Predicting Clinical Efficacy of Photoangiolytic and Cutting/Ablating Lasers using the Chick Chorioallantoic Membrane Model: Implications for Endoscopic Voice Surgery:

Investigation of photothermal treatment with 532 nm laser light on laryngeal cancer in an in vivo tumor model

Laryngeal cancer is the second most common cancer in the upper aerodigestive tract, with its incidence increasing across all ages. The conventional treatments for laryngeal cancer include surgical procedure, radiation, and chemotherapy; however, these treatments can lead to various complications. Photothermal therapy (PTT) using laser light has been employed form cancer effective treatment because of its minimal invasion and short operation time. The current study aims to investigate the feasibility of 532 nm PTT on laryngeal cancer in an invivo tumor model. Ex vivo dosimetry evaluation was conducted to determine the laser irradiation conditions, and HEP-2 tumor bearing mice were used to demonstrate in vivo photothermal effects. In addition, histology and western blot analysis were conducted to verify tumor necrosis and any changes in cancer-associated factors in the tumor tissues. The current in vivo results showed that PTT at 5 W for 40 s and 20 W for 10 s had comparable effects in terms of temperature increase and tumor removal. The 532 nm PTT significantly decreased the remaining tumor and downregulated the expression levels of MMP- 9 and ERK. The current study demonstrated that the 532 nm PTT could be a feasible option for treatment of laryngeal tumor with high power delivery for a short exposure time. Further investigations will confirm the endoscopic application of the 532 nm PTT for the treatment of intralaryngeal tissue prior to clinical translation.

Photoangiolysis with the 445-nm Blue Laser and the Potassium-Titanyl-Phosphate Laser: A Comparison

OBJECTIVES

Photoangiolytic lasers have yielded significant innovation in laryngeal surgery in the last 25 years. After the discontinuation of the potassium titanyl phosphate (KTP) laser, a novel 445-nm blue laser was developed. The optimal balance between a laser's desired tissue effects and collateral tissue damage is a major determinant of laser selection in microlaryngeal surgery. The shell-less incubation system for the chick chorioallantoic membrane (CAM) simulates the microvasculature of the human vocal fold and is useful for testing effects of laser settings and in simulated surgery. The aim of this study is to compare the tissue effects of the KTP and blue lasers using the shell-less CAM model.

METHODS

The shell-less incubation system contains: polymethylpentene film (used as a culture vessel), calcium lactate and distilled water supplementations. By using this system, the chick chorioallantoic membrane (CAM) can be fully exposed with a good field for surgery simulation. The effects of the 2 lasers (532 nm KTP and 445 nm blue) were quantified at clinically relevant energy settings and laser distances from target. Measures included imaging real-time vascular reactions in the CAM model, post-procedure histologic analysis of CAM tissue and temperature changes.

RESULTS

Vessel coagulation and rupture rates were less common with the blue laser compared with the KTP laser. Histologic analysis demonstrated less tissue disruption with the blue laser. Temperature changes were less with the blue laser.

CONCLUSION

In this CAM model with specific conditions, the blue laser reveals less tissue damage than the KTP laser. Suitable working distance and power setting of the laser are necessary for desired tissue effects.Level of Evidence: Level 3.

Photoangiolytic Lasers for Treatment of Benign Laryngeal Lesions: A Systematic Review and Meta-Analysis

OBJECTIVES

To compare the efficacy of the 445-nm blue laser to the 585-nm pulsed dye laser (PDL) and 532-nm potassium-titanyl-phosphate (KTP) laser in the treatment of benign laryngeal lesions.

DATA SOURCES

Cochrane Library, PubMed, Scopus, and CINAHL.

REVIEW METHODS

Following PRISMA guidelines, databases were searched from inception through January 29, 2024, for studies reporting the use of photoangiolytic lasers for treatment of benign laryngeal lesions, including the 585-nm PDL, 532-nm KTP laser, and 445-nm blue laser. Outcome measures included lesion resolution (%), mean differences (Δ) in Voice Handicap Index (VHI-10), and summed dysphonia grade, roughness, and breathiness (GRB) scale.

RESULTS

A total of 45 studies were included for meta-analysis, consisting of 348 patients treated with PDL, 550 patients with KTP laser, and 338 patients with blue laser. Treatment with blue laser resulted in the greatest lesion resolution (94.0%; 95% confidence interval [CI]: 90.2%-96.7%), followed by KTP laser (90.4%; 95% CI: 84.1%-95.2%), and PDL (86.9%; 95% CI: 62.9%-99.2%). VHI-10 improved significantly in patients following treatment with blue laser (Δ13.3; 95% CI: 10.7-16.0; p < 0.0001), KTP laser (Δ10.3; 95% CI: 7.4-13.3; p < 0.0001), and PDL (Δ7.4; 95% CI: 4.8-10.1; p < 0.0001). GRB improved significantly in patients following treatment with blue laser (Δ4.1; 95% CI: 2.9-5.2; p < 0.0001), KTP laser (Δ3.0; 95% CI: 2.0-4.0; p < 0.0001), and PDL (Δ2.5; 95% CI: 0.8-4.2; p = 0.005).

CONCLUSIONS

Photoangiolytic lasers are effective in treating benign laryngeal lesions. Blue lasers are promising for laryngeal laser surgery. Laryngoscope, 2024.

