Clinical phenomenology and phenotype variability in Tourette syndrome.

Tourette syndrome (TS) is a neurodevelopmental disorder with a rich phenomenology that includes simple and complex motor and vocal tics as well as multiple comorbidities. From a nosological perspective, it is evident that a continuum of tic severity exists, of which TS is the most severe and rare form, while transient tics and chronic tics represent milder forms. From a psychopathology perspective, TS is often concurrent with obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD); these disorders appear to define TS "types" TS only, TS+OCD, and TS+OCD+ADHD. Additional clinical aspects of TS include more frequent than expected occurrence of anger episodes, anxiety disorders, mood disorders, impulse control disorders, learning disorders, and pervasive developmental disorders. Data reduction techniques have been used more recently to define a "simple" and "complex" tic symptom clusters or factors. Phenomenologic approaches can be used in TS to guide future pathophysiologic research.