Onychomycosis : what, why and how to get rid of Nail Fungus

by Dr. Jeffrey A. Oster,

Onychomycosis refers to a fungal infection of the toe or finger nail. Onycho refers to the nail and mycosis refers to a fungal condition. Onychomycosis is very common in the toe nail and seen to a much lesser degree in the finger nail. It is estimated that 25 million Americans suffer from onychomycosis. The organisms that cause onychomycosis are usually fungus (90% of cases) or yeast (7% of cases).

Onychomycosis has nothing to do with hygiene. Many people feel that they have in some way contributed to a fungal nail infection. There is only one way we do contribute to this condition and that is in that we create an environment that is wonderfully conducive to the growth of fungus. We jump out of the shower in the morning, put on our socks and shoes for 18 hours and create a greenhouse that promotes fungal growth.

It is safe to say that 50% of folks over the age of 50 have a fungal toe nail infection to some degree. But this doesnt necessarily mean that onychomycosis is due to old age. We can imply that over the course of our lifetimes we would have more opportunities to acquire a fungal infection of the nail.

Trauma makes the nail much more susceptible to fungal infections. Its also reasonable to assume that folks in professions that abuse their feet would tend to have a higher rate of onychomycosis. An injury to the nail is a common precursor to a fungal nail infection. Trauma may be something abrupt such as a can of beans hitting the nail from the top shelf or something as benign as a pair of ill-fitting shoes constantly rubbing on the nail. As an example, a machinist or mechanic would tend to show earlier signs of onychomycosis than a housewife.

The appearance of onychomycosis can vary but most cases begin at the distal tip of the nail and slowly progress into the nail over a period of months to years. The nail will thicken as the fungus continues to grow. The filaments of fungus take up space in the nail causing it to swell. The nail can be yellow, white or even green to black. The nail also begins to be chalky and flakey.

Treatment of toe nail fungus and onychomycosis

Prevention of injuries to the nail is very important. Once the nail is injured, the door of susceptibility swings open, allowing entry of the fungus. There are some very simple preventative measures that can be taken on a regular basis. Keep the feet dry. Keeping the feet dry will inhibit the ability of the fungus to thrive. You can do this in several ways. Frequent changes of socks, the use of powder, such as baby powder and rotating shoes so that they are worn only every other day, can help tremendously.

Medications for onychomycosis fall into two categories; topical and oral. There are any number of effective topical medications available over the counter. Topical medications are most helpful in treating early, small infections and for maintaining clear nails. Topical medications do have a limited ability to penetrate the nail to reach all of the fungal elements. Topical medication inhibit the growth of the fungus allowing for faster growth of the nail. Remember, the fungus doesnt take a day off. Compliance is a big issue when using topical antifungals.

The FDA approved a new prescription strength topical medication for treating onychomycosis in 1999 called Penlac. (Dermik Laboratories, Collegeville, PA). Penlac is manufactured in Frankfurt, Germany by Aventis Pharma Deutschland GmbH. Penlac doesnt carry the side effects of the oral medications but the jury is still out on the efficacy of this medication.

The older generations of oral antifungal medications, such as Fulvicin or Griseofulvin, have been used successfully for years and are making a comeback due to their economic value.

The newer generation of oral antifungals, including Sporanox and Lamisil have been received very well by the medical community. Care should be taken when using Sporanox due to its potential liver toxicity. Both Sporanox and Lamisil are expensive medications costing several hundred dollars for the recommended three month course of treatment.

When all else fails, the fungal toe nail can be permanently removed. This procedure is not difficult to perform and most patients return to their normal shoes in just a Band-Aid in 24hrs. The removal of the nail is permanent.

Which choice is right for you?

Consider the following two examples;

Case 1. Sandy is a 24 year old hairdresser who has intimate hands on contact with her clients on a daily basis. She has developed a fungal infection in several of her finger nails. She is concerned that the fungal infection will have a direct impact on her livelihood and does not want to spread the infection to others.

