NIH Public Access Author Manuscript J Med Speech Lang Pathol. Author manuscript; available in PMC 2014 October 20.
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Published in final edited form as: J Med Speech Lang Pathol. ; 21(3): .
Stroboscopic Parameters Reported as Voice Outcome Measures in Patients Treated for Laryngeal Cancer: A Systematic Review Kendrea L. Focht, C.Sc.D., CCC-SLP1, Bonnie Martin-Harris, Ph.D., CCC-SLP, BRS-S1,2,3, and Heather Shaw Bonilha, Ph.D., CCC-SLP1 1Department
of Health Sciences and Research, Medical University of South Carolina, Charleston,
SC 2Evelyn
Trammell Institute of Voice and Swallowing Medical University of South Carolina, Charleston, SC
3Department
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of Otolaryngology – Head and Neck Surgery Medical University of South Carolina, Charleston, SC
Abstract Background—A systematic review of the use of stroboscopy as a treatment outcome measure of vocal fold function in patients treated for laryngeal cancer is presented. Methods—Computerized literature searches were performed. Eligible articles were admitted when stroboscopy was used to measure vocal fold function before and after treatment in patients with laryngeal cancer. Data extracted included: tumor stage and location, treatment modality, stroboscopy parameters, parameter scale, number of raters, rater reliability, methodology, and level of evidence. Results—Of 520 articles retrieved, 11 studies met inclusion criteria. A total of twenty-four parameters were reported. Rating scales and rater reliability varied.
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Discussion—Major methodological differences exist in studies using stroboscopic findings as voice outcome measures in patients’ post-cancer treatment. These differences lead to equivocal findings when assessing the utility of stroboscopy as an outcome measure. Standardized, reliable scoring and reporting systems for laryngeal stroboscopic examinations are needed. Keywords laryngeal cancer; stroboscopy; treatment; voice; systematic review
INTRODUCTION Approximately 13,000 men and women will be diagnosed with laryngeal cancer in the United States in 2012.1 Voice preservation is a primary functional goal in the treatment of laryngeal cancer. Laryngeal stroboscopy, which is considered the “gold standard” for observing vocal fold motion during voice evaluations, is a unique method for observing
Correspondence Author: Heather Shaw Bonilha, Ph.D., CCC-SLP, 77 President Street, MUSC 700, Charleston, SC, 29425, Phone: 843-792-2527, [email protected].
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normal and pathological vocal fold vibration during phonation.2,3 Stroboscopy uses a synchronized, flashing light passed through a flexible or rigid endoscope to create a slow motion view of vocal fold vibration, which is derived from many successive vocal fold vibration cycles.2,3 This slow motion view enables the examiner to observe the rapidly changing vocal fold vibratory properties during phonation.2,3 Stroboscopy is commonly used to assist in the differential diagnosis of voice disorders and in the evaluation of medical, surgical, and behavioral treatment outcomes for persons with voice disorders. Stroboscopy has been shown to improve accuracy of diagnosis and aid in targeted treatment planning for persons with voice disorders. Studies have demonstrated the use of stroboscopy frequently alters the diagnosis or treatment plan.4–6 Sataloff et al.4 reported the use of stroboscopy altered the diagnosis or treatment plan in approximately one-third of the patients for whom the procedure was indicated. A similar study of 732 patients found that stroboscopy improved diagnostic accuracy in 92% of cases.5 In addition to stroboscopy confirming diagnoses and making additional diagnoses in various patient populations with dysphonia, the use of stroboscopy has also been shown to correct previous diagnostic errors.4 von Leden6 reported that malignant laryngeal tumors could be diagnosed earlier when using stroboscopy compared with continuous light endoscopy.
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Although stroboscopy has been shown to aid in diagnosis of early laryngeal cancers, the usefulness of stroboscopy to assess voice outcomes after head and neck cancer treatments remains unspecified. The purpose of this literature review was two-fold: 1) evaluate the use of laryngeal stroboscopy as a treatment outcome measure of vocal fold function after laryngeal cancer treatments and 2) compare existing evidence to determine which therapeutic technique is related to the best voice outcomes as evidenced by stroboscopy. To achieve the first aim, we reviewed the literature and summarized the methods used and the results reported from laryngeal stroboscopic examinations. To achieve the second aim, we sought to perform a meta-analysis on the voice outcomes reported from the stroboscopic examinations.
MATERIALS and METHODS Search Strategy
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A search strategy was developed and implemented in two computerized journal databases (Pubmed and Cochrane) to identify all English language studies where stroboscopy was used as an outcome measure for assessing the effect of treatment on vocal fold function in patients post-cancer treatment. The following search terms were used: “laryngostroboscopy”, “stroboscopy”, “strobovideolaryngoscopy”, “strobolaryngoscopy”, “videostroboscopy”, and “videolaryngostroboscopy”. Each of the search terms was combined with “treatment.” Studies were reviewed with sole focus on patients treated for laryngeal cancer. All studies published from database inception through February 2011 were reviewed for eligibility. Unpublished reports were not considered for this review.
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Inclusion Criteria
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One reviewer (KF) assessed each study based on the following inclusion criteria in the following order: English language; original article; human study; laryngeal cancer; and stroboscopic findings reported both pre- and post-treatment. Duplicated results were deleted. Assessment of Evidence Eligible articles included in this review were categorized and evaluated for the use of stroboscopy parameters (i.e., features of laryngeal structure or function judged from stroboscopy examinations), parameter scale, number of raters, and rater reliability reported. Eligible articles were also evaluated on methodological quality and strength of the evidence.7 Methodological quality was evaluated independently by two raters (KF and HB) until 100% agreement was reached. Eligible studies were categorized according to an adapted version from the Oxford Centre for Evidence-based Medicine (see Table 1). This adapted framework follows traditional model of evidence hierarchies, which places the strongest evidence at Level I (e.g., randomized controlled trial) and the lowest level of evidence at Level V (e.g., expert report).7
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Data Synthesis The analysis was descriptive in nature because the heterogeneity of stroboscopic parameters reported, study design, and methodology precluded a robust statistical analysis (i.e., metaanalysis). Eligible studies are summarized in Table 2.
