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Ultrasound-Guided Pudendal Nerve Block Combined with Propofol Deep Sedation versus Spinal Anesthesia for Hemorrhoidectomy: A Prospective Randomized Study. Pain Res Manag 2021; 2021:6644262. [PMID: 33727997 PMCID: PMC7935604 DOI: 10.1155/2021/6644262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/26/2021] [Accepted: 02/20/2021] [Indexed: 11/18/2022]
Abstract
Background and Objectives. Several anesthesia techniques were applied to hemorrhoidectomy, but postoperative pain and urinary retention were still two unsolved problems. The aim of this prospective randomized study was to evaluate the effect of ultrasound-guided pudendal nerve block (PNB) combined with deep sedation compared to spinal anesthesia for hemorrhoidectomy. Methods. One hundred and twenty patients undergoing Milligan-Morgan hemorrhoidectomy were randomized to receive PNB combined with deep sedation using propofol (Group PNB, n = 60) or spinal anesthesia (Group SA, n = 60). Pain intensity was assessed using the visual analogue scale (0: no pain to 10: worst possible pain). The primary outcome was pain scores recorded at rest at 3, 6, 12, 24, 36, and 48 h and on walking at 12, 24, 36, and 48 h postoperatively. Secondary outcomes were analgesic consumption, side effects, and patient satisfaction after surgery. Results. Ultrasound-guided bilateral PNB combined with deep sedation using propofol could successfully be applied to Milligan-Morgan hemorrhoidectomy. Postoperative pain intensity was significantly lower in Group PNB compared to Group SA at rest at 3, 6, 12, 24, 36, and 48 h (p < 0.001) and during mobilization at 12, 24, 36, and 48 h (p < 0.001) postoperatively. Sufentanil consumption in Group PNB was significantly lower than that in Group SA, during 0-24 h (p < 0.001) and during 24-48 h (p < 0.001) postoperatively. Urinary retention was significantly lower in Group PNB compared to Group SA (6.9% vs 20%, p=0.034). The patients in Group PNB had higher satisfaction compared to Group SA (p < 0.001). Conclusions. Ultrasound-guided PNB combined with propofol sedation is an effective anesthesia technique for Milligan-Morgan hemorrhoidectomy.
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Best KL, Ethans K, Craven BC, Noreau L, Hitzig SL. Identifying and classifying quality of life tools for neurogenic bladder function after spinal cord injury: A systematic review. J Spinal Cord Med 2017; 40:505-529. [PMID: 27734771 PMCID: PMC5815152 DOI: 10.1080/10790268.2016.1226700] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE To identify and classify quality of life (QoL) tools for assessing the influence of neurogenic bladder after spinal cord injury/disease (SCI). DESIGN Systematic Review Methods: Medline/Pubmed, CINAHL, and PsycInfo were searched using terms related to SCI, neurogenic bladder and QoL. Studies that assessed the influence neurogenic bladder on QoL (or related construct) in samples consisting of ≥50% individuals with SCI were included. Two independent reviewers screened titles and abstracts of 368 identified references; 118 full-text articles were assessed for eligibility, and 42 studies were included. Two reviewers independently classified outcomes as objective (societal viewpoint) or subjective (patient perspective) using a QoL framework. RESULTS Ten objective QoL measures were identified, with the Medical Outcomes Short Form (SF-36/SF-12) used most frequently. Fourteen subjective QoL measures were identified; 8 were specific to neurogenic bladder. Psychometric evidence for SCI-specific neurogenic bladder QoL tools was reported for the Quality of Life Index (QLI), Qualiveen, Bladder Complications Scale, Spinal Cord Injury-Quality of Life (SCI-QOL) Bladder Management Difficulties, and the SCI-QOL Bladder Management Difficulties-Short Form. The QLI and Qualiveen showed sensitivity to neurogenic bladder in experimental designs. CONCLUSION Several objective and subjective tools exist to assess the influence of neurogenic bladder on QoL in SCI. The QLI and Qualiveen, both subjective tools, were the only validated SCI-specific tools that showed sensitivity to neurogenic bladder. Further validation of existing subjective SCI-specific outcomes is needed. Research to validate objective measures of QoL would be useful for informing practice and policy related to resource allocation for bladder care post-SCI.