Case 2. Joe is a 62 year old farmer and has a long history of injuries to his hands and feet. His last visit to the doctor showed signs of an increase in his liver enzyme studies indicating an overall decrease in his liver function. Joe has developed onychomycosis in most of his toe nails.

I think the choices for Joe and Sandy are clear but in most cases the criteria to make recommendations for treatment of onychomycosis are not as obvious. In those cases, patients should consult their physician to discuss the pros and cons of oral antifungal treatment.

Nomenclature:

• Beaus lines - deep longitudinal grooves in the nail plate.
• Eponychium - thin layer of skin overlying the matrix at the base of the nail.
• Koilonychia - spoon shaped nails.
• Lunula - a small white moon shaped area at the base of the nail. The purpose of the lunula is not clear but it appears to be an extension of the nail matrix.
• Matrix - the cells beneath the eponychium that produce the nail.
• Onychocryptosis - onycho is derived from Greek and refers to any nail condition. Crypt, or to bury is combined to form a word that describes an ingrown nail where the nail is buried in the nail fold. This term can be used to describe an ingrown nail both with or without an infection.
• Onychomycosis - a fungal nail infection
• Paronychia - para refers to parallel. Onychia is derived from Greek and refers to nail. Paronychia is a condition that present with pain along the entire border (parallel to) of the nail. This term is often used to describe chronic pain at the edge of the nail with or without an infection. This term is also used to describe irritation form the nail at the base of the nail.
• Pincer nails - nails that are pinched.
• Splinter hemorrhages - small bruises beneath the nail plate. Common to endobacterial carditis or atrial fibrillation.
• Subungual - beneath the nail.
• Subungual exostosis - a bone spur beneath the nail.
• Subungual hematoma - dark discoloration of the nail due to bruising beneath the nail.
• Ungual - refers to nail.

Anatomy:

Nail is an elastic, transparent layer of keratin. It is surrounded on two sides by soft skin referred to as the periungual folds. The base of the nail is called the eponychium and the distal tip of the nail is called the hyponychium. Nail cells are created in a small envelope called the nail matrix.

Symptoms:

The symptoms of a fungal nail infection can vary. Pain can be chronic due to a low grade mechanical irritation of the periungual folds or be acute due to a foreign body reaction by the skin adjacent to the nail. When the skin adjacent to the nail perceives the nail to be a foreign object, it will mount a response to push out the nail, just as the skin would respond to a splinter. This response is usually a low grade soft tissue infection.

Fungal infections of the nail are not by themselves painful. As the nail thickens, pressure from shoes and adjacent toes will put pressure on the skin surrounding the toe nail resulting in pain and possible soft tissue infections.

Differential Diagnosis:

The differential diagnosis for this condition should include;

• Abscess
• Blister
• Benign soft tissue tumor Bone spur
• Lister corn or callus
• Gout
• Malignant soft tissue tumor
• Onychocryptosis - (ingrown nail)
• Psoriatic arthritis
• Ulcer
• Verrucae
• Wart

Additional references include;

• Elewski BE: Diagnostic techniques for confirming onychomycosis. J Am Acad Dermatol 35 (3 Pt 2): S6, 1996
• Scherer WP, Kinmon KK; Dermatophyte test medium culture versus mycology laboratory analysis for suspected onychomycosis.
• JAPMA 90:9 2000
• McCarthy DJ: Origins of onychomycosis. Clin Podiatric Med Surg 12:221, 1995
• Habif TP: "Nail diseases" in Clinical Dermatology, 3rd edition, p 765 CVMosby, St. Louis, 1996

Jeffrey A. Oster, DPM, C.Ped is a board certified foot and ankle surgeon. Dr. Oster is also board certified in pedorthics. Dr. Oster is medical director of Myfootshop.com and is in active practice in Granville, Ohio.