Tourette syndrome

Abstract

This chapter addresses research applications of transcranial magnetic stimulation (TMS) in Tourette syndrome (TS). TS is a primary, idiopathic, neurological disorder characterized by multiple motor and vocal tics of childhood onset, with duration greater than 1 year, and associated in the majority of cases with attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), and/or other psychiatric disorders. The majority of the chapter is a critical synopsis of case-control studies applying basic single- and paired-pulse TMS techniques to "resting" motor cortex. Newer applications of theta-burst stimulation are also analyzed. A number of intriguing findings have emerged, which may reflect abnormalities in several disrupted inhibitory or modulatory pathways that may underlie the tendency to manifest tics as well as commonly co-occurring problems such as ADHD and OCD. Chapter sections are organized by type of TMS measurement, with each section describing briefly the technique, the pitfalls of the technique with regard to the above-described challenges, the findings in TS using that technique, and the possible implications for those findings in furthering our understanding of TS. Possible future applications for TMS in studying TS are also discussed.

Keywords: Tourette syndrome; attention-deficit/hyperactivity disorder (ADHD); child nervous system; motor cortex; motor evoked potential (MEP); neuroplasticity; short-interval cortical inhibition (SICI).