Nail diseases are distinct from diseases of the skin. Although nails are a skin appendage, they have their own signs and symptoms which may relate to other medical conditions. Nail conditions that show signs of infection or inflammation require medical assistance. Deformity or disease of the nails may be referred to as onychosis.
Anatomy of the basic parts of a human nail. A. Nail plate; B. lunula; C. root; D. sinus; E. matrix; F. nail bed; G. eponychium; H. free margin.
Onychia is an inflammation of the nail folds (surrounding tissue of the nail plate) of the nail with formation of pus and shedding of the nail. Onychia results from the introduction of microscopic pathogens through small wounds.
Onychocryptosis, commonly known as "ingrown nails" (unguis incarnatus), can affect either the fingers or the toes. In this condition, the nail cuts into one or both sides of the nail bed, resulting in inflammation and possibly infection. The relative rarity of this condition in the fingers suggests that pressure from the ground or shoe against the toe is a prime factor. The movements involved in walking or other physical disturbances can contribute to the problem. Mild onychocryptosis, particularly in the absence of infection, can be treated by trimming and rounding the nail. More advanced cases, which usually include infection, are treated by surgically excising the ingrowing portion of the nail down to its bony origin and thermally or chemicallycauterizing the matrix, or 'root', to prevent recurrence. This surgery is called matrixectomy. The best results are achieved by cauterizing the matrix with phenol. The Vandenbos Procedure is a highly effective method that focuses on excision of excessive nail fold tissue without affecting the healthy nail and nail matrix. The Vandenbos procedure is showing high success rates in eliminating Onychocryptosis without altering the normal nail. Another, much less effective, treatment is excision of the matrix, sometimes called a 'cold steel procedure'.
Onychogryposis, also called "ram's-horn nail", is a thickening and increase in curvature of the nail. It is usually the result of injury to the matrix. It may be partially hereditary and can also occur as a result of long-term neglect. It is most commonly seen in the great toe but may be seen in other toes as well as the fingernails. An affected nail has many grooves and ridges, is brownish in color, and grows more quickly on one side than on the other. The thick curved nail is difficult to cut, and often remains untrimmed, exacerbating the problem.
Erythronychia, red bands in the nail from some inflammatory conditions.
Melanonychia, a black or brown discoloration of the nail, with numerous causes.
Nail changes and conditions associated with them
Nail inspection can give hints to the internal condition of the body as well. Nail disease can be very subtle and should be evaluated by a dermatologist with a focus in this particular area of medicine. A nail technician may be the first to note a subtle change in nail health.
In approximately half of suspected nail fungus cases there is actually no fungal infection, but only some nail dystrophy. Before beginning oral antifungal therapy the health care provider should confirm a fungal infection. Administration of treatment to persons without an infection is unnecessary health care and causes needless exposure to side effects.
Roberts, D. T.; Taylor, W. D.; Boyle, J.; British Association of Dermatologists (2003). "Guidelines for treatment of onychomycosis". The British journal of dermatology148 (3): 402–410. doi:10.1046/j.1365-2133.2003.05242.x. PMID12653730.
Mehregan, D. R.; Gee, S. L. (1999). "The cost effectiveness of testing for onychomycosis versus empiric treatment of onychodystrophies with oral antifungal agents". Cutis64 (6): 407–410. PMID10626104.