Comparison of Angiolytic Effects Between the 445-nm Blue Laser and 532-nm Pulsed KTP Laser

OBJECTIVE

This study aimed to compare the selective absorption of the 445-nm Blue laser (BL) and the 532-nm pulsed potassium-titanyl-phosphate (KTP) laser by blood vessels.

METHODS

Thirty-six chicken eggs at day 14 of incubation were dissected to expose the chick chorioallantoic membrane (CAM). Third-order vessels of the CAM were identified and irradiated using BL and KTP lasers using various settings at a laser-to-vessel distance of 3 mm using 0.4 mm fiber size. In total, 494 vessels segments were irradiated. Mean (standard deviation) number of irradiations for each setting was 26.0 (4.6), range from 15 to 39. Outcome measures included ablation rate (AR) and rupture rate (RR).

RESULTS

The two lasers were compared for AR and RR at long and medium pulse width (PW) associated with different power levels. At long PW (above 100 ms), BL showed significantly higher AR than KTP at high energy (600 mJ/pulse) and low energy (400 mJ/pulse); they did not show different AR and RR at medium energy levels (500 mJ/pulse). Using medium PW settings plus high and medium energy levels, BL and KTP showed relatively high AR and did not significantly differ in performance. However, at medium PW plus low energy (400-450 mJ/pulse), KTP showed significantly higher AR compared to BL.

CONCLUSION

At long PW, BL appeared to show higher AR than KTP at high or low energy levels, but they showed equivalent performance at medium energy. At medium PW, both performed similarly from high to medium energy, but KTP appeared to perform better than BL at lower energy settings.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:3220-3225, 2024.

Minimizing Thermal Damage During Thulium Laser-Assisted Partial Arytenoidectomy: Pulsed Versus Continuous Cutting in an Ex-Vivo Calf Model

OBJECTIVES

The 2 µm-wavelength thulium laser is an effective cutter during partial arytenoidectomy, but thermal trauma can damage adjacent laryngeal tissue. Pulsing laser energy may reduce trauma when compared to continuous-wave cutting. This study measured temperature changes, thermal trauma, and time to complete partial arytenoidectomy, with and without pulsing, in an ex-vivo calf model.

METHODS

Tissue temperature and time to complete a trans-cartilaginous cut were measured during partial arytenoidectomy on ex-vivo calf vocal folds (N = 24) using a thulium laser in continuous-wave (CW, N = 12) and pulsed-wave (PW, N = 12) modes. Energy was 5 W for CW and PW cuts; pulse-widths were 250, 500, and 750 ms. Thermal damage was analyzed histologically by measuring the depth of lactate dehydrogenase (LDH) inactivation perpendicular to the laser-cut edge at the vocal process. Paired t-tests compared CW and PW modes.

RESULTS

Change in temperature was lower using CW (6.5°C) compared to PW modes (250 ms = 18°; 500 ms = 16°; 750 = 19°; P < .05). Trans-cartilaginous cuts were completed faster using CW (37 seconds) compared to PW (250 ms = 136 seconds; 500 ms = 61 seconds; 750 = 44 seconds; P < .05), and both modes delivered the same total Joules. The average depth of LDH depletion (thermal damage) was similar for all cuts.

CONCLUSIONS

1. Thulium laser cuts in continuous-mode unexpectedly produced less tissue heating yet created similar thermal damage than pulsed-mode cuts during simulated partial arytenoidectomy. 2. Trans-cartilaginous cuts were completed significantly faster in continuous-mode as compared to pulsed-mode cutting. 3. Pulsing the thulium laser does not minimize thermal damage compared to continuous wave cutting during thulium laser-assisted partial arytenoidectomy.

Indications, Efficacy, Safety, and Clinical Outcomes of 585 nm Pulsed Dye Laser in Non-Malignant Laryngeal Lesions: A Systematic Review

The objective of this manuscript was to review the indications, efficacy, and safety of a 585 nm pulsed dye laser (PDL) in non-malignant laryngeal lesions. Following the PRISMA statement recommendations, three independent authors searched for articles published in PubMed/MEDLINE, the Cochrane Library, Google Scholar, Scielo, and Web of Science. A bias analysis was performed following NICE guidance tools. From the 506 identified publications, 19 observational studies met the inclusion criteria. The PDL improves vocal quality objectively and subjectively in vascular lesions (p < 0.005) and improves vocal quality in patients with dysplasia/leukoplasia without changing the natural history of the disease compared to other treatments. Reinke's edema and granulomas require an average of 1.5 PDL sessions for resolution. Treatment of recurrent respiratory papillomatosis requires multiple sessions, with complete remission achieved in 50-70% of patients. Regardless of the lesion, the tolerance of the procedure under local anesthesia is exceptional (84-97%), and the results in terms of regression and vocal quality are promising. The complication rate is minimal, and the procedure does not interfere with other treatment alternatives. There is no consensus on laser settings. The lack of consistent use in evaluating vocal outcomes, whether objective or subjective, prevents the comparability between studies. The 585 nm pulsed dye laser appears to be an effective and safe therapeutic option in patients with non-malignant laryngeal pathology. Future controlled studies are needed to compare the 585 nm pulsed dye laser with other lasers or cold instrument procedures.

Phonosurgery: A review of current methodologies

Cold-steel has served as the gold standard modality of phonosurgery for most of its history. Surgical laser technology has revolutionized this field with its wide use of applications. Additional modalities have also been introduced such as coagulative lasers, photodynamic therapy, and cryotherapy. This review will compare the surgical modalities of cold steel, surgical lasers, phototherapy and cryotherapy. The mechanism of action, tissue effects and typical uses will be addressed for each modality.

