Thalamic Deep Brain Stimulation for Refractory Tourette Syndrome: Clinical Evidence for Increasing Disbalance of Therapeutic Effects and Side Effects at Long-Term Follow-Up

ObjectiveThalamic deep brain stimulation (DBS) is effective in reducing tics in patients with refractory Tourette syndrome at the short-term. Here, we report on the long-term outcome. Materials and MethodsSeven patients underwent bilateral DBS between 2001 and 2008. The target was the centromedian nucleus, substantia periventricularis and nucleus ventro-oralis internus cross point of the thalamus. The effect on tics and side effects were evaluated with a variable follow-up duration of 12 to 78 months. ResultsPatient 1 and 2 showed good tic improvements of 81.6% (60 months) and 50% (36 months), respectively. However, side effects like reducing levels of energy and visual disturbances increased. In patient 1, the target was changed to the anterior part of the internal pallidum and patient 2 switched the stimulator permanently off. Patient 3 experiences still satisfying results with a tic improvement of 88.9% (78 months). Patient 4 and 7 showed minor tic improvements of 34% (16 months) and 9% (60 months), respectively. In both patients side effects became more severe and the target was changed to the anterior part of the internal pallidum. Patient 5 showed a tic improvement of 27.5% (12 months) and went abroad for stimulation of the external globus pallidus. Patient 6 developed cerebellar atrophy. He experienced several nonstimulation related side effects and turned the stimulator off. ConclusionsThere seems to be an increasing disbalance of therapeutic effects and side effects at long-term follow-up, often leading to either switching the stimulator off or new surgery with a different neuro-anatomic target.