of laryngeal movements during phonation of sustained vowel /i /at the individual's comfortable pitch. Participants who were overly sensitive to presence of scope in the oral cavity were given a topical anesthetic (lignocaine) to diminish the gag reflex. Following the stroboscopic recording, the otolaryngologist accompanied by two speech language pathologists experienced in voice disorders commented upon various aspects of glottic and supraglottic structures. Individuals, diagnosed as sulcus vocalis were alone recruited as participants for the current study which accounted up to 40.
The stroboscopic recordings, case histories and voice samples are obtained during the stroboscopic procedure of the participants were further reviewed in greater detail and were categorized as physiologic or pathologic sulcus types. For categorizing as physiologic sulcus certain criteria followed were: (1) Mostly an intact lamina propria, (2) a small depression/furrow extending posterior near vocal process, (3) lesser severity of voice complaints reported and voice quality perceptually observed to be near normal, and (4) most importantly having an intact mucosal wave. For categorizing as pathologic sulcus, criteria observed were: (1) Vocal folds bowing, (2) deep sulcus abnormality, (3) evident obliteration of functional lamina propria and body cover parting of the vocal cords, and (4) stiffened vocal tissue and disrupted vibratory properties, (5) spindle-shaped glottal insufficiency, (6) comparatively severe breathy and high-pitched voice on perceptual inspection.
Categorizing as physiologic and pathologic sulcus types 17 and 23 participants were found to constitute each group, respectively. Following this, all the participants were made to undergo the EGG procedure (EGG from KayPentax model 6103). Each participant was instructed to produce their typical voice by chanting "1, 2, 3 /i/" and sustaining phonation of vowel /i/ for a minimum of 6-8 s. Signal was thus recorded by passing high frequency low voltage current through the electrodes which captured the vocal fold contact pattern reflecting it as a waveform. Four main features of the resulting waveform observed qualitatively were: (I) A steep rising edge (analogous to closing phase), (II) a maximum peak (maximum closure), (III) a shallow falling edge (opening phase), and (IV) a trough essentially constant with time (analogous to open phase).  Relative lengths of these phases were found to fluctuate with voice quality. Thus, the waveform was interpreted by analyzing the patterns of wave morphology.
Following this, similar patterns of waveforms were grouped. Using descriptive statistics mean frequencies of each of the patterns under both the physiologic and the pathologic groups were calculated.
| Results|| |
Six patterns of EGG wave morphologies were obtained from the participants recordings which are: (1) Normal wave morphologies, (2) Prolonged open and opening phases, (3) Pit like depression in the closed phase of the waveform, (4) Abrupt closing phase and prolonged opening phase, (5) Prolonged open phase, (6) Weak or reduced amplitude of the waveforms. Using descriptive statistics, the mean percent frequency of these EGG waveform patterns occurring in physiologic, as well as pathologic sulcus groups were calculated. EGG waveform representations of patterns that were seen in physiologic and pathologic sulcus are provided in [Figure 1] and [Figure 2], respectively.
|Figure 1: Electroglottograph waveforms seen in physiologic group of sulcus|
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|Figure 2: Electroglottograph waveforms seen in pathologic group of sulcus|
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Of the total 40 EGG wave morphologies obtained, 17 constituted the physiologic group. Participants under the physiologic group demonstrated the following wave patterns with the following mean percent frequencies.
- 13 EGG recordings with normal wave morphologies (76.6%)
- Two EGG waveforms with reduced amplitude weak wave morphologies (11.7%)
- Two waveforms with a slightly prolonged open and the opening phases (11.7%).
Under the pathologic group of the sulcus, 23 EGG wave morphologies were obtained, the types and frequencies of which are given below:
- 9 EGG waveforms with a prolonged open phase (39.2%)
- 5 EGG waveforms with pit like/step like depressions in the closed phase (21.7%)
- 5 EGG waveforms with an abrupt closing phase and an increased opening phase (21.7%)
- 4 EGG waveforms with weak or reduced amplitudes (17.4%).
