It’s not uncommon to see clients with nail deformities characterized by ridges on the nail plate. Called habit tic, it is a benign habit that often relieves a person’s anxiety. The ridges can vary in appearance, but the deformity is caused by picking and/or stroking the posterior nail fold, the matrix, or the nail bed.

The damage is usually no one or both thumbnails and is most often inflicted by a finger on the same hand. The repeated stroking or picking stimulates the matrix and causes its tissue to proliferate. The overgrowth occurs in spurts because the stimulation is not continuous, and the nail grows out with characteristic wavy ridges. Often the cuticle pulls away from the nail, and the posterior nail fold thickens.

The deformed nails grow rapidly because the stimulation caused by picking and stroking increases the nails’ blood supply. Most often just one or two nails are affected, but some patients pick and stroke all the nails. The fingers can also develop lesions much like nail biters have except they are caused by picking instead of biting.

In my experience, males are more likely to have a habit tic nail deformity. One of my patients is a 14-year-old boy who has stroked, picked, and dug at all of his nails so much that all 10 nails are severely deformed.

In my experience, most patients are aware of their repeated picking or stroking, but they are surprised to discover that the habit is related to the deformity. Others are completely unaware of their habit, and several patients have insisted the deformity was heredity. In these cases, there is little doubt that they learned the habit from observing a parent.

One patient, a doctor, asked me about treating his condition, insisting he had inherited it from his father. When I explained how the condition was caused, the doctor denied his role. Two weeks later he sent me a photograph of himself stroking his nails and said he had told his wife about my “silly explanation.” His wife told him, “You have been driving me crazy doing that for the last 25 years.”

Many people are embarrassed by this habit, and they often respond best to therapy such as injections, applying protective nail products, and wearing gloves. If they are made conscious of their habits they try harder to correct them. I suggest that both female and male clients have the deformed nail smoothed, covered with artificial nails, and worn as short as possible. This way, they can’t pick at the smooth surface, and stroking does not produce the matrix changes caused by stroking a ridged, irregular nail plate.

When the cuticle is repeatedly picked and stroked, it thickens and the nerves in it enlarge. Patients then complain of itching or discomfort. But the more they pick at the cuticle, the more it thickens, which cause even greater discomfort. You have heard of this phenomenon but usually the term is being misused: It is called a “worry wart.” Artificial nails will not stop clients from picking at the cuticles, but I can markedly reduce the symptoms by injecting a type of cortisone into the lesions.

Clients can be discouraged from picking at their nails by applying artificial nails, but because the habit is unconscious it cannot be broken unless the client becomes aware of her actions. Encourage clients with a habit tic deformity to wear cotton gloves when they’re not in public and while sleeping. Wearing cotton gloves may make them aware of their hands and the habit. No matter how badly the nails are deformed, they can return to normal if the habit is broken.

A less common phenomenon, but similar to a habit tic, is delusion of parasites. A patient with delusion of parasites is much more aggressive at digging and picking at the nails because she believes she is doing out parasites. The individual thinks that parasites, or bugs, are crawling underneath her skin. It is always a delusion. I’ve seen an upsurge in the number of these patients in my practice. I used to see the condition mostly from older women, but more and more young women are complaining of parasites. I see this condition frequently among patients who use amphetamines. The crawling sensation is caused from nerve endings that are stimulated and irritated by using amphetamines. The complaints from these sufferers are so typical that my receptionist can diagnose the condition over the phone. Almost all of them describe it as “bugs crawling under my skin.”

If a salon client makes a similar complaint, refer her to a dermatologist. The client will not believe there aren’t parasites under her nails, even if you assure her there aren’t. Do not be distressed if she claims you gave her the parasites, because they don’t exist.

Orville J. Stone, M.D., is a dermatologist practicing in Southern California. He has taught at medical schools for 30 years and has published 150 scientific papers. His first paper on nail disorders appeared in 1962.


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