RESULTS Assessment of Evidence Of the 520 articles reviewed, 509 articles did not meet inclusion criteria as described above (see Figure 1). Of the 11 articles that met inclusion criteria, 7 articles reported stroboscopic parameters prior to and after cancer treatment, 3 articles reported stroboscopic parameters prior to and after voice restoration surgery after cancer treatment and 1 article reported parameters prior to and after behavioral voice treatment in patients’ post-cancer treatment. Participant Demographics
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The 11 studies that met inclusion criteria were comprised of a total of 480 patients (90% male; 10% female) who underwent pre- and post-cancer treatment laryngeal stroboscopic examinations. Mean age was not provided in all studies deemed eligible for this review. For the eight studies that provided age information, the mean age reported was 51.8 years (range: 15–78 years). Race and ethnicity were not reported in any study eligible for this review. Diagnosis and Treatment All studies reported patients treated for carcinoma of the glottic or supraglottic regions. Seven studies explicitly reported squamous cell carcinoma (see Table 3).8–14 The remaining four studies did not report histologic findings.15–18 Two studies examined longitudinal voice outcomes in patients treated with cordectomy for early glottic cancer,11,16 and three studies
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evaluated outcomes in cordectomy patients with an additional intervention.9,10,13 Knott et al.10 assessed outcomes in patients who underwent adjuvant cryotherapy in conjunction with surgery. Su and colleagues13 examined voice outcomes in cordectomy patients who subsequently underwent medialization laryngoplasty with bipedicled strap muscle transposition, and Guven et al.9 evaluated the use of autologous fat augmentation in patients with previous cordectomy procedures. For the remaining five studies, three studies14,17,18 assessed vocal fold function in patients who underwent radiotherapy, one study15 included patients treated with either concomitant chemotherapy and radiotherapy or radiotherapy alone, one study8 included patients treated with either concomitant chemotherapy and radiotherapy or radiotherapy alone, and the final study included patients who underwent modified arytenoid adduction after surgery and radiotherapy.12 In addition to examining vocal fold function after medical and surgical treatment for laryngeal cancer, vocal fold function prior to and after behavioral voice treatment in patients’ post-cancer treatment was reported in two studies.15,18 Levels of Evidence
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Varying methodologies and differing levels of evidence were reported in the studies reviewed. Most studies (72%) were prospective or retrospective non-experimental (case series) studies (Level III) (see Table 2). Only one study used a randomized-control design (Level I) by allocating patients post-endoscopic laser surgery to a voice therapy arm or a non-voice therapy arm.17 Stroboscopic Parameters and Scales Stroboscopic parameters used to describe vocal fold function as an outcome of cancer treatment varied across studies, with a total of 24 parameters reported (Table 4). The number of stroboscopic parameters reported also varied and ranged from one parameter to eight parameters when ratings of both the left and right vocal folds were considered as one parameter. The parameter scale used also varied, ranging from dichotomous items (yes/no, present/absent) to continuous rating scales with up to 100 levels.
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Parameters—The most commonly reported parameter across studies was glottal closure, followed by mucosal wave pattern, and amplitude of vocal fold vibration as detailed in Table 4. Glottal closure was used in 7 of the 11 eligible studies (63.6%). The next most common stroboscopic parameter reported was mucosal wave, which was reported in six studies (54.5%). The third most commonly reported parameter was true vocal fold vibratory amplitude (27.2%). Vocal fold vibratory amplitude and mucosal wave were both reported in three studies (27.2%). Vocal fold vibratory amplitude was never reported in the absence of report of mucosal wave; however, mucosal wave was reported without amplitude in three studies (27.2%). Less frequently reported parameters included: neoglottal closure, anterior commissure web, nonvibratory segment, and vascular injection (latter was undefined). Each of these parameters was cited in only one study. Two studies17,18 appeared to have used an adapted version of the Hirano and Bless rating form, although parameters reported were not consistent across these two studies.
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Rating Scales—Glottal closure, mucosal wave, amplitude of vibration, vocal fold edge, and arytenoid movement were the only vocal fold vibratory features rated in more than one study, which allowed for a comparison of rating scales across these parameters alone. Glottal closure was rated on a dichotomous scale in two studies,11,18 a three-point rating scale in one study,8 and a five-point rating scale in two studies.9,13 The scale used to measure glottal closure was not reported in two studies.12,17 Mucosal wave was rated in six studies,9,13,14,16–18 although in two studies, the scale used was not reported.16,17 In four studies that reported the mucosal wave rating scale, a dichotomous scale was used in two,13,14 a five-point rating scale was used in one,9 and a six-point rating scale was used in one.18 Amplitude of vibration was reported in three studies with a dichotomous scale was used in two,12,13 and a six-point scale was used in one.18 Of the two studies that reported vocal fold edge, a six-point scale was used in one,18 while the scale used in the other study was not reported.17 The scale used for arytenoid movement was not reported in either study where this parameter was used.12,17 Raters and Rater Reliability
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In seven of the 11 studies (63.6%) reviewed, the number of raters involved in scoring the stroboscopic parameters was reported.9,10,12,13,16–18 Two raters participated in three of the studies,9,13,17 while three raters participated in four of the studies.10,16,18 Inter-rater reliability was not reported in any of the studies reviewed. Intra-rater reliability was reported in one study, which found weighted k values ranging from 0.46 to 0.88 for 13 of the 14 parameters assessed.17 Phase symmetry was the one parameter found to have reliability below the acceptable level for that study (weighted k = 0.098) and was subsequently discarded from their analysis.17 Efficacy of Stroboscopic Assessment of Vocal Fold Function as Voice Outcome Measure in Patients Treated for Laryngeal Cancer
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Out of the 11 articles reviewed, two articles included statements of the benefits of using stroboscopic observations of vocal fold function as an outcome measure pre- and posttreatment for laryngeal cancer.14,18 Tsunoda et al.14 concluded stroboscopy may be a useful clinical tool during follow-up of patients treated with radiotherapy for early detection of recurrence of glottal carcinoma. Verdonck-de Leeuw and colleagues18 concluded the basic protocol for functional assessment of voice should include objective and subjective measures of the voice, including stroboscopic examination.
DISCUSSION Laryngeal stroboscopy has been identified as the “single most important tool for evaluation of voice disorders” (p. 423).19 Stroboscopy is useful for diagnosing laryngeal pathology, monitoring progress, providing biofeedback during treatment, educating patients, assessing treatment outcomes, and as a research method for investigating the larynx and laryngeal disorders.3–5,19,20 This systematic review demonstrated that stroboscopic findings are used in research as a voice outcome measure in patients treated for laryngeal cancer. However, the differences in the methods used and results reported from the stroboscopic examinations prohibited the comparison of therapeutic techniques.
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The parameters reported in the studies that used stroboscopy as an outcome measure varied greatly. Only two parameters, glottal closure and mucosal wave pattern, were reported in the majority of studies. A total of 24 different parameters were used across the 11 eligible studies. If the same parameters are not scored, then results of studies cannot be compared and a conclusion regarding best practices cannot be made. In this age of evidence-based practice and healthcare reform, it is important that research studies are comparable. Clinicians are told that they must make evidence-based decisions, yet the evidence is unavailable to make these decisions even when research has been published on the topic. With healthcare reform, the pressure is increasing to demonstrate comparative and cost effectiveness of clinical practices. If the evidence is not comparable, this cannot be accomplished. Without evidence to demonstrate comparative effectiveness, clinicians risk losing funding for unsupported practices.
