Five-Year Followup Results of a Prospective, Multicenter Study of Patients with Overactive Bladder Treated with Sacral Neuromodulation

PURPOSE

We evaluated the therapeutic success rate, changes in quality of life and safety of sacral neuromodulation 5 years after InterStim™ implantation. Included in study were subjects with bothersome symptoms of overactive bladder, including urinary urge incontinence and/or urgency-frequency, in whom at least 1 anticholinergic medication failed and 1 medication had not been tried.

MATERIALS AND METHODS

Therapeutic success was defined as a urinary urge incontinence or urgency-frequency response of 50% or greater improvement in average leaks or voids per day, or return to normal voiding, defined as fewer than 8 voids per day. Quality of life was evaluated by ICIQ-OABqol (International Consultation on Incontinence Modular Questionnaire). Safety was evaluated through adverse events.

RESULTS

Of the 340 subjects who completed the test stimulation 272 had an implant, of whom 91% were female. Mean age was 57 years. At baseline 202 subjects with urinary urge incontinence had a mean ± SD of 3.1 ± 2.7 leaks per day and 189 with urgency-frequency had a mean of 12.6 ± 4.5 voids per day. The 5-year therapeutic success rate was 67% (95% CI 60-74) using modified completers analysis and 82% (95% CI 76-88) using completers analysis. Subjects with urinary urge incontinence had a mean reduction from baseline of 2.0 ± 2.2 leaks per day and subjects with urgency-frequency had a mean reduction of 5.4 ± 4.3 voids per day (each completers analysis p <0.0001). Subjects showed improvement in all ICIQ-OABqol measures (p <0.0001). The most common device related adverse events were an undesirable change in stimulation in 60 of the 272 subjects (22%), implant site pain in 40 (15%) and therapeutic product ineffectiveness in 36 (13%).

CONCLUSIONS

This multicenter study shows that sacral neuromodulation had sustained efficacy and quality of life improvements, and an acceptable safety profile through 5 years in subjects with overactive bladder.

Contribution of the external urethral sphincter to urinary void size in unanesthetized unrestrained rats

AIMS

In anesthetized rats, voiding is typically associated with phasic activation (bursting) of the external urethral sphincter (EUS). During spontaneous voiding in unanesthetized, unrestrained rats, EUS bursting is the most common form of EUS activity exhibited, but it is not necessary for productive voiding to occur. The aim of the present study was to determine which aspects of EUS activity contributed to void size during bursting and non-bursting voiding in conscious, freely moving rats.

METHODS

Female rats were implanted with electrodes adjacent to the EUS for recording electromyographic activity (EMG). EUS EMG recordings were performed during 24-hr sessions in a metabolic cage while voided urine was continuously collected and weighed.

RESULTS

Void size was positively correlated with the duration of the intra-burst silent and active periods and variables reflecting the overall intensity and duration of bursting, particularly at lower frequencies within the 3-10 Hz range of EUS bursting. In addition, void size was inversely related to the frequency of bursting and to the average EMG amplitude during voiding, both in voids with and without bursting.

CONCLUSIONS

EUS bursting contributes to productive voiding when bursting is present. Lower bursting frequencies elicit more productive voiding than do higher frequencies. In the absence of bursting, the association of increased void size with smaller average EUS EMG amplitude suggests that conscious rats can perform synergic voiding (i.e., bladder contraction with EUS relaxation) that is comparable to that seen in humans and other typically non-bursting species. Neurourol. Urodynam. 35:696-702, 2016. © 2015 Wiley Periodicals, Inc.

Safety and efficacy of explanting or replacing suprachoroidal electrode arrays in a feline model

BACKGROUND

A key requirement for retinal prostheses is the ability for safe removal or replacement. We examined whether suprachoroidal electrode arrays can be removed or replaced after implantation.

METHODS

Suprachoroidal electrode arrays were unilaterally implanted into 13 adult felines. After 1 month, arrays were surgically explanted (n = 6), replaced (n = 5) or undisturbed (n = 2). The retina was assessed periodically using fundus photography and optical coherence tomography. Three months after the initial implantation, the function of replaced or undisturbed arrays was assessed by measuring the responses of the visual cortex to retinal electrical stimulation. The histopathology of tissues surrounding the implant was examined.

