DBS dysfunction mimicking transient ischemic attacks-a case report.

We report on a patient with thalamic deep brain stimulation (DBS) for essential tremor who was admitted to a stroke unit with transient vertigo, dysarthria, and gait disturbance. Transient ischemic attacks were assumed but fluctuating neurological symptoms persisted until presentation to a DBS center. Here, unstable high monopolar impedances of the right-hemispheric electrode contacts were detected. Surgical revision revealed a fracture of the pocket adaptor connecting this electrode to the impulse generator. Replacement resulted in stable impedances and remitted the transient neurological symptoms. Emergency and stroke doctors should be aware of neurological symptoms induced by technical dysfunctions in DBS.

Unstable impedance of a single electrode contact resulting in loss of DBS therapy-a case report.

Open and short circuits of electrode contacts are important technical dysfunctions of DBS. Here, we report on another type of dysfunction restricted to a single electrode contact: impedance instability within regular absolute values. After 9-year subthalamic DBS, a Parkinson patient developed unilateral motor symptoms and intermittent dysaesthesia due to impedance instability of the active contact. DBS efficacy could be restored without surgical revision by activation of the neighboring contact. During 3-year-follow-up, impedances of the dysfunctional contact varied between 1 and 3 kΩ whereas the other three contacts remained stable. Impedance documentation is crucial to identify such dysfunctions.

Long-Term Stability of Short Circuits in Deep Brain Stimulation.

OBJECTIVES: To evaluate the long-term course of DBS electrodes with short-circuited contacts. MATERIALS AND METHODS: Electrodes with bipolar impedances below 150 Ω were identified from a cohort of 1044 patients with 2082 electrodes for variable movement disorders. The long-term course was analyzed from follow-up data. RESULTS: Short circuits were found in 62 electrodes (3.0%) from 60 patients (5.7%). They were restricted to two contacts in 57 electrodes (91.9%) and included more than two contacts in five electrodes. Onset was related to surgery (implantation, impulse generator replacements, or other surgical revisions) in 42 electrodes (67.7%). The onset was undetermined in 11 electrodes. In eight electrodes (12.9%) with previously normal impedances, the short circuit occurred spontaneously during long-term DBS and in one electrode after a fall. Repeated impedance checks at follow-ups of ≥3 months were available in 41 electrodes with short circuits. Twenty-six electrodes (63.4%) showed stable low impedances during observation up to nine years and two months (median 29 months). In four electrodes low impedances were stable until surgical revisions. In eight electrodes (19.5%) with observation up to nine years and seven months (median 54 months), short circuits were only detected intermittently but remained restricted to two contacts. In three electrodes (7.3%) intermittent short circuits between more than two contacts were found during long-term DBS. CONCLUSIONS: An increasing cumulative incidence demonstrates the clinical importance of short circuits. In the majority of electrodes, short circuits are restricted and remain restricted to two contacts during long-term stimulation.

DBS Electrodes With Single Disconnected Contacts: Long-Term Observation and Implications for the Management.

OBJECTIVES: To evaluate the long-term course of quadripolar DBS electrodes with disconnected single contacts that cannot be used for DBS. MATERIALS AND METHODS: Quadripolar electrodes with open circuits of single contacts or monopolar impedances >6500 Ω were identified from a cohort of 2082 electrodes from 1044 patients with variable movement disorders. The long-term course was analyzed from follow-up data. RESULTS: Disconnected contacts were found in 58 electrodes (2.8%) from 49 patients (4.7%). The dysfunction was restricted to one contact in 51 electrodes (87.9%), two contacts in 5 electrodes (8.6%), three contacts in 2 electrodes (3.4%). Onset was related to surgery (implantation, impulse generator replacement, or other surgical revision) in 34 electrodes (58.6%), trauma in 2 electrodes, undetermined in 11 electrodes, and occurred spontaneously after previous normal measurements in 11 electrodes (19.0%). Repeated measurements at follow-ups of ≥3 months were available in 39 electrodes. In 16 electrodes (41.0%) abnormal impedances persisted constantly during observations up to 11½ years (47 ± 35 months, median 41 months). In 21 electrodes (53.8%) abnormal impedances remained restricted to the initial contact(s) but varied considerably between measurements during up to six years (39 ± 18 months, median 38 months). Only two electrodes (5.1%) with initially one disconnected contact developed a disconnection of a second contact. CONCLUSIONS: Disconnections of single contacts occur with increasing cumulative incidence during long-term DBS. Surgery is the main causative risk factor. In the majority of electrodes, the dysfunction remains restricted to the initial contact(s).