Use of 532 nm Potassium Titanyl Phosphate Laser on Vocal Fold Scars Under Topical Anesthesia: A Pilot Study

OBJECTIVE

This pilot study aims to evaluate the efficacy of 532 nm potassium titanyl phosphate (KTP) laser under topical anesthesia in patients with vocal fold scars.

METHODS

A series of 18 patients with vocal fold scars of varying degrees were treated. The KTP laser was used under local anesthesia in the outpatient clinic. It was set to deliver 6 W of power using a continuous output mode. Close-to-contact mode was used for laser irradiation, and contact mode was used for ablation and excision of the lesions. Some of the patients received laser scar ablation on both vocal folds; the scarred vocal fold on one side and the hypertrophic vocal fold on the other. Parameters include glottic closure, amplitude, and mucosal wave pattern were measured using laryngeal stroboscopic examination. Aerodynamic and voice evaluations were carried out using maximum phonation time (MPT), jitter, shimmer, Voice Handicap Index questionnaire (VHI-30), and GRBAS scale.

RESULTS

In total, 21 surgeries were performed on 18 patients. Glottic closure, amplitude, and mucosal wave pattern showed improvement 2 months postoperatively (P < .05). There was significant improvement in the postoperative scores for VHI-30, VHI-emotional sub-scale, VHI-physical sub-scale, and GRBAS (P < .05). There was no significant difference in the MPT and VHI-functional sub-scale before and after the operation (P > .05). Re-adhesion of the anterior commissure was observed in 2 patients with Type III scars.

CONCLUSION

The 532 nm KTP laser is an effective tool for the treatment of vocal fold scars. Further research is required to determine if serial laser applications could improve outcomes for this challenging condition.

LEVEL OF EVIDENCE

Level IV.

Effects of 445-nm Laser on Vessels of Chick Chorioallantoic Membrane with Implications to Microlaryngeal Laser Surgery

Objective

Previous research has shown that effective application of angiolytic lasers in microlaryngeal surgery is determined by wavelength, pulse width (PW), and fluence. Recently, a 445‐nm (blue) laser (BL) has been developed with a potentially greater hemoglobin absorption than previous lasers. The chick chorioallantoic membrane (CAM) represents a suitable model for testing various settings to find out the most optimal settings of this laser. This study used the CAM model to examine whether successful photoangiolytic effects could be obtained using BL.

Methods

Seven hundred and ninety three third‐order vascular segments of viable CAM were irradiated using BL via 400‐μm diameter fiber, 1 pulse/second, with PW and power varied systematically at standardized fiber‐to‐vessel distances of 1 and 3 mm. Outcome measures including vessel ablation rate (AR), rupture rate (RR), and visible tissue effects were analyzed using Chi‐square test.

Results

Energy levels of 400, 540, and 600 mJ (per pulse) were most effective for vessel ablation. A working distance of 3 mm resulted in higher ablation and less vessel rupture compared with 1 mm at these optimal energy levels. At 3 mm, a longer PW resulted in higher AR. At 1 mm, AR increased with shorter PW and higher power. The 1‐mm working distance resulted in lower tissue effects than 3 mm.

Conclusion

Findings in this study showed that BL was effective in vessel ablation using relevant combination of working distance, PW, and energy levels. To obtain high AR, longer working distance plus longer PW was required and if working distance was reduced, shorter PW should be set.

Level of Evidence

NA Laryngoscope, 131:E1950–E1956, 2021

Doppler optical coherence tomography for energy seal evaluation and comparison to visual evaluation

Laser energy sealing systems have attracted much attention over the past decade given the general shift in surgical paradigm toward less invasive surgical approaches. Given this, it is paramount to have an objective method with which the quality of energy seals can be evaluated. Current methodologies used for this purpose can be problematic in the evaluation of small vessel seals. A methodology employing Doppler optical coherence tomography (DOCT) for the evaluation of energy seals is introduced. Avian chorioallantoic membrane vessels were subjected to thulium laser irradiation and were then scanned via OCT. Outcomes were classified based on several markers, predominantly the presence or absence of flow postirradiation. Vessel diameter and general morphology were also taken into consideration. Vessels were classified into four groups: seal (29%), rupture (30%), partial seal (19%), and unaffected (22%). All vessels were also evaluated visually by a trained neurovascular surgeon, and these visually classified outcomes were compared with DOCT evaluated outcomes. It was found that whether the vessel was considered sealed or not sealed was dependent on the evaluation method (p  =  0.01) where visual classification resulted in 18% more seals than DOCT classification. Further, the specificity of visual classification was found to be strongly dependent on the number of partial seals (p  <  0.0001). DOCT has shown to be an indispensable method for the evaluation of energy seals not only solely due to its high velocity resolution but also due to valuable microscopic morphological insight regarding the biological mechanisms responsible for energy sealing.

The Use of 532-Nanometer-Pulsed Potassium-Titanyl-Phosphate (KTP) Laser in Laryngology: A Systematic Review of Current Indications, Safety, and Voice Outcomes

OBJECTIVE

To investigate the indications, efficacy, safety, and outcomes of potassium-titanyl-phosphate (KTP) laser procedures for treatment of laryngeal disease.

