Tissue Vaporization Research Articles

Individualized therapy of sterility caused by endometriosis

In the case of infertility the macroscopically and/or histologically confirmed diagnosis of endometriosis alone is not an indication for surgical or medical treatment of endometriosis. Treatment is necessary only when additional clinical symptoms of pain caused by the disease, active proliferative implants, severe mechanical disturbances of Fallopian tubes and ovaries, or deep infiltration endometriosis is judged as a relevant cause of sterility. The presence of implants alone – especially in mild or minimal stages – is probably an accidental finding with no correlation to the infertility problems. The therapeutic options are surgical – mainly endoscopic surgery – medical or a combination of both. Regression of the implants and shrinkage of the cysts can be achieved with medically induced ovarian suppression. Clinical trials have demonstrated that high doses of progestins, Danazol and GnRH agonists are effective. Because low differentiated types of endometriosis and deep infiltration nodules can only be influenced with permanent estrogen deprivation, an endoscopic surgical procedure– resection, coagulation or vaporisation of endometriotic tissue, plus resection of adhesions and fibrosis – is the main therapeutic principle. Because microscopic implants and deep infiltration foci surrounded by fibrosis can not be treated sufficiently with endoscopic surgery alone, an individual therapeutic strategy must be adopted in each case of endometriosis and infertility. Taking in account the age of the patient, the duration of infertility, and other factors we have to consider medical and/or surgical treatment of endometriosis.

Cutaneous resurfacing with CO2 and erbium: YAG lasers: preoperative, intraoperative, and postoperative considerations.

The development and integration of pulsed and scanned CO2 and erbium:YAG laser systems into mainstream surgical practice over the past years has revolutionized cutaneous resurfacing. These lasers are capable of delivering to skin high peak fluences to effect controlled tissue vaporization, while leaving an acceptably narrow zone of residual thermal damage. The inherent technological differences that exist between the two distant laser systems in terms of ablation depths, degree of thermal coagulation, and postoperative side-effects and complications guide patient selection and management. This article reviews the basic principles of CO2 and erbium:YAG laser resurfacing, including preoperative, intraoperative, and postoperative patient considerations. Side-effects and complications encountered after laser resurfacing are discussed with specific guidelines provided on their appropriate management. Anticipated future developments and cutting-edge research endeavors in cutaneous laser resurfacing are also briefly outlined.

Thick Loop Transurethral Resection of the Prostate

Objectives: To evaluate the safety and efficacy of the new resection loops for transurethral resection of the prostate (TURP). These loops, which are both thicker and have a modified shape, allow simultaneous resection, increased tissue vaporization, and improved hemostasis. Methods: Two open studies have been performed with the thick resection loop. In one series, 91 patients underwent TURP with the Vapor Cut (G. Vallancien, Paris), and in another series, 65 patients underwent Wedge (Microvasive, Natick, Mass., USA) resection (A. Perlmutter, New York). Results: At 1 year follow-up, patients who underwent thick loop resection enjoyed the same clinical benefit of thin loop TURP without additional morbidity. Peak urinary flow rate improved to 18.4 and 16.3 cm³/s at 1 year with the Vapor Cut and Wedge, respectively. IPSS fell to 7.2 (Vapor Cut) and 6.2 (Wedge). Postoperative bleeding, meatal stenosis, and urethral stricture were noted, but no impotence or incontinence was observed. Conclusions: Thick loop resection offers the advantage of improved surgical vision during resection, thus allowing a more accurate and safer resection. This can be performed with only minor modifications of the standard TURP technique.

Diamond-shaped optical fiber delivery system.

