Nd:YAG laser therapy of an oral verrucous leukoplakia.

A 75-year-old female patient afflicted with an extensive verrucous oral leukoplakia is reported. With treatment by the Nd:YAG laser under local anesthesia on an outpatient basis, the disease could be kept under control for 4 years.

[Condylomata acuminata gigantea (Buschke-Löwenstein tumor). Treatment with the CO2 laser and interferon]. / Condylomata acuminata gigantea (Buschke-Löwenstein-Tumor). Behandlung mit dem CO2-Laser und Interferon.

CO2 laser resection of giant condylomata acuminata of the penis, histologically confirmed, was successfully achieved with excellent cosmetic results in a 58-year-old man, penis amputation having previously been advised. Postoperative recurrence has been prevented, for six months so far, with low-dose, systemic administration of alpha-2b interferon.

Fundamentals of laser light interaction with human tissue, especially in the cardiovascular system.

The absorption of single photons in the molecules of biological tissue can induce various reactions. For the most medical laser applications the transformation from radiation energy into heat is relevant. The laser beam is used for coagulation or vaporization of tissue. The changes in tissue, which are created by light of different wavelengths depends on the thermal and optical properties (absorption and scatting) of tissue but also on the parameters of irradiation. As an example measurements from human skin are discussed. In the cardiovascular system laser light must have a clearly defined effect. Atherosclerotic plaques of different consistence have to be vaporized without damage of the vessel walls. From different reasons the usual medical CW-lasers, Argon-laser, CO2-laser and Nd:YAG-laser, are not optimal for direct ablation of arterial occlusions. In order to mimize reocclusion the walls of the channels have to be completely smooth and free of coagulation necrosis. This can be obtained by short laser pulses. Selection of a light wavelength, which is stronger absorbed in atherosclerotic plaques than in vessel walls and additional selective staining are two ways to reduce the risk of damaging the vessel walls.

[The CO2 laser in dermatotherapy--use and indications]. / Der CO2-Laser in der Dermatotherapie--Anwendung und Indikation.

Due to the high absorption of infrared light in water the CO2 laser (lambda = 10,600 nm) is suitable for cutting and vaporizing tissue. The ablation of pathological tissue by means of the CO2 laser can be exactly controlled. The treated area is usually dry and clear since blood and lymph vessels up to a diameter of 1 mm are sealed. Postoperative swelling and pain are reduced compared with electrosurgery. Important and frequent indications for CO2 laser application are HPV papillomas (condylomata acuminata, common warts, bowenoid papules) and the removal of tattoos. The CO2 laser is also suitable for the removal of benign and disseminated lesions such as angiofibromas, syringomas, trichoepitheliomas, epidermal nevi etc. Lesions of the oral mucosa (leukoplakias, mucosal warts) can be removed by means of the CO2 laser. Additionally, the treatment of vascular lesions (nevi flammei, lymphangiomas, telangiectasias) has been described, although the CO2 laser does not operate in a vessel-specific manner. As this review article demonstrates, the CO2 laser has a broad range of applications and represents an enrichment of dermatotherapy.

[Treatment of naevi flammei with the argon laser]. / Zur Behandlung von Naevi flammei mit dem Argon-Laser.

We report on 901 patients with port wine stains treated by means of an argon laser. The treatment results have been definitively evaluated in 371 patients. They were significantly influenced by the patients' age and by the colour of the lesions. The worst response to the therapy was seen in pink port wine stains in children and juvenile patients (20% good results), in contrast to red and purple lesions in adult patients (80% excellent and good results). The size of the port wine stains did not significantly influence the treatment results, but in extensive lesions homogeneous lightening could not usually be attained and treatment often extended over some years. Port wine stains in the head and neck area responded best to therapy, and lesions on the legs, worst. Altogether, in 60%-70% of adult patients excellent or good results were obtained, the lesions being completely removed or significantly lightened and reduced in size. The side-effects of laser therapy were scar formation (7.3%) and changes in pigmentation (8.6%).

Comparison of the maximum coagulation depth in human skin for different types of medical lasers.

The values for the maximum coagulation depth (MCD) of various types of lasers which are specified in the literature are not comparable, because often different irradiation times were used. MCD depends not only on the wavelength of laser light, but also on the time of action of the laser beam, because of heat transfer. In excised human skin MCD was determined histologically for irradiation with the argon laser, Nd:YAG laser, and CO2 laser. Extending the irradiation time from 0.2 s to 10 s results in a 4-6-fold increase in MCD. Coagulation experiments performed with a soldering iron have shown results similar to those obtained with the CO2 laser. Enlargement of the laser-beam diameter from 1 to 2 mm leads to a 50% increase in MCD. Additional chilling of the skin with water during laser irradiation protects the skin from evaporation, and the values for MCD increase to 3.5 mm for the argon laser and 5.5 mm for Nd:YAG laser. Detailed knowledge of the MCD is necessary to obtain the desired therapeutic effect, and also to avoid unwanted effects.

Laser therapy of bowenoid papulosis and Bowen's disease.

Six patients with bowenoid papulosis and two patients with Bowen's disease of the genital area were treated by means of an argon, Nd:YAG, and CO2 laser. In all of the patients, complete resolution of the lesions was achieved. Due to a superficial coagulating effect, application of the argon laser should be restricted to macular and papular pigmented lesions. In contrast, Nd:YAG and CO2 lasers could be used even for treatment of extensive leukoplakia-like and verrucous lesions. Advantages and disadvantages of these two lasers are discussed.

Neodymium-YAG laser therapy for vascular lesions.