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Affiliation(s)
- Krista L. Best
- Department of Rehabilitation, Université Laval, Quebec City, QC, Canada,Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Institut de réadaptation en déficience physique de Québec, Quebec City, QC, Canada,Correspondence to: Krista L. Best, Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), 525 Blvd Hamel, Québec, QC, G1M 2S8, Canada.
| | - Karen Ethans
- University of Manitoba, Department of Medicine, Winnipeg, MB, Canada,Health Sciences Centre, Section of Physical Medicine and Rehabilitation, Winnipeg, MB, Canada
| | - B. Catharine Craven
- Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada,Department of Medicine, Division of Physical Medicine and Rehabilitation, University of Toronto, Toronto, ON, Canada
| | - Luc Noreau
- Department of Rehabilitation, Université Laval, Quebec City, QC, Canada,Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Institut de réadaptation en déficience physique de Québec, Quebec City, QC, Canada
| | - Sander L. Hitzig
- Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada,St-John's Rehab Research Program, Sunnybrook Research Institute, Toronto, ON, Canada,School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, ON, Canada
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Li JY, Liao R. Prevention of catheter-related bladder discomfort - pudendal nerve block with ropivacaine versus intravenous tramadol: study protocol for a randomized controlled trial. Trials 2016; 17:448. [PMID: 27618967 PMCID: PMC5020438 DOI: 10.1186/s13063-016-1575-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 08/25/2016] [Indexed: 02/05/2023] Open
Abstract
Background Catheter-related bladder discomfort (CRBD) is a common distressing symptom complex during the postoperative period, especially after urologic procedures with a relatively greater size urinary catheter. In this study, we will enroll male patients undergoing elective prostate surgery with urinary catheterization under general anesthesia, and we will compare the efficacy of pudendal nerve block (PNB) and intravenous tramadol in CRBD prevention. Methods/design This trial is a prospective, randomized controlled trial that will test the superiority of bilateral PNB with 0.33 % ropivacaine compared with intravenous tramadol 1.5 mg/kg for CRBD prevention. A total of 94 male patients undergoing elective prostate surgery with urinary catheterization after anesthesia induction will be randomized to receive either bilateral PNB with 0.33 % ropivacaine (the PNB group) or intravenous tramadol 1.5 mg/kg (the tramadol group) after the completion of surgery. The primary outcome is the incidence of CRBD. The most important secondary outcome is the severity of postoperative CRBD, and other secondary outcomes include Numeric Rating Scale (NRS) score for postoperative pain; incidence of postoperative side effects such as postoperative nausea/vomiting, sedation, dizziness, and dry mouth; postoperative requirement for tramadol as a rescue treatment for CRBD and sufentanil as a rescue analgesic for postoperative pain; and NRS score for acceptance of an indwelling urinary catheter. Discussion This trial is planned to test the superiority of PNB with 0.33 % ropivacaine compared with intravenous tramadol 1.5 mg/kg. It may provide a basis for a new clinical practice for the prevention of CRBD. Trial registration ClinicalTrials.gov identifier NCT02683070. Registered on 11 February 2016. Electronic supplementary material The online version of this article (doi:10.1186/s13063-016-1575-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jing-Yi Li
- Department of Dermatovenereology, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Ren Liao
- Department of Anesthesiology, West China Hospital of Sichuan University, 37 Guoxue Lane, Chengdu, 610041, Sichuan Province, People's Republic of China.
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Barbalat Y, Rutman M. Detrusor-External Sphincter Dyssynergia: Review of Minimally Invasive and Endoscopic Management. Urology 2016; 90:3-7. [PMID: 26826587 DOI: 10.1016/j.urology.2015.11.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/10/2015] [Accepted: 11/30/2015] [Indexed: 11/24/2022]
Abstract
Detrusor-external sphincter dyssynergia (DSD) is a debilitating problem in patients with spinal cord injury. DSD carries a high risk of complications, and even life expectancy can be affected. Management of this condition includes the use of antimuscarinic agents in combination with intermittent catheterization, indwelling urethral catheterization, suprapubic catheterization, and a variety of surgical options, depending on patient and physician preference. This paper will review the current literature and data on minimally invasive and endoscopic management of DSD.
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Affiliation(s)
| | - Matthew Rutman
- Department of Urology, Columbia University, New York, NY
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Utomo E, Groen J, Blok BFM. Surgical management of functional bladder outlet obstruction in adults with neurogenic bladder dysfunction. Cochrane Database Syst Rev 2014; 2014:CD004927. [PMID: 24859260 PMCID: PMC11162557 DOI: 10.1002/14651858.cd004927.pub4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The most common type of functional bladder outlet obstruction in patients with neurogenic bladder is detrusor-sphincter