Laser welding of fascial grafts and its potential application in tympanoplasty: an animal model

Lasers in endoscopic middle ear surgery: where do we stand today?

OBJECTIVE

To provide an overview of the current status regarding the parallel use of the endoscope and the laser in middle ear surgery.

METHODS

Comprehensive Pubmed search from 1975 to 2020 including clinical articles, of any type, reporting the combined use of a laser and an endoscope. Purely experimental and non-human studies were excluded.

RESULTS

Reports on the application of the laser in pediatric and adult endoscopic middle ear surgery (EES) are increasing since 2013. Laser-assisted EES is performed for cholesteatoma, non-squamous chronic otitis media, ossicular fixation, otosclerosis and tympanic paraganglioma. The improved haemostasis and the non-contact ablation of tissue around the ossicles and inaccessible areas, represent unique advantages. In stapes surgery, the resection of stapes superstructure with minimal force and the non-contact footplate fenestration are potential advantages. Proper use of the laser, i.e. direction away from the facial nerve and the open labyrinth and safe energy settings have resulted in minimal complications.

CONCLUSION

Based on the increasing number of publications, endoscopic ear surgeons show an interest in using a laser for specific operative tasks. The configuration of a hand-held laser probe does not differ significantly from other otological instruments and therefore is easy to use alongside the endoscope, even in children. The 'handicap' of single-handed surgery can be partially offset by the bloodless and non-contact laser ablation of tissue.

NIR laser tissue welding of in vitro porcine cornea and sclera tissue

BACKGROUND AND OBJECTIVE

The objective of this study was to test the hypothesis that an near infrared (NIR) laser system (1,455 nm) in combination with a motorized translational stage to control the position and speed of the laser beam and a shutter to control the laser exposure to the tissue being welded could be used to successfully weld ocular tissues.

STUDY DESIGN/MATERIALS AND METHODS

Seventy-five porcine corneas and 23 porcine scleral tissues were welded in vitro in this study. The welded tissues were examined using histopathology and tensile strength analysis. Eight different welding conditions were analyzed for porcine cornea and one for sclera tissues. The tensile strength of the welded groups was compared to a sutured cornea control group.

RESULTS

The NIR laser welding system provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. Mean weld strengths of 0.15-0.45 kg/cm(2) were obtained for the cornea and 1.01 kg/cm(2) for sclera welds. The native H(2)O in the ocular tissue serves as an absorber of the 1,455 nm radiation and helps to induce the welds.

CONCLUSIONS

We conclude that an NIR laser system using an optimal laser radiation wavelength of 1,455 nm can effectively weld cornea and sclera tissue and that this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity. The optimization of a laser welding system that leads to a strong full thickness tissue bond without tissue destruction, an instant seal that promotes wound healing, and the absence of a continued presence of a foreign substance like a suture, is of considerable importance to the ophthalmology medical community. This need is especially apparent with respect to corneal transplantation and fixing the position of corneal flaps in Laser-Assisted In Situ Keratomileusis (LASIK), a laser procedure used to permanently change the shape of the cornea.

Minimally Invasive Laser Contraction Myringoplasty for Tympanic Membrane Atelectasis*

OBJECTIVE: We sought to develop a minimally invasive surgical technique using the CO2 laser to reduce or eliminate tympanic membrane atelectasis in a select group of patients.

STUDY DESIGN: Thirty-seven ears with varying degrees of tympanic membrane atelectasis underwent CO2 laser myringoplasty with the patients under intravenous sedation in the operating room setting. Atelectasis severity was graded for each patient and documented before and after laser myringoplasty through photodocumentation. Patients were followed for 1 year with comparison tympanic membrane photography.

SETTING: The study was conducted in a tertiary care private otology-neurotology practice.

RESULTS: Laser myringoplasty significantly reduced retraction pocket severity in most patients. No patients required resection of the retraction pocket or tympanoplasty. The most favorable outcomes were observed in patients with atelectasis addressed early rather than later in its more advanced stages.

CONCLUSION: Laser contraction myringoplasty can reduce or eliminate atelectatic areas of the tympanic membrane through immediate contraction and “tightening” of the tympanic membrane tissues. Clinicians should use a standardized tympanic membrane atelectasis grading format.

SIGNIFICANCE: A minimally invasive surgical technique for addressing tympanic membrane atelectasis is described, and a tympanic membrane at-electasis grading system is presented based on size, location, and depth of the atelectatic region.

Potential use of diode laser soldering in middle ear reconstruction

BACKGROUND AND OBJECTIVES

To assess the potential use of diode laser soldering to improve mechanical stability of middle ear reconstruction. The diode laser with a biological solder may offer benefits over traditional methods. We evaluated the strength of soldered bonds and a means to apply such a technique in the human middle ear.

STUDY DESIGN/MATERIALS AND METHODS

The strength of soldered junctions using fascia, cartilage, bone, and hydroxyappatite was evaluated in vitro. A diode laser (810-nm wavelength) and 50% albumin with 0.1% indocyanine green dye was used. Soldered bonds were compared to those obtained with adhesive alone. A fiberoptic delivery system was evaluated. Ten hydroxyappatite prostheses were soldered to the stapes in human cadaver temporal bones, and the force required to disrupt the bonds were measured.

