Keys To Managing Severe Onychomycosis

Author(s): 
Myron Bodman, DPM

   One can determine the Onychomycosis Severity Index score by multiplying the score for the area of involvement (range, 0-5) by the score for the proximity of disease to the matrix (range, 1-5). Add 10 points for the presence of a longitudinal streak or a patch (dermatophytoma) or for greater than 2 mm of subungual hyperkeratosis. Mild onychomycosis corresponds to a score of 1 through 5, moderate onychomycosis would have a score of 6 through 15 and severe onychomycosis would range between 16 and 35.11

   Most importantly, the Onychomycosis Severity Index criteria have been validated.11 Using the Onychomycosis Severity Index scoring system, clinicians are likely to determine the same severity score given the same patient. This methodology is particularly important in diseases like onychomycosis in which there is a wide degree of severity among individual patients.

   It also helps to quantify the varying difficulties of clearing cases with nail root involvement or when the nail plate is thicker. For example, one can easily clear white superficial onychomycosis with topical medications and simple debridement while total dystrophic onychomycosis seldom clears without oral therapy.

   Severity indices are more economical and better benchmarks to monitor treatment progress rather than expensive mycological tests or just proximal clear zones. The Onychomycosis Severity Index numerically estimates the severity factors that limit the potential for clearing. Using this validated method, we can define cases of severe onychomycosis as those with scores from 16 through 35.

   Schemer states that the evaluation of the outcome of clinical cure, mycological cure and total cure should be based on the well-defined worldwide criteria.12 Otherwise, a comparison of results is impossible due to a lack of uniformity in different studies.

What You Should Know About Diagnostic Testing

Diagnostic testing has evolved over time. It used to be that we could culture suspected cases of onychomycosis with dermatophyte test media, incubate the specimens in desk drawers and speciate the results using a color chart. Interpretation could be difficult with many phenotypic variations. No two fungi look exactly alike. The KOH wet mount preparation of subungual debris is not a very sensitive method and clinicians seldom perform it on nail specimens.13

   Currently, the most sensitive test is a pathologist read biopsy of nail clippings stained with periodic acid Schiff (PAS) and or Grocott’s methenamine silver. A mycologist interprets fungal culture testing, which is very specific but not as sensitive as PAS. Fungal cultures are relatively slow growing, adding weeks and more cost to the workup. Fungal culturing is appropriate for atypical cases or when one suspects primary saprophytic infections. In that case, it is recommended that two subsequent cultures of the same saprophytic mold be in evidence before concluding that the saprophyte is the primary pathogen and not a contaminant.

   A new development has demonstrated the usefulness of dermoscopy in clinical differentiation of onychomycosis from common nail dystrophies. Piraccini and colleagues observed a characteristic of jagged proximal edges with spikes and longitudinal striations in patients with culture-proven onychomycosis while mycologically negative cases of traumatic onycholysis all have linear transverse edges without spikes.14 A dermatoscope is basically a handheld 10X polarized magnifying lens illuminated with 11 small halogen lamps. It allows the examiner to easily look through a translucent nail plate and visualize the nail bed directly.

Comments

A great article on "fungus nail" involvement with methods, drugs & outcome by my friend Dr. Ron Bodman. I also noticed over the years that there is most definitely an immune system involvement in nail fungus & C. albicans infection. As we say in WV, "it runs in the family." I have seen patients with specific toenails involved & some of their offspring have identical involvement. Some people do not have the ability to defend against the fungus organisms. They are then resistant to curative measures & tend to become reinfected after treatment.

We know fungi like a dark, warm, moist place to grow with a food source. I would like to suggest that perhaps contributing factors leading to an increase in nail & skin fungal infections over the last 20+ years may be connected to external changes in clothing & shoe gear. Over this time, we have seen a real increase in the use of artificial fibers such as nylon and polyester in socks/hosiery. These fabrics do not absorb moisture & raise the local temperature of the foot. There is no wick action with these fibers . Once again, today's shoe gear is entirely or mostly artificial uppers & lowers. These have the same characteristics. The feet are warmer, wetter, dark & there is little or no air circulation. The insoles/linings of the shoes are plastic fibers. The soles are rubber/vinyl.

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