RESULTS

Array explantation or replacement was successful in all cases. Fundus photography showed localized disruption to the tapetum lucidum near the implant's tip in seven subjects following implantation. Although optical coherence tomography showed localized retinal changes, there were no widespread statistically significant differences in the thickness of the retinal layers or choroid. The distance between the electrodes and retina increased after device replacement but returned to control values within eight weeks (P < 0.03). Staphylomas developed near the scleral wound in five animals after device explantation. Device replacement did not alter the cortical evoked potential threshold. Histopathology showed localized outer nuclear layer thinning, tapetal disruption and pseudo-rosette formation, but the overall retinal morphology was preserved.

CONCLUSIONS

It is feasible to remove or replace conformable medical grade silicone electrode arrays implanted suprachoroidally. The scleral wound requires careful closure to minimize the risk of staphylomas.

Optimizing the neuron-electrode interface for chronic bioelectronic interfacing

Engineering approaches have vast potential to improve the treatment of disease. Brain-machine interfaces have become a well-established means of treating some otherwise medically refractory neurological diseases, and they have shown promise in many more areas. More widespread use of implanted stimulating and recording electrodes for long-term intervention is, however, limited by the difficulty in maintaining a stable interface between implanted electrodes and the local tissue for reliable recording and stimulation.This loss of performance at the neuron-electrode interface is due to a combination of inflammation and glial scar formation in response to the implanted material, as well as electrical factors contributing to a reduction in function over time. An increasing understanding of the factors at play at the neural interface has led to greater focus on the optimization of this neuron-electrode interface in order to maintain long-term implant viability.A wide variety of approaches to improving device interfacing have emerged, targeting the mechanical, electrical, and biological interactions between implanted electrodes and the neural tissue. These approaches are aimed at reducing the initial trauma and long-term tissue reaction through device coatings, optimization of mechanical characteristics for maximal biocompatibility, and implantation techniques. Improved electrode features, optimized stimulation parameters, and novel electrode materials further aim to stabilize the electrical interface, while the integration of biological interventions to reduce inflammation and improve tissue integration has also shown promise.Optimization of the neuron-electrode interface allows the use of long-term, high-resolution stimulation and recording, opening the door to responsive closed-loop systems with highly selective modulation. These new approaches and technologies offer a broad range of options for neural interfacing, representing the possibility of developing specific implant technologies tailor-made to a given task, allowing truly personalized, optimized implant technology for chronic neural interfacing.

Treprostinil in the treatment of pulmonary arterial hypertension

Despite progress over the past 30 years, pulmonary arterial hypertension remains a condition with high morbidity and mortality. Pharmacological and technological advances have shifted the approach to treating pulmonary arterial hypertension. Recent developments revolve heavily around novel routes of drug administration and delivery. In 2009, inhaled treprostinil was approved followed by oral treprostinil in 2013 providing patients with more convenient routes of administration compared with the parenteral alternatives. We are on the cusp of having the first fully implantable infusion pump for continuous intravenous treprostinil delivery. In 2019, generic treprostinil was approved, making the medication much more affordable for patients. In this review, we discuss in detail the recent developments surrounding both traditional and novel treprostinil products.

Environmentally-controlled microtensile testing of mechanically-adaptive polymer nanocomposites for ex vivo characterization

Implantable microdevices are gaining significant attention for several biomedical applications. Such devices have been made from a range of materials, each offering its own advantages and shortcomings. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control. To this end, a custom microtensile tester was designed to accommodate microscale samples with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation. The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Methodological Recommendations for Studies on the Daily Life Implementation of Implantable Communication-Brain-Computer Interfaces for Individuals With Locked-in Syndrome

