Fractional CO(2) laser-assisted drug delivery

BACKGROUND AND OBJECTIVES

Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug.

MATERIALS AND METHODS

Two Yorkshire swine were treated with single-hole CO(2) laser AFR and subsequent topical application of MAL (Metvix(R), Photocure ASA, Oslo, Norway), placebo cream and no drug. MAL-induced porphyrin fluorescence was measured by fluorescence microscopy at skin depths down to 1,800 microm. AFR was performed with a 10.6 microm wavelength prototype CO(2) laser, using stacked single pulses of 3 millisecond and 91.6 mJ per pulse.

RESULTS

AFR created cone-shaped channels of approximately 300 microm diameter and 1,850 microm depth that were surrounded by a 70 microm thin layer of thermally coagulated dermis. There was no porphyrin fluorescence in placebo cream or untreated skin sites. AFR followed by MAL application enhanced drug delivery with significantly higher porphyrin fluorescence of hair follicles (P<0.0011) and dermis (P<0.0433) versus MAL alone at skin depths of 120, 500, 1,000, 1,500, and 1,800 microm. AFR before MAL application also enhanced skin surface (epidermal) porphyrin fluorescence. Radial diffusion of MAL from the laser-created channels into surrounding dermis was evidenced by uniform porphyrin fluorescence up to 1,500 microm from the holes (1,000, 1,800 microm depths). Skin massage after MAL application did not affect MAL-induced porphyrin fluorescence after AFR.

CONCLUSIONS

Ablative fractional laser treatment facilitates delivery of topical MAL deeply into the skin. For the conditions of this study, laser channels approximately 3 mm apart followed by MAL application could produce porphyrins throughout essentially the entire skin. AFR appears to be a clinically practical means for enhancing uptake of MAL, a photodynamic therapy drug, and presumably many other topical skin medications.

Fractional CO(2) laser-assisted drug delivery

BACKGROUND AND OBJECTIVES

Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug.

MATERIALS AND METHODS

Two Yorkshire swine were treated with single-hole CO(2) laser AFR and subsequent topical application of MAL (Metvix(R), Photocure ASA, Oslo, Norway), placebo cream and no drug. MAL-induced porphyrin fluorescence was measured by fluorescence microscopy at skin depths down to 1,800 microm. AFR was performed with a 10.6 microm wavelength prototype CO(2) laser, using stacked single pulses of 3 millisecond and 91.6 mJ per pulse.

RESULTS

AFR created cone-shaped channels of approximately 300 microm diameter and 1,850 microm depth that were surrounded by a 70 microm thin layer of thermally coagulated dermis. There was no porphyrin fluorescence in placebo cream or untreated skin sites. AFR followed by MAL application enhanced drug delivery with significantly higher porphyrin fluorescence of hair follicles (P<0.0011) and dermis (P<0.0433) versus MAL alone at skin depths of 120, 500, 1,000, 1,500, and 1,800 microm. AFR before MAL application also enhanced skin surface (epidermal) porphyrin fluorescence. Radial diffusion of MAL from the laser-created channels into surrounding dermis was evidenced by uniform porphyrin fluorescence up to 1,500 microm from the holes (1,000, 1,800 microm depths). Skin massage after MAL application did not affect MAL-induced porphyrin fluorescence after AFR.

CONCLUSIONS

Ablative fractional laser treatment facilitates delivery of topical MAL deeply into the skin. For the conditions of this study, laser channels approximately 3 mm apart followed by MAL application could produce porphyrins throughout essentially the entire skin. AFR appears to be a clinically practical means for enhancing uptake of MAL, a photodynamic therapy drug, and presumably many other topical skin medications.

Treatment of hypertrophic and resistant port wine stains with a 755 nm laser: a case series of 20 patients

BACKGROUND AND OBJECTIVE

Port wine stains (PWS) are heterogeneous vascular malformations that can be treated with vascular-selective pulsed dye lasers (PDL). Hypertrophic PWS, especially in adults, are consistently less responsive to PDL. Furthermore, many PWS that respond well initially to PDL treatment may reach a response plateau, becoming unresponsive to further PDL treatments, a phenomenon termed "treatment resistance." Based on the theory of selective photothermolysis, vessels in such lesions may also be specifically targeted with a 755 nm laser that has selectivity for deoxyhemoglobin as well as oxyhemoglobin and increased depth of skin penetration.

