Sierra Farris

Deep brain stimulation hardware complications: The role of electrode impedance and current measurements

Deep brain stimulation (DBS) is an effective therapy for advanced Parkinsons disease patients. Successful DBS outcomes depend on appropriate patient selection, surgical placement of the lead, intact hardware systems, optimal programming, and medical management. Despite its importance, there is little guidance in reference to hardware monitoring, hardware troubleshooting, and patient management. Technical manuals produced by the hardware manufacturer (Medtronic, Minneapolis, MN) are not presented in an applied clinical format, making impedance and current measurements difficult to interpret when the results are not straightforward. We present four patients with evolving DBS hardware complications that occurred during long‐term follow‐up, that shaped our clinical protocol for long‐term care management and hardware troubleshooting.

Deep brain stimulation hardware complications

Deep brain stimulation (DBS) is an effective therapy for advanced Parkinsons disease patients. Successful DBS outcomes depend on appropriate patient selection, surgical placement of the lead, intact hardware systems, optimal programming, and medical management. Despite its importance, there is little guidance in reference to hardware monitoring, hardware troubleshooting, and patient management. Technical manuals produced by the hardware manufacturer (Medtronic, Minneapolis, MN) are not presented in an applied clinical format, making impedance and current measurements difficult to interpret when the results are not straightforward. We present four patients with evolving DBS hardware complications that occurred during long‐term follow‐up, that shaped our clinical protocol for long‐term care management and hardware troubleshooting.

Psychosis from subthalamic nucleus deep brain stimulator lesion effect

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) in particular is highly effective in relieving symptoms of Parkinsons disease (PD). However, it can also have marked psychiatric side effects, including delirium, mania, and psychosis. The etiologies of those effects are not well-understood, and both surgeons and consulting psychiatrists are in need of treatment strategies. Case Description: Two patients with young onset of PD and without significant prior psychiatric problems presented for bilateral STN DBS when medications became ineffective. Both had uneventful operative courses but developed florid psychosis 1-2 weeks later, before stimulator activation. Neither showed signs of delirium, but both required hospitalization, and one required treatment with a first-generation antipsychotic drug. Use of that drug did not worsen PD symptoms, contrary to usual expectations. Conclusion: These cases describe a previously unreported post-DBS syndrome in which local tissue reaction to lead implantation produces psychosis even without electrical stimulation of subcortical circuits. The lesion effect also appears to have anti-Parkinsonian effects that may allow the safe use of otherwise contraindicated medications. These cases have implications for management of PD DBS patients postoperatively, and may also be relevant as DBS is further used in other brain regions to treat behavioral disorders.

Retrospective review of factors leading to dissatisfaction with subthalamic nucleus deep brain stimulation during long-term management.

Background: Subthalamic nucleus deep brain stimulation is effective in reducing motor symptoms in appropriately selected patients with Parkinsons disease. We identified factors that contribute to poor outcomes during early, middle and late stages of stimulation management in a series of patients that were referred for troubleshooting poor outcomes. Methods: We performed a retrospective review of 50 patients with bilateral STN DBS seen in our movement disorders clinic with unsatisfactory clinical response and/or patient dissatisfaction with deep brain stimulation outcome. All patients underwent a systematic evaluation to assess the primary cause of suboptimal outcome including lead position, hardware integrity, patient selection, patient expectations, effective use of stimulation settings, and pre- and postoperative levodopa responsive symptoms. The data was also analyzed by duration of stimulation to determine if these factors varied by stage of DBS management. Results: Our series included patients implanted 4-68 months. We identified the following primary factors impacting outcome: Suboptimal stimulation settings (52%), disease progression (16%), inappropriate patient selection (10%), hardware damage (8%), lead malposition (8%), met expected motor outcomes (6%). Lead revision surgery occurred in 14%. Reversible factors accounted for dissatisfaction in 74%. Suboptimal stimulation was the dominant factor affecting outcomes in early and long-term management phases. Conclusion: STN DBS outcomes can be improved even years after implantation. Stimulation parameters warrant investigation throughout the continuum of DBS management as a reversible cause of poor outcomes.

Model-Based Deep Brain Stimulation Programming for Parkinson's Disease: The GUIDE Pilot Study

Background: Achieving optimal results following deep brain stimulation (DBS) typically involves several months of programming sessions. The Graphical User Interface for DBS Evaluation (GUIDE) study explored whether a visual programming system could help clinicians accurately predetermine ideal stimulation settings in DBS patients with Parkinsons disease. Methods: A multicenter prospective, observational study was designed that utilized a blinded Unified Parkinsons Disease Rating Scale (UPDRS)-III examination to prospectively assess whether DBS settings derived using a neuroanatomically based computer model (Model) could provide comparable efficacy to those determined through traditional, monopolar review-based programming (Clinical). We retrospectively compared the neuroanatomical regions of stimulation, power consumption and time spent on programming using both methods. Results: The average improvement in UPDRS-III scores was 10.4 ± 7.8 for the Model settings and 11.7 ± 8.7 for the Clinical settings. The difference between the mean UPDRS-III scores with the Model versus the Clinical settings was 0.26 and not statistically significant (p = 0.9866). Power consumption for the Model settings was 48.7 ± 22 μW versus 76.1 ± 46.5 μW for the Clinical settings. The mean time spent programming using the Model approach was 31 ± 16 s versus 41.4 ± 29.1 min using the Clinical approach. Conclusion: The Model-based DBS settings provided similar benefit to the Clinical settings based on UPDRS-III scores and were often arrived at in less time and required less power than the Clinical settings.