Physicians who use laser systems are looking for new fiberoptic delivery systems with better performance. We searched for a delivery system with high power and with a tip of high durability that may be reused many times. The delivery systems currently found on the market can burn and break easily. The surgeon may either finish the surgery with a damaged delivery system, or have to switch to a new one during surgery, thus increasing the inconvenience and cost of the surgery. Distal tips of fibers used with Nd:YAG and diode lasers have been shaped and polished according to their specific function, including excision, vaporization, and coagulation of tissue. We have developed several prototypes of optical fiber delivery systems, and in particular, we have developed a prototype of a delivery system, called the Diamond-Shaped Optical Fiber Delivery System, or Diamond. By making the tip of an optical fiber diamond shaped, we are able to obtain greater mechanical resistance than that of other delivery systems that were tested in our laboratory. In the Colorectal Unit, we applied it in surgical procedures such as perianal fistulectomy, hemorrhoidectomy, and excision of condilomata acuminata and pilonidal cyst and sinuses. During cutting and coagulating, the system performed well with no technical problems. A new delivery system (Diamond) gave satisfactory performance during surgical operations. Its main component, the diamond-shaped distal end, provided high durability and was reused many times, thus improving the quality of operations and reducing expenses greatly.

Transurethral electrovaporization-resection of the prostate using the “wing” cutting electrode: preliminary results of safety and efficacy in the treatment of men with prostatic outflow obstruction

Objectives. Transurethral vaporization-resection of the prostate (TUVRP) is a modification of the standard transurethral prostatectomy (TURP). The technique uses the “Wing” resection loop with electrovaporization current to achieve simultaneous resection, vaporization, and coagulation of prostatic tissue. We evaluate the early safety and efficacy results of TUVRP in the treatment of patients with prostatic outflow obstruction. Methods. The first 31 patients treated with TUVRP since September 1997 are reported. The group included 19 patients with urinary retention and 12 patients with lower urinary tract symptoms (LUTS). Patients with symptoms were assessed at baseline with the International Prostate Symptom Score (IPSS) and maximum flow rate (Qmax). The same parameters were evaluated at 3 months for the entire group. Safety parameters included changes in serum hematocrit and sodium concentration, incidence of side effects, and changes in sexual function. Results. All patients with retention were voiding spontaneously with an IPSS of 3.9 ± 3.1 and Qmax of 21.3 ± 10.2 mL/s. In the patients who presented with LUTS, the IPSS decreased from 24.3 ± 8.3 to 4.1 ± 4.9 at 3 months and Qmax increased from 5.2 ± 4.5 mL/s to 16 ± 7.5 mL/s at 3 months ( P <0.001). Mean resection weight was 27.9 ± 18.4 g. Mean postoperative catheter time was 24.1 hours. Mean change in hematocrit concentration was 2.5 mL/dL and the change in sodium concentration was 0.8 mEq/L. Complications included 1 patient with a bladder neck contracture, 1 with a urethral stricture, and 1 with clot retention; 1 patient developed transurethral syndrome. No change in sexual function was noted in this group. Conclusions. TUVRP is a promising new modification of TURP. This procedure combines the excellent debulking capabilities of TURP (with preservation of the entire specimen for histopathologic examination) and adds the benefits of electrovaporization, resulting in minimal blood loss and electrolyte disturbance.

Carbon dioxide laser resurfacing of the aged face.

Aging of the skin of the face consists of an intrinsic aging process that is genotypically inherent and inevitable, which accounts for the thinness of tissue that is lax and redundant. It can include benign and premalignant neoplasms [1, 2]. While photoaging or extrinsic aging is environmentally mediated and is characterized by fine and deep facial skin wrinkling; it can be characterized by thickened, coarse, yellow, sallow skin, that is studded with telangiectasia, macules of hyper-and hypopigmentation, benign, premalignant and malignant neoplastic lesions [1, 3—6]. There are many ways to rejuvenate aged skin, which include topical treatments with vitamin A acid [7,8], alpha and beta hydroxy acids [9, 11] and various types of skin resurfacing either by chemical peelings of glycolic, trichloracetric or phenolic acids for superficial, medium to deep depth resurfacing respectively [12, 13], or by performing a mechanical dermabrasion [14, 17]. This presentation will highlight rejuvenating the photodamaged and aged skin of the face by the currently most popular modality of resurfacing, which is using a high energy carbon dioxide laser that is either pulsed or flashscanned [18—23].

