Table 1.
Examples of Invasive Stimulation in GTS. The table provides a condensed overview of invasive stimulation approaches presented in this article, as well as additional studies of interest, that have been used thus far to ameliorate or investigate symptoms in GTS.
| Reference | n | Target | Outcome |
|---|---|---|---|
| Visser-Vandewalle et al. (33) | 3 | Thalamus: centromedian nucleus, substantia periventricularis, and nucleus ventro-oralis internus | Tic reduction ranging from 72.2 to 90.1% reduction at long-term follow-up, although specific tic persistence was reported for the 3 patients |
| Maciunas et al. (34) | 5 | Thalamus: centromedian–parafascicular (CM–Pf) and ventralis oral complex (Voi) | 3 out of 5 patients’ improvement in [Yale Global Tic Severity Scale (YGTSS) and TS Symptom List scores]. 2 patients did not improve after 3-month follow-up |
| Servello et al. (35) | 18 | Thalamus: bilateral CM–Pf and Voi | 6 patients showed progressive improvement in tic severity, and 12 showed recurrent motor and phonic tics after stimulation, with 3 showing waxing and waning of symptoms |
| Welter et al. (36) | 3 | Thalamus: bilateral CM–Pf GPi: ventromedial locations | YGTSS showed that GPi stimulation reduced tic severity to 65, 96, and 74%, respectively. Bilateral stimulation of the CM–Pf produced a 64, 30, and 40%, respectively, reduction in tic severity. In patient 2, the improvement decreased after 2 months |
| Porta et al. (37) | 15 | Thalamus: bilateral CM–Pf and Voi | 15 out of 18 patients improved in tic severity and behavioral ratings (including anxiety and depression) Data not available for 3 patients |
| Kwon et al. (23) | Transcranial magnetic stimulation (TMS). Supplementary motor area (SMA) of the cortex | Normalization of the right hemisphere hyperexcitability leading to clinical improvement | |
| Martínez-Fernández et al. (38) | 5 | GPi: 2 patients in the bilateral posterolateral location, 2 patients in the bilateral anteromedial location, 1 initially in the posterolateral was switched to the anteromedial location after 18 months | 2 patients with stimulation the bilateral posterolateral location: 1 patient showed a 54.7% reduction in motor tics and the second patient only showed a plateau in motor and phonic tics but still interfered with lifestyle according to YGTSS 2 patients in stimulation in bilateral anteromedial location: 1 patient showed a 60% reduction in motor tics. Motor and phonic tics resolved for the second patient 1 patient with anteromedial location switch after 18 months: only a 19% reduction for motor tics in the YGTSS |
| Cannon et al. (39) | 11 | GPi: bilateral anteromedial globus pallidus internus | 10 patients (91%) showed improvement in tic severity, with a 48% reduction in motor tics and a 56.5% reduction in phonic tics. 6 patients (54.5%) had more than 50% reduction; sustained for at least 3 months in YGSS. 2 patients required pharmacotherapy for tics after surgery. 1 patient was a non-responder |
| Maling et al. (40) | 5 | Thalamus: bilateral CM–Pf and Voi | 3 out of 5 patients showed significant YGTSS decrease. The remaining 2 showed only a small clinical improvement corresponding to small changes in gamma power |
| Porta et al. (41) | 18 | Thalamus: bilateral CM–Pf and Voi | Reduction in tic severity, as well as improvements in the comorbid obsessive–compulsive behaviors (OCB), and co-existing psychopathologies (anxiety and depressive symptomatology). However, only 7 out of 15 patients did the overall global assessment of improvement indicate improvement |
| Huys et al. (42) | 8 | Thalamus: bilateral for 6 patients; ventral anterior and ventrolateral motor areas | YGTSS showed a 51% reduction in motor tics and a 53% in vocal tics, with a total of 58% reduction score compared to baseline |
| Dehning et al. (43) | 6 | GPi: bilateral postero-ventrolateral location | 2 patients did not respond to stimulation, and the mean YGTSS score for the remaining 4 patients was 29.5 at the last follow-up, with a mean Tourette Syndrome Quality-of-Life Scale (TSQOL) of 7.75 |
| Zhang et al. (44) | 13 | GPi: bilateral posterolateral location | YGTSS scores at the last visit compared with baseline were reduced in all 13 patients by a mean of 52.1%. 12 of the 13 showed a mean TSQOL of 45.7%, with 1 patient denying improvement. Only 6 patients reported a significantly high response with overall marked reduction in all tic types |
| Bloch and Levkovitz (45) | 12 | TMS. Bilateral SMA inhibition | Improvement in clinical symptoms in children with GTS for at least 6 months |
| Kefalopoulou et al. (46) | 15 | GPi: bilateral anteromedial location | Mild improvement in YGTSS, with 80.7 for the off-stimulation period, and 68.3 for the on-stimulation period form a baseline of 87.9. No significant improvement in mean quality-of-life scores (GTS-QOL) |
The table provides a condensed overview of invasive stimulation approaches presented in this article, as well as additional studies of interest, that have been used thus far to ameliorate or investigate symptoms in GTS. Beyond the demonstration of DBS as a therapeutic option, the number of insufficient responders is shown.