[Figure 3] and [Figure 4] provided below illustrate the mean percent frequencies of EGG wave morphologies for the physiologic and the pathologic sulcus groups, respectively.
|Figure 3: Percent frequencies of electroglottograph waveforms for physiologic sulcus group|
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|Figure 4: Percent frequencies of electroglottograph waveforms for pathologic sulcus group|
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| Discussion|| |
The current study revealed certain explicit and distinct trends in EGG patterns with respect to pathologic, as well as physiologic sulcus types. There were largely regular and typical patterns seen in physiologic sulcus participants accounting for about 76.6%. Interpretation of normal EGG pattern was based upon a report by Abberton et al.,  who provide typical EGG waveform features for normal modal voice. Evidence of normal EGG waveforms despite the presence of physiologic sulcus can be attributed to the presence of a mostly undamaged superficial lamina propria, vocal ligament, and an undamaged mucosal wave resulting in minimally altered or impaired voice quality.  Mostly regular and smooth periodic vocal cord vibrations were present in the majority of physiologic sulcus group participants despite the presence of slender grooved depression along the medial surface.
In four of the physiologic sulcus participants, the case history revealed the surgical excision of vocal fold cyst and polyp in two participants each, 5-6 months prior to the study. This could also be one of the antecedents to the development of trifling sulcus groove in these individuals leaving behind an almost intact lamina propria. This speculation can be further justified by the studies of Bouchayer et al.  and Ford et al.  who reported that vocal fold cysts are closely related to the development of sulcus. In these four participants specifically, reduced amplitude of EGG waveforms and prolonged open-opening phases were noticed. In remaining 13 participants, the presence of the sulcus groove can be attributed to the congenital developmental defects and deviancies in the vocal folds.  There was no evidence of vocal fold bowing or greater vocal fold atrophy in all the physiologic sulcus participants
In 23 of the 40 participants, a diagnostic inference of pathologic sulcus was concluded, and certain distinct EGG waveform patterns were observed. Most frequently obtained EGG waveform pattern was the prolonged open phase in the waveform. This could be predominantly owing to the presence of spindle-shaped glottal insufficiency, bowing of vocal cords containing deep sulcus deformity resulting in a breathy voice. These participants demonstrating prolonged open phase were predominantly noticed to exhibit breathiness invoice. Pit shaped/step like undulations in the closed phase was observed in five pathologic sulcus participants suggesting an abrupt or irregular closure between the two vocal folds at the point of sulcus deformity. Lim et al.  report similar findings of pit shaped undulations to be inherent in EGG waveforms of patients with Type III pathologic sulcus. Roughness invoice was the main perceptual feature inferred in these participants.
The presence of abrupt closing and a prolonged opening phase was found in five participants of pathologic sulcus, which could be attributed to reduced contact resulting in decreased closing phase between the vocal folds in action. This could be specifically escalating with increasing groove depth of sulcus deformity. With reduced closing time, opening or abducting time of the vocal folds was observed to be longer in EGG wave reflections too. Hoarseness with a dominant breathy quality of voice was the core perceptual feature in these participants. Weakened and reduced amplitude of waveforms was noticed in four participants, which may be owing to much-impaired lamina propria resulting in impaired glottic closure and an incomplete compensation.  Voice quality associated with these participants was an overall breathy and a feeble voice.
| Conclusions|| |
The present study was a preliminary attempt to explore the various EGG waveform patterns associated with physiologic and pathologic types of sulcus vocalis. The study clearly illustrates that in physiologic sulcus though there is slightly grooved depression, owing to a mostly intact lamina propria, EGG waveform usually abides with normalcy. In cases of the pathologic sulcus, varied deviant patterns of waveforms were obtained. Thus, the present study enhances the comprehension of sulcus deformity and its features through EGG patterns. In addition, the study provides an insight into the role of qualitative EGG pattern analysis in the differential diagnosis of sulcus types to voice clinicians. Future studies are warranted exploring EGG patterns and its quantitative measures among other sulcus types such as the pathologic sulcus Types II and III and in cases of Psuedosulcus.
| Acknowledgements|| |
We the authors hereby would like to acknowledge the director of AIISH, Dr. S.R. Savithri for providing us with the platform to conduct this research study. We further would like to thank Dr. Girish Kulkarni, consultant phonosurgeon Apollo hospital, Mysore; for his timely services and also all the participants of the study.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]