Nail-Associated Body-Focused Repetitive Behaviors: Habit-Tic Nail Deformity, Onychophagia, and Onychotillomania

Habit-tic nail deformity, onychophagia (also referred to as nail biting) and onychotillomania (also referred to as nail picking) are body-focused repetitive behaviors that can involve the nails and periungual skin. Patients with habit-tic nail deformity are typically unaware that repeatedly using their nail, often the adjacent index finger, to rub the proximal nail fold and its underlying matrix - usually of one or both of their thumbnails - is the cause of the longitudinal depressed groove that extends along the entire the nail plate. Nail biters usually bite multiple nails - most commonly on the digits of the hands - and the patient is cognizant of their behavior. However, the term onychophagia is a misnomer and onychodaxia would be a more appropriate nomenclature. Nail pickers also often realize that their dystrophic nail results from using other nails or tools to pick, pull, or excessively manicure the affected nail. Individuals with habit-tic nail deformity or onychophagia or onychotillomania may concurrently have other repetitive behaviors involving the skin or the hair or both. Three patients with a nail-associated body-focused repetitive behavior are described who not only presented with dystrophy of their nails but also abnormalities of the adjacent nail apparatus: a 36-year-old woman with habit-tic nail deformity and dermatodaxia, a 64-year-old man with biting of both the nails and the skin, and a 63-year-old man with nail picking and skin picking. The nail dystrophy and concurrent skin biting or skin picking were not the issues that prompted the reported patients to seek evaluation by a physician; the body-focused repetitive behaviors of the nails and skin were incidental findings during their cutaneous examination. The management of nail-associated body-focused repetitive behavior may include non-pharmacologic treatments (such as physical modalities and behavior modifications) and/or pharmacologic agents. The reported woman with habit-tic nail deformity was willing to consider an attempt to modify her repetitive behavior by using paper tape as a physical modality to cover the area on her thumbs that she would unconsciously rub. However, similar to the men in this report with onychophagia and onychotillomania, many of the patients with nail-focused repetitive behaviors do not want to initiate any interventions that might decrease or eliminate their nail condition.