Longitudinal Impedance Variability in Patients with Chronically Implanted DBS Devices

Cheung, Tyler; Nuño, Miriam A; Hoffman, Matilde; Katz, Maya; Kilbane, Camilla; Alterman, Ron L.; Tagliati, Michele

doi:10.1016/j.brs.2013.03.010

Cited by 58 publications

(59 citation statements)

References 19 publications

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“…To the best of our knowledge, our study is the first to reveal a continuous decrease of therapeutic impedance values from 1036U to 786U within 10 years of STN-DBS, and it corresponds well to previous findings of a continuous decline of impedance over time [8]. As the stimulation settings remained constant over time and therefore cannot explain our findings, progressive neurodegeneration may be hypothesized as a possible explanation, because an associated increase of mean diffusivity and isotropy [9] would directly affect brain conductivity and hence impedance measurements [7].…”

Section: Discussionsupporting

confidence: 90%

Long-term evaluation of impedance levels and clinical development in subthalamic deep brain stimulation for Parkinson's disease

Hartmann

Wojtecki

Vesper

et al. 2015

Parkinsonism & Related Disorders

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Section: Discussionsupporting

confidence: 90%

Long-term evaluation of impedance levels and clinical development in subthalamic deep brain stimulation for Parkinson's disease

Hartmann

Wojtecki

Vesper

et al. 2015

Parkinsonism & Related Disorders

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“…2). Thickness and conductivity of the encapsulation layer around the electrode, bulk tissue conductivity, and electrical stimulation activity itself contribute significantly to electrode impedance [20][21][22]. The time course of the transient changes in impedance may be related to microglial activation and subsequent fusion into multinuclear giant cells or mild to moderate inflammation as a potential mechanism of action for peri-implant impedance change with resulting GFAP positive pathology findings [23,24] (Fig.…”

Section: Discussionmentioning

confidence: 99%

Long-Term Surface Electrode Impedance Recordings Associated with Gliosis for a Closed-Loop Neurostimulation Device

Sillay

Ondoma

Wingeier³

et al. 2018

Ann Neurosci

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Background: Closed-loop neurostimulation is a novel alternative therapy for medically intractable focal epilepsy for patients who are not candidates for surgical resection of a seizure focus. Electrodes for this system can be implanted either within the brain parenchyma or in the subdural space. The electrodes then serve the dual role of detecting seizures and delivering an electrical signal aimed at aborting seizure activity. The Responsive Neurostimulation (RNS®) system (Neuropace, Mountain View, CA, USA) is an FDA-approved implantable device designed for this purpose. Objective: One of the challenges of the brain machine interface devices is the potential for implanted neurostimulator devices to induce progressive gliosis, apart from that associated with the minimal trauma at implantation. Gliosis has the potential to alter impedances over time, thereby affecting the clinical efficacy of these devices, and also poses a challenge to the prospects of in vivo repositioning of depth electrodes. We present a clinical case with 3-year follow-up and pathology. Methods: Single-case, retrospective review within a randomized trial with specific minimum follow-up and impedance measurements. Results: Impedance changes in the surface electrode over time were observed. Surgical pathological findings revealed significant gliosis in the leptomeninges of the cortices. Conclusion: We report, for the first time, long-term impedance recordings from a surface electrode associated with pathologic findings of gliosis at the Neuropace device-tissue interface in a patient who was enrolled in the multicenter RNS System Pivotal Clinical Investigation. Further study is required to elucidate the temporal relationship of pathological findings over time. Impedance changes were more complex than can be explained by a progressive or transient pathological mechanism. Further effort is required to elucidate the relationship between impedance change and seizure event capture.

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“…The chronology of impedance fluctuations after DBS electrode implantation has been investigated by several groups in different experimental and clinical situations [7,8,14,28,29,30]. Clinically relevant impedance increases occur in the first few weeks after implantation, possibly as a result of changes at the electrode-brain interface [31].…”

Section: Discussionmentioning

confidence: 99%

“…The safety and efficacy of CC DBS in newly operated PD patients has been established [12]. The main benefit of CC stimulation is thought to be in the initial phase after surgery (weeks to months) when impedances change most rapidly, primarily as the result of changes at the electrode-brain tissue interface [7,8]. This may shorten the time needed to reach optimal programming [13].…”

Section: Introductionmentioning

confidence: 99%

“…Impedance is further influenced by many variables including the frequency and waveform of the stimulation [6], the time from implantation [7], from onset of stimulation and even the implanted target [8]. Collectively, the factors contributing to the impedance of the DBS system play an important role in the shape of the stimulation waveform and in the amount of electrical charge reaching the tissue.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease

Noriega

Eitan²,

Marmor³

et al. 2015

Stereotact Funct Neurosurg

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Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for advanced Parkinson's disease (PD). Motor efficacy and safety have been established for constant voltage (CV) devices and more recently for constant current (CC) devices. CC devices adjust output voltage to provide CC stimulation irrespective of impedance fluctuation, while the current applied by CV stimulation depends on the impedance that may change over time. No study has directly compared the clinical effects of these two stimulation modalities. Objective: To compare the safety and clinical impact of CC STN DBS to CV STN DBS in patients with advanced PD 2 years after surgery. Methods: Patients were eligible for inclusion if they had undergone STN DBS surgery for idiopathic PD, had been implanted with a Medtronic Activa PC and if their stimulation program and medication had been stable for at least 1 year. This single-center trial was designed as a double-blind, randomized, prospective study with crossover after 2 weeks. Motor equivalence of the 2 modalities was confirmed utilizing part III of the Unified Parkinson's Disease Rating Scale (UPDRS). PD diaries and multiple subjective and objective evaluations of quality of life, depression, cognition and emotional processing were evaluated on both CV and on CC stimulation. Analysis using the paired t test with Bonferroni correction for multiple comparisons was performed to identify any significant difference between the stimulation modalities. Results: 8 patients were recruited (6 men, 2 women); 1 patient did not complete the study. The average age at surgery was 56.7 years (range 47-63). Disease duration at the time of surgery was 7.5 years (range 3-12). Patients were recruited 23.8 months (range 22.5-24) after surgery. At the postoperative study baseline, this patient group showed an average motor improvement of 69% (range 51-97) as measured by the change in UPDRS part III with stimulation alone. Levodopa equivalent medication was reduced on average by 67% (range 15-88). Patients were poorly compliant with PD diaries, and these did not yield useful information. The minor deterioration in quality-of-life scores (Parkinson's Disease Questionnaire-39, Quality of Life Enjoyment and Satisfaction Questionnaire) with CC stimulation were not statistically significant. Two measures of depression (Hamilton Rating Scale D17, Quick Inventory of Depressive Symptomatology - Self-Report) showed a nonsignificant lower score (less depression) with CC stimulation, but a third (Beck Depression Inventory) showed equivalence. Cognitive testing (Mini Mental State Examination) and emotional processing (Montreal Affective Voices) were equivalent for CC and CV. Conclusion: CC STN DBS is safe. For equivalent motor efficacy, no significant difference could be identified between CC and CV stimulation for nonmotor evaluations in PD patients 2 years after surgery.

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Longitudinal Impedance Variability in Patients with Chronically Implanted DBS Devices

Cited by 58 publications

References 19 publications

Long-term evaluation of impedance levels and clinical development in subthalamic deep brain stimulation for Parkinson's disease

Long-term evaluation of impedance levels and clinical development in subthalamic deep brain stimulation for Parkinson's disease

Long-Term Surface Electrode Impedance Recordings Associated with Gliosis for a Closed-Loop Neurostimulation Device

Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease

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