Implantable brain-computer interfaces (BCIs) promise to be a viable means to restore communication in individuals with locked-in syndrome (LIS). In 2016, we presented the world-first fully implantable BCI system that uses subdural electrocorticography electrodes to record brain signals and a subcutaneous amplifier to transmit the signals to the outside world, and that enabled an individual with LIS to communicate via a tablet computer by selecting icons in spelling software. For future clinical implementation of implantable communication-BCIs, however, much work is still needed, for example, to validate these systems in daily life settings with more participants, and to improve the speed of communication. We believe the design and execution of future studies on these and other topics may benefit from the experience we have gained. Therefore, based on relevant literature and our own experiences, we here provide an overview of procedures, as well as recommendations, for recruitment, screening, inclusion, imaging, hospital admission, implantation, training, and support of participants with LIS, for studies on daily life implementation of implantable communication-BCIs. With this article, we not only aim to inform the BCI community about important topics of concern, but also hope to contribute to improved methodological standardization of implantable BCI research.

The implantable peritoneal pump--a patient's perspective

A participant in a study of implantable insulin pump therapy recounts his experiences with on-and-off use of the pump over the past 18 years. Christopher Witkowski, 55, first had a pump implanted in 1990. Despite occasional difficulties over the years, Witkowski reports that his overall experience has been extremely positive. With delivery of insulin directly into the peritoneal cavity, he feels better, has more flexibility in eating, and experiences fewer insulin reactions. Witkowski expresses disappointment that the manufacturer of the pump, Medtronic, no longer plans to seek Food and Drug Administration approval for this therapy. Witkowski expresses his hope that research on the device will continue, believing that this therapy could be of benefit to millions of diabetes patients. This article is accompanied by a detailed description of the pump refill procedure by Dr. Christopher Saudek of Johns Hopkins University, current leader of the ongoing research study.

A review of the management of implanted medical devices for diabetes: trends and directions

The management of diabetes is progressing rapidly from the use of traditional finger sticks for glucose monitoring and multiple daily injections of insulin to more user-friendly devices and approaches. These advances hold the promise of freeing persons with diabetes from the need for continued daily compliance, thereby improving their quality of life and improving control of their underlying diabetes. An underlying theme to solutions based on percutaneous or fully implanted devices is that the useful lifetime of such devices is often limited by the body's foreign body response. This review briefly outlines general factors associated with point-in-time needle stick approaches to the growing use of short-term percutaneous implants (< or =7 days) to the challenges of more extended devices, both technical and regulatory, faced by developers of these devices.

Do Patients Discontinue Overactive Bladder Medications after Sacral Neuromodulation?

PURPOSE

Overactive bladder medications often have poor tolerability or lack of efficacy with many patients progressing to third line therapy such as sacral neuromodulation. Those treated with sacral neuromodulation may avoid the potential side effects of overactive bladder medications while achieving symptom improvement. We evaluated the postoperative rate of discontinuing overactive bladder medications in patients who underwent sacral neuromodulation of refractory overactive bladder.

MATERIALS AND METHODS

We queried a prospectively collected, institutional review board approved database for patients who underwent sacral neuromodulation. Patients were excluded from analysis if the surgical indication was urinary retention or a sacral neuromodulation device was removed 1 year or less postoperatively. We assessed clinical characteristics, urodynamic parameters and filled overactive bladder medications using an external prescription database. Patient perceived postoperative outcomes were examined. Groups were compared by the Student t-test and the chi-square test.

RESULTS

Of the 78 patients who met inclusion criteria 82.1% stopped and never restarted overactive bladder medications (the sacral neuromodulation only group). Of the patients 14.1% consecutively continued filling overactive bladder medications 1 year or more following surgery (the concurrent group). There was no difference between the groups in body mass index, gender, sacral neuromodulation revision, urodynamic parameters, the PGI-I (Patient Global Impression of Improvement) or patient perceived percent improvement. However, concurrent patients were significantly older than those who received sacral neuromodulation only (p = 0.002).