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Even when the same parameters were used in studies being compared, the rating scales for those parameters differed. In some cases the scale used for one parameter varied from 2- to 100-levels. The discrepancy in the rating scales impedes the ability to compare treatment results. If one study found a treatment to be a “2” on a two-level scale compared to another treatment that was rated a “60”on a 100-level scale, then a comparison between the treatments is not possible.
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The rating methodologies (number of raters, rater reliability) also varied greatly across studies. The number of raters was reported in only a modest majority (64%) of the studies. Further, intra-rater reliability was only reported in one study, and inter-rater reliability was not reported in any of the studies. Intra-rater reliability found poor to moderate reliability for several parameters in the one study where it was reported, which is in line with our knowledge of the rater reliability difficulties in laryngeal endoscopy. These discrepancies in rater methodology and reporting significantly impede the ability to confidently interpret study findings. It is necessary that this information be reported in published studies for accurate conclusions to be drawn. Without such information, clinicians cannot evaluate evidence to inform clinical practice. The results of these 11 studies suggest that stroboscopy has potential to be a valuable and useful voice outcome measure tool in patients treated for laryngeal cancer. The utility of using stroboscopy during long-term follow-up after treatment for laryngeal cancer was evidenced by 6 studies using stroboscopy up to 10 years after patients completed their cancer treatment. However, the lack of a standard, reliable and valid method to measure and report findings from stroboscopy hinders its use as a treatment outcome measurement tool. The lack of standardization impedes communication regarding patients within and between clinics, diminishes the ability to identify changes following treatment, and precludes meaningful comparisons of treatment studies evaluated for evidence-based practice.19,21 There are three main limitations of this study. 1) This review used only published data available on two electronic databases. 2) The search terms used may not have been comprehensive enough to obtain all articles that have used stroboscopy as a treatment outcome measure. 3) The study is descriptive nature because the methods used in the sample of studies were not sufficiently similar to permit meta-analysis. These limitations
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notwithstanding, this review highlights critical issues that impede the understanding of true functional results when stroboscopic findings are reported as the primary outcome measure.
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CONCLUSIONS
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Anecdotal and clinical observational evidence support the value of stroboscopy in the assessment of patients treated for laryngeal cancer on vocal fold function. This review of the research demonstrates that stroboscopic findings are used as a voice outcome measure in patients treated for laryngeal cancer. This review revealed major methodological differences in studies using stroboscopic findings as voice outcome measures for patients following cancer treatment. The main differences noted in the review were: stroboscopic parameters reported, rating scales of those parameters used, and the reporting of number of raters and rater reliability. The differences found in study method, interpretation and reporting lead to equivocal findings about the effect of treatment on vocal fold function when assessing the utility of stroboscopy as a voice outcome measure. The ambiguity found in reporting stroboscopic findings, which are critical to the evaluation of voice outcome assessment, speak to the need for empirical development of a standardized, valid, and reliable method for interpretation and reporting of laryngeal stroboscopic findings as voice treatment outcome measures in patients with laryngeal cancer.
Acknowledgments This publication was supported by the South Carolina Clinical & Translational Research (SCTR) Institute, with an academic home at the Medical University of South Carolina, NIH/NCRR Grant number UL1 RR029880.
References
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1. National Cancer Institute. [Accessed June 18, 2012] What you need to know about the cancer of the larynx. NCI Web site. 2011. Available at: http://www.cancer.gov/cancertopics/wyntk/larynx/page1. 2. Hirano, M.; Bless, DM. Videostroboscopic examination of the larynx. San Diego: Singular Publishing Group; 1993. 3. Bless DM, Hirano M, Feder RJ. Videostroboscopic evaluation of the larynx. Ear Nose Throat J. 1987; 66:289–296. [PubMed: 3622324] 4. Sataloff RT, Spiegel JR, Hawkshaw MJ. Strobovideolaryngoscopy: results and clinical value. Ann Otol Rhinol Laryngol. 1991; 100:725–727. [PubMed: 1952664] 5. Remacle M. The contribution of videostroboscopy in daily ENT practice. Acta Otorhinolaryngol Belg. 1996; 50:265–281. [PubMed: 9001636] 6. von Leden H. The electronic synchron-stroboscope: its value for the practicing laryngologist. Ann Otol Rhinol Laryngol. 1961; 70:881–893. [PubMed: 14463406] 7. Centre for Evidence-based Medicine. [Accessed November 11, 2011] Levels of evidence. CEBM Web site. 2009. Available at: http://www.cebm.net/index.aspx?o=1025. 8. Dursun G, Ozgursoy OB. Laryngeal reconstruction by platysma myofascial flap after vertical partial laryngectomy. Head Neck. 2005; 27:762–770. [PubMed: 16097014] 9. Guven M, Suoglu Y, Kiyak E, Demir D. Autologous fat augmentation for voice and swallow improvement after cordectomy. ORL J Otorhinolaryngol Relat Spec. 2006; 68:164–169. [PubMed: 16465071] 10. Knott PD, Milstein CF, Hicks DM, Abelson TI, Byrd MC, Strome M. Vocal outcomes after laser resection of early-stage glottic cancer with adjuvant cryotherapy. Arch Otolaryngol Head Neck Surg. 2006; 132:1226–1230. [PubMed: 17116819]
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11. Peretti G, Piazza C, Balzanelli C, Cantarella G, Nicolai P. Vocal outcome after endoscopic cordectomies for Tis and T1 glottic carcinomas. Ann Otol Rhinol Laryngol. 2003; 112:174–179. [PubMed: 12597292] 12. Shi J, Chen S, Chen D, Wang W, Xia S, Zheng H. Modified arytenoid adduction for cancer-related unilateral vocal fold paralysis. J Laryngol Otol. 2011; 125:173–180. [PubMed: 21106137] 13. Su CY, Chuang HC, Tsai SS, Chiu JF. Bipedicled strap muscle transposition for vocal fold deficit after laser cordectomy in early glottic cancer patients. Laryngoscope. 2005; 115:528–533. [PubMed: 15744171] 14. Tsunoda K, Soda Y, Tojima Het al. Stroboscopic observation of the larynx after radiation in patients with T1 glottic carcinoma. Acta Otolaryngol Suppl. 1997; 527:165–166. [PubMed: 9197511] 15. Iloabachie K, Nathan CO, Ampil F, Morgan ML, Caldito G. Return of vocal cord movement: an independent predictor of response to nonsurgical management of laryngeal cancers. Laryngoscope. 2007; 117:1925–1929. [PubMed: 17828050] 16. Keilmann A, Napiontek U, Engel C, Nakarat T, Schneider A, Mann W. Long-term functional outcome after unilateral cordectomy. ORL J Otorhinolaryngol Relat Spec. 73:38–46. [PubMed: 21150233] 17. van Gogh CDL, Verdonck-de Leeuw IM, Boon-Kamma BA, Rinkel RNPM, de Bruin MD. The efficacy of voice therapy in patients after treatment for early glottic carcinoma. Cancer. 2005; 106:95–105. [PubMed: 16323175] 18. Verdonck-de Leeuw IM, Hilgers FJ, Keus RBet al. Multidimensional assessment of voice characteristics after radiotherapy for early glottic cancer. Laryngoscope. 1999; 109:241–248. [PubMed: 10890774] 19. Rosen CA. Stroboscopy as a research instrument: development of a perceptual evaluation tool. Laryngoscope. 2005; 115:423–428. [PubMed: 15744150] 20. Faure M-A, Muller A. Stroboscopy. J Voice. 1992; 6:139–148. 21. Altman KW. Dysphagia evaluation and care in the hospital setting: the need for protocolization. Otolaryngol Head Neck Surg. 2011; 145:895–898. [PubMed: 21750340]
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Figure 1.