METHODS

PubMed, Cochrane Library, and Scopus were searched for studies providing information about the indications, efficacy, and safety of both in-office and operative suspension microlaryngoscopy KTP laser procedure in treatment of laryngeal disease. Diagnostic criteria and clinical outcome evaluation of included studies were analyzed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria.

RESULTS

Of the initial screened 140 papers, 17 met our inclusion criteria. Six papers involved KTP laser procedures for benign and malignant vocal fold lesions in suspension microlaryngoscopy only, 10 papers focused on only in-office KTP laser procedures for benign vocal fold lesions, and 1 paper included both in-office and suspension microlaryngoscopy procedures. The following lesions may be considered as indications for KTP laser procedures: Reinke's edema, sulcus vocalis, vocal fold hemorrhage, polyp, granuloma, cyst, scar, papillomatosis, dysplasia, leukoplakia, and early vocal fold malignancies. Irrespective of the types of procedure (in-office vs suspension microlaryngoscopy), the KTP laser is associated with a low complication rate and overall good vocal fold vibration recovery. There is an important heterogeneity among studies concerning laser settings, indications, and outcomes used for the assessment of treatment effectiveness. There are no controlled studies directly comparing KTP laser with other lasers (ie, carbon dioxide laser).

CONCLUSION

The use of KTP laser procedures for treatment of laryngeal disease has increased over the past decade, especially for office-based management of vocal fold lesions. Future controlled studies are needed to compare the safety and outcomes of the KTP laser to other techniques.

Infectivity of murine papillomavirus in the surgical byproducts of treated tail warts

OBJECTIVES/HYPOTHESIS

Human papillomavirus (HPV) is a highly stable DNA virus that causes disease in human organ systems, including the larynx and oropharynx. The treatment of HPV-associated diseases with scalpels, lasers, and other surgical instruments has the potential to release infectious particles, placing healthcare workers at risk. The objectives of this study were to create a reproducible in vivo animal model of papillomavirus infectivity and to compare the infectivity of byproducts of surgically treated mouse papillomavirus (MmuPV1) warts.

STUDY DESIGN

Animal study.

METHODS

Nude laboratory mice (Mus musculus) with established MmuPV1 tail warts were treated with scalpel excision, potassium titanyl phosphate (KTP) laser ablation, and coblator treatment. Uninfected nude mice were challenged with surgical byproducts, including ablated and heated tissue, and surgical smoke products. The incidence and time course of the appearance of warts was recorded.

RESULTS

There was rapid transmission of virus in mice challenged with scalpel-treated warts, with 50% penetrance of infection at day 13 and 100% at day 32. For KTP-treated warts, there was the slower development of infection (50% by day 35) but 100% penetrance by day 52. Coblator-treated tissue reached 50% penetrance at day 59 and a maximum of 73% penetrance. Smoke plume captured during treatment with the KTP laser and coblator was highly infectious, as was the material captured in a laser filter.

CONCLUSIONS

MmuPV1 remains infectious in all modes of surgically treated tissue, and the smoke plume is capable of transmitting infection. Healthcare workers should use appropriate precautions to lower their risk of infection when treating papillomavirus-associated diseases.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:712-717, 2020.

Carbon debris and fiber cleaving: Effects on potassium-titanyl-phosphate laser energy and chorioallantoic membrane model vessel coagulation

OBJECTIVES/HYPOTHESIS

Photoangiolytic precision afforded by the 532-nm potassium-titanyl-phosphate (KTP) laser relies on predictable energy delivery. Inadequate energy output can cause vessel rupture, and excessive energy can cause thermal damage. The quality of the cleaved surface and carbon deposits from ablated tissue are two factors that could negatively impact fiber performance. The effects of these on energy output and blood vessel coagulation were assessed using a chorioallantoic membrane (CAM) model.

STUDY DESIGN

Comparative analysis.

METHODS

Laser fibers with carbon debris, optimal fiber cleaving, and suboptimal cleaving were inspected at three times magnification, and the light dispersion pattern of each fiber was rated. The average energy output from consecutive pulses through each fiber configuration was recorded. The effect of these fiber conditions on clinical efficacy was estimated by measuring vessel coagulation versus rupture in the CAM model. Repeated measures analysis of variance compared results.

RESULTS

Carbon debris and suboptimal cleaving resulted in decreased energy output in comparison to optimal cleaving ([-Δ244 mJ, d = 4.31, P < .001] and [-Δ195 mJ, d = 6.04, P < .001]). Optimal cleaving resulted in immediate coagulation of vessels. Fibers with suboptimal cleaving and carbon debris had unpredictable outcomes, requiring multiple pulses for coagulation or causing vessel rupture.

CONCLUSIONS

KTP laser fiber function is significantly affected by fiber tip condition. Carbon debris and suboptimal cleaving create significant attenuation of energy, which results in an unpredictable angiolytic effect, as demonstrated by increased vessel rupture in the CAM model. Optimal recleaving of KTP laser fibers restores prior energy output and predictable coagulation. Care should be taken to avoid carbon debris on laser-fiber tips and to cleave fibers properly.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2244-2248, 2019.

Histologic effect of the potassium-titanyl phosphorous laser on laryngeal papilloma

Objectives

Tissue effects occurring with potassium‐titanyl phosphorous (KTP) laser treatment are difficult to quantify due to the multiple variables that affect not only the fluence (energy delivered) but also the laser–tissue interaction. This histopathologic analysis of recurrent respiratory papilloma (RRP) removed after treatment with KTP laser therapy permits correlation of histologic effect with method of laser treatment.

