A Guide To Treatments For Onychomycosis

By John Mozena, DPM

Onychomycosis is the number one diagnosed and treated disease by podiatrists today. While the disease was first recognized in the United States in 1928, it has only recently been brought under control with drugs that have been introduced in the last 10 years. With the advent of safer oral and topical medications, there has been a renewed focus on increasing efficacy rates. The current research seems to be centered on synergistic activity of oral and topical medications as well as different vehicles to add additional penetration of the medication. Onychomycosis is present in 2 to 3 percent of the population with the most common source of contamination coming from the patient’s own skin. Currently, 70 percent of the population has fungus recovered from the feet. Fifteen to 20 percent of people between the ages of 40 and 60 have onychomycosis, 32 percent of 60- to 70-year-olds have nail fungus and approximately 50 percent of those over 70 are afflicted. A 1965 U.S. study stated fungus can also be contagious throughout the patient’s own body and can also spread among individuals. In a study of 963 children cultured for onychomycosis, 263 (30.74 percent) were positive. The number of cases rose quickly with the age of the child, with only 25 percent of the patients being below the age of six. The question of treatment is always present due to the fact that onychomycosis has been considered a cosmetic problem in the past. This has led many physicians to falsely believe that this infection should be monitored and not treated. However, recent evidence shows this is not the case. Seventy-five percent of the people who have this infection exhibit psychosocial concerns. These people face the dilemma of not being able to go to the swimming pool, public shower areas or even wear open-toed sandals. More important is the fact that 48 percent of the people with onychomycosis have pain. The pain is intense enough to have these patients miss 1.8 days of work on average over a six-month period.1,2,3 Understanding Nail Anatomy And The Etiology Of Onychomycosis The anatomy of the nail area starts with the proximal nail fold known as the eponychial area. This is where nail growth begins. The growth cells extend to the distal end of the lanula. The nail itself consists of dorsal, intermediate and ventral layers. The dorsal layer is the horny zone and is made up of hard keratin. The ventral nail plate is held to the nail bed by a specialized onychodermal band known as the solehorn. The nail separates distally from the solehorn at the hyponychium. The medial and lateral ungual labial folds enclose the nail completely. The function of the nail is one of protection and sensory discrimination. The nail plate acts as a buttress that opposes the opposite force, placing pressure on the finger or toe. This increases the discrimination ability of the acral pulp and skin whenever the object is felt. Without the nail, the skin around the digit would deform and not allow for fine proprioception. With the advent of fungus infections, the intermediate layer hypertrophies and distorts the nail.4,5 Nail infections from fungus are believed to have four different entry ports, according to Zaisis.6 Distal subungual onychomycosis is the most common variety and accounts for 90 percent of onychomycosis. The disease begins with initial fungal penetration of the stratum corium from the hyponychial area or from the lateral nail fold. The most common cause of the organism is Trichophyton rubrum. Superficial white onychomycosis is the second most common type and accounts for 10 percent of onychomycosis. In this type, the organism Trichophyte metagraphytes directly invades the nail plate and creates a white crumbly appearance to the surface. Proximal subungual onychomycosis (commonly caused by T. rubrum) is the least common type, accounting for less than 1 percent of onychomycosis. The infection penetrates the proximal portion of the nail, resulting in hyperkeratosis and onycholysis. This type is usually associated with immunocompromised patients and the AIDS population. Finally, candidal onychomycosis, primarily caused by Candida albicans, occurs in less than 1 percent of onychomycosis infections.6,7 Several conditions can mimic onychomycosis and should be considered as a possible differential diagnoses.

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