Steps in Identification of Eligible Studies.
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Table 1
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Levels of Evidence.* Level
Description
Ia
Well-designed meta-analysis of >1 randomized controlled trial
Ib
Well-designed randomized controlled study
IIa
Well-designed controlled study without randomization
IIb
Well-designed quasi-experimental study
III
Well-designed non-experimental studies, i.e., correlation and case studies
IV
Expert committee report, consensus conference, clinical experience of respected authorities
*
Adapted from the Scottish Intercollegiate Guidelines Network. Retrieved online at http://www.asha.org/members/ebg/assessing.htm
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Table 2
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Summary of Eligible Studies. First Author
Publication Year
Methodology*
Level of Evidence*
Dursun8
2005
Prospective longitudinal case series
Level IV
Guven9
2006
Prospective longitudinal case series
Level IV
Iloabachie15
2007
Retrospective case series
Level IV
Keilmann16
2011
Prospective longitudinal case series
Level IV
Knott10
2006
Retrospective case series
Level IV
Peretti11
2003
Prospective longitudinal cohort
Level IIa
Shi12
2011
Retrospective case series
Level IV
Su13
2005
Prospective longitudinal case series
Level IV
Tsunoda14
1997
Prospective case series
Level IV
2006
Randomized-controlled trial
Level Ib
1999
Prospective longitudinal cohort
Level IIa
van
Gogh17
Verdonck-de Leeuw18 *
http://www.cebm.net/index.aspx?o=1025
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Table 3
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Summary of Cancer-Related Information.
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First Author
Participants
Lesion Stage and Lesion Site
HNC Treatment and Reconstruction
Dursun8
15 M
T2 Glottic SCC
Vertical partial laryngectomy with laryngeal reconstruction by platysma myofascial flap
Guven9
9M 1F
Early-stage Glottic SCC
Endoscopic laser and laryngofissure cordectomy with subsequent autologous fat injection into neocord
Iloabachie15
13 M 1F
T2 Laryngeal tumor (n=6) T3 Laryngeal tumor (n=8) Supraglottic tumor (n=7) Glottic tumor (n=7)
Radiotherapy (n=9) Concomitant chemotherapy and radiotherapy (n=5)
Keilmann16
16 M
T1a VF tumor (n=11) T1b VF tumor (n=1) T2 VF tumor (n=4)
Endoscopic CO2 laser resection
Knott10
20 males
Tis (n=3) T1a Glottic SCC (n=10) T1b Glottic SCC (n=3) T2 Glottic SCC (n=4)
Endoscopic CO2 laser resection in conjunction with cryoablation
Peretti11
97 M 4F
Glottic SCC
Endoscopic CO2 laser resection
Shi12
20 M 17 F
Thyroid cancer (n=12) Esophageal cancer (n=8) Lung cancer (n=2) Metastatic SCC of unknown primary site (n=2) Nasopharyngeal cancer (n=4) Not reported (n=9)
Surgery and radiotherapy with subsequent modified arytenoid adduction
Su13
13 M
T1 Glottic SCC
Endoscopic laser cordectomy with subsequent medialization laryngoplasty with bipedicled strap muscle transposition
Tsunoda14
9M 1F
T1 Glottic SCC
Radiotherapy
23 M
T1 Early glottic carcinoma T2 Early glottic carcinoma
Radiotherapy
60 M
T1 Early glottic carcinoma
Radiotherapy
van Gogh17 Verdonck-de
Leeuw18
M-males; SCC-squamous cell carcinoma; F-females; CO2-carbon dioxide
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Table 4
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Summary of Stroboscopic Parameters Reported in Eligible Studies. Article (First Author)
Stroboscopy Reported Findings
Dursun8
Neoglottal closure (3-point rating scale) Status of neofold during inspiration and phonation (normal/abnormal)
Guven9
Glottal closure (5-point rating scale) Mucosal wave pattern (5-point rating scale)
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Iloabachie15
Vocal cord mobility (yes/no)
Keilmann16
Ott et al. classification assessment (15-point rating scale) Morphological changes Glottal closure Mucosal wave pattern Level of phonation (3-point categorical scale)
Knott10
100-point continuous data scale
Peretti11
Glottal closure (complete/incomplete) Anterior commissure web (present/absent)
Shi12
Glottal closure Vertical vocal fold difference Arytenoid movement Bowing (yes/no) Atrophy (yes/no)
Su13
Mucosal wave pattern (normal/decreased) Mucosal wave amplitude (normal/decreased) Glottal closure (5-point rating scale)
Tsunoda14
Mucosal wave (presence/absence) Amplitude of vocal fold vibration (normal/reduced)
van Gogh17
Adapted Hirano and Bless rating form: Overall laryngeal anatomy Vocal fold edge Arytenoid movement Arytenoid symmetry Vocal fold movement Mucosal wave pattern Irregularity Periodicity Glottal closure
Verdonck-de Leeuw18
Adapted Hirano and Bless rating form: Overall laryngeal anatomy Glottic edema (4-point rating scale) Supraglottic edema (4-point rating scale) Vascular injection (4-point rating scale) Supraglottic involvement (6-point rating scale) Regularity of vocal cord edge (6-point rating scale) Amplitude of vocal fold (6-point rating scale) Mucosal wave (6-point rating scale) Nonvibrating portion (6-point rating scale) Glottal closure (yes/no, description)
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Table 5
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Summary of Reported Reliability in Eligible Studies. Reported Reliability (yes/no)
Number of Raters
Dursun8
No
Not reported
N/A
Guven9
No
2
N/A
Iloabachie15
No
Not reported
N/A
Article (First Author)
Results of Reliability
Keilmann16
No
3
N/A
Knott10
No
3
N/A
Peretti11
No
Not reported
N/A
Shi12
No
3
N/A
Su13
No
2
N/A
Tsunoda14
No
Not reported
N/A
Yes
2
Weighted k values range: 0.098 – 0.88
No
3
N/A
van
Gogh17
Verdonck-de
Leeuw18
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N/A-Not Applicable
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Published in final edited form as: J Med Speech Lang Pathol. ; 21(3): .