STUDY DESIGN/PATIENTS AND METHODS

Retrospective case review of 20 patients with either hypertrophic or PDL-resistant PWS treated with a 755 nm laser alone or in combination with other lasers, including PDL.

RESULTS

Hypertrophic PWS showed significant lightening after treatment with a 755 nm laser in combination with PDL. Most PDL-resistant PWS showed moderate improvement after treatment with either a 755 nm laser alone or in combination with another laser, including PDL. Some lesions showed only mild improvement or did not respond. Serious side effects were infrequent. Most commonly encountered complications included pain, edema, bullae, crusting, and rare scarring.

CONCLUSIONS

Alexandrite 755 nm laser can be useful for the treatment of hypertrophic and treatment-resistant PWS in adult and pediatric patients. Complications are infrequent and predictable. Careful attention to using a fluence at or near the threshold for clinical response with this deeply penetrating laser is essential to prevent serious sequelae.

Treatment endpoints for resistant port wine stains with a 755 nm laser

Laser therapy of port wine stains (PWS) resistant to pulsed dye laser is challenging and controversial. Based on the theory of selective photothermolysis, vessels in such lesions may be specifically targeted with the laser wavelength of 755 nm. There is much deeper penetration of the near-infrared light and it is difficult to visualize laser-induced changes within the deeper dermis. The recognition of an appropriate immediate endpoint response with this wavelength would be helpful. This is a clinical observations report. We present examples of an appropriate PWS tissue response endpoint based on our clinical observations in resistant PWS treated with a 755 nm laser at high fluences (40-100 J/cm(2)), 1.5-ms pulse duration, with dynamic cooling device (DCD) cooling. Mild-to-moderate PWS lightening was associated with the immediate endpoint of a transient gray color that gradually evolved into persistent deep purpura within several minutes. We also discuss the clinical endpoints that represent undertreatment and overtreatment of PWS. It is important to attain, and maintain, the correct endpoint when treating PWS with this deeply penetrating near-infrared laser at high fluences in order to (a) induce lesional lightening, and (b) avoid deep dermal burns that may produce scarring. Judicious use of the 755 nm laser can be beneficial for resistant PWS.

Motivation for contemporary tattoo removal: a shift in identity

OBJECTIVE

To compare the results of a 1996 study of tattoo possession and motivation for tattoo removal with those of a 2006 study, in light of today's current strong mainstream tattoo procurement and societal support within the young adult population.

DESIGN

Descriptive, exploratory study.

SETTING

Four dermatology clinics in Arizona, Colorado, Massachusetts, and Texas.

PARTICIPANTS

The 2006 study included 196 tattooed patients (66 men and 130 women).

MAIN OUTCOME MEASURES

Incidence of purchase and possession risk, as measured by a 127-item survey and factor analysis.

RESULTS

In contrast to the 1996 study, more women (69%) than men (31%) presented for tattoo removal in 2006. Women in the 2006 study were white, single, college educated, and between the ages of 24 and 39 years; they reported being risk takers, having stable family relationships, and moderate to strong religious beliefs (prayer and closeness to God). Commonly, tattoos were obtained at approximately 20 years of age, providing internal expectations of uniqueness and self-identity. Tattoo possession risks were significant, cited when the quest for uniqueness turned into stigmata (P < .001), negative comments (P < .003), and clothes problems (P < .004).

CONCLUSIONS

In both the 1996 and the 2006 studies, a shift in identity occurred, and removal centered around dissociating from the past. However, in the 2006 study, more women than men were notably affected by possession risks. Societal support for women with tattoos may not be as strong as for men. Rather than having visible tattoos, women may still want to choose self-controlled body site placement, even in our contemporary society.

