Table 2. Effect of deep brain stimulation in patients with Tourette syndrome.

Reference(s)	Patients	Stimulation site	Effect*
Visser-Vandewalle et al., 2003 (18)	3	Thalamus (ventro-oral nucleus, centromedian nucleus, periventricular substance)	Observation for 8–60 months: between 72% and 90% reduction in tic frequency (video-based measurement)
Servello et al., 2007 (12)	18	Thalamus (ventro-oral nucleus, centromedian nucleus)	Observation for 3–18 months: 31–95% improvement rates, as measured by YGTSS total tic score
Maciunas et al., 2007 (13)	5	Thalamus (centromedian nucleus)	Blinded period with on and off phases over 4 weeks: significant (>50%) reduction in tics in 3 of 5 patients in on phase, as measured by a video score (primary target parameter) and the YGTSS (secondary target parameter), compared with off phase; improvement in only 2 of 5 patients after 3 months’ open stimulation
Welter et al., 2008 (17)	3	Thalamus (centromedian nucleus and parafascicular nucleus) and globus pallidus internus	Observation for 20–60 months (10-month blinded period): 65–96% reduction in symptoms with globus pallidus internus stimulation; 30–64% reduction with thalamic stimulation (as measured by YGTSS)
Kuhn et al., 2007 (14)Kuhn et al., 2008 (15) Kuhn et al., 2008 (16)	8*	Nucleus accumbens (2 patients) Head of caudate nucleus (1 patient) Thalamus (4 patients) Globus pallidus internus (2 patients)	Observation for 3–60 months: improvement in symptoms as measured by YGTSS: Nucleus accumbens: 20–41% Thalamus: 33–80% Globus pallidus internus: 50% (1 patient) No response (1 patient) Caudate nucleus: 33%

^* One patient was initially treated with DBS of the globus pallidus internus, but after failure to respond new electrodes were implanted bilaterally in the thalamus;DBS, deep brain stimulation; YGTSS, Yale Global Tic Severity Scale