Three patients with port-wine stains with a nodular surface, one patient with macrocheilia resulting from a port-wine stain, and one patient with a capillary hemangioma were treated with a Nd-YAG laser (mediLas, MBB-AT, Munich). Irradiance was between 800 and 1,600 watts/cm2, with energy fluence between 400 and 1,600 joules/cm2. Treatments were performed with local anesthesia on an outpatient basis. In all patients, marked improvements could be obtained after only a few treatments. Histologically there was necrosis of epidermis and dermis immediately after laser application, and ectatic vessels contained coagulated erythrocytes. Depth of coagulation was up to 3.5 mm. Quick restoration of epidermis was observed. After some days, macrophages, fibroblasts, and capillary blood vessels grew into the agglutination thrombi and ectatic vessels were replaced by granulation tissue and, later, by fibrous tissue. In comparison with the argon laser, the Nd-YAG laser coagulates at a much deeper level, but processes of tissue repair take longer and fibrosis is more pronounced after Nd-YAG laser application. Clinically, therefore, scar formation is more likely. Chilling the skin surface during irradiation and shorter exposure times may be effective in reducing the risk of scar formation in the future.

Effects of argon, dye, and Nd:YAG lasers on epidermis, dermis, and venous vessels.

The aim of the present study, which was performed at the dorsal aspects of the ears of guinea pigs, was to compare effects of different lasers on epidermis, dermis, and small venous vessels. Irradiations were performed with argon, dye, and Nd:YAG lasers. In the first series tissue repair processes were studied after argon laser application. Laser defects were excised after 1, 4, 8, and 14 days and were prepared for routine histological examination. The breadth of epidermal defect and extent of dermal coagulation and occlusion of vessels by thrombus formation were examined histologically. In a second series parameters of irradiation (ie, exposure time, laser power) of the three different lasers were changed systematically. Laser-induced morphological tissue changes could be best observed 24 hours after irradiation. Each of the lasers led to occlusion of vessels by thrombus formation and also coagulated epidermis and dermis. The extent of dermal and epidermal coagulation was less pronounced after dye laser application. Using short exposure times it was possible to reduce the extent of epidermal damage caused by argon and Nd:YAG lasers. Only 50-msec dye laser pulses led to intravascular thrombus formation without epidermal and dermal damage.

Treatment of benign, semimalignant, and malignant skin tumors with the Nd:YAG laser.

Reported are first experiences with Nd:YAG laser treatment of benign, semimalignant, and malignant skin tumors in 90 patients. Treated lesions included condylomata acuminata, basal cell carcinomas, solar keratosis, squamous cell carcinomas, and secondary malignant skin tumors. First clinical and histological results are promising, but long-term follow-up is required to judge the definite efficacy of this therapeutical modality.

Argon laser therapy of verrucous nevi.

In one patient afflicted with a systemic verrucous nevus, a marked improvement was obtained by repeated treatments with an argon laser. In two patients it was possible to remove localized verrucous nevus completely. There was no recurrence in the follow-up of 8 and 14 months, respectively.

A three-year experience with the argon laser in dermatotherapy.

Since January 1980, 477 patients were treated with an argon laser, 337 afflicted with vascular lesions and 140 with nonvascular lesions. Laser therapy of portwine stains gave good results in 70% of the adult patients, but it was disappointing in patients younger than 18 years of age. Other vascular lesions, such as telangiectasia, venous lake, angiofibroma, lymphangioma, and cherry angioma, were also treated with success. For the removal of tattoos the argon laser is not an optimal modality. In our experience it should only be used in skin areas, where dermabrasion cannot be performed. Therapy of epidermal nevi, xanthelasma of the eyelids, verrucae, vulgares , and sebaceous gland hyperplasia gave preliminary promising results in some patients.

Laser therapy of venous lakes (Bean-Walsh) and telangiectasias.

In 18 patients, venous lakes, and in 77 patients, telangiectasias were successfully treated with the argon laser. Because treatments were easy to perform and patients were not impaired by therapy, the argon laser is the treatment of choice for these conditions in our experience.

The effects of laser light on sperm motility and velocity in vitro.

The effect of Laser light on the motility and the velocity of human spermatozoa were measured by means of multiple exposure photography. Total sperm motility increased after Laser irradiation at 4 J/cm2, 8 J/cm2 and 32 J/cm2 respectively with respect to control. However, no influence on sperm velocity was demonstrated after Laser irradiation. This observation suggests that Laser light stimulates non-motile live spermatozoa.

[Morphologic studies in the treatment of nevus flammeus with argon laser]. / Morphologische Untersuchungen zur Behandlung von Naevi flammei mit dem Argonlaser.

Immediately after the argon laser impact one finds necrosis of epidermis and superficial dermis. Dilated vessels down to a depth of 0.8 mm are filled with coagulated erythrocytes. After 2 days there is initial restoration of epidermis, and dilated vessels are filled with agglutination thrombi. With and after the 6th day fibroblasts and capillary blood vessels grow into the thrombi, and later on vessels are completely replaced by granulation tissue and after 2-4 weeks by newly formed fibrous tissue.

[Treatment of zoster, post-zoster pain and herpes simplex recidivans in loco with laser light]. / Behandlung von Zoster, postzosterischen Schmerzen und Herpes simplex recidivans in loco mit Laser-Licht.

Red light of a krypton laser (lambda = 647 nm) was used for treatment of patients suffering from herpes zoster (n = 4), postherpetic neuralgias (n = 8) and herpes simplex recidivans in loco (n = 13). The afflicted skin was irradiated daily for ten days (laserpower 50 mw, exposure time 90 sec). Improvement was observed in 7 out of the 12 patients suffering from herpes zoster and postherpetic neuralgias respectively, and in 8 out of 13 patients afflicted with recurrent herpes simplex.