1594 BLADDER OVERACTIVITY SUPPRESSED BY ELECTRICAL STIMULATION OF THE FOOT

1594 BLADDER OVERACTIVITY SUPPRESSED BY ELECTRICAL STIMULATION OF THE FOOT

e616 THE JOURNAL OF UROLOGY姞 spinal level was abolished. Taken together, glutamatergic pathways play a crucial role at the spinal level in the activ...

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e616

THE JOURNAL OF UROLOGY姞

spinal level was abolished. Taken together, glutamatergic pathways play a crucial role at the spinal level in the active urethral closure mechanism during sneezing. Source of Funding: None

1593 THE ROLE OF OPIATE RECEPTORS IN THE INHIBITORY PUDENDAL-TO-BLADDER REFLEX IN CATS Mang Chen*, Bing Shen, Jicheng Wang, Hailong Liu, James Roppolo, William de Groat, Changfeng Tai, Pittsburgh, PA INTRODUCTION AND OBJECTIVES: The inhibitory pudendalto-bladder reflex that promotes bladder storage is likely mediated by the inhibitory neurotransmitters glycine, GABA (gamma-aminobutyric acid), and enkephalins (i.e. opioids). To determine the role of opioids in the inhibitory pudendal-to-bladder reflex, the influence of naloxone (an opioid receptor antagonist) on pudendal nerve-mediated inhibition of bladder activity was investigated. METHODS: Spinal intact female cats (N⫽10) anesthetized with alpha-chloralose underwent unilateral pudendal nerve stimulation (PNS) via cuff electrodes at various frequencies (0.5-40 Hz) and intensities (0.5-10 V). Bladder capacity was determined by cystometrograms (CMGs). Under isovolumetric conditions, the optimal PNS frequencies for inhibiting rhythmic bladder activity were identified in every cat and subsequently tested during CMGs (infusion rate 0.5-4 ml/min) to inhibit the micturition reflex and increase bladder capacity. Naloxone was then intravenously administered at incremental doses (0.01-1 mg/kg) followed by PNS during isovolumetric bladder contractions. After the maximal dose (1 mg/kg), PNS was tested again during CMGs. RESULTS: Five Hz to 10 Hz PNS at threshold intensity (T) completely inhibited isovolumetric bladder contractions. Naloxone (0.03-1 mg/kg) nullified this inhibitory effect. However, naloxone did not alter the inhibition elicited by PNS at higher intensities (1.5-3 T), nor did it alter the frequency dependence of inhibitory PNS. During CMGs, PNS increased bladder capacity to 163.4 ⫾ 10.0% of control capacity. After administration of naloxone (1 mg/kg), bladder capacity was not significantly different from control capacity when PNS was applied during CMG. However, naloxone alone markedly reduced bladder capacity to 43.0 ⫾ 11.1% of control, and PNS completely reversed this excitatory effect. In some experiments, naloxone induced transient (5-15 min) increases in isovolumetric bladder activity; but on average, it did not produce a long-lasting significant change. CONCLUSIONS: Activation of opioid receptors contributes to or facilitates the pudendal-to-bladder inhibitory reflex. Understanding the neurotransmitter mechanisms involved in the control of bladder activity by somatic afferent pathways could promote the development of new treatments for bladder overactivity and incontinence that combine pharmacotherapy and neuromodulation. Source of Funding: NIH grants DK-068566, DK-077783, and the Christopher and Dana Reeve Foundation

1594 BLADDER OVERACTIVITY SUPPRESSED BY ELECTRICAL STIMULATION OF THE FOOT Mang Chen*, Bing Shen, Jicheng Wang, Hailong Liu, James Roppolo, William de Groat, Changfeng Tai, Pittsburgh, PA INTRODUCTION AND OBJECTIVES: Sacral or tibial nerve neuromodulation can suppress medically refractory detrusor overactivity. However, they require either surgery to implant a stimulator (InterStim®, Meditronic Inc) or repeated clinic visits for treatment using a percutaneously inserted needle electrode (Urgent PC®, Uroplasty Inc). The purpose of this study is to investigate a non-invasive method of suppressing bladder overactivity via electrical activation of somatic afferent nerves in the foot. METHODS: Spinal intact cats anesthetized with alpha-chloralose underwent unilateral foot stimulation at either low (5Hz) or high