Rapid battery depletion and loss of therapy due to a short circuit in bipolar DBS for essential tremor.

Technical dysfunctions have been reported reducing efficacy of deep brain stimulation (DBS). Here, we report on an essential-tremor patient in whom a short circuit in bipolar DBS resulted not only in unilateral loss of therapy but also in high current flow and thereby rapid decline of the impulse-generator battery voltage from 2.83 V a week before the event to 2.54 V, indicating the need for an impulse-generator replacement. Immediate re-programming restored therapeutic efficacy. Moreover, the reduction in current flow allowed the battery voltage to recover without immediate surgical intervention to 2.81 V a week later.

The Effect of Uni- and Bilateral Thalamic Deep Brain Stimulation on Speech in Patients With Essential Tremor: Acoustics and Intelligibility.

BACKGROUND: Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) is performed to suppress medically-resistant essential tremor (ET). However, stimulation induced dysarthria (SID) is a common side effect, limiting the extent to which tremor can be suppressed. To date, the exact pathogenesis of SID in VIM-DBS treated ET patients is unknown. OBJECTIVE: We investigate the effect of inactivated, uni- and bilateral VIM-DBS on speech production in patients with ET. We employ acoustic measures, tempo, and intelligibility ratings and patient's self-estimated speech to quantify SID, with a focus on comparing bilateral to unilateral stimulation effects and the effect of electrode position on speech. METHODS: Sixteen German ET patients participated in this study. Each patient was acoustically recorded with DBS-off, unilateral-right-hemispheric-DBS-on, unilateral-left-hemispheric-DBS-on, and bilateral-DBS-on during an oral diadochokinesis task and a read German standard text. To capture the extent of speech impairment, we measured syllable duration and intensity ratio during the DDK task. Naïve listeners rated speech tempo and speech intelligibility of the read text on a 5-point-scale. Patients had to rate their "ability to speak". RESULTS: We found an effect of bilateral compared to unilateral and inactivated stimulation on syllable durations and intensity ratio, as well as on external intelligibility ratings and patients' VAS scores. Additionally, VAS scores are associated with more laterally located active contacts. For speech ratings, we found an effect of syllable duration such that tempo and intelligibility was rated worse for speakers exhibiting greater syllable durations. CONCLUSION: Our data confirms that SID is more pronounced under bilateral compared to unilateral stimulation. Laterally located electrodes are associated with more severe SID according to patient's self-ratings. We can confirm the relation between diadochokinetic rate and SID in that listener's tempo and intelligibility ratings can be predicted by measured syllable durations from DDK tasks.

Arachnophobia alleviated by subthalamic nucleus stimulation for Parkinson's disease.

We report on a Parkinson patient with motor fluctuations and dyskinesias in whom deep brain stimulation (DBS) of the subthalamic nucleus (STN) not only improved motor symptoms but also pre-existing arachnophobia. Arachnophobia had been unchanged by the course of Parkinson's disease but rapidly improved with STN-DBS. Both, motor effects and the improvement of arachnophobia were stable during 2 years follow-up. To our knowledge this is the first report on STN stimulation effects on a specific phobia.

Fear of Progression is Determined by Anxiety and Self-Efficacy but not Disease-Specific Parameters in Patients with Parkinson's Disease: Preliminary Data from a Multicenter Cross-Sectional Study.

BACKGROUND: Fear of progression (FoP) is a reactive, conscious concern about chronic disease progression and its consequences which may limit quality of life substantially. Only one study has examined FoP in Parkinson's disease (PD), showing the second highest FoP scores among chronic diseases. OBJECTIVE: To examine FoP prevalence and to exploratorily analyze determinants of FoP in PD. METHODS: Within a multicenter cross-sectional study, 120 PD inpatients (age: 64.45±9.20; 60.8% male; UPDRS-III: 28.86±16.12) were examined with the FoP questionnaire (FoP-Q; max. 20 points). Stepwise multiple linear regression analysis examined sociodemographic, clinical, and (neuro-) psychological determinants of FoP. RESULTS: With a mean FoP-Q score of 8.08±2.17, 63.0% of the patients were classified with moderate FoP and 17.6% with dysfunctional (i.e., severe) FoP. The highest scores were shown for the subscale 'loss of autonomy'. Increased levels of anxiety, less self-efficacy, female gender, current employment, and lower health literacy were identified as significant determinants associated with FoP. CONCLUSION: With more than 80% of patients showing moderate to dysfunctional FoP, it must be regarded as a frequent symptom in PD, which needs to be further understood and addressed in clinical practice. Clinical parameters like PD duration and severity were no determinants for FoP, indicating that FoP awareness must be considered by professionals at all disease stages.

