Zhi Wang

A 585-nanometer pulsed dye laser treatment of laryngeal papillomas: Preliminary report†

Objectives/Hypothesis: Standard management of recurrent respiratory papillomatosis (RRP) currently consists of CO2 laser microsurgical ablation of papillomas. Because of the recurrent nature of this viral disease, patients are often faced with significant cumulative risk of soft tissue complications. As a minimally traumatic alternative to management of RRP, we have investigated the use of the 585‐nm pulsed dye laser (PDL) to cause regression of papillomas by selective eradication of the tumor microvasculature. Study Design: Nonrandomized prospective pilot study. Methods: Patients with laryngeal papillomas were treated with the PDL at fluences of 6 J/cm 2 (double pulses per irradiated site), 8 J/cm 2 (single pulses), and 10 J/cm 2 (single pulses), at noncritical areas within the larynx, using a specially designed micromanipulator. Lesions on the true cords were treated with the CO2 laser, using standard methodology. Results: Clinical examination of three patients treated to date showed that PDL treatment appeared to produce complete regression of papillomas. Unlike the sites of lesions treated by the CO2 laser, the epithelial surface at the PDL treatment sites was preserved intact. Conclusions: These preliminary results suggest the PDL may eradicate respiratory papillomas with minimal damage to normal laryngeal tissue. Further analysis of the ongoing study is required to demonstrate potential benefits of the technique.

Fat Implantation into Reinke's Space: A Histologic and Stroboscopic Study in the Canine:

The scarred vocal fold is a cause of persistent dysphonia after laryngeal trauma, microsurgery, and tumor resection. The loss of Reinkes space with scar and stiffness is the primary cause. This study explores the technical aspects of endoscopic implantation of fat as an autologous implant for restoring the bulk and pliability of the vocal folds. Fat from the buccal area was harvested and prepared in 6 dogs. A mucosal flap submucosal pocket was prepared by means of microlaryngoscopy instrumentation. The fat implant was placed into the submucosal pocket. The mucosal flap was sutured endoscopically. Six weeks later, the larynx was harvested and mounted, and vocal fold oscillation was studied while driven by a humidified flow source. The vibratory patterns were studied by stroboscopy. Histologic sections of the vocal folds were made in the coronal plane. All 6 specimens had histologic evidence of viable implanted fat and/or fibrous tissue at the implant site. The site of implantation was in the superior aspect of the vocal fold, but contributed to mass in vocal fold bulk. This increase in bulk histologically corresponded to stroboscopic evidence of increased mass. On stroboscopy, the implant side continued to demonstrate good vibratory function. The study shows that fat implantation can be carried out as an endoscopic procedure. Fat implantation may be useful as a surgical procedure for restoration of Reinkes space. It may be applicable in patients with scars, sulcus vocalis, or vocal fold atrophy.

Laser-assisted cartilage reshaping: in vitro and in vivo animal studies

Correction of cartilaginous defects in the head and neck area remains a challenge for the surgeon. This study investigated a new technique for laser-assisted cartilage reshaping. The pulsed 1.44 micrometers Nd:YAG laser was used in vitro and in vivo experiments to irradiate cartilage to change its shape without carbonization or vaporization of tissue. Two watts of average power in non contact manner was used to irradiate and reshape the cartilage. The extracted reshaped cartilage specimens underwent testing of elastic force with a computer assisted measurement system that recorded the changes in elastic force in the specimens from 1 hr to 11 days post-irradiation. An animal model of defective tracheal cartilage (collapsed tracheal wall) was created, allowed to heal for 6 weeks and then corrected endoscopically with the laser-assisted technique. The results of the in vitro and in vivo investigations demonstrated that it was possible to alter the cartilage and that cartilage would retain its new shape. The clinical significance of the technique is evident and warrants further animal studies and clinical trials.

Tumor growth inhibition and regression induced by photothermal vascular targeting and angiogenesis inhibitor retinoic acid.

The effect of photothermal vascular targeting, alone and in combination with antiangiogenic therapy, was evaluated using tumors produced in mice by transplantation of KB cells. Tumor growth inhibition and regression followed vascular damage produced by pulsed dye laser (PDL) radiation. Administration of the antiangiogenic agent all-trans-retinoic acid (RA) was associated with smaller average tumor volumes in the presence and absence of PDL irradiation, but this effect was not statistically significant. The ability of PDL photothermal vascular targeting to cause regression of tumors without harming normal tissue may be a consequence of preferential damage to supplying vessels at the tumor periphery.

Endoscopic diode laser welding of mucosal grafts on the larynx: a new technique.