RESULTS

Statistically significant greater strength was obtained with soldering. Ossicular prostheses can be effectively secured to the stapes in a cadaver model.

CONCLUSIONS

Soldering techniques show promise in middle ear reconstruction.

AlloDerm tympanoplasty of tympanic membrane perforations

PURPOSE

To study the effectiveness of AlloDerm (LifeCell Corporation, Branchburg, NJ) as a graft material in underlay tympanoplasty by comparison to autologous fascia in a chronic tympanic membrane perforation animal model.

MATERIALS AND METHODS

Seventeen chinchillas underwent creation of bilateral chronic tympanic membrane perforations over a 6-week period. Twenty-two stable perforations were divided equally between the experimental AlloDerm and control fascia graft groups. The grafts were surgically placed through a postauricular tympanomeatal flap. The tympanic membranes were examined at 4 and 10 weeks and then harvested for histopathological analysis. Tympanoplasty operative times, perforation closure rates, and gross and histological analyses were compared between the AlloDerm and fascia grafts.

RESULTS

A statistically significant difference in mean surgical time was recorded between the AlloDerm (47 minutes) and fascia (68 minutes) grafting procedures (t test, P =.001). Perforation closure was achieved in 90% of the AlloDerm and 100% of the fascia treated tympanic membranes. Gross and histopathologic inspections revealed no significant differences. Microscopically, AlloDerm and fascia grafts had similar inflammatory responses, but AlloDerm showed increased fibroblast infiltration and neovascularization.

CONCLUSION

The avoidance of donor site morbidity, reduction of surgical time, and excellent gross and histologic outcomes in this animal model reveal that AlloDerm could be a safe, cost-effective alternative to autologous fascia. Further study would be necessary in human clinical trials.

Carbon dioxide laser and silver halide infrared transmitting fibers for tympanoplasty: an experimental animal model

OBJECTIVE

This study evaluates the effectiveness and safety of fiberoptic carbon dioxide (CO2) laser welding for graft closure of tympanic membrane perforations in an animal model.

STUDY DESIGN AND SETTING

Tympanic membrane perforation was surgically induced in 11 eardrums of 7 given pigs. A lumbar facial graft was placed over the wound, and albumin drops served as a biologic solder. CO2 laser energy, transmitted through silver halide infrared transmitting fibers, was used for "spot-welding" along the circumference of the graft. The welded sites were evaluated by using a surgical microscope as well as by evaluating the sites histologically.

RESULTS

Healing started 3 to 4 days after surgery and was completed within 3 weeks with the formation of a neotympanum. Some inflammation with granulation tissue was noted in 5 eardrums.

CONCLUSIONS AND SIGNIFICANCE

These preliminary results indicate that CO2 laser tympanoplasty with a fiberoptic delivery system may be a promising new technique for the clinical setting.

Laser-assisted myringoplasty--technical aspects

At lower power, lasers fuse collagen fibres and weld tissues. Welded collagen fibres make a solid bond and allow tissue growth along the bonded edges. Our aim was to study applicability of lasers in myringoplasty. We used a KTP-532 laser in outpatient myringoplasty. The laser beam was delivered through a micromanipulator connected to a microscope or through a 200-400-micron silica fibre. The perichondrium was used for transplantant and harvested from the tragus. The margins of the perforation in the eardrum were evaporated, with the laser operating in a continuous mode at 2-4 W. The middle ear was filled with gelfilm to provide support for the transplant. The perichondrium was placed under the margins of the tympanic membrane and lazed at low power (0.2-1.5 W) in continuous mode. In pale tissues, venous blood, methylene blue or fluorescein was used to enhance the tissue admittance of laser energy. Surgical failures were linked to thermal tissue damage due to excessive energy during lazing. In two cases, visibility via microscope into the anterior edge was not complete and the transplantant did not adhere in the relatively limited area. One patient had epidermal growth under the tympanic membrane and developed local cholesteatoma. Laser-assisted myringoplasty provides several advantages over traditional myringoplasty: it is minimally invasive, no manipulation of the ossicles is needed and it is convenient in anterior perforations, where it can be done endoscopically. We prefer a fibre delivery system to a micromanipulator, as lazing with endoscopes is possible and thermal damage is easier to prevent.

Recent advances in the use of lasers in otolaryngology

The laser (Light Amplification by Stimulated Emission of Radiation) has been used in Otolaryngology for over 20 years and is by now an accepted part of the armamentarium. A tremendous amount of work is being done in refining existing techniques and developing new ones, and this review discusses some of the recent advances.

Clinical applications of lasers in otolaryngology--head and neck surgery

The use of lasers in otolaryngology--head and neck surgery is described from the invention of the laser in 1960, through the current uses of the laser, and concludes with a summary for the future directions of laser surgery. The various lasers, including the argon, the KTP, and the carbon dioxide lasers used in otolaryngology, are briefly described. The applications of lasers in the larynx, sinuses, and the ear are separately covered, as well as pediatric otolaryngology. In addition to a brief description of the procedure, the complications and limitations are given. Anesthetic considerations are also covered.