Stroboscopic Parameters Reported as Voice Outcome Measures in Patients Treated for Laryngeal Cancer: A Systematic Review Kendrea L. Focht, C.Sc.D., CCC-SLP1, Bonnie Martin-Harris, Ph.D., CCC-SLP, BRS-S1,2,3, and Heather Shaw Bonilha, Ph.D., CCC-SLP1 1Department
of Health Sciences and Research, Medical University of South Carolina, Charleston,
SC 2Evelyn
Trammell Institute of Voice and Swallowing Medical University of South Carolina, Charleston, SC
3Department
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of Otolaryngology – Head and Neck Surgery Medical University of South Carolina, Charleston, SC
Abstract Background—A systematic review of the use of stroboscopy as a treatment outcome measure of vocal fold function in patients treated for laryngeal cancer is presented. Methods—Computerized literature searches were performed. Eligible articles were admitted when stroboscopy was used to measure vocal fold function before and after treatment in patients with laryngeal cancer. Data extracted included: tumor stage and location, treatment modality, stroboscopy parameters, parameter scale, number of raters, rater reliability, methodology, and level of evidence. Results—Of 520 articles retrieved, 11 studies met inclusion criteria. A total of twenty-four parameters were reported. Rating scales and rater reliability varied.
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Discussion—Major methodological differences exist in studies using stroboscopic findings as voice outcome measures in patients’ post-cancer treatment. These differences lead to equivocal findings when assessing the utility of stroboscopy as an outcome measure. Standardized, reliable scoring and reporting systems for laryngeal stroboscopic examinations are needed. Keywords laryngeal cancer; stroboscopy; treatment; voice; systematic review
INTRODUCTION Approximately 13,000 men and women will be diagnosed with laryngeal cancer in the United States in 2012.1 Voice preservation is a primary functional goal in the treatment of laryngeal cancer. Laryngeal stroboscopy, which is considered the “gold standard” for observing vocal fold motion during voice evaluations, is a unique method for observing
Correspondence Author: Heather Shaw Bonilha, Ph.D., CCC-SLP, 77 President Street, MUSC 700, Charleston, SC, 29425, Phone: 843-792-2527, [email protected].
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normal and pathological vocal fold vibration during phonation.2,3 Stroboscopy uses a synchronized, flashing light passed through a flexible or rigid endoscope to create a slow motion view of vocal fold vibration, which is derived from many successive vocal fold vibration cycles.2,3 This slow motion view enables the examiner to observe the rapidly changing vocal fold vibratory properties during phonation.2,3 Stroboscopy is commonly used to assist in the differential diagnosis of voice disorders and in the evaluation of medical, surgical, and behavioral treatment outcomes for persons with voice disorders. Stroboscopy has been shown to improve accuracy of diagnosis and aid in targeted treatment planning for persons with voice disorders. Studies have demonstrated the use of stroboscopy frequently alters the diagnosis or treatment plan.4–6 Sataloff et al.4 reported the use of stroboscopy altered the diagnosis or treatment plan in approximately one-third of the patients for whom the procedure was indicated. A similar study of 732 patients found that stroboscopy improved diagnostic accuracy in 92% of cases.5 In addition to stroboscopy confirming diagnoses and making additional diagnoses in various patient populations with dysphonia, the use of stroboscopy has also been shown to correct previous diagnostic errors.4 von Leden6 reported that malignant laryngeal tumors could be diagnosed earlier when using stroboscopy compared with continuous light endoscopy.
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Although stroboscopy has been shown to aid in diagnosis of early laryngeal cancers, the usefulness of stroboscopy to assess voice outcomes after head and neck cancer treatments remains unspecified. The purpose of this literature review was two-fold: 1) evaluate the use of laryngeal stroboscopy as a treatment outcome measure of vocal fold function after laryngeal cancer treatments and 2) compare existing evidence to determine which therapeutic technique is related to the best voice outcomes as evidenced by stroboscopy. To achieve the first aim, we reviewed the literature and summarized the methods used and the results reported from laryngeal stroboscopic examinations. To achieve the second aim, we sought to perform a meta-analysis on the voice outcomes reported from the stroboscopic examinations.
MATERIALS and METHODS Search Strategy
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A search strategy was developed and implemented in two computerized journal databases (Pubmed and Cochrane) to identify all English language studies where stroboscopy was used as an outcome measure for assessing the effect of treatment on vocal fold function in patients post-cancer treatment. The following search terms were used: “laryngostroboscopy”, “stroboscopy”, “strobovideolaryngoscopy”, “strobolaryngoscopy”, “videostroboscopy”, and “videolaryngostroboscopy”. Each of the search terms was combined with “treatment.” Studies were reviewed with sole focus on patients treated for laryngeal cancer. All studies published from database inception through February 2011 were reviewed for eligibility. Unpublished reports were not considered for this review.
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Inclusion Criteria
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One reviewer (KF) assessed each study based on the following inclusion criteria in the following order: English language; original article; human study; laryngeal cancer; and stroboscopic findings reported both pre- and post-treatment. Duplicated results were deleted. Assessment of Evidence Eligible articles included in this review were categorized and evaluated for the use of stroboscopy parameters (i.e., features of laryngeal structure or function judged from stroboscopy examinations), parameter scale, number of raters, and rater reliability reported. Eligible articles were also evaluated on methodological quality and strength of the evidence.7 Methodological quality was evaluated independently by two raters (KF and HB) until 100% agreement was reached. Eligible studies were categorized according to an adapted version from the Oxford Centre for Evidence-based Medicine (see Table 1). This adapted framework follows traditional model of evidence hierarchies, which places the strongest evidence at Level I (e.g., randomized controlled trial) and the lowest level of evidence at Level V (e.g., expert report).7
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Data Synthesis The analysis was descriptive in nature because the heterogeneity of stroboscopic parameters reported, study design, and methodology precluded a robust statistical analysis (i.e., metaanalysis). Eligible studies are summarized in Table 2.
