Nail tic disorders: Manifestations, pathogenesis and management.

Nail tic disorders are classic examples of overlap between the domains of dermatology and psychiatry. They are examples of body-focused repetitive behaviors in which there is an irresistible urge or impulse to perform a certain behavior. The behavior is reinforced as it results in some degree of relief and pleasure. Nail tic disorders are common, yet poorly studied and understood. The literature on nail tic disorders is relatively scarce. Common nail tics include nail biting or onychophagia, onychotillomania and the habit tic deformity. Some uncommon and rare nail tic disorders are onychoteiromania, onychotemnomania, onychodaknomania and bidet nails. Onychophagia is chronic nail biting behavior which usually starts during childhood. It is often regarded as a tension reducing measure. Onychotillomania is recurrent picking and manicuring of the fi ngernails and/or toenails. In severe cases, it may lead to onychoatrophy due to irreversible scarring of the nail matrix. Very often, they occur in psychologically normal children but may sometimes be associated with anxiety. In severe cases, onychotillomania may be an expression of obsessive-compulsive disorders. Management of nail tic disorders is challenging. Frequent applications of distasteful topical preparations on the nail and periungual skin can discourage patients from biting and chewing their fi ngernails. Habit-tic deformity can be helped by bandaging the digit daily with permeable adhesive tape. Fluoxetine in high doses can be helpful in interrupting these compulsive disorders in adults. For a complete diagnosis and accurate management, it is imperative to assess the patient’s mental health and simultaneously treat the underlying psychiatric comorbidity, if any.

Stereotyped movement disorder in ICD-11

According to current proposals for ICD-11, stereotyped movement disorder will be classified in the grouping of neurodevelopmental disorders, with a qualifier to indicate whether self-injury is present, similar to the classification of stereotypic movement disorder in DSM-5. At the same time, the WHO ICD-11 Working Group on the Classification of Obsessive-Compulsive and Related Disorders has proposed a grouping of body-focused repetitive behavior disorders within the obsessive-compulsive and related disorders (OCRD) cluster to include trichotillomania and skin-picking disorder. DSM-5 has taken a slightly different approach: trichotillomania and excoriation (skin picking) disorder are included in the OCRD grouping, while body-focused repetitive behavior disorder is listed under other specified forms of OCRD. DSM-5 also includes a separate category of nonsuicidal self-injury in the section on “conditions for further study.” There are a number of unresolved nosological questions regarding the relationships among stereotyped movement disorder, body-focused repetitive behavior disorders, and nonsuicidal self-injury. In this article, we attempt to provide preliminary answers to some of these questions as they relate to the ICD-11 classification of mental and behavioral disorders.