Longitudinal Ridging (Onychorrhexis) 
Basics
Longitudinal ridging is a very common nail issue and is considered a normal variant in elderly persons.
It consists of parallel ridges that run lengthwise along the nail plates (Fig. 22.1) and are more commonly observed in fingernails than in toenails.
Occasionally, longitudinal ridging is seen in younger persons.
The etiology is unknown and the condition is not indicative of any trauma, infection, or nutritional deficiency.
Management Brittle Nails (Onychoschizia)
Basics
Brittle and split nails (onychoschizia) are common in adults (Fig. 22.2). In some people, nails become fragile and easily break off at the free edge.
Onychoschizia has traditionally been considered a sign of nail plate dehydration; however, a recent study has indicated that the water content of brittle nails is not significantly different from that of normal nails.
Brittle nails are a common complaint in adult and elderly women and can also be observed in people with iron deficiency and thyroid disease.
Elderly men are less apt to present with this problem. The increased incidence in women may be a result of their higher cosmetic awareness, their frequent use of nail products, menopausal status, or frequent exposure to harmful extrinsic factors (e.g., detergents and water).
|
Basics
Onycholysis represents a separation of the nail plate from its underlying attachment to the pink nail bed (Fig. 22.3). The separated portion is white and opaque, in contrast to the pink translucence of the attached portion. Normal physiologic onycholysis is seen at the distal free margin of healthy nails as they grow.
Onycholysis is most frequently seen in women, particularly in those with long fingernails.
Onycholysis usually starts distally and progresses proximally. When the separation progresses more proximally, the onycholysis is more obvious, becomes cosmetically objectionable, and may interfere with the routine function of the nails (e.g., picking up small objects, such as coins and paper clips).
In some patients, the separated part of the nail takes on a green or yellow tinge (see the discussion of green nail syndrome later in the next section).
Pathogenesis
Irritants such as nail polish, nail wraps, nail hardeners, and artificial nails.
Frequent contact with water as seen in bartenders, hairdressers, manicurists, citrus fruit handlers, and domestic workers.
Trauma, especially habitual finger sucking, athletic injuries to the toes, wearing of tight shoes, and the use of fingernails as a tool.
Lack of appropriate nail care. It is often difficult for elderly patients to trim toenails frequently because of arthritis, decreased fine motor control or flexibility.
Fungal infections such as chronic paronychia and onychomycosis (see Chapter 18: Superficial Fungal Infections).
Certain drugs can act as phototoxic agents to induce fingernail onycholysis. Such drugs include diuretics, sulfa drugs, tetracycline, doxycycline, and, particularly, demethylchlortetracycline. Hemorrhagic onycholysis may result from taxanes, chemotherapeutic agent used in the treatment of various cancers (see Fig. 26.14).
Psoriasis is the most common cause of onycholysis. Often there is evidence of psoriasis elsewhere on the body, or there may be other psoriatic nail findings, such as pitting, subungual hyperkeratosis, and “oil spots” (see discussion in Chapter 14: Psoriasis).
Inflammatory skin diseases of the nail matrix (root), such as eczematous dermatitis (see below) or lichen planus.
Thyroid disease, pregnancy, and anemia have been reported as potential associations.
Subungual warts and subungual neoplasms (see Chapters 17 and 31).
Helpful Hint Basics
Green nail syndrome is a painless, blue-green discoloration under the nail that is a consequence of a Pseudomonas infection of an onycholytic nail and should not be confused with a subungual fungal infection.
Pathogenesis
The “dead space” under the onycholytic nail serves as an excellent breeding ground for microbes.
Infection with Pseudomonas aeruginosa results in a green, greenish-yellow, or green-black nail color due to the bacteria's production of pyocyanin pigment (Fig. 22.4).
Outline