RESULTS Assessment of Evidence Of the 520 articles reviewed, 509 articles did not meet inclusion criteria as described above (see Figure 1). Of the 11 articles that met inclusion criteria, 7 articles reported stroboscopic parameters prior to and after cancer treatment, 3 articles reported stroboscopic parameters prior to and after voice restoration surgery after cancer treatment and 1 article reported parameters prior to and after behavioral voice treatment in patients’ post-cancer treatment. Participant Demographics
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The 11 studies that met inclusion criteria were comprised of a total of 480 patients (90% male; 10% female) who underwent pre- and post-cancer treatment laryngeal stroboscopic examinations. Mean age was not provided in all studies deemed eligible for this review. For the eight studies that provided age information, the mean age reported was 51.8 years (range: 15–78 years). Race and ethnicity were not reported in any study eligible for this review. Diagnosis and Treatment All studies reported patients treated for carcinoma of the glottic or supraglottic regions. Seven studies explicitly reported squamous cell carcinoma (see Table 3).8–14 The remaining four studies did not report histologic findings.15–18 Two studies examined longitudinal voice outcomes in patients treated with cordectomy for early glottic cancer,11,16 and three studies
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evaluated outcomes in cordectomy patients with an additional intervention.9,10,13 Knott et al.10 assessed outcomes in patients who underwent adjuvant cryotherapy in conjunction with surgery. Su and colleagues13 examined voice outcomes in cordectomy patients who subsequently underwent medialization laryngoplasty with bipedicled strap muscle transposition, and Guven et al.9 evaluated the use of autologous fat augmentation in patients with previous cordectomy procedures. For the remaining five studies, three studies14,17,18 assessed vocal fold function in patients who underwent radiotherapy, one study15 included patients treated with either concomitant chemotherapy and radiotherapy or radiotherapy alone, one study8 included patients treated with either concomitant chemotherapy and radiotherapy or radiotherapy alone, and the final study included patients who underwent modified arytenoid adduction after surgery and radiotherapy.12 In addition to examining vocal fold function after medical and surgical treatment for laryngeal cancer, vocal fold function prior to and after behavioral voice treatment in patients’ post-cancer treatment was reported in two studies.15,18 Levels of Evidence
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Varying methodologies and differing levels of evidence were reported in the studies reviewed. Most studies (72%) were prospective or retrospective non-experimental (case series) studies (Level III) (see Table 2). Only one study used a randomized-control design (Level I) by allocating patients post-endoscopic laser surgery to a voice therapy arm or a non-voice therapy arm.17 Stroboscopic Parameters and Scales Stroboscopic parameters used to describe vocal fold function as an outcome of cancer treatment varied across studies, with a total of 24 parameters reported (Table 4). The number of stroboscopic parameters reported also varied and ranged from one parameter to eight parameters when ratings of both the left and right vocal folds were considered as one parameter. The parameter scale used also varied, ranging from dichotomous items (yes/no, present/absent) to continuous rating scales with up to 100 levels.
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Parameters—The most commonly reported parameter across studies was glottal closure, followed by mucosal wave pattern, and amplitude of vocal fold vibration as detailed in Table 4. Glottal closure was used in 7 of the 11 eligible studies (63.6%). The next most common stroboscopic parameter reported was mucosal wave, which was reported in six studies (54.5%). The third most commonly reported parameter was true vocal fold vibratory amplitude (27.2%). Vocal fold vibratory amplitude and mucosal wave were both reported in three studies (27.2%). Vocal fold vibratory amplitude was never reported in the absence of report of mucosal wave; however, mucosal wave was reported without amplitude in three studies (27.2%). Less frequently reported parameters included: neoglottal closure, anterior commissure web, nonvibratory segment, and vascular injection (latter was undefined). Each of these parameters was cited in only one study. Two studies17,18 appeared to have used an adapted version of the Hirano and Bless rating form, although parameters reported were not consistent across these two studies.
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Rating Scales—Glottal closure, mucosal wave, amplitude of vibration, vocal fold edge, and arytenoid movement were the only vocal fold vibratory features rated in more than one study, which allowed for a comparison of rating scales across these parameters alone. Glottal closure was rated on a dichotomous scale in two studies,11,18 a three-point rating scale in one study,8 and a five-point rating scale in two studies.9,13 The scale used to measure glottal closure was not reported in two studies.12,17 Mucosal wave was rated in six studies,9,13,14,16–18 although in two studies, the scale used was not reported.16,17 In four studies that reported the mucosal wave rating scale, a dichotomous scale was used in two,13,14 a five-point rating scale was used in one,9 and a six-point rating scale was used in one.18 Amplitude of vibration was reported in three studies with a dichotomous scale was used in two,12,13 and a six-point scale was used in one.18 Of the two studies that reported vocal fold edge, a six-point scale was used in one,18 while the scale used in the other study was not reported.17 The scale used for arytenoid movement was not reported in either study where this parameter was used.12,17 Raters and Rater Reliability
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In seven of the 11 studies (63.6%) reviewed, the number of raters involved in scoring the stroboscopic parameters was reported.9,10,12,13,16–18 Two raters participated in three of the studies,9,13,17 while three raters participated in four of the studies.10,16,18 Inter-rater reliability was not reported in any of the studies reviewed. Intra-rater reliability was reported in one study, which found weighted k values ranging from 0.46 to 0.88 for 13 of the 14 parameters assessed.17 Phase symmetry was the one parameter found to have reliability below the acceptable level for that study (weighted k = 0.098) and was subsequently discarded from their analysis.17 Efficacy of Stroboscopic Assessment of Vocal Fold Function as Voice Outcome Measure in Patients Treated for Laryngeal Cancer
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Out of the 11 articles reviewed, two articles included statements of the benefits of using stroboscopic observations of vocal fold function as an outcome measure pre- and posttreatment for laryngeal cancer.14,18 Tsunoda et al.14 concluded stroboscopy may be a useful clinical tool during follow-up of patients treated with radiotherapy for early detection of recurrence of glottal carcinoma. Verdonck-de Leeuw and colleagues18 concluded the basic protocol for functional assessment of voice should include objective and subjective measures of the voice, including stroboscopic examination.
DISCUSSION Laryngeal stroboscopy has been identified as the “single most important tool for evaluation of voice disorders” (p. 423).19 Stroboscopy is useful for diagnosing laryngeal pathology, monitoring progress, providing biofeedback during treatment, educating patients, assessing treatment outcomes, and as a research method for investigating the larynx and laryngeal disorders.3–5,19,20 This systematic review demonstrated that stroboscopic findings are used in research as a voice outcome measure in patients treated for laryngeal cancer. However, the differences in the methods used and results reported from the stroboscopic examinations prohibited the comparison of therapeutic techniques.
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The parameters reported in the studies that used stroboscopy as an outcome measure varied greatly. Only two parameters, glottal closure and mucosal wave pattern, were reported in the majority of studies. A total of 24 different parameters were used across the 11 eligible studies. If the same parameters are not scored, then results of studies cannot be compared and a conclusion regarding best practices cannot be made. In this age of evidence-based practice and healthcare reform, it is important that research studies are comparable. Clinicians are told that they must make evidence-based decisions, yet the evidence is unavailable to make these decisions even when research has been published on the topic. With healthcare reform, the pressure is increasing to demonstrate comparative and cost effectiveness of clinical practices. If the evidence is not comparable, this cannot be accomplished. Without evidence to demonstrate comparative effectiveness, clinicians risk losing funding for unsupported practices.