A theoretical comparison of energy sources - microwave, ultrasound and laser - for interstitial thermal therapy

A number of heating sources are available for minimally invasive thermal therapy of tumours. The purpose of this work was to compare, theoretically, the heating characteristics of interstitial microwave, laser and ultrasound sources in three tissue sites: breast, brain and liver. Using a numerical method, the heating patterns, temperature profiles and expected volumes of thermal damage were calculated during standard treatment times with the condition that tissue temperatures were not permitted to rise above (to ensure tissue vaporization did not occur). Ideal spherical and cylindrical applicators ( and radii respectively) were modelled for each energy source to demonstrate the relative importance of geometry and energy attenuation in determining heating and thermal damage profiles. The theoretical model included the effects of the collapse of perfusion due to heating. Heating patterns were less dependent on the energy source when small spherical applicators were modelled than for larger cylindrical applicators due to the very rapid geometrical decrease in energy with distance for the spherical applicators. For larger cylindrical applicators, the energy source was of greater importance. In this case, the energy source with the lowest attenuation coefficient was predicted to produce the largest volume of thermally coagulated tissue, in each tissue site.

Internally cooled power laser for MR-guided interstitial laser-induced thermotherapy of liver lesions: initial clinical results.

To evaluate experimentally and clinically an internally cooled power laser system for percutaneous treatment of liver metastases, with magnetic resonance (MR) imaging guidance, to increase the volume of coagulative necrosis with single laser beam applications. The power laser system consisted of standard cannulation paraphernalia and a specially designed 7-F protective catheter for cooling the laser tip during treatment to avoid carbonization. A microdome laser beam applicator with a laser tip diameter of 0.95 mm kept the entire device as small as possible. After the unit was tested in 40 porcine livers, 532 laser beam applications (mean power, 27.5 W [range, 22.1-30.0 W]; mean application time, 19.8 minutes [range, 14-30 minutes]) were performed with MR guidance in 127 patients with 318 liver metastases. The safety of the procedure and the volume of induced necrosis were evaluated. In vitro, cuboid areas of coagulative necrosis with a mean greatest diameter of 4.3 cm +/- 0.5 (SD) were demonstrated after single applications. In vivo, MR thermometry allowed accurate demarcation of changes induced by heat, with a mean diameter of necrosis of 3.3 cm +/- 1.4. No carbonization or vaporization of tissue or damage of equipment occurred during treatment. This power laser system can increase the volume of laser-induced necrosis in liver metastases with a single application, thereby simplifying and accelerating the treatment of larger lesions.

Noninvasive diagnostic work-up correlated with operative findings in non-small lung cell cancer (NSCLC) patients

procedure is carried out using rigid or flexible unipolar electrodes. An ERBE (ACC 350) generator produces the HFT, which is automatically controlled and regulated by the current output in the treatment area. White coagulation is induced by heating up to 70-100°C causing tissue vaporization. We treated 51 patients (men = 42; women = 9; mean age 64 years) with inoperable malignant turnouts obstructing the trachea or bronchi. Response to treatment was evaluated on clinical manifestations and endoscopic findings. Haemostasis was immediately obtained in 18/20 cases and tumour destruction of more than 50% in 44/51 cases. Complications included haemotysia in three patients followed by death due to respiratory failure in one, and tracheal stenosis in one. HFT has an immediate effect, somewhat ‘laser like’. It’s a simple technique for rapid palliation and immediate tumour debulking. The equipment is relatively cheap. Morbidity is low. HFT could be very useful, particularly in countries where treatment by means of laser is not available due to prohibitive cost. Ref. J.P. Homasson. Endobronchial electrocautery. Semin Resp Crit Care Med. 1997;18:535-543.

Laser-assisted shoulder surgery.