Photoangiolytic Laser Treatment of Early Glottic Cancer: A New Management Strategy

The 532 nm pulsed KTP (potassium titanyl phosphate) laser and the 585 nm pulsed dye laser (PDL) are photoangiolytic lasers that have been demonstrated to be effective for managing vocal fold dysplasia. The putative mechanism of action is selective photoangiolysis of the sublesional microcirculation. On the basis of this experience, early glottic cancers were treated by selectively targeting the intralesional and sublesional microvasculature. This approach was derived from Folkman's concepts of neoplastic growth resulting from tumor angiogenesis. Staged microlaryngeal treatment was adopted, because it facilitated optimal functional results, and was considered safe, because early glottic cancer rarely metastasizes. Furthermore, intercurrent disease during conventional incremental radiotherapy is typical in treating early glottic cancer. A pilot group of 22 patients with early glottic cancer (13 T1, 9 T2) were treated with a fiber-based angiolytic laser. Eleven of the 22 had unilateral disease and were entirely treated by laser photoangiolysis as a sole modality. Eleven of the 22 had bilateral disease; 5 of the 11 were treated entirely (bilaterally) by laser photoangiolysis, and 6 of the 11 only underwent laser treatment of the less involved vocal fold, with conventional resection being done on the dominant side of the cancer. The initial 8 of the 22 were treated with the PDL, and the latter 14 of the 22 were treated with the pulsed KTP laser. No patient has cancer presently, and none have undergone posttreatment radiotherapy or open surgery. The mean follow-up is 27 months, 13 of the 22 patients have at least 2 years of follow-up, and the first patient was treated just over 5 years ago. Objective measures of vocal function revealed that photoangiolytic treatment of early glottic cancer resulted in significant postoperative improvements despite the fact that half of the patients had bilateral disease. Angiolytic lasers effectively involuted early glottic cancer, with microsurgically directed nonionizing radiation of the dense neoplastic blood supply resulting in complete tumor regression. This approach is conceptually attractive, because it is repeatable, it preserves all conventional cancer treatment options, and it results in excellent vocal function by improving phonatory mucosal wave vibration. Observations from this investigation suggest that this new and novel cancer treatment strategy is effective; however, larger patient cohorts, longer follow-up, and multi-institutional confirmation will be necessary to establish incontrovertible oncological efficacy.

Clues to the pathogenesis of psoriasis and psoriatic arthritis from imaging: a literature review

This article summarizes a presentation on imaging of skin and joints in patients with psoriasis and psoriatic arthritis (PsA) from the 2007 Annual Meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA). Plain radiography provides valuable insights into the pathogenesis of PsA but is limited because only calcified tissue can be imaged. Newer techniques such as magnetic resonance imaging (MRI) and ultrasound (US) provide additional clues to the pathogenesis of this peripheral, axial, and dermatologic disease. MRI and to a lesser extent US allow visualization of articular and periarticular structures, showing widespread juxtaarticular inflammation in PsA. Bone edema, a surrogate marker of inflammation, can occur throughout the digit in psoriatic dactylitis. Localization of inflammatory change at the juxtaarticular entheses suggests this as the primary site of inflammation. Recent imaging studies provide insights into the relationship between nail and articular disease, demonstrating extension of inflammation from entheseal structures at the distal interphalangeal joint to the nail bed, but the temporal or anatomical progression of these changes remains elusive. Imaging of the skin lags behind that of the articular structures, partly because the skin is readily available for biopsy; however, newer techniques such as laser Doppler imaging provide insights into angiogenesis at the advancing edge of psoriatic plaques. Future work will explore the relationship between immunohistology and imaging of skin and joints. Improvements in imaging articular soft tissues with ultra-short echo time MRI and skin with multiphoton fluorescence microscopy promise insights into anatomical and functional changes.