Methods

The histopathology of RRP resected specimens in a single patient was compared following treatment with KTP laser in contact and non‐contact modes as documented with intraoperative photography and video imaging.

Results

Epithelial‐sparing injury selective to the microvasculature was identified on histopathologic assessment of a specimen treated with noncontact angiolysis. Highly cauterized papillomatous epithelium without identifiable vascular structures was identified on tissue removed after treatment with the KTP laser in contact mode.

Conclusion

The histopathologic assessment of acute KTP laser effect on papilloma permits correlation between technique of application and tissue effect. Similar assessments may be helpful to modify dosimetry for individual patients requiring repeated treatment and may also assist in refining the development of existing KTP laser treatment classification systems.

Level of Evidence

4

Randomized controlled single-blinded clinical trial of functional voice outcome after vascular targeting KTP laser microsurgery of early laryngeal cancer

Background

Local control rate (LCR) of early glottic cancer is high after radiation therapy or transoral laser microsurgery (TLM). The aim of this study was to investigate functional voice outcome after TLM using a microvessel‐ablative potassium‐titanyl‐phosphate (KTP) laser in comparison with a gold standard cutting CO₂ laser.

Methods

The primary end point of this prospective, randomized, single‐blinded, clinical phase II study with control group was voice outcome during a follow‐up of 6 months assayed by Voice Handicap Index (VHI‐30)‐questionnaires in patients with unilateral high‐grade dysplasia, carcinoma in situ or early glottic cancer undergoing TLM‐KTP (n = 8) or TLM‐CO₂ (n = 12). The secondary end point was LCR.

Results

Starting from the 9‐week‐follow‐up visit, TLM‐KTP yielded significantly reduced VHI scores compared to TLM‐CO₂. No relapse occurred after TLM‐KTP in contrast to one recurrence after TLM‐CO₂ within 6 months.

Conclusion

Multicenter phase II or III studies on voice outcome or local control rate after TLM‐KTP in early glottic cancer are warranted enrolling larger patient cohorts.

The Art and Craft of Phonomicrosurgery in Grammy Award–Winning Elite Performers

Background:

Since the renowned opera maestro Manuel Garcia presented “Observations on the Human Voice” using mirror laryngoscopy in 1855, there has been an inextricable link between performing vocalists and laryngologists. Today, specialized laryngeal surgeons continue the tradition of integrating medical and surgical management of performers with those skilled in vocal arts, voice science, and voice therapy. With advances in surgical instrumentation and techniques, increasing opportunities have evolved to surgically restore lost performing voices. However, it is especially challenging because of a range of factors, including the need for optimal technical precision, management of expectations, complexity of informed consent, public visibility of these patients, and the economics related to the success and failure of surgery. A number of these key issues apply to phonomicrosurgical procedures in nonsingers as well. Consequently, reviewing the art and craft of phonomicrosurgery in elite performers provides valuable insights into the optimal management of any patient.

Methods:

A retrospective review was done of microlaryngeal procedures for the past 20 years, and 18 elite performers were identified who were Grammy Award winners. Microsurgical methods for different lesions are illustrated. Composite analyses of the group along with their associated pathology was done to provide insights into key issues.

Results:

The 18 patients in this cohort have won 80 Grammy Awards, which were garnered from 242 nominations. All 18 had substantial deterioration in voice quality and could retain more than 1 pathology. Significant loss of superficial lamina propria (SLP) pliability was present in 15 of 18, varices and/or ectasias leading to vocal hemorrhage in 6, vocal polyps in 9, fibrovascular nodules in 6, arytenoid granuloma in 1, sulcus from prior microlaryngeal surgery leading to vocal fold SLP scarring in 4, sulcus from long-term phonotrauma leading to vocal fold SLP scarring in 4, benign cyst in 1, precancerous dysplasia in 2, and invasive carcinoma in 2. Subsequent to phonomicrosurgery, all reported improvement in their performance.

Conclusions:

Laryngologists and laryngeal surgeons have shouldered a burden of responsibility for elite performing vocalists since the origin of our specialty. Most lesions and diagnoses that are encountered result from phonotrauma. Optimizing singers’ care provides surgeons with extremely complex technical, emotional, social, and financial challenges. Focused analysis of managing elite performing vocalists effectively integrates a range of essential issues, which provide key insights to assist clinicians treating nonperforming patients requiring phonomicrosurgery.

Treatment of early-stage laryngeal cancer: A comparison of treatment options

Over the course of the last several decades, the treatment options for early laryngeal cancers (T1 and T2) have evolved; however, simultaneously the mortality rate has increased. As larynx preservation approaches have become the standard of care, the selection of the proper treatment modality has become paramount. Radiation therapy or transoral laser microsurgery are the most common options for treatment of these early lesions. Oncologic and functional outcomes are considered equivalent between the two modalities for early glottic cancers; however, no direct comparisons exist for robust analysis. In terms of larynx preservation, there also is not compelling data favoring one treatment option or another. For early stage lesions, the goal for any larynx-sparing technique, either radiation or surgery, should be the intent to cure with single modality treatment and minimal short- and long-term toxicity. This article is designed to create a frame of reference for managing early stage disease with respect to lesions of the glottis and supraglottis while weighing treatment implications from an oncologic, functional, and cost perspective.