CONCLUSIONS

More than 80% of patients who progressed to sacral neuromodulation discontinued overactive bladder medications and received sacral neuromodulation as the sole treatment. A small portion of patients concurrently used overactive bladder medications following sacral neuromodulation for 1 year or more. However, outcomes were similar in the 2 groups. Sacral neuromodulation is a strategy to provide a successful outcome in refractory cases and yet avoid the potentially detrimental side effects related to overactive bladder medications.

Acute pericarditis with cardiac tamponade induced by pacemaker implantation

An 87-year-old woman was diagnosed with third-degree atrioventricular block and underwent pacemaker implantation. On postoperative day 12, she experienced cardiac tamponade that was suspected on computed tomography to be caused by lead perforation; therefore, we performed open-heart surgery. However, we could not identify a perforation site on the heart, and drained a 400-mL exudative pericardial effusion. Subsequently, we diagnosed the pericardial effusion as due to pericarditis induced by pacemaker implantation. It is sometimes difficult to distinguish pericarditis from pacemaker lead perforation, so both should be included in the differential diagnosis.

Functional Electrical Stimulation of the Feline Larynx With a Flexible Ribbon Electrode Array

OBJECTIVES

Success of laryngeal reanimation through neurorrhaphy has been limited by synkinesis and preoperative muscle atrophy. The objective of this study was to investigate the use of epimysial electrode arrays as a means of delivering electrical stimulation to the posterior cricoarytenoid muscles in order to control laryngeal abduction.

METHODS

Ribbon electrode arrays with 4 or 8 electrode contacts were used. Four cats underwent implantation of electrode arrays along the surface of the posterior cricoarytenoid muscles. The glottis was visualized with a 0° telescope while electrodes were stimulated at different amplitudes and pulse-width durations. Recordings of stimulated vocal folds were analyzed, and the degree of vocal fold abduction was measured in order to create recruitment curves for the left and right posterior cricoarytenoid. Recruitment curves from electrode channels within the array were compared.

RESULTS

Electrodes oriented along the medial aspect of the posterior cricoarytenoid stimulated graded physiologic degrees of abduction depending on the amplitude of stimulation. Electrodes oriented laterally along the posterior cricoarytenoid stimulated greater degrees of simultaneous adduction with abduction.

CONCLUSION

Acute studies of ribbon surface electrode arrays placed onto the posterior cricoarytenoid reproduce graded degrees of abduction necessary for the precise function of respiration and speech.

Coronary Venous Lead Extraction

The increasing number of cardiac resynchronization therapy devices implanted, coupled with the increasing incidence of cardiac implantable electronic device infection, has led to a greater need for extraction of coronary venous pacing leads. The objectives of this study were to review the indications, techniques and published results of coronary venous lead extraction. In this study, we searched PubMed using the search terms "lead extraction," "coronary sinus," "coronary venous," "pacing," and "cardiac resynchronization therapy" for relevant papers. The reference lists of relevant articles were also searched, and personal experience was drawn upon. Published success rates and complications were found to be similar to those reported for non-coronary venous leads in experienced centers. However, reimplantation success differs and can be limited by vessel occlusion postextraction. The available active fixation coronary sinus lead (Attain Starfix™; Medtronic, MN, USA) is a particularly complex lead to extract, whereas limited data on the newer active fixation leads (Attain Stability™, Medtronic, MN, USA) suggest that they are less challenging to remove. The study concluded that coronary venous lead extraction presents unique challenges, especially reimplantation, that require special consideration and planning to overcome.

Endovascular extraction techniques for pacemaker and ICD lead extraction: Part 1

In the last few years, comprehensive endovascular techniques have been developed to extract chronically implanted pacemaker and defibrillator leads. It is important that referring physician have knowledge of the advantages and limitations of the different techniques. In this paper we discuss the techniques and results of the currently used endovascular extraction techniques.

Endovascular extraction techniques: Part 2: Complications and indications

The use of lead extraction is expanding with the introduction of new endovascular extraction techniques. Indications for extraction of chronically implanted pacemaker leads have been classified as mandatory, necessary or discretionary, but their rationale is often based on clinical judgement without corresponding support from the literature. We reviewed the literature of pacemaker lead-related complications as a starting point for discussing the indications for lead extraction.