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DESCRIPTIONOnychomycosis is a common fungal infection of the nail. Currently available treatments for onychomycosis, including systemic and topical antifungal medications, have relatively low efficacy and require a long course of treatment. Laser systems are proposed as another treatment option.
Onychomycosis is a common chronic fungal infection of the nail. It is estimated to cause up to 50% of all nail disease and 33% of cutaneous fungal infections. The condition can affect toenails or fingernails but is more frequently found in toenails. Primary infectious agents include dermatophytes (e.g.,Trichophyton species), yeasts (e.g., Candida albicans) and non-dermatophytic molds. In temperate Western countries, infections are generally caused by dermatophytes.
Aging is the most common risk factor for onychomycosis, most likely due to decreased blood circulation, longer exposure to fungi, and slower nail growth. In addition, various medical conditions increase the risk of comorbid onychomycosis. These include diabetes, obesity, peripheral vascular disease, immunosuppression, and HIV infection. In certain populations, onychomycosis may lead to additional health problems. Although there is limited evidence of a causal link between onychomycosis and diabetic foot ulcers, at least one prospective study with diabetic patients found onychomycosis to be an independent predictor of foot ulcer. Moreover, onychomycosis, especially more severe cases, may adversely impact quality of life. Patients with onychomycosis have reported pain, discomfort wearing shoes, nail pressure, and embarrassment.
The diagnosis of onychomycosis can be confirmed by potassium hydroxide preparation, culture or histology. Treatments for onychomycosis include topical antifungals such as nail paints containing ciclopirox (ciclopiroxolamine) or amorolfine, and oral antifungals such as terbinafine and itraconazole. These generally have low to moderate efficacy and a high relapse rate. Topical antifungals and some long-available oral medications such as griseofulvin require a long course of treatment, which presents issues for patient compliance. Moreover, oral antifungal medications have been associated with adverse effects such as a risk of hepatotoxicity.
Several types of device-based therapies are under investigation for treatment of onychomycosis, including ultrasound, iontophoresis, photodynamic therapy and laser systems. A potential advantage of lasers is that they have greater tissue penetration than antifungal medication and thus may be more effective at treating infection embedded within the nail. Another potential advantage is that laser treatments are provided in a clinical setting in only one or several sessions and thus long-term patient compliance is less of an issue than with medications.
Laser treatment of onychomycosis uses the principle of selective photothermolysis. This is defined as the precise targeting of a tissue using a specific wavelength of light. The premise is that light is absorbed into the target area and heat generated by that energy is sufficient to damage the target area while sparing the surrounding area. The aim of laser treatment of onychomycosis is to heat the nail bed to temperatures required to disrupt fungal growth (approximately 40-60oC) and at the same time avoid pain and necrosis to surrounding tissues.
Characteristics of laser systems used to treat onychomycosis are as follows:
Wavelength: Lasers are single-wavelength light sources. There needs to be sufficient tissue penetration to adequately treat nail fungus. The near-infrared spectrum tends to be used because this is the part of the spectrum that has maximum tissue penetrance in the dermis and epidermis and the nail plate is similar to the epidermis. To date, most laser systems for treating onychomycosis have been Neodymium yttrium aluminum garnet (Nd:YAG) lasers that are typically operated at 1064nm; 940-1320nm and 1440nm wavelengths are also options.
Pulse duration: Pulses need to be short to avoid damage to the tissue surrounding the target area. For example, short-pulse systems have microsecond pulse durations and Q-switched lasers have nanosecond pulse durations.
Repetition rate (frequency of laser pulses, Hz): Selective photothermolysis requires that there be time between pulses to allow for dispersal of heat energy.
Spot size: This refers to the diameter of the laser beam. For treating onychomycosis, laser spot sizes range from 1 to 10 nm.
Fluence: This refers to the amount of energy delivered into the area and is measured in J/cm2).
A number of Nd:YAG laser systems have been cleared by the FDA for marketing for the temporary increase of clear nail in patients with onychomycosis. The FDA determined that these devices were substantially equivalent to existing devices. Cleared devices and year of FDA decision are as follows:
Dual wavelength Nd:YAG 1064nm and 532nm laser system:
POLICYLaser treatment of onychomycosis is considered investigational.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY07/18/2013: Approved by Medical Policy Advisory Committee.
SOURCE(S)Blue Cross and Blue Shield Association Policy # 2.01.89
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.