The Clinical Characterization of Blocking Tics in Patients With Tourette Syndrome

OBJECTIVE: Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the presence of motor and phonic tics. Blocking phenomena, characterized by arrests in motor activity causing interruptions in movements or speech, have also been described in patients with TS. In this study, we aimed to characterize the frequency and features of blocking tics in patients with TS. METHODS: We studied a cohort of 201 patients with TS evaluated at our movement disorders clinic. RESULTS: We identified 12 (6%) patients with blocking phenomena. Phonic tic intrusion causing speech arrest was the most common (n = 8, 4%), followed by sustained isometric muscle contractions arresting body movements (n = 4, 2%). The following variables were statistically related to blocking phenomena: shoulder tics, leg tics, copropraxia, dystonic tics, simple phonic tics, and number of phonic tics per patient (all p < 0.050). In the multivariate regression, the presence of dystonic tics (p = 0.014) and a higher number of phonic tics (p = 0.022) were associated with blocking phenomena. CONCLUSION: Blocking phenomena are present in approximately 6% of patients with TS, and the presence of dystonic tics and a higher frequency and number of phonic tics increase the risk for these phenomena.