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Even when the same parameters were used in studies being compared, the rating scales for those parameters differed. In some cases the scale used for one parameter varied from 2- to 100-levels. The discrepancy in the rating scales impedes the ability to compare treatment results. If one study found a treatment to be a “2” on a two-level scale compared to another treatment that was rated a “60”on a 100-level scale, then a comparison between the treatments is not possible.
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The rating methodologies (number of raters, rater reliability) also varied greatly across studies. The number of raters was reported in only a modest majority (64%) of the studies. Further, intra-rater reliability was only reported in one study, and inter-rater reliability was not reported in any of the studies. Intra-rater reliability found poor to moderate reliability for several parameters in the one study where it was reported, which is in line with our knowledge of the rater reliability difficulties in laryngeal endoscopy. These discrepancies in rater methodology and reporting significantly impede the ability to confidently interpret study findings. It is necessary that this information be reported in published studies for accurate conclusions to be drawn. Without such information, clinicians cannot evaluate evidence to inform clinical practice. The results of these 11 studies suggest that stroboscopy has potential to be a valuable and useful voice outcome measure tool in patients treated for laryngeal cancer. The utility of using stroboscopy during long-term follow-up after treatment for laryngeal cancer was evidenced by 6 studies using stroboscopy up to 10 years after patients completed their cancer treatment. However, the lack of a standard, reliable and valid method to measure and report findings from stroboscopy hinders its use as a treatment outcome measurement tool. The lack of standardization impedes communication regarding patients within and between clinics, diminishes the ability to identify changes following treatment, and precludes meaningful comparisons of treatment studies evaluated for evidence-based practice.19,21 There are three main limitations of this study. 1) This review used only published data available on two electronic databases. 2) The search terms used may not have been comprehensive enough to obtain all articles that have used stroboscopy as a treatment outcome measure. 3) The study is descriptive nature because the methods used in the sample of studies were not sufficiently similar to permit meta-analysis. These limitations
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notwithstanding, this review highlights critical issues that impede the understanding of true functional results when stroboscopic findings are reported as the primary outcome measure.
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CONCLUSIONS
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Anecdotal and clinical observational evidence support the value of stroboscopy in the assessment of patients treated for laryngeal cancer on vocal fold function. This review of the research demonstrates that stroboscopic findings are used as a voice outcome measure in patients treated for laryngeal cancer. This review revealed major methodological differences in studies using stroboscopic findings as voice outcome measures for patients following cancer treatment. The main differences noted in the review were: stroboscopic parameters reported, rating scales of those parameters used, and the reporting of number of raters and rater reliability. The differences found in study method, interpretation and reporting lead to equivocal findings about the effect of treatment on vocal fold function when assessing the utility of stroboscopy as a voice outcome measure. The ambiguity found in reporting stroboscopic findings, which are critical to the evaluation of voice outcome assessment, speak to the need for empirical development of a standardized, valid, and reliable method for interpretation and reporting of laryngeal stroboscopic findings as voice treatment outcome measures in patients with laryngeal cancer.
Acknowledgments This publication was supported by the South Carolina Clinical & Translational Research (SCTR) Institute, with an academic home at the Medical University of South Carolina, NIH/NCRR Grant number UL1 RR029880.
References
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1. National Cancer Institute. [Accessed June 18, 2012] What you need to know about the cancer of the larynx. NCI Web site. 2011. Available at: http://www.cancer.gov/cancertopics/wyntk/larynx/page1. 2. Hirano, M.; Bless, DM. Videostroboscopic examination of the larynx. San Diego: Singular Publishing Group; 1993. 3. Bless DM, Hirano M, Feder RJ. Videostroboscopic evaluation of the larynx. Ear Nose Throat J. 1987; 66:289–296. [PubMed: 3622324] 4. Sataloff RT, Spiegel JR, Hawkshaw MJ. Strobovideolaryngoscopy: results and clinical value. Ann Otol Rhinol Laryngol. 1991; 100:725–727. [PubMed: 1952664] 5. Remacle M. The contribution of videostroboscopy in daily ENT practice. Acta Otorhinolaryngol Belg. 1996; 50:265–281. [PubMed: 9001636] 6. von Leden H. The electronic synchron-stroboscope: its value for the practicing laryngologist. Ann Otol Rhinol Laryngol. 1961; 70:881–893. [PubMed: 14463406] 7. Centre for Evidence-based Medicine. [Accessed November 11, 2011] Levels of evidence. CEBM Web site. 2009. Available at: http://www.cebm.net/index.aspx?o=1025. 8. Dursun G, Ozgursoy OB. Laryngeal reconstruction by platysma myofascial flap after vertical partial laryngectomy. Head Neck. 2005; 27:762–770. [PubMed: 16097014] 9. Guven M, Suoglu Y, Kiyak E, Demir D. Autologous fat augmentation for voice and swallow improvement after cordectomy. ORL J Otorhinolaryngol Relat Spec. 2006; 68:164–169. [PubMed: 16465071] 10. Knott PD, Milstein CF, Hicks DM, Abelson TI, Byrd MC, Strome M. Vocal outcomes after laser resection of early-stage glottic cancer with adjuvant cryotherapy. Arch Otolaryngol Head Neck Surg. 2006; 132:1226–1230. [PubMed: 17116819]
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11. Peretti G, Piazza C, Balzanelli C, Cantarella G, Nicolai P. Vocal outcome after endoscopic cordectomies for Tis and T1 glottic carcinomas. Ann Otol Rhinol Laryngol. 2003; 112:174–179. [PubMed: 12597292] 12. Shi J, Chen S, Chen D, Wang W, Xia S, Zheng H. Modified arytenoid adduction for cancer-related unilateral vocal fold paralysis. J Laryngol Otol. 2011; 125:173–180. [PubMed: 21106137] 13. Su CY, Chuang HC, Tsai SS, Chiu JF. Bipedicled strap muscle transposition for vocal fold deficit after laser cordectomy in early glottic cancer patients. Laryngoscope. 2005; 115:528–533. [PubMed: 15744171] 14. Tsunoda K, Soda Y, Tojima Het al. Stroboscopic observation of the larynx after radiation in patients with T1 glottic carcinoma. Acta Otolaryngol Suppl. 1997; 527:165–166. [PubMed: 9197511] 15. Iloabachie K, Nathan CO, Ampil F, Morgan ML, Caldito G. Return of vocal cord movement: an independent predictor of response to nonsurgical management of laryngeal cancers. Laryngoscope. 2007; 117:1925–1929. [PubMed: 17828050] 16. Keilmann A, Napiontek U, Engel C, Nakarat T, Schneider A, Mann W. Long-term functional outcome after unilateral cordectomy. ORL J Otorhinolaryngol Relat Spec. 73:38–46. [PubMed: 21150233] 17. van Gogh CDL, Verdonck-de Leeuw IM, Boon-Kamma BA, Rinkel RNPM, de Bruin MD. The efficacy of voice therapy in patients after treatment for early glottic carcinoma. Cancer. 2005; 106:95–105. [PubMed: 16323175] 18. Verdonck-de Leeuw IM, Hilgers FJ, Keus RBet al. Multidimensional assessment of voice characteristics after radiotherapy for early glottic cancer. Laryngoscope. 1999; 109:241–248. [PubMed: 10890774] 19. Rosen CA. Stroboscopy as a research instrument: development of a perceptual evaluation tool. Laryngoscope. 2005; 115:423–428. [PubMed: 15744150] 20. Faure M-A, Muller A. Stroboscopy. J Voice. 1992; 6:139–148. 21. Altman KW. Dysphagia evaluation and care in the hospital setting: the need for protocolization. Otolaryngol Head Neck Surg. 2011; 145:895–898. [PubMed: 21750340]
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Figure 1.
