Abstract
(1) Aims: To test a newly designed helical-wire hook electrode implanted in the bladder wall to induce contraction and promote voiding. (2) Methods: In three minipigs with a created lesion of the sacral spinal cord, four electrodes were implanted in the bladder wall, ventral to the trigone. Stimulation tests were conducted initially in conscious pigs, and later after general anesthesia. (3) Results: Electrical stimulation in the conscious animals on postoperative days 4 and 7 at 40 Hz was limited to 10 mA, because of abdominal, leg, and anal contractions with animal discomfort; bladder contractions were not induced. Electrical stimulation on postoperative days 9 and 28 at 60 mA under anesthesia induced sustained vesical wall contractions with bladder pressure variations, but without voiding. Simultaneous abdominal contractions occurred, with strong leg and anal contractions. Subsequent stimulation with a single set of electrodes or at 20 Hz induced less vesical pressure response. At autopsy, the electrodes had not migrated, and extraction forces were high, at 7.9 ± 0.9 Newtons (n = 12). (4) Conclusions: Our 28-day study has confirmed the utility of the new electrode design, preventing migration from the bladder wall and making it suitable for long-term electrode implants.
Highlights
The use of catheters for neurogenic bladder management is a source of significant morbidity, so different alternatives such as neuroprosthetic devices using electrical stimulation were developed and put into clinical use [1,2,3,4]
More recent studies were published by Merrill (1975) and by Jonas and Hohenfellner (1978), using the MentorTM bladder stimulator in patients with “urinary vesical hypotonia”, with a few good long-term results [12,13]
The primary limitation encountered in the current protocol was animal discomfort and aversive skeletal muscle contractions at levels of stimulating currents which were lower than necessary for inducing vesical wall contractions
Summary
The use of catheters for neurogenic bladder management is a source of significant morbidity, so different alternatives such as neuroprosthetic devices using electrical stimulation were developed and put into clinical use [1,2,3,4]. For complete suprasacral spinal cord lesions, the Brindley sacral anterior root stimulator is commercially available [5]. For complete sacral cord lesions resulting in a decentralized bladder and sphincter (“second neuron damage”), direct bladder wall stimulation (DBWS) is still in development, as post-ganglionic nerves located in the bladder wall (intramural nerve network) are viable. The most recent clinical studies were conducted by Magasi and Simon (1986) [14]. They concluded that the best location for electrode implantation was ventral to the ureters and trigone area, which was in line with prior results [14]
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