Key Features

Surgical management of the head and neck has some distinctive features. Access to specific areas may be restricted by limiting anatomy. Many types of disorders involve highly vascular tissues or pathology. Lasers are tools that are adaptable to certain of the necessary surgical procedures in these regions. Use of lasers has some advantages regarding hemostasis. The energy in the laser beam exists as focused light and may be used for diagnostic and therapeutic interventions.

Laser Biophysics

The word “laser” was originally an acronym for Light Amplification by Stimulated Emission of Radiation. A laser contains a substance called the lasing medium, which a power source excites by pumping energy into it. The medium releases this energy in the form of light at a uniform wavelength (frequency) that is coherent, meaning that all the waves are in phase. As such, the laser provides a source of relatively uniform, concentrated power with predictable effects. The effects of laser light, applied to tissues, depend on several variables, including the specific targeted chromophore, competing chromophores, pulse duration, pulse frequency, pulse pattern, beam diameter, and depth of penetration. Furthermore, associated tissue cooling techniques can also alter the effects of the laser.

A chromophore is a substance that absorbs a specific wavelength of light. Some of the chromophores directly targeted by current laser technology include water, melanin, oxyhemoglobin, deoxyhemoglobin, and ink pigments. Lasers can also affect a competing chromophore; that is, something other than the targeted substance that also absorbs that particular wavelength. Depending on the goals of treatment, this may provide added benefit or may be undesirable. Laser wavelength selection is therefore key in order to generate the desired tissue effect.

When using lasers, it is important to consider how far the laser energy travels inside the treated tissues. This depth effect is important to consider because the laser beam might fail to reach its target or might reach well beyond its target. The actual depth of laser penetration depends on multiple factors including, but not limited to, the laser wavelength, the beam diameter, tissue characteristics (e.g., presence or absence of chromophore), and the amount of scatter. Relative scatter can also vary depending on the diameter of the laser beam.

In addition to the depth of penetration, the extent of associated tissue interactions is also related to adjacent thermal effects. Adjacent thermal effects can alter the effects of the laser treatment, beneficially (e.g., such as by stimulating neocollagen production in the heated tissues) or not. These effects can extend laterally within the horizontal plane of the treated tissues as well as deeper to these tissues. Adjacent thermal effects can vary depending on pulse duration, number of pulses, rate of energy absorption, sequencing, beam diameter, any associated cooling techniques, and whether the beam is passing through previously laser-treated tissues with secondarily altered characteristics, such as residual “char.” For some lasers, residual char can act as a heat sink, increasing adjacent changes.

Fluence is the measure of the laser′s energy per unit of area (usually reported in joules per square centimeter). This is an important measure for use in medicine. Typically, a certain amount of fluence is necessary to achieve a given effect. For some procedures, subthreshold fluence may provide no benefit. However, on other occasions “low-energy” lasers may be beneficial. Alternatively, excessive fluence can result in undesirable excessive thermal effects.

Laser Applications

Specific laser applications in otolaryngology—head and neck surgery include:

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  General otolaryngology: treatment of benign oral lesions, sleep medicine

  
  
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  Otology: middle ear surgery, stapedotomy

  
  
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  Rhinology: treatment of nasal polyposis, reduction of conchal hypertrophy, management of bleeding from the Kiesselbach area in chronic recurrent nasal bleeding, control of epistaxis in patients with hereditary hemorrhagic telangiectasia

  
  
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  Laryngology: treatment of exudative lesions of the Reinke space, intracordal mucosal or epidermal cysts, sulcus vocalis, webs, recurrent respiratory papilloma, vocal fold vascular lesions/ectasias, laryngeal and tracheal stenosis, some laryngeal cancers

  
  
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  Facial plastic surgery: treatment of vascular anomalies of the skin, facial skin rejuvenation, hair removal, pigment removal

Laser selection for a specific application will vary depending upon the desired effects and the laser characteristics. Optimal device selection for any application can be challenging because lasers are an evolving technology. As with all procedures in medicine, risk/benefit ratios should be considered. Only well-constructed studies can determine whether there is an optimal device for a given procedure.