Steps in Identification of Eligible Studies.
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Table 1
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Levels of Evidence.* Level
Description
Ia
Well-designed meta-analysis of >1 randomized controlled trial
Ib
Well-designed randomized controlled study
IIa
Well-designed controlled study without randomization
IIb
Well-designed quasi-experimental study
III
Well-designed non-experimental studies, i.e., correlation and case studies
IV
Expert committee report, consensus conference, clinical experience of respected authorities
*
Adapted from the Scottish Intercollegiate Guidelines Network. Retrieved online at http://www.asha.org/members/ebg/assessing.htm
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Table 2
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Summary of Eligible Studies. First Author
Publication Year
Methodology*
Level of Evidence*
Dursun8
2005
Prospective longitudinal case series
Level IV
Guven9
2006
Prospective longitudinal case series
Level IV
Iloabachie15
2007
Retrospective case series
Level IV
Keilmann16
2011
Prospective longitudinal case series
Level IV
Knott10
2006
Retrospective case series
Level IV
Peretti11
2003
Prospective longitudinal cohort
Level IIa
Shi12
2011
Retrospective case series
Level IV
Su13
2005
Prospective longitudinal case series
Level IV
Tsunoda14
1997
Prospective case series
Level IV
2006
Randomized-controlled trial
Level Ib
1999
Prospective longitudinal cohort
Level IIa
van
Gogh17
Verdonck-de Leeuw18 *
http://www.cebm.net/index.aspx?o=1025
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Table 3
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Summary of Cancer-Related Information.
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First Author
Participants
Lesion Stage and Lesion Site
HNC Treatment and Reconstruction
Dursun8
15 M
T2 Glottic SCC
Vertical partial laryngectomy with laryngeal reconstruction by platysma myofascial flap
Guven9
9M 1F
Early-stage Glottic SCC
Endoscopic laser and laryngofissure cordectomy with subsequent autologous fat injection into neocord
Iloabachie15
13 M 1F
T2 Laryngeal tumor (n=6) T3 Laryngeal tumor (n=8) Supraglottic tumor (n=7) Glottic tumor (n=7)
Radiotherapy (n=9) Concomitant chemotherapy and radiotherapy (n=5)
Keilmann16
16 M
T1a VF tumor (n=11) T1b VF tumor (n=1) T2 VF tumor (n=4)
Endoscopic CO2 laser resection
Knott10
20 males
Tis (n=3) T1a Glottic SCC (n=10) T1b Glottic SCC (n=3) T2 Glottic SCC (n=4)
Endoscopic CO2 laser resection in conjunction with cryoablation
Peretti11
97 M 4F
Glottic SCC
Endoscopic CO2 laser resection
Shi12
20 M 17 F
Thyroid cancer (n=12) Esophageal cancer (n=8) Lung cancer (n=2) Metastatic SCC of unknown primary site (n=2) Nasopharyngeal cancer (n=4) Not reported (n=9)
Surgery and radiotherapy with subsequent modified arytenoid adduction
Su13
13 M
T1 Glottic SCC
Endoscopic laser cordectomy with subsequent medialization laryngoplasty with bipedicled strap muscle transposition
Tsunoda14
9M 1F
T1 Glottic SCC
Radiotherapy
23 M
T1 Early glottic carcinoma T2 Early glottic carcinoma
Radiotherapy
60 M
T1 Early glottic carcinoma
Radiotherapy
van Gogh17 Verdonck-de
Leeuw18
M-males; SCC-squamous cell carcinoma; F-females; CO2-carbon dioxide
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Table 4
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Summary of Stroboscopic Parameters Reported in Eligible Studies. Article (First Author)
Stroboscopy Reported Findings
Dursun8
Neoglottal closure (3-point rating scale) Status of neofold during inspiration and phonation (normal/abnormal)
Guven9
Glottal closure (5-point rating scale) Mucosal wave pattern (5-point rating scale)
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Iloabachie15
Vocal cord mobility (yes/no)
Keilmann16
Ott et al. classification assessment (15-point rating scale) Morphological changes Glottal closure Mucosal wave pattern Level of phonation (3-point categorical scale)
Knott10
100-point continuous data scale
Peretti11
Glottal closure (complete/incomplete) Anterior commissure web (present/absent)
Shi12
Glottal closure Vertical vocal fold difference Arytenoid movement Bowing (yes/no) Atrophy (yes/no)
Su13
Mucosal wave pattern (normal/decreased) Mucosal wave amplitude (normal/decreased) Glottal closure (5-point rating scale)
Tsunoda14
Mucosal wave (presence/absence) Amplitude of vocal fold vibration (normal/reduced)
van Gogh17
Adapted Hirano and Bless rating form: Overall laryngeal anatomy Vocal fold edge Arytenoid movement Arytenoid symmetry Vocal fold movement Mucosal wave pattern Irregularity Periodicity Glottal closure
Verdonck-de Leeuw18
Adapted Hirano and Bless rating form: Overall laryngeal anatomy Glottic edema (4-point rating scale) Supraglottic edema (4-point rating scale) Vascular injection (4-point rating scale) Supraglottic involvement (6-point rating scale) Regularity of vocal cord edge (6-point rating scale) Amplitude of vocal fold (6-point rating scale) Mucosal wave (6-point rating scale) Nonvibrating portion (6-point rating scale) Glottal closure (yes/no, description)
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Table 5
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Summary of Reported Reliability in Eligible Studies. Reported Reliability (yes/no)
Number of Raters
Dursun8
No
Not reported
N/A
Guven9
No
2
N/A
Iloabachie15
No
Not reported
N/A
Article (First Author)
Results of Reliability
Keilmann16
No
3
N/A
Knott10
No
3
N/A
Peretti11
No
Not reported
N/A
Shi12
No
3
N/A
Su13
No
2
N/A
Tsunoda14
No
Not reported
N/A
Yes
2
Weighted k values range: 0.098 – 0.88
No
3
N/A
van
Gogh17
Verdonck-de
Leeuw18
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N/A-Not Applicable
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