The application of laser/thermal energy in arthroscopic shoulder surgery remains controversial. Laser proponents tout the benefits of coagulation and vaporization of tissue, whereas opponents cite costs, complications, and the fact that the laser has not yet shown results superior to presently available mechanical techniques. A lack of basic science studies and the aversion of many physicians to the marketing aspects of laser technology have undermined the widespread orthopaedic acceptance of laser techniques. Newer applications, such as capsular shrinkage are just now being evaluated as to effect and efficacy. Orthopaedists should be assured that, at present, they are not compromising patient care by not using laser techniques.

Carbon Dioxide Laser-assisted Hair Transplantation

"Char-free" carbon dioxide lasers are capable of precise tissue vaporization with minimum residual thermal damage. These lasers deliver very high bursts of energy for extremely short durations, and can vaporize recipient sites during hair transplantation, which are consistent in depth and diameter. To determine the depth of ablation and lateral thermal damage of scalp tissue using various laser parameters with the Sharplan 80XJ Silklaser. Two hundred forty laser recipient sites were created, using 24 different laser parameters in each of 10 specimens of scalp tissue removed during scalp reduction. These specimens were evaluated histologically for depth of ablation and lateral thermal damage. While some laser parameters worked better regarding consistent depth of ablation of scalp tissue, lateral thermal damage was quite narrow (average, 20-50 microns). None of the laser parameters tested in this study should be problematic when used clinically for hair transplantation.

Treatment of Periorbital Wrinkles

Chemical peels are an effective treatment for wrinkles, but their use is limited because of the associated risk of scarring, hypopigmentation, and the inability to accurately control the depth of tissue injury. High energy, pulsed, or computer scanned continuous wave carbon dioxide (CO2) lasers cause minimal thermal injury, decrease the risk of scarring, and allow for precise control of tissue vaporization to predictable depths.To compare the effectiveness and side effect profile of a medium-depth chemical peel to that of the SilkTouch CO2 laser in the treatment of periorbital wrinkles.Twenty-four subjects (nine male, 15 female) with moderate to severe periorbital wrinkles were assigned a wrinkle score (1 = mild through 5 = severe) before treatment and 6 months after treatment. Each subject was treated with Jessner's solution and 35% trichloroacetic acid on one side and the SilkTouch CO2 laser on the other side.The average periorbital wrinkle score decreased from 4.00 +/- 0.78 before laser treatment to 1.75 +/- 0.68 6 months after treatment. The chemical peel wrinkle score decreased from 4.13 +/- 0.85 to 3.29 +/- 0.99. The degree in which the wrinkle score improved after laser treatment compared with after chemical peel treatment was statistically significant. Posttreatment erythema lasted an average of 4.5 months for the laser-treated areas and 2.5 months for the chemical peel-treated areas.Treatment of periorbital wrinkles with the SilkTouch CO2 laser resulted in a greater degree of improvement than treatment with a medium-depth chemical peel but had longer lasting posttreatment erythema.

LASER RESURFACING OF ATROPHIC SCARS

Many patients seek treatment for the disfigurement caused by obvious variations in skin texture secondary to atrophic scarring. Many different procedures, including dermabrasion, chemical peels, punch grafting, and augmentation with filling materials, have been implemented for the treatment of atrophic scars. With the advent of high-energy, pulsed and scanned CO2 laser technology, precisely controlled, layer-by-layer tissue vaporization may be achieved with minimal thermal damage to adjacent skin. Atrophic scars resulting from acne, surgery, or trauma respond more favorably to laser resurfacing than to other, more conventional forms of treatment when proper techniques are employed.