KTP laser assisted endoscopic tissue fibrin glue biocauterization for congenital pyriform sinus fistula in children

OBJECTIVE

This study aims to assess the efficacy of a novel endoscopic management for congenital pyriform sinus fistula (CPSF) using potassium titanyl phosphate (KTP) laser assisted endoscopic tissue fibrin glue biocauterization in children.

METHOD

From 2010 to 2014, a total of 5 children with recurrent or acute suppurative thyroiditis or neck abscess secondary to CPSF were enrolled retrospectively in this study.

RESULTS

Mean age at the first time of endoscopic biocauterization was 6.2 ± 0.7 (5-7) years. The barium swallow study detected a fistula in four cases. Endoscopy identified an internal opening at the pyriform sinus in all cases with four on the left side and one on the right side. All patients underwent KTP laser assisted endoscopic tissue fibrin glue biocauterization as treatment for CPSF. Only one case required the second endoscopic procedure due to fluctuation of symptoms. Post-endoscopic follow-up duration of these patients was 24.6 ± 11.6 (7-36) months. Neither complications nor recurrences were noted during follow-up in all patients.

CONCLUSIONS

For children presenting with repeated acute suppurative thyroiditis or neck infections, clinicians should highly suspect the possibility of CPSF. Endoscopy should be performed not only to confirm the diagnosis but also could be served as an initial treatment modality of biocauterization by KTP laser and tissue fibrin glue, which was demonstrated as a less invasive, safe, and effective method in children.

Voice outcomes for photoangiolytic KTP laser treatment of early glottic cancer

OBJECTIVES

Surgery and radiotherapy routinely provide high cure rates in treating early glottic cancer. Therefore, key metrics for success are optimal voice outcome and preservation of future cancer treatment options. Remarkably, there is a paucity of pretreatment versus posttreatment voice outcome data. Angiolytic KTP (potassium titanyl phosphate) laser treatment of early glottic cancer with ultranarrow margins was initiated to better preserve vocal function. Given that effective oncological results have been achieved, it was hypothesized that this approach would also result in improved posttreatment measures of vocal function that more closely approximate historical norms than pretreatment values.

METHODS

Pretreatment and posttreatment voice outcome data were obtained for 92 patients (64 with T1 cancer and 28 with T2 cancer) who underwent 532-nm KTP laser treatment of early glottic cancer in a study design in which each patient essentially served as his or her own control. The evaluations included objective measures (acoustic and aerodynamic) and patients' self-assessments of vocal function (Voice-Related Quality of Life; V-RQOL). A series of mixed analyses of variance were conducted for all vocal function measures, with tumor stage and depth of invasion as the between-subjects variables and time (presurgery versus postsurgery) as the within-subject variable.

RESULTS

There were statistically significant (p < or = 0.05) postoperative improvements for acoustic (perturbation and noise-to-harmonics ratio) and aerodynamic (subglottic pressure and vocal efficiency) measures of vocal function, as well as for V-RQOL assessment.

CONCLUSIONS

Comprehensive pretreatment and posttreatment voice measures in a large patient cohort demonstrated that the KTP laser significantly improved postoperative vocal function in patients with early glottic cancer. Furthermore, radiotherapy was preserved as an oncological treatment option.

KTP 532 nm laser for laryngeal lesions. a systematic review

OBJECTIVE

To evaluate the effectiveness and safety of the 532 nm potassium titanyl phosphate (KTP) laser for vocal fold surgery.

STUDY DESIGN

Systematic literature review.

METHODS

Our systematic review was conducted using the meta-analysis of observational studies in epidemiology guidelines. We applied the criteria of the Oxford Centre for Evidence-based Medicine to assess the level of evidence.

RESULTS

We identified seven observational studies of eight case series, which reported a total of 243 KTP procedures carried out for vocal fold lesions: two series each concerning ectasias and varices, early glottic cancer, and recurrent papillomatosis, and one series each for keratosis with dysplasia and various benign laryngeal pathologies. There was also a retrospective review of the use of KTP laser in 387 endoscopic laryngeal surgeries. No studies compared the use of KTP laser with that of other technologies. Thus, according to the Oxford criteria, there is only level 4 evidence of KTP's efficacy and safety. In selected cases, the KTP instrument can be used without general anesthesia in the clinic setting.

CONCLUSIONS

The use of KTP laser for laryngeal surgery is still relatively innovative. Several surgeons have found KTP laser to be the equivalent of, or superior to, the CO2 or pulsed dye lasers, and none have reported inferiority. However, there are currently no published data to support these conclusions. To establish equality/superiority, it is desirable that further evidence of efficacy and safety be obtained, either through randomized controlled trials or at least through well-documented prospective observational studies with reporting of all relevant input and outcome data.

Subepithelial Vocal Fold Infusion: A Useful Diagnostic and Therapeutic Technique

Objectives:

Preservation of the maximum amount of subepithelial superficial lamina propria (SLP) remains an important goal during microlaryngoscopic surgery of phonatory mucosa. Volume expansion of the SLP (Reinke's space) with subepithelial infusion of saline solution has been widely adopted since its introduction in 1991. This technique has evolved so that it is currently used to assist with determining the depth of vocal fold disease, defining residual pliable SLP, enhancing microsurgical precision, and identifying unrecognized disease. The purpose of this investigation was to examine the indications, methods, and benefits of subepithelial infusion of saline solution as an adjunct technique during phonomicrosurgery.

