title: Tic related local field potentials in the thalamus and the effect of deep brain stimulation in Tourette syndrome: Report of three cases.
abstract: OBJECTIVE
  Three patients with intractable Tourette syndrome (TS) underwent thalamic deep brain stimulation (DBS). To investigate the role of thalamic electrical activity in tic generation, local field potentials (LFP), EEG and EMG simultaneously were recorded.
  
  
  METHODS
  Event related potentials and event related spectral perturbations of EEG and LFP, event related cross-coherences between EEG/LFP and LFP/LFP were analyzed. As time locking events, the tic onsets were used. Spontaneous tics were compared to voluntary tic mimicking. The effect of tic suppression and DBS on thalamic LFPs was evaluated.
  
  
  RESULTS
  All three patients showed time-locked and prior to onset of spontaneous motor tics thalamic synchronization and thalamo-cortical cross-coherence. Also in three patients, not time-locked to motor tics, increased intra-thalamic coherences in the 1-8Hz frequency band were found. In one patient it was demonstrated that voluntary mimicked tics were preceded by premotor cortical and thalamic potentials. In this patient unilateral thalamic DBS contralaterally decreased the background thalamic activity.
  
  
  CONCLUSIONS
  The present study in three cases with TS shows that spontaneous tics in TS are preceded by repetitive coherent thalamo-cortical discharges, indicating that preceding a tic the basal ganglia circuits are "charged up", ultimately leading to a motor tic.
  
  
  CONCLUSIONS
  Thalamic LFP recording may lead to more insight in underlying pathophysiological mechanisms in TS.
authors.affiliation: Department of Neurology and Clinical Neurophysiology of the Academic Medical Center, University of Amsterdam, The Netherlands. Electronic address: Bour@amc.nl.
authors.forename: L J
authors.initials: LJ
authors.lastname: Bour
authors.affiliation: Department of Neurosurgery, Maastricht University Medical Center, The Netherlands; MIND (Maastricht Institute for Neuromodulative Development), The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Ackermans
authors.affiliation: Department of Neurology of the Free University of Amsterdam, The Netherlands.
authors.forename: E M J
authors.initials: EM
authors.lastname: Foncke
authors.affiliation: Department of Clinical and Health Psychology, Utrecht University/Altrecht, Anxiety Outpatient Program, Utrecht, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Cath
authors.affiliation: Center for Movement Disorders, St. Lucas Hospital Ghent, Ghent, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: van der Linden
authors.affiliation: Department of Stereotactic and Functional Neurosurgery, University of Cologne, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Visser Vandewalle
authors.affiliation: Department of Neurology, University of Groningen, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Tijssen
mesh_terms: D000328:Adult; D046690:Deep Brain Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D008297:Male; D013788:Thalamus / Q000503:physiopathology*; D020323:Tics / Q000503:physiopathology / Q000628:therapy*; D005879:Tourette Syndrome / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome
keywords: Deep brain stimulation; Local field potentials; Thalamus; Tics; Tourette syndrome