Quantitative assessment of variables that influence soft-tissue electrovaporization in a fluid environment

Objectives. To evaluate the process of soft-tissue electrovaporization and to study variables that affect tissue clearance rates in a laboratory setting, in order to identify parameters that can optimize transurethral electrovaporization of the prostate. Methods. Fresh bovine skeletal muscle, equivalent in impedance and surface properties to the human prostate, was submerged in 3.3% sorbitol solution and electrovaporized with a grooved monopolar electrode attached to the weighted arm of a linear actuator. The effects of excursion rate, applied mechanical load, power setting, electrode configuration, and generator performance on the volume of tissue removed, were assessed. Results. Tissue removal increased significantly when electrode excursion rate was slowed from 25 to 15 mm/s ( P <0.05) and then to 10 mm/s ( P <0.05); when the load was increased from 20 to 50 g ( P <0.005); and when dial power was increased from 120 to 150 W ( P <0.01). Tissue removal was generator dependent. There was no significant difference between the Force 40 and the Force 2 ( P > 0.4), but a new computer-controlled constant power output generator (Force FX) did significantly improve tissue vaporization at an equivalent power setting ( P <0.005 and P <0.01, respectively). Tissue removal was also dependent upon electrode configuration, with the VaporTrode-Grooved Bar removing significantly more tissue than either an ungrooved roller bar of equivalent size or 2-mm smooth roller ball, respectively, both after a single pass ( P <0.001 and P <0.05) and after five repeated passes ( P <0.05 and P <0.005). The histologic depth of tissue thermal effect was less than 1 mm, but it was 38% greater for the VaporTrode-Grooved Bar (0.68 mm) than for the standard cutting loop (0.5 mm, P <0.01). Conclusions. Using a novel method to quantify tissue removal, we have demonstrated that electrode configuration, excursion rate, applied load, power setting, and generator performance are interdependent factors that influence the efficacy of the electrovaporization process in a fluid environment.

High-power (60-watt) potassium-titanyl-phosphate laser vaporization prostatectomy in living canines and in human and canine cadavers

Objectives We studied the safety and efficacy of 60-W potassium-titanyl-phosphate (KTP) laser prostatectomy in living dogs and compared the efficacy with that in fresh human and dog cadavers. Methods Ten dogs underwent 60-W KTP laser prostatectomy and were sacrificed 3 hours (n = 5) or 7 weeks (n = 5) after operation. Two thawed fresh-frozen human cadaver prostates and two thawed fresh-frozen canine prostates were also vaporized with the 60-W KTP laser. All prostates were weighed, measured, serially sectioned, and whole mounted for histologic analysis. Results In dogs, the in vivo procedure was hemostatic, and no irrigant absorption was detected. Prostatic defects with a mean diameter of 3.0 and 2.5 cm at 3 hours and 7 weeks postoperatively, respectively, were produced. With experience, resection time was reduced to 14 minutes. Of the 5 dogs that were studied for 7 weeks, 4 voided immediately after removal of the urethral catheter on the morning after operation, and 1 dog required recatheterization but voided with a strong stream when the urethral catheter was removed 4 days later. All 5 dogs were continent and had normal erectile function postoperatively. Defects of 2.0 and 2.5 cm were produced in the two human cadaver prostates (weight, 29.5 and 55 g) with resection times of 26 and 54 minutes, respectively. Human and canine cadaver prostates required similar energies for tissue vaporization (15.2 and 13.7 kJ/cm 3 cavity created, respectively, P > 0.6), whereas living canine prostates required only 7.0 kJ/cm 5 cavity created ( P < 0.01 compared with cadaver tissue). Conclusions The 60-W KTP laser allows technically easy, safe, rapid, and hemostatic removal of canine prostatic tissue in vivo. Furthermore, there is no difference in the efficacy of KTP laser vaporization between human and canine cadaver prostates. These findings suggest that KTP laser vaporization may be as effective in living human prostates as it is in living dogs, and thus it may be a useful technique in the surgical treatment of human benign prostatic hyperplasia.