Role of dysphagia in evaluating Parkinson patients for subthalamic nucleus stimulation: a case report.

In the selection of Parkinson patients for deep brain stimulation (DBS) of the subthalamic nucleus (STN) a risk-benefit-analysis is performed regarding symptoms that commonly improve and symptoms that may deteriorate. Speech is among the symptoms that may deteriorate. In contrast, the differential effects of STN-DBS on swallowing are less clear. Here, we present a Parkinson patient with dysphagia from concomitant oculo-pharyngeal muscle dystrophy successfully treated by STN-DBS. The role of dysphagia in evaluating Parkinson patients for STN-DBS is discussed.

Is a patient controller for Parkinson's disease patients with subthalamic nucleus deep brain stimulation reasonable?

BACKGROUND: A patient controller (PC) is an optional device for patients with deep brain stimulation (DBS) to have limited control of their stimulator system. OBJECTIVES: We investigated the impact of a PC on DBS safety, most notably the handling/prevention of unexpected DBS failure in patients with Parkinson's disease (PD). METHODS: PD patients with subthalamic DBS were educated in the use of a PC. After a first impulse generator (IPG) replacement, data on the use of the PC were obtained from the patients' records and by a patient questionnaire. RESULTS: A total of 27 patients with IPG replacements after 4.4 ± 0.8 years (118.8 patient-years) were included. Thirteen patients transiently used the PC to optimize stimulation amplitudes. Eighteen patients reported events when they used the PC to ensure DBS being on. No accidental switch off by environmental electromagnetism was confirmed. In contrast, 4 patients accidentally turned the IPG off with the PC. Sixteen patients regularly checked the IPG battery but only 1 patient noted a low battery status before quarterly control visits. Of the 27 patients, 26 had anticipated and only 1 an unanticipated IPG replacement. CONCLUSIONS: A PC is not needed for patient safety. However, in some patients, a PC is helpful to optimize stimulation amplitudes and to increase the patients' own perception of safety.

A role of diffusion tensor imaging fiber tracking in deep brain stimulation surgery: DBS of the dentato-rubro-thalamic tract (drt) for the treatment of therapy-refractory tremor.

INTRODUCTION: Deep brain stimulation (DBS) can alleviate tremor of various origins. A number of regions are targeted. In recent work our group was able to show the involvement of the dentato-rubro-thalamic tract (drt) in tremor control with fiber tracking techniques. Here we report for the first time the successful use of magnetic resonance tractography in combination with traditional landmark-based targeting techniques to perform the implantation of a bilateral DBS system in a patient with dystonic head tremor. METHODS: We report on a 37-year-old female with long-standing pure head tremor from myoclonus dystonia. She was identified as a candidate for thalamic DBS. The use of head fixation in a stereotactic frame would blur target symptoms (head tremor) during surgery and was therefore avoided. Her dentate-rubro-thalamic tracts were visualized with preoperative diffusion tensor imaging (DTI) and tractography, and then directly targeted stereotactically with DBS electrodes. RESULTS: Three months after implantation, tremor control was excellent (>90%). A close evaluation of the active electrode contact positions revealed clear involvement of the drt. CONCLUSION: This is the first time that direct visualization of fiber tracts has been employed for direct targeting and successful movement disorder tremor surgery. In the reported case, additional knowledge about the position of the drt, which previously has been shown to be a structure for modulation to achieve tremor control, led to a successful implantation of a DBS system, although there was a lack of intra-operatively testable tremor symptoms. In concordance with studies in optogenetic neuromodulation, fiber tracts are the emerging target structures for DBS. The routine integration of DTI tractography into surgical planning might be a leading path into the future of DBS surgery and will add to our understanding of the pathophysiology of movement disorders. Larger study populations will have to prove these concepts in future research.

Electrode dysfunctions in patients with deep brain stimulation: a clinical retrospective study.

BACKGROUND: Electrode fractures are known hardware problems in patients with deep brain stimulation (DBS) and require surgical revision. Short circuits, loose connections or disconnections of only single contacts of the common quadripolar stimulation electrodes are more subtle dysfunctions and can result in decreased efficacy of DBS. Measuring the impedances of electrodes helps detect such technical dysfunctions. This study evaluates the frequency and clinical implications of abnormal impedance measurements. METHODS: We retrospectively analyzed findings of systematic impedance checks in 591 consecutive patients with DBS for various movement disorders treated in our DBS center between 2005 and 2010. FINDINGS: A technical dysfunction was found in 36 out of 1,142 electrodes (3.2%). Short circuits (22 electrodes) were more frequent than disconnections of single contacts (8 electrodes) or loose contacts (6 electrodes). Moreover, after 109 replacements of impulse generators another 16 electrodes revealed technical dysfunctions, again with short circuits (9 electrodes) exceeding disconnections of single contacts (5 electrodes) and loose contacts (2 electrodes). Most of the short circuits occurred immediately after surgical interventions. In contrast, among dysfunctions occurring later during long-term DBS, disconnections and loose contacts prevailed. Surgical revision was performed in 4 of the overall 52 electrodes with dysfunctions, whereas in the other electrodes adjustment of stimulation parameters resulted in stable and satisfying symptom control. CONCLUSIONS: Technical dysfunctions of stimulation electrodes or extension leads are rare but important sources of unsatisfying DBS efficacy. In the majority of cases DBS programming or reprogramming allows avoiding surgical revision.

Secondary failure after ten years of pallidal neurostimulation in a patient with advanced Parkinson's disease.

Deep-brain stimulation of the subthalamic nucleus and internal globus pallidus are both surgical options in advanced Parkinson's disease. The best target is still debated with data suggesting better motor outcome in subthalamic stimulation but higher rates of psychiatric problems. Failure of pallidal stimulation within the first 2 years has been described. Here, we report a patient with good response to pallidal neurostimulation who developed a secondary failure after 10 years of treatment which was successfully reversed by reimplanting the electrodes into the subthalamic nucleus. This case suggests that a controlled comparison of treatment efficacy of pallidal and subthalamic neurostimulation may require a very long follow-up period to yield reliable results.

Stuttering induced by thalamic deep brain stimulation for dystonia.

We report a patient in whom deep brain stimulation of the ventral intermediate nucleus of the thalamus (Vim) for treating dystonia reversibly induced stuttering at suboptimal stimulation parameters. Adjustments of stimulation parameters resulted in excellent control of dystonic motor symptoms and complete resolution of speech dysfluency. This is the first report on stuttering as an adverse effect of Vim stimulation which is primarily used to treat tremors of various etiologies.

Feasibility of Music-Assisted Treadmill Training in Parkinson's Disease Patients With and Without Deep Brain Stimulation: Insights From an Ongoing Pilot Randomized Controlled Trial.

Background: Music-assisted treadmill training (MATT) is a new therapeutic approach for Parkinson's disease (PD) patients, combining treadmill training with rhythmic auditory cueing and visual feedback. PD studies have shown larger positive effects on motor outcomes than usual treadmill training. However, effects on cognition, in contrast, are less clear. Existing studies provided intensive training protocols and included only stable medicated patients. Thus, a pilot randomized controlled trial was designed to analyze the feasibility of a shorter training protocol as well as preliminary effects on cognition, motor function, and patient-centered outcomes in a rehabilitation setting where PD patients with and without deep brain stimulation (DBS) undergo adaptation of medication and DBS settings. Here, we present the results from the feasibility analysis of the still ongoing trial. Methods: Non-demented PD patients with and without DBS were recruited during their inpatient rehabilitation and randomized to an experimental group (EG; 20 min MATT) or an active control group (CG; 20 min bike ergometer training). The trainings took place for 8 consecutive days and were added to the usual rehabilitation. Feasibility was assessed with the following parameters: patients' study protocol acceptance, study protocol transferability into clinical routine, training-induced adverse events, and patients' training perception. Results: Thirty-two patients (EG: n = 15; CG: n = 17; 72% DBS) were included. The study protocol was well-accepted (inclusion rate: 84%). It was transferable into clinical routines; dropout rates of 40% (EG) and 18% (CG) were observed. However, an in-depth analysis of the dropout cohort did not reveal intervention-related dropout reasons. The MATT and the standard ergometer training showed no adverse events and were positively perceived by PD patients with and without DBS. Conclusion: MATT was shown to be a feasible, safe, and enjoyable treatment option in PD patients with and without DBS. Furthermore, the dropout cohort analysis revealed some exciting first insights into possible dropout reasons that go beyond the form of intervention. Therefore, research would benefit from a common practice of dropout analyses, as this would enhance our understanding of patients' therapy adherence and expectations.

Stability of symptom control after replacement of impulse generators for deep brain stimulation.

OBJECT: Impulse generators (IPGs) for deep brain stimulation (DBS) need to be replaced when their internal batteries fail or when technical problems occur. New IPGs are routinely programmed with the previous stimulation parameters. In this study, the authors evaluate the stability of symptom control after such IPG replacements. METHODS: The authors retrospectively analyzed the outcome of 56 IPG replacements in 42 patients with various movement disorders treated using DBS. RESULTS: Stable symptom control was found in 65% of single-channel IPG replacements and 53% of dual-channel IPG replacements. Worsening of symptoms resulted primarily from changes in stimulation effects requiring reprogramming of stimulation parameters (17% of dual-channel IPG and 25% of single-channel IPG). In 14% of dualchannel IPG replacements, instability resulted from erroneous extension adjustment with change in laterality. A new short circuit of active with previously inactive contacts of the quadripolar stimulation lead resulted in a worsening of symptoms in 4% of replacements. CONCLUSIONS: Replacement of the IPG requires careful follow-up of patients with DBS to ensure stable symptom control.

The impact of subthalamic deep brain stimulation on bradykinesia of proximal and distal upper limb muscles in Parkinson's disease.

OBJECTIVE: To assess the differential effects of bilateral deep brain stimulation of the subthalamic nucleus on proximal and distal muscle groups of the upper limb in Parkinson's disease. METHODS: Eight parkinsonian subjects with chronic bilateral stimulation of the subthalamic nucleus performed index finger tapping (differentially drawing upon distal arm muscles), horizontal pointing (differentially drawing upon proximal arm muscles) and a complex reach-to-grasp task with cubes of different sizes, which involved both proximal and distal arm muscles. An ultrasound based system was used for kinematic motion analysis. Subjects were investigated in two clinical conditions: on and off subthalamic nucleus stimulation. Clinical symptom severity was rated with the Unified Parkinson's Disease Rating Scale (UPDRS) motor subscore. RESULTS: Stimulation of the subthalamic nucleus improved the UPDRS motor subscore (68 %). Bradykinesia of index finger tapping and horizontal pointing were equally improved by subthalamic nucleus stimulation. In contrast, in a complex reach-to-grasp task bradykinesia was differentially ameliorated for the grasp component. CONCLUSION: The data suggest that bilateral stimulation of the subthalamic nucleus improves bradykinesia of both distal and proximal muscles of the arm and hand in Parkinson's disease; however, dependent upon task complexity proximal and distal movement components may be affected differentially. Kinematic motion analysis is an efficient tool to objectively evaluate the beneficial effects of subthalamic nucleus stimulation on dexterity in Parkinson's disease.

DBS of the PSA and the VIM in essential tremor: A randomized, double-blind, crossover trial.

OBJECTIVE: To evaluate deep brain stimulation (DBS) of the posterior subthalamic area (PSA) in essential tremor (ET) and compare it to the ventral intermediate nucleus of the thalamus (VIM) in terms of stimulation efficacy, efficiency, and side effects. METHODS: DBS leads were implanted such that contacts were placed in the VIM, on the intercommissural line, and in the PSA. Thirteen patients with ET entered a randomized, double-blind crossover phase and completed a 1-year follow-up. RESULTS: PSA-DBS significantly reduced tremor severity and improved quality of life. There were no relevant differences in quality and frequency of stimulation side effects between VIM and PSA, with a tendency toward greater tremor improvement with PSA stimulation. Clinical benefit was achieved at significantly lower stimulation amplitudes in the PSA. The majority of patients remained with PSA-DBS after 1 year. CONCLUSION: In accordance with previous retrospective investigations, our prospective data suggest that PSA-DBS is at least equally effective as but possibly more efficient than VIM-DBS. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for patients with essential tremor, PSA-DBS is not significantly different from VIM-DBS in suppressing tremor, but clinical benefit from PSA-DBS is attained at lower stimulation amplitudes.

Postoperative rehabilitation after deep brain stimulation surgery for movement disorders.

Deep brain stimulation (DBS) is a highly efficient, evidence-based therapy for a set of neurological and psychiatric conditions and especially movement disorders such as Parkinson's disease, essential tremor and dystonia. Recent developments have improved the DBS technology. However, no unequivocal algorithms for an optimized postoperative care exist so far. The aim of this review is to provide a synopsis of the current clinical practice and to propose guidelines for postoperative and rehabilitative care of patients who undergo DBS. A standardized work-up in the DBS centers adapted to each patient's clinical state and needs is important, including a meticulous evaluation of clinical improvement and residual symptoms with a definition of goals for neurorehabilitation. Efficient and complete information transfer to subsequent caregivers is essential. A coordinated therapy within a multidisciplinary team (trained in movement disorders and DBS) is needed to achieve the long-range maximal efficiency. An optimized postoperative framework might ultimately lead to more effective results of DBS.