Vol. 183, No. 4, Supplement, Tuesday, June 1, 2010

(20Hz) frequencies with surface pad electrodes attached to the skin of the fore foot or hind foot. Saline infusion cystometrograms (CMGs) performed with a urethral catheter determined bladder capacities during both control (no stimulation) and stimulation periods. Acetic acid (AA) was then intravesically administered to induce bladder overactivity. Foot stimulation was also tested during AA infusion CMGs. RESULTS: Reflex micturition was inhibited by electrical stimulation of the hind foot at either low (5 Hz) or high (20 Hz) frequencies, but stimulation of the fore foot was not effective. On average, bladder capacity significantly (P⬍0.05) increased to 153.2 ⫾ 18.2% and 136.9 ⫾ 14.3% of the control capacity with stimulation at frequencies of 5 Hz and 20 Hz, respectively. Intravesical infusion of 0.25% AA reduced bladder capacity to 20.3 ⫾ 8.9% of the control capacity. Foot stimulation inhibited the AA-induced bladder overactivity and significantly (P⬍0.05) increased bladder capacity. However, it only restored bladder capacity to about 40-50% of the control capacity measured during saline infusion. The effects of foot stimulation did not persist beyond the stimulation period. CONCLUSIONS: This pre-clinical study demonstrated that stimulation of somatic afferent nerves in the foot can suppress bladder overactivity. This offers patients a potential non-invasive neuromodulatory alternative that can be self-administered for treatment of their overactive bladder symptoms. Source of Funding: NIH under grants DK-068566, DK077783, and by the Christopher and Dana Reeve Foundation

1595 “TWO-STAGE-IMPLANTATION” VS. “CONVENTIONAL” PERIPHERAL NERVE EVALUATION - COMPARISON OF RESPONSE RATES IN SACRAL NERVE STIMULATION Andreas Bannowsky*, Osnabru¨ck, Germany; Shuji Sugimoto, Tokyo, Japan; Georg Bo¨hler, Kiel, Germany; Raina van Ahlen, Hermann van Ahlen, Osnabru¨ck, Germany; Klaus-Peter Ju¨nemann, Kiel, Germany INTRODUCTION AND OBJECTIVES: Prior to implantation of a chronical sacral neurostimulator, it is important to establish which patients might profit from this kind of therapy in order to ensure, by means of a PNE (peripheral nerve evaluation) test, that the implantation of a permanent stimulating device is effective. In a retrospective study we compared the two different techniques used in our department (implantation of the permanent neurostimulation electrodes socalled ‘two-stage-implantation‘ vs. conventional PNE). METHODS: We performed a sacral nerve stimulation in 53 patients (mean age: 49.7 yrs (14-75 yrs); 31 with neurogenic or ideopathic urinary retention, 13 with a hyperactive detrusor and 9 with sensory urge or pelvic pain) over a minimum of 5 days. In 42 patients we performed a conventional PNE, 11 patients received ‘two-stageimplantation‘ with implantation of the permanent electrodes. RESULTS: 52 of 53 patients received bilateral test stimulation (9% at S2, 91% at S3). One patient underwent unilateral PNE (S3) because of anatomical deformity of the os sacrum. In 20 cases the conventional PNE-test (cPNE) was successful according to standard criteria (47.6% of all cPNE). 12 of these patients suffered from a neurogenic bladder dysfunction, in 8 cases the causes were idiopathic; 9 patients suffered from retention, 7 from overactive bladder symptoms and 4 patients from sensory urge or pelvic pain. The response rate of ‘two-stage-implantation‘ with implantation of the permanent electrodes was 81.8% (9 of 11 patients). 7 patients with neurogenic and 2 with idiopathic bladder dysfunction; 3 patients suffered from retention, 4 from overactive bladder symptoms and 2 patients from sensory urge. CONCLUSIONS: Success rate of implantation of permanent neurostimulation electrodes in selecting patients for the permanent implant is significantly higher than the conventional PNE. In this group patients with neurogenic and overactive bladder dysfunctions showed the highest response rates to sacral nerve stimulation and are the most likely to benefit from sacral neuromodulation. Source of Funding: None