Ablation of Urethral Strictures Using Contact Chisel Crystal Firing Neodymium: Yag Laser

The technique for ablation of urethral strictures using the contact crystal tip firing neodymium:YAG laser was evaluated for adequacy and long-term durability of the ablation. A total of 42 male spinal cord injured patients with suspected urethral strictures approximately 1 to 4 cm. long was evaluated. The strictures were localized and the men underwent endoscopic laser ablation using a contact laser chisel probe (2.5 or 3.5 mm.) screwed onto the end of a semirigid fiber. The usual power setting was 25 to 35 watts. Circumferential vaporization of fibrous tissue was done to achieve complete ablation. For pinpoint strictures with dense fibrosis, subsurface buttonholes were also made to vaporize and ablate expediently all fibrous tissue. A catheter was usually left indwelling overnight only. Estimated blood loss was 25 to 50 ml. All patients were followed for a mean of 28.2 months (range 12 to 46). Of the patients 39 (93%) have adequate voiding and have maintained durability of the stricture ablation. Laser ablation was successfully repeated in 1 patient with initial failure and in 2 with partial failure. Both patients were well for 7 to 18 months. No patient required bougie dilation. For strictures of the urethra the success rate following ablation was greater than that after other reported techniques. Contact laser ablation is simple to perform, with the least morbidity following the procedure, and it can be easily repeated for lasting results.

Prostate Heating Patterns Comparing Electrosurgical Transurethral Resection and Vaporization: A Prospective Randomized Study

A prospective study was performed to determine if transurethral electrosurgical vaporization of the prostate is associated with unseen heat damage to vital periprostatic structures compared to conventional loop resection. In addition, energy consumption and its relationship to observed tissue temperature at the prostate periphery were evaluated for each treatment. Patients with moderate to severe symptoms of benign prostatic bladder outflow obstruction and objective evidence of diminished flow or acute urinary retention were randomized to undergo either transurethral loop resection or electrosurgical vaporization after stratification for gland volume. Instrumentation was standardized for both groups except for the monopolar electrode used. The radiofrequency power source in the study was a new computer controlled generator with a constant power delivery feature. Regional tissue heating patterns were evaluated with optical fiber probes in real time. Four stationary sites were chosen for temperature measurements, namely the lateral lobe of the prostate, neurovascular bundle beside the prostatic apex at the level of the external sphincter, and anterior rectal wall at the level of the prostatic base and apex. A pull back technique was used to search for hot points in the long axis of the probe (3-dimensional temperature mapping) in 2 patients from each group. Incident generator panel power settings for the electrosurgical vaporization treatments were equivalent to those commonly used for loop resection (150 watts) and were adjusted up or down as needed. Prostate electrosurgical vaporization was possible at generator panel settings that were nearly equivalent to those for transurethral resection of the prostate (130 to 190 watts). No significant rectal or sphincteric heating was detected with either procedure. Conductive cooling of the neurovascular bundles was observed in 2 patients in each group toward the end of the operation. More energy was used per minute of treatment during electrosurgical vaporization than with regular loop resection (p < 0.004) but this was not associated with unwanted tissue heating. Neither conventional loop resection nor electrosurgical vaporization of the prostate appeared to be unsafe treatments with respect to unseen deep heating effects to vital periprostatic structures when performed at equivalent low incident power. The extra energy used during electrosurgical vaporization provided the benefit of improved coagulative hemostasis concurrently with shallow tissue vaporization using pure cutting current alone, without compromising treatment safety.

Treatment of periorbital wrinkles. A comparison of the SilkTouch carbon dioxide laser with a medium-depth chemical peel.

Chemical peels are an effective treatment for wrinkles, but their use is limited because of the associated risk of scarring, hypopigmentation, and the inability to accurately control the depth of tissue injury. High energy, pulsed, or computer scanned continuous wave carbon dioxide (CO2) lasers cause minimal thermal injury, decrease the risk of scarring, and allow for precise control of tissue vaporization to predictable depths. To compare the effectiveness and side effect profile of a medium-depth chemical peel to that of the SilkTouch CO2 laser in the treatment of periorbital wrinkles. Twenty-four subjects (nine male, 15 female) with moderate to severe periorbital wrinkles were assigned a wrinkle score (1 = mild through 5 = severe) before treatment and 6 months after treatment. Each subject was treated with Jessner's solution and 35% trichloroacetic acid on one side and the SilkTouch CO2 laser on the other side. The average periorbital wrinkle score decreased from 4.00 +/- 0.78 before laser treatment to 1.75 +/- 0.68 6 months after treatment. The chemical peel wrinkle score decreased from 4.13 +/- 0.85 to 3.29 +/- 0.99. The degree in which the wrinkle score improved after laser treatment compared with after chemical peel treatment was statistically significant. Posttreatment erythema lasted an average of 4.5 months for the laser-treated areas and 2.5 months for the chemical peel-treated areas. Treatment of periorbital wrinkles with the SilkTouch CO2 laser resulted in a greater degree of improvement than treatment with a medium-depth chemical peel but had longer lasting posttreatment erythema.