Photoangiolytic Laser Treatment of Early Glottic Cancer: A New Management Strategy

The 532 nm pulsed KTP (potassium titanyl phosphate) laser and the 585 nm pulsed dye laser (PDL) are photoangiolytic lasers that have been demonstrated to be effective for managing vocal fold dysplasia. The putative mechanism of action is selective photoangiolysis of the sublesional microcirculation. On the basis of this experience, early glottic cancers were treated by selectively targeting the intralesional and sublesional microvasculature. This approach was derived from Folkman's concepts of neoplastic growth resulting from tumor angiogenesis. Staged microlaryngeal treatment was adopted, because it facilitated optimal functional results, and was considered safe, because early glottic cancer rarely metastasizes. Furthermore, intercurrent disease during conventional incremental radiotherapy is typical in treating early glottic cancer. A pilot group of 22 patients with early glottic cancer (13 T1, 9 T2) were treated with a fiber-based angiolytic laser. Eleven of the 22 had unilateral disease and were entirely treated by laser photoangiolysis as a sole modality. Eleven of the 22 had bilateral disease; 5 of the 11 were treated entirely (bilaterally) by laser photoangiolysis, and 6 of the 11 only underwent laser treatment of the less involved vocal fold, with conventional resection being done on the dominant side of the cancer. The initial 8 of the 22 were treated with the PDL, and the latter 14 of the 22 were treated with the pulsed KTP laser. No patient has cancer presently, and none have undergone posttreatment radiotherapy or open surgery. The mean follow-up is 27 months, 13 of the 22 patients have at least 2 years of follow-up, and the first patient was treated just over 5 years ago. Objective measures of vocal function revealed that photoangiolytic treatment of early glottic cancer resulted in significant postoperative improvements despite the fact that half of the patients had bilateral disease. Angiolytic lasers effectively involuted early glottic cancer, with microsurgically directed nonionizing radiation of the dense neoplastic blood supply resulting in complete tumor regression. This approach is conceptually attractive, because it is repeatable, it preserves all conventional cancer treatment options, and it results in excellent vocal function by improving phonatory mucosal wave vibration. Observations from this investigation suggest that this new and novel cancer treatment strategy is effective; however, larger patient cohorts, longer follow-up, and multi-institutional confirmation will be necessary to establish incontrovertible oncological efficacy.

Thermal damage during thulium laser dissection of laryngeal soft tissue is reduced with air cooling: ex vivo calf model study

OBJECTIVES

The 2-microm-wavelength thulium laser has recently been shown to be an effective cutting instrument in endolaryngeal surgery, although there is increased thermal trauma as compared with the carbon dioxide laser. This study investigated temperature changes and thermal trauma during thulium laser dissection of laryngeal tissue, with and without air cooling, in an ex vivo model.

METHODS

A continuous-wave thulium laser (400-microm fiber, 4-W continuous power, 4-second duration) was used to incise 10 calf vocal folds. Paired cooled and uncooled cuts were made in each fold with a dermatologic cooling device. A thermistor inserted into the glottic subepithelium was used to measure tissue temperatures. Thermal damage was analyzed histologically by measuring the depth of the zone of lactate dehydrogenase inactivation surrounding the mucosal incision.

RESULTS

The initial vocal fold temperature averaged 24.3 degrees C without cooling and 4.4 degrees C with cooling. The peak temperature during cutting averaged 59.1 degrees C without cooling and 28.0 degrees C with cooling. The thermal damage zone surrounding the cooled incisions was approximately 27% less than that surrounding the uncooled incisions.

CONCLUSIONS

Air cooling can reduce the extent of thermal trauma associated with thulium laser surgery of the vocal folds, and the high-temperature plume generated during laser cutting is effectively cleared.

Foresight in laryngology and laryngeal surgery: a 2020 vision

Laryngology and laryngeal surgery have been in the vanguard of minimally invasive human procedural interventions for approximately 150 years. The natural passages through the oral cavity, nose, and pharynx have provided an accessible gateway to the larynx that has allowed for rapid translation of a variety of diagnostic and therapeutic technologies. Transoral and transcervical laryngeal surgery have been further facilitated by progressive advancements in local, topical, intravenous, and general anesthesia. With rapid developments in engineering disciplines (ie, tissue, chemical, mechanical) and voice science, there are a variety of current and near-term opportunities to advance our field. This report represents a panel at the 2005 American Broncho-Esophagological Association meeting that sought to use present perspectives, combined with cutting-edge research insights, to provide foresight into key aspects of laryngology that we believe will be developed by the year 2020. We hope that aspiring laryngeal surgeons will find elements of this discussion valuable for devising a strategic roadmap for research initiatives in laryngology and laryngeal surgery.

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa

OBJECTIVES

Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice.