Methods:

In a prospective case series, we collected data on 280 consecutive microlaryngoscopy procedures performed over a 12-month period. Subepithelial infusion of saline solution was included in 178 procedures.

Results:

New disease was identified in 20 of the 178 patients (scar in 15, sulcus in 4, and a mucosal bridge in 1). The depth of needle placement varied depending on the specific disease: 118 of the 178 infusions were done just below the epithelial basement membrane, and 60 infusions were performed deeper within the SLP, just superficial to the vocal ligament. The infusion technique provided surgical assistance in multiple ways, including identifying residual SLP (130 patients), defining the SLP-lesion interface (65 patients), lifting scar (60 patients), providing tension for cordotomy (47 patients), expanding the SLP volume to protect against laser damage (45 patients), and providing hydrostatic compression of vascular ectasias or varices for photoangiolysis (7 patients). The microlaryngoscopy procedures during which infusion was not performed (102 of 280 procedures) were primarily for nonglottic cancer (46 patients), stenosis (30 patients), or arytenoid granuloma (13 patients).

Conclusions:

Subepithelial infusion of the SLP with saline solution is a useful microsurgical adjunct during diagnosis and treatment of phonatory mucosal lesions.

Pulse dye and other laser treatments for vocal scar

PURPOSE OF REVIEW

Vocal fold scar is a challenging clinical problem, resulting in a spectrum of voice-related complaints. While there are a variety of treatment options available, it is rare to obtain outcomes similar to the perfectly normal voice. The pulsed dye and other lasers are an emerging treatment option for cutaneous scar and have shown promise for the treatment of vocal fold scarring. The purpose of this review is to summarize the theory, and describe clinical outcomes from both cutaneous and vocal fold scarring treated with lasers.

RECENT FINDINGS

There are a growing number of papers in the literature substantiating the use of pulsed dye and other lasers used to treat cutaneous scars. Some experimental models describe potential mechanisms of laser effect, which include the development of a sub-basement membrane cleavage plane, as well as up-regulation of proteins which may actively modulate continued fibrosis. One prospective pilot study of 11 patients with vocal fold scarring treated with the pulsed dye laser has also shown statistically significant improvement in subjective and objective voice measures, as well as laryngeal stroboscopy findings after treatment.

SUMMARY

The pulsed dye and other lasers have shown effectiveness and potential in treating cutaneous and vocal scarring.

Pulsed potassium-titanyl-phosphate laser photoangiolytic treatment of mucosal squamous cell carcinoma in the hamster cheek pouch

OBJECTIVES/HYPOTHESIS

Early glottic cancer has been involuted by treatment with the 532 nm pulsed potassium-titanyl-phosphate (KTP) laser in initial clinical studies. Selective photoangiolysis of the sublesional circulation that allows for relative sparing of surrounding tissue is the presumed mechanism. No prior controlled animal-model study has analyzed the ability of selective coagulation of lesional microvasculature coagulation with the KTP laser to involute malignant lesions. This study tests the efficacy of photoangiolysis with the KTP laser in treating squamous cell carcinoma in an established animal model.

STUDY DESIGN

In vivo.

METHODS

Malignant lesions were induced unilaterally in the cheek pouches of 21 hamsters by applying 9,10-dimethyl-1,2-benzanthrancene. The contralateral cheek pouch served as a control. Weekly lesion photodocumentation and pulsed KTP laser (30 W, 15 msec pulse width, 2 pulses/sec) treatments were done. The endpoint of each treatment was a uniform white-blanching of the lesion. Hamsters were sacrificed 1 week after the last treatment and cheek pouches were analyzed histologically.

RESULTS

Carcinoma was confirmed in 19 hamsters, and lesions that were initially <2 mm were more effectively treated than lesions that were >2 mm (P = .0004). Every lesion (10/10) that initially measured <2 mm resolved completely after laser treatment with minimal scarring noted at the treatment site based on histology. Lesions measuring between 2 and 5 mm resolved 33% of the time (2/6), and none (0/3) of the lesions >5 mm resolved after completion of the treatment period.

CONCLUSIONS

Pulsed KTP laser photoangiolysis can effectively involute small malignant lesions, but may be less effective at involuting larger (>2 mm) lesions.

Cooling the "oven": a temperature study of air and glottal tissue during laser surgery in an ex vivo calf larynx model

OBJECTIVES

Endoscopic microlaryngeal laser surgery performed with general anesthesia through a laryngoscope speculum generates heat that accumulates at the distal lumen, creating an "oven" effect and potentially causing bystander thermal damage to nontarget tissue such as the contralateral vocal fold. We report the effects of cooling on air and tissue temperatures that occurred during simulated laryngeal laser surgery with KTP and thulium lasers in an ex vivo calf model.

METHODS

Ten fresh excised calf larynges were studied at room temperature. Laser energy was applied to one vocal fold for 2 minutes, with or without cooling, while temperatures were monitored with sensors placed within the glottal lumen or inserted superficially into the contralateral vocal fold. A pulsed KTP laser (525 mJ) was used for 5 larynges, and a thulium laser (7 W, continuous) was used for the other 5 larynges.

RESULTS

Heating was slightly greater for the KTP laser than for the thulium laser with use of these parameters. The lumen temperatures for both lasers increased an average of 13.2 degrees C without cooling, but only 6.7 degrees C with cooling (p < 0.05). The contralateral vocal fold (subepithelial space) temperature increased an average of 6.8 degrees C without cooling, but only 4.2 degrees C with cooling (p > 0.05).