Effect of Nd:YAG laser on experimental disc degeneration. Part II. Histological and MR imaging findings.

The potential advantages of percutaneous procedures over traditional discectomy are multiple, but the use of laser energy to ablate disc tissue appears entirely empirical. To date, no experimental study exists investigating the results of laser on degenerated intervertebral disc. The present study was therefore undertaken to determine the histological and radiological changes induced by neodymium-yttrium-aluminum-garnet (Nd:YAG) laser on such disc tissue. It was shown that the vaporization of disc tissue was caused by Nd:YAG laser in early period, but this was gradually replaced by cartilaginous fibrous tissue at 60 days after laser irradiation as a result of the proliferation of cartilaginous cells and fibrous tissues. Accordingly the magnetic resonance (MR) imaging index histogram moved to the left in the early period, but it moved to the right again at 60 days after laser irradiation. In view of these data, we conclude that the use of laser in degenerated disc disease does not represent an effective treatment as an alternative to conventional surgical methods.

Experimental and clinical standards, and evolution of lasers in neurosurgery.

From initial experiments of ruby, argon and CO2 lasers on the nervous system so far, dramatic progress was made in delivery systems technology as well as in knowledge of laser-tissue interaction effects and hazards through various animal experiments and clinical experience. Most surgical effects of laser light on neural tissue and the central nervous system (CNS) are thermal lesions. Haemostasis, cutting and vaporization depend on laser emission parameters--wavelength, fluence and mode--and on the exposed tissues optical and thermal properties--water and haemoglobin content, thermal conductivity and specific heat. CO2 and Nd-YAG lasers have today a large place in the neurosurgical armamentarium, while new laser sources such as high power diode lasers will have one in the near future. Current applications of these lasers derive from their respective characteristics, and include CNS tumour and vascular malformation surgery, and stereotactic neurosurgery. Intracranial, spinal cord and intra-orbital meningiomas are the best lesions for laser use for haemostasis, dissection and tissue vaporization. Resection of acoustic neuromas, pituitary tumours, spinal cord neuromas, intracerebral gliomas and metastases may also benefit from lasers as accurate, haemostatic, non-contact instruments which reduce surgical trauma to the brain and eloquent structures such as brain stem and cranial nerves. Coagulative lasers (1.06 microns and 1.32 microns Nd-YAG, argon, or diode laser) will find an application for arteriovenous malformations and cavernomas. Any fiberoptic-guided laser will find a use during stereotactic neurosurgical procedures, including image-guided resection of tumours and vascular malformations and endoscopic tumour resection and cysts or entry into a ventricle. Besides these routine applications of lasers, laser interstitial thermotherapy (LITT) and photodynamic therapy (PDT) of brain tumours are still in the experimental stage. The choice of a laser in a neurosurgical operating room implies an evaluation of the laser use (applications, frequency), of the available budget and costs--including purchase, maintenance and staff training--, and material that will be necessary: unit, peripherals, safety devices and measures, training programme. Future applications of lasers in neurosurgery will come from technological advances and refined experimental applications. The availability of new wavelength, tunable, small sized and "smart" laser units, will enlarge the thermal and non-thermal interactions between laser energy and neural tissue leading to new surgical applications. Tissue photo-ablation, photohynamic therapy using second generation of photosensitizers, updated thermotherapy protocols, are current trends for further use of lasers in neurosurgery.