Epithelial coverage of a laryngotracheal wound is an important factor in preventing stenosis, and endoscopic transplantation of a free mucosal graft without stents or sutures would be a significant therapeutic advance. In vitro and in vivo canine studies were performed to explore the feasibility of transplantation with a low‐power diode laser (400 mW) enhanced by indocyanine green dye‐doped albumin. The tensile strength of graft adherence in 10 cadaver larynges was strong (35.25 ± 10.39 g). Survival studies in live canine models with a specially designed endoscopic instrument set showed excellent healing at 6, 14, and 28 days. Healing was documented with photography and by histologic examination. Successful endoscopic transplantation of a free mucosal graft should improve results of treatment for laryngotracheal stenosis and laryngeal reconstructive surgery.

A combined endoscopic Co2 laser and external approach for treatment of glottic cancer involving the anterior commissure: an animal study.

Endoscopic laser resection usually has been discouraged for anterior commissure (AC) carcinoma because of inadequate exposure and close proximity to underlying cartilage. A new technique combining endoscopic CO2 laser incision and an external approach, creating a window in the thyroid cartilage, was tested in this in vivo study of six dogs. An en bloc specimen including adjacent cartilage was excised while preserving the thyroid framework. The glottic reconstruction was accomplished with external placement of a sternohyoid muscle flap, by either using a bipedicled muscle flap with overlying skin or a unipedicled muscle flap with a graft of free mucosa.

Pulsed-Dye Laser and Retinoic Acid Delay Progression of Oral Squamous Cell Carcinoma: A Murine Model†

Objectives/Hypothesis This study examined the role of the pulsed‐dye laser (PDL) at 585 nm coupled with retinoic acid at therapeutic (5.0 mg/kg) and nontherapeutic (0.5 mg/kg) doses to delay the progression of cancer with a two‐hit approach. The existing vasculature is selectively targeted by the laser, whereas retinoic acid inhibits future angiogenesis.

Tracheal anastomosis with the diode laser and fibrin tissue adhesive: An in vitro and in vivo investigation

Absorbable sutures have been advocated for tracheal anastomosis to reduce fibrosis and foreign body reaction leading to recurrent stenosis. Fibrin tissue adhesive (FTA) and diode laser welding with indocyanine green‐dyed fibrinogen were evaluated in tracheal anastomosis to reduce the number of sutures and to improve healing. In vitro studies demonstrated strong anastomoses with a combination of laser welding and FTA with minimal tissue damage. In a controlled in vivo study, circumferential resections of canine tracheas were repaired with laser welding and FTA augmented with a few stay sutures. These anastomoses had less fibrosis and tissue damage than anastomoses in control animals repaired with sutures alone. This study supports investigation of laser welding and FTA in human beings for tracheal anastomosis and other procedures in which suturing may be difficult.

Atraumatic laser treatment for laryngeal papillomatosis

Ten to fifteen thousand new cases of recurrent respiratory papillomatosis (RRP) are diagnosed each year in the United States. RRP is caused by the human papillomavirus (HPV) and is characterized by recurrent, non-malignant, proliferative lesions of the larynx. Patients with RRP undergo numerous microsurgical procedures to remove laryngeal papilloma threatening airway patency and interfering with phonation. The standard surgical technique involves CO2 laser vaporization of laryngeal epithelium affected by the lesions, and requires general anesthesia. The pulsed dye laser operating at 585 nm has previously been demonstrated to be effective in clearing HPV lesions of the skin (verrucae). For treatment of RRP, the fiber- compatible pulsed dye laser radiation may be delivered under local anesthesia using a flexible intranasal laryngoscope. Potential advantages of the pulsed dye laser treatment over CO2 laser surgery include (1) reduced morbidity, especially a lower risk of laryngeal scarring; (2) lower cost; (3) reduced technical difficulty; and (4) reduced risk of viral dissemination or transmission. In vivo studies are underway to determine the effect of pulsed dye laser radiation on normal canine laryngeal tissue.

Uptake of indocyanine green by hamster sebaceous glands

Photothermal injury to the sebaceous glands is a potential curative treatment for the common skin disease acne vulgaris. Accumulation of the exogenous chromophore indocyanine green in the sebaceous glands may be accomplished using an emulsion or liposomal formulation applied to the skin surface. An emulsion containing 0.09% by weight indocyanine green (ICG) was applied to the epidermis of hamster ears ex vivo and the flank organ in vivo. Fluorescence microscopy demonstrated selective accumulation of ICG in the underlying sebaceous glands. The concentration of ICG that may be expected to accumulate in sebaceous glands of humans was then estimated on the basis of the gland size and orifice area, for the case of topical application of a more concentrated 1% ICG liposomal formulation. Monte Carlo modeling and heat transfer calculations showed that the sebaceous glands containing the exogenous chromophore may be selectively damaged by pulsed 810 nm laser radiation in conjunction with cryogen spray cooling.