CONCLUSIONS

Cooling with room-temperature air during laryngeal laser surgery reduces luminal air and contralateral vocal fold temperatures. This effect is believed to be due to elimination of the plume of steam and smoke that significantly heats surrounding structures.

Effects of Gold laser on the avian chorioallantoic membrane

OBJECTIVES

Office-based lasers have revolutionized the treatment of laryngeal disease. The 980-nm Gold laser is a device that may offer some practical advantages over other office lasers. The chick chorioallantoic membrane has been proposed as a model for predicting the effects of photoangiolytic lasers on vocal fold microvasculature. We sought to evaluate the effects of the Gold laser in this model.

METHODS

Vascular reactions in first-order vessels were determined for the Gold laser with both 0 degree straight and 30 degrees angled laser fibers. Vessels were treated at 15 W and a 500-ms pulse interval, with a 1-mm working distance. Pulse widths of 300 ms and 500 ms were evaluated. All vessels were treated until selective coagulation or vessel rupture.

RESULTS

We performed 60 trials on 30 embryos. The mean energy delivered was 33.7 J for the straight fiber and 51.2 J for the angled fiber. The laser achieved selective vessel coagulation without rupture in 100% (30 of 30) of straight fiber trials and in 100% (30 of 30) of angled fiber trials. In 6.7% (2 of 30) of straight fiber and 10% (3 of 30) of angled fiber trials, it caused minor injury to the surrounding albumin as indicated by white coagulum outside the vessel.

CONCLUSIONS

The Gold laser effectively coagulates small vessels without rupture at a working distance of 1 mm and settings of 15 W, 500-ms pulse interval, and 300- to 500-ms pulse width.

Pulsed dye laser-induced inflammatory response and extracellular matrix turnover in rat vocal folds and vocal fold fibroblasts

BACKGROUND AND OBJECTIVES

Disruption of the vocal fold extracellular matrix (ECM) can induce a profound and refractory dysphonia. Pulsed dye laser (PDL) irradiation has shown early promise as a treatment modality for disordered ECM in patients with chronic vocal fold scar; however, there are limited data addressing the mechanism by which this laser energy might induce cellular and extracellular changes in vocal fold tissues. In this study, we examined the inflammatory and ECM modulating effects of PDL irradiation on normal vocal fold tissues and cultured vocal fold fibroblasts (VFFs).

STUDY DESIGN/MATERIALS AND METHODS

We evaluated the effects of 585 nm PDL irradiation on inflammatory cytokine and collagen/collagenase gene transcription in normal rat vocal folds in vivo (3-168 hours following delivery of approximately 39.46 J/cm(2) fluence) and VFFs in vitro (3-72 hours following delivery of 4.82 or 9.64 J/cm(2) fluence). We also examined morphological vocal fold tissue changes 3 hours, 1 week, and 1 month post-irradiation.

RESULTS

PDL irradiation altered inflammatory cytokine and procollagen/collagenase expression at the transcript level, both in vitro and in vivo. Additionally, PDL irradiation induced an inflammatory repair process in vivo that was completed by 1 month with preservation of normal tissue morphology.

CONCLUSIONS

PDL irradiation can modulate ECM turnover in phenotypically normal vocal folds. Additional work is required to determine if these findings extend to disordered ECM, such as is seen in vocal fold scar. Lasers Surg. Med. 41:585-594, 2009. (c) 2009 Wiley-Liss, Inc.

Radiophonosurgery of vocal fold nodules

PURPOSE OF REVIEW

To describe the current support in the literature for radiophonosurgery in cases of vocal fold nodules.

RECENT FINDINGS

Radiophonosurgery is a recent innovation in the field of laryngeal surgery. It is emerging as a reliable and practical method for treating benign superficial vocal fold lesions that is increasingly becoming popular. It induces an excellent subjective and objective improvement in voice parameters. Histologically, it produces unremarkable lateral thermal damage and char penetration, which is quite crucial in a functional surgery such as in phonosurgery. Well designed probes are still lacking in the market.

SUMMARY

Radiophonosurgery provides a new approach for patients with vocal fold nodules. It combines the advantages of both cold knife and laser phonosurgery and is easy, well tolerated, precise and effective with excellent tactile and hemostatic properties.

Use of lasers in laryngeal surgery

Lasers are a relatively recent addition to laryngeal surgery. Since their invention, laser use and applications have expanded rapidly. In this article, we discuss the benefits and disadvantages of lasers for different procedures, as well as ways to overcome commonly faced clinical problems. The use of lasers in surgery has offered a time- and cost-efficient alternative to cold surgical techniques, and has been used in the treatment of numerous laryngeal pathologies, including stenoses, recurrent respiratory papillomatosis, leukoplakia, nodules, malignant laryngeal disease, and polypoid degeneration (Reinke's edema). However, lasers can incur adjacent tissue damage and vocal fold scarring. These problems can be minimized through understanding the mechanisms by which lasers function and correctly manipulating the parameters under a surgeon's control. By varying fluence, power density, and pulsation, tissue damage can be decreased and lasers can be used with greater confidence. The various types of lasers and their applications to the treatment of specific pathologies are reviewed with the intention of helping surgeons select the best tool for a given procedure. Recent applications of lasers to treat benign laryngeal lesions and severe laryngomalacia demonstrate that additional research must be conducted to realize the full potential of this surgical tool.