STUDY DESIGN

The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture.

METHODS

Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically.

RESULTS

Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm).

CONCLUSIONS

This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Effects of skin temperature on lesion size in fractional photothermolysis

BACKGROUND AND OBJECTIVES

Fractional photothermolysis is a new concept in cutaneous re-modeling whereby laser-induced microscopic zones of thermal injury (MTZ-Microscopic Treatment Zones) are surrounded by normal, viable tissue. This unique thermal damage pattern allows re-epithelialization in less than 24 hours. To increase patient comfort level during the procedure of fractional photothermolysis, simultaneous skin cooling has been proposed and is now extensively used. The purpose of this in vitro study was to examine the influence of skin temperature on the diameter of the epidermal microthermal zone and the extent of thermal injury per unit area. The determination of the changes in these parameters that are due to skin temperature will allow the better control and understanding of fractional photothermolysis at different skin temperatures.

MATERIALS AND METHODS

Fractional photothermolysis was performed with a 1,550 nm fiber laser (Fraxel SR Laser) with 10 mJ per pulse on full-thickness cadaver skin. The skin samples were brought prior to exposure to temperatures that ranged from 0 to 45 degrees C. The epidermis of the skin samples was separated by dispase treatment, stained for thermal damage by NBTC stain, and lesion diameter was assessed by a blinded investigator.

RESULTS

The average MTZ diameter exhibits a positive, linear relationship with skin temperature (R(2) = 0.904, P < 0.0001). As the skin temperature increases from 0 to 45 degrees C. The MTZ diameter increases from 93 to 147 microm (58%), and the MTZ area from 6,870 to 17,050 microm(2) (148%).

CONCLUSION

The skin temperature affects the size of epidermal MTZs during fractional photothermolysis and is an important variable factor. The use of simultaneous skin cooling increases patient comfort; however, as it also decreases MTZ size, it may interfere with treatment efficacy. The control of skin temperature is necessary to provide a consistent outcome and to be able to compare treatments.

Virtual biopsy of the joint tissues using near-infrared, reflectance confocal microscopy. A pilot study

Standard noninvasive imaging techniques applied to joints provide gross morphological features, insufficient for assessing histological detail. On the other hand, biopsying is invasive, time consuming, and may involve unwanted processing artifacts. Near-infrared reflectance confocal microscopy is a technique that allows serial, high-resolution optical sectioning through intact tissues without employing exogenous fluorescent stains. The aim of this work was to evaluate the potential utility of near-infrared reflectance confocal microscopy for providing immediate histological information on meniscus, articular cartilage, epiphyseal plate, bone, muscle, and tendon. Images from near-infrared reflectance confocal microscopy were compared with mirror routine histology sections. Characteristic architectural features were readily visualized in the three dimensions of space. Additionally, the use of experimental contrast agents highlighted the localization of nuclei. Limitations include penetration depth and minor optical artifacts. In conclusion, near-infrared reflectance confocal microscopy is a useful technique for immediate, nondestructive, serial "virtual" sectioning through intact tissues, being thus a potential adjunct to current imaging techniques in orthopedics.

Evaluation of human knee meniscus biopsies with near-infrared, reflectance confocal microscopy. A pilot study

Knee cartilage biopsy is used to confirm the pathology in both clinical and experimental conditions and often guides diagnosis and therapeutic strategies. Current histopathological techniques are time consuming, induce tissue artefacts and often prevent further evaluation, once the tissue has been fixed. Hence, there is a potential need for a fast and nondestructive imaging technique for unfixed tissue. Near-infrared, reflectance confocal microscopy (CM) allows real-time, virtual sectioning of unstained, bulk tissue samples. This pilot study evaluates the use of CM in the assessment of meniscus histopathology in a series of 26 freshly-excised human meniscus samples compared to standard light microscopy of stained sections. CM images of the meniscus show cell and matrix detail, depicting morphologic features of collagen and elastic fibres, vessels and nerve endings. In addition, crystal deposits of gout and pseudogout are also demonstrable. Thus, CM is a novel imaging technique that could enable the pathologist to make a rapid microscopic evaluation of cartilage in a fresh and unfixed fashion.