Background: Detection of defective deep brain stimulation (DBS) contacts/electrodes is sometimes challenging.

Case Report: We report a patient with Tourette syndrome (TS), who presented with abrupt tic increase and mild generalized headache 9 years after DBS implantation. On the suspicion of a hardware defect, a fracture of the DBS electrode and extension lead was ruled out by radiography and standard implantable pulse generator readouts. Further investigation revealed position-dependent modifiable therapeutic impedances, suggesting an impaired contact of the extension lead/adaptor. After replacement normal impedances were recorded, and the patient fully recovered.

Discussion: In DBS dysfunction with inconspicuous hardware check, position-dependent defects might be suspected

Blahak, Christian

Krauss, Joachim K.

Majewski, Olaf

Müller-Vahl, Kirsten R.

Schulte, Dirk-Michael

Wolf, Marc E.

English

Columbia University Academic Commons

1Case ReportsPosition-Dependent Dysfunction of Deep Brain Stimulation in Tourette Syndrome: Diagnostic CluesMarc E. Wolf1,2*, Olaf Majewski3, Kirsten R. Müller-Vahl4, Christian Blahak1,5, Dirk-Michael Schulte3 & Joachim K. Krauss61Department of Neurology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, DE, 2Department of Neurology, Neurocentre, Klinikum Stuttgart, Stuttgart, DE, 3Department of Neurosurgery, Universitätsmedizin Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, DE, 4Clinic of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, Hannover, DE, 5Department of Neurology, Ortenau Klinikum Lahr-Ettenheim, Lahr, DE, 6Department of Neurosurgery, Hannover Medical School, Hannover, DEIntroductionDeep brain stimulation (DBS) in patients with Tourette syndrome (TS) results in a tic reduction of  about 40%.1 Most often used targets are the globus pallidus internus (GPi) and thalamic nuclei (centromedian parafascicular/ventral oral internus nucleus [CMPF/Voi]).1 The overall reported DBS hardware complication rate in patients with movement disorders is about 8%, mainly due to infections, lead migration, and fractures typically manifested with elevated therapeutic impedances.2,3 In contrast, in patients with TS hardware complications and particularly infections seem to occur more often.4Case reportWe report on a male patient with TS, who suffered from severe motor and vocal tics as well as obsessive-compulsive disorder and therefore underwent bilateral DBS electrode implantation (model 3387; Medtronic Inc., Minneapolis, MN) using computed tomography (CT)-stereotactic Columbia University LibrariesFreely available onlineTremor and Other Hyperkinetic Movementshttp://www.tremorjournal.orgAbstractBackground: Detection of  defective deep brain stimulation (DBS) contacts/electrodes is sometimes challenging.Case Report: We report a patient with Tourette syndrome (TS), who presented with abrupt tic increase and mild generalized headache 9 years after DBS implan-tation. On the suspicion of  a hardware defect, a fracture of  the DBS electrode and extension lead was ruled out by radiography and standard implantable pulse generator readouts. Further investigation revealed position-dependent modifiable therapeutic impedances, suggesting an impaired contact of  the extension lead/adaptor. After replacement normal impedances were recorded, and the patient fully recovered.Discussion: In DBS dysfunction with inconspicuous hardware check, position-dependent defects might be suspected.Keywords: Deep brain stimulation, hardware complications, headache, impedance, Tourette syndromeCitation: Wolf  ME, Majewski O, Müller-Vahl KR, Blahak C, Schulte D-M, Krauss JK. Position-dependent dysfunction of  deep brain stimulation in Tourette syndrome: Diagnostic clues. Tremor Other Hyperkinet Mov. 2019; 9. doi: 10.7916/tohm.v0.713*To whom correspondence should be addressed. E-mail: ma.wolf@klinikum-stuttgart.deEditor: Elan D. Louis, Yale University, USAReceived: May 1, 2019; Accepted: August 12, 2019; Published: October 23, 2019Copyright: © 2019 Wolf  et al. This is an open-access article distributed under the terms of  the Creative Commons Attribution–Noncommercial–No Derivatives License, which permits the user to copy, distribute, and transmit the work provided that the original authors and source are credited; that no commercial use is made of  the work; and that the work is not altered or transformed.Funding: None.Financial Disclosures: MEW, OM, CB, DMS: The authors declare that there are no disclosures to report. KMV has received financial or material research support from the EU (FP7-HEALTH-2011 No. 278367, FP7-PEOPLE-2012-ITN No. 316978), the German Research Foundation (DFG: GZ MU 1527/3-1), the German Ministry of  Education and Research (BMBF: 01KG1421), the National Institute of  Mental Health (NIMH), the Tourette Gesellschaft Deutschland e.V., the Else-Kroner-Fresenius-Stiftung, and GW, Almirall, Abide Therapeutics, and Therapix Biosiences and has received consultant’s honoraria from Abide Therapeutics, Fundacion Canna, Therapix Biosiences, and Wayland Group, speaker’s fees from Tilray, and royalties from Medizinisch Wissenschaftliche Verlagsgesellschaft Berlin. JKK is a consultant to Medtronic and to Boston Scientific, he received honoraria from Abbvie and St. Jude.Conflicts of Interest: The authors report no conflicts of  interest.Ethics Statement: This study was performed in accordance with the ethical standards detailed in the Declaration of  Helsinki. All patients have provided written informed consent.Wolf ME, Majewski O, Müller-Vahl KR, et al. Position-Dependent Dysfunction of DBSColumbia University LibrariesTremor and Other Hyperkinetic Movementshttp://www.tremorjournal.org 2surgery guided by magnetic resonance imaging and microelectrode recording in both the GPi and the CMPF/Voi at the age of  29 years. Electrodes were connected to an implantable pulse generator (IPG) (Soletra® Model 7426; Medtronic) on each side using a Y-junction. Stereotactic CT demonstrated appropriate placement of  the DBS elec-trodes. After several adaptations of  the stimulation settings, best clinical results were achieved with bilateral DBS of  the CMPF/Voi. The patient was followed every 3–6 months in the long-term course. Forty months postoperatively, IPG replacement with switch to a dual-channel rechargeable IPG (Activa® RC; Medtronic) was performed. A specific adapter was used as an interface to allow connection of  the lead exten-sions with the new IPG. The patient received a patient programmer to adapt stimulation intensities within a predefined range. Overall disease course was stable with marked improvement of  tics and compulsions compared with the preoperative situation (last DBS settings: left: monopolar stimulation 6-/C+, 2.1mA, 60 µs, 130 Hz; right: monopolar stimulation 3-/C+, 1.5 mA, 60 µs, 130 Hz).Nine years after surgery, the patient asked for an urgent appointment and reported an abrupt and marked deterioration of  his tics since about 1 week. In parallel, he had developed an unspecific general headache, while his programmer indicated a DBS dysfunction. Clinical examina-tion showed aggravated tics; however, the IPG check in supine position showed unremarkable therapeutic and single-contact electrode imped-ances. System check with the patient programmer neither notified any dysfunction. In addition, DBS electrode or extension lead fracture was excluded by radiography. Therefore, spontaneous fluctuations of  tics were assumed and a slight augmentation of  stimulation intensities was performed.During reassessment 1 week later, the patient still reported worsened tics. Again, his programmer had displayed DBS dysfunction, which the patient reported to be possibly motion dependent. Therefore, we checked the DBS system once more and found out that therapeutic impedance of  the left electrode was not measurable, when the patient held his head in upright position. Furthermore, the active monopolar contact 6 showed elevated impedances (>40,000 Ohm). Remarkably, therapeutic and electrode impedances were found to be perfectly  normal (contact 6: 896 Ohm), when the patient inclined his head to the left (see Figure 1). To ensure movement-dependent variations in Figure 1. Assessment of  Therapeutic Impedances in Position-Dependent Manner. Improved values with head inclination to the left are illustrated.Wolf ME, Majewski O, Müller-Vahl KR, et al. Position-Dependent Dysfunction of DBSColumbia University LibrariesTremor and Other Hyperkinetic Movementshttp://www.tremorjournal.org 3Figure 2. Radiography in (A) Upright and (B) Inclined Head Position. A mild traction of  the cable (red circle) in the upright position might be observed.impedances, the described procedure was repeated twice, resulting in the same effect, indicating an impaired contact of  the left cable exten-sion. This assumption was further supported by additional dynamic radiography, which showed a traction of  the left extension lead, improv-ing with inclination of  the head to the left (Figure 2). As the inclined head position could not be hold on in daily practice for longer intervals, a formal clinical assessment of  tic frequency could unfortunately not be performed.We decided for replacement of  the left extension lead and adaptors because an impaired contact seemed to be the most obvious cause. Postoperative IPG check showed regular impedances followed by a rapid improvement of  the tics to previous levels and relief  of  headache. The further course was unremarkable with no episodes of  dysfunction of  the neurostimulation system.DiscussionThis case is instructive for two reasons. First, hardware defects are well-known complications in DBS, which are always considered when acute clinical worsening occurs. Yet, despite extensive hardware check and radiography to exclude fractures of  the DBS electrode or the exten-sion lead, the underlying cause and diagnosis was not established at first glance. Normal radiography does not exclude a hardware dysfunction and relevant changes such as a traction of  the cable might only manifest very discreetly. In case of  clinical DBS dysfunction without obvious evi-dence for elevated therapeutic or electrode impedances, a defective con-tact with fluctuating current flow might be considered and uncovered by investigating the IPG function in various head positions. Noteworthy, the patient reported in parallel to the tic increase newly developed gen-eralized headache that relieved after restoration of  continuous DBS. It can be speculated that the patient’s headache might have been caused by recurrent on–off  effects with fluctuating movement-dependent cur-rent flow. Even though unspecific, generalized mild headache might be considered as a clinical hint for DBS dysfunction caused by recurrent changes between on and off  mode.References1. Martinez-Ramirez D, Jimenez-Shahed J, Leckman JF, Porta M, Servello D, Meng FG, et al. Efficacy and safety of  deep brain stimulation in Tourette syn-drome: the International Tourette Syndrome Deep Brain Stimulation Public Database and Registry. JAMA Neurol  2018;75(3):353–359. doi: 10.1001/ jamaneurol. 2017.43172. Farris S, Vitek J, Giroux ML. Deep brain stimulation hardware complica-tions: the role of  electrode impedance and current measurements. Mov Disord 2008;23(5):755–760. doi: 10.1002/mds.219363. Baizabal Carvallo JF, Mostile G, Almaguer M, Davidson A, Simpson R, Jankovic J. Deep brain stimulation hardware complications in patients with movement disorders: risk factors and clinical correlations. Stereotact Funct Neurosurg 2012;90(5):300–306. doi: 10.1159/0003382224. Jitkritsadakul O, Bhidayasiri R, Kalia SK, Hodaie M, Lozano AM, Fasano A. Systematic review of  hardware-related complications of  deep brain stimulation: do new indications pose an increased risk? Brain Stimul 2017;10(5):967–976. doi: 10.1016/j.brs.2017.07.003

Position-Dependent Dysfunction of Deep Brain Stimulation in Tourette Syndrome: Diagnostic Clues

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Position-Dependent Dysfunction of Deep Brain Stimulation in Tourette Syndrome: Diagnostic Clues

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