This article reflects discussion by the WHO ICD-11 Working Group on the Classification of Obsessive-Compulsive and Related Disorders. After reviewing the historical classification of tic disorders, this article discusses their placement in ICD-11. Existing problems with diagnostic labels and criteria, appropriate placement of the tic disorders category within the ICD-11 system, and pragmatic factors affecting classification are reviewed. The article ends with recommendations to (a) maintain consistency with the DSM-5 diagnostic labels for tic disorders, (b) add a minimum duration guideline for a provisional tic disorder diagnosis, (c) remove the multiple motor tic guideline for the diagnosis of Tourette disorder, and (d) co-parent the tic disorder diagnoses in the disorders of the nervous system and the mental and behavioral disorders categories, with secondary co-parenting in the obsessive-compulsive and related disorders and neurodevelopmental disorders sections.

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.