Deep Brain Stimulation and the Ethics of Protection and Caring for the Patient with Parkinson's Dementia

Deep brain stimulation (DBS) is an effective neurosurgical treatment for patients with advanced Parkinsons disease (PD) suffering from motor complications that are refractory to further medication management. DBS requires an invasive procedure of implanting brain electrodes while awake, followed by implantation of neurostimulators under general anesthesia. The neurostimulator requires battery monitoring and replacement approximately every 3 to 5 years. These two elements of the technology provide numerous decision points about continuing therapies that can involve ethical choices. Although motor function can be improved with subthalamic nucleus (STN) DBS, the long‐term risks of living with implanted hardware should be carefully evaluated for patients with diminishing cognitive capacity. We describe two cases where ethical dilemmas occurred postoperatively as a result of cognitive decline and describe salient ethical dimensions that illustrate the need for a proactive postoperative plan for supervision as a prerequisite for surgery to include neuropsychological testing to predict the likelihood of net benefit to the patient and family beyond just motor improvement.

Deep brain stimulation: a review of the procedure and the complications.

&NA; This procedure is no longer experimental, and more conditions are being considered for DBS treatment. Pas should be prepared to care for patients with these implanted devices.

Lead Wire Fracture Associated With Normal Therapeutic Impedance Measurements in a Patient With a Kinetra Neurostimulator

Objectives. We present a case report of a patient with complete lead wire fracture with approximately 3‐mm separation of the wire fragments that had three electrode impedance measurements and therapy impedance measurement that would be consistent with an intact wire. Materials and Methods. Retrospective chart review. Results. The patient experienced abrupt worsening of gait freezing while tremor control remained stable. Despite normal therapeutic impedance measurement, clinical suspicion for a hardware problem remained due to her description of brief dystonic hand posturing witnessed during impedance measurements in the clinic. This led to further diagnostic evaluation and eventual surgical replacement of the lead wire. Conclusions. Impedance measurements are not absolutely reliable for the detection of hardware malfunction in a patient with a Kinetra neurostimulator.

Long-Term Task- and Dopamine-Dependent Dynamics of Subthalamic Local Field Potentials in Parkinson’s Disease

Subthalamic nucleus (STN) local field potentials (LFP) are neural signals that have been shown to reveal motor and language behavior, as well as pathological parkinsonian states. We use a research-grade implantable neurostimulator (INS) with data collection capabilities to record STN-LFP outside the operating room to determine the reliability of the signals over time and assess their dynamics with respect to behavior and dopaminergic medication. Seven subjects were implanted with the recording augmented deep brain stimulation (DBS) system, and bilateral STN-LFP recordings were collected in the clinic over twelve months. Subjects were cued to perform voluntary motor and language behaviors in on and off medication states. The STN-LFP recorded with the INS demonstrated behavior-modulated desynchronization of beta frequency (13–30 Hz) and synchronization of low gamma frequency (35–70 Hz) oscillations. Dopaminergic medication did not diminish the relative beta frequency oscillatory desynchronization with movement. However, movement-related gamma frequency oscillatory synchronization was only observed in the medication on state. We observed significant inter-subject variability, but observed consistent STN-LFP activity across recording systems and over a one-year period for each subject. These findings demonstrate that an INS system can provide robust STN-LFP recordings in ambulatory patients, allowing for these signals to be recorded in settings that better represent natural environments in which patients are in a variety of medication states.

Treating Parkinsonʼs Disease: The Impact of Different Care Models on Quality of Life

Parkinsons disease is a progressive neurologic disorder that impacts critical domains of daily living. Movement, autonomic, cognitive, and behavioral problems can significantly impair quality of life. In addition, medical treatment is complex and its progressive course requires long-term care. Given this, it represents a model disease to study with reference to healthcare strategies aimed at improving quality of life for chronic debilitating illness in our aging society. This article will examine the evolution of care for PD, beginning with the medical model, followed by a rehabilitation model. Finally, a patient-centered approach is presented that explores concepts of wellness in the setting of illness, and individualizes personal management rather than primary symptom treatment. This divergence from disease-centered to patient-centered care allows this approach to be generalized to the care needs of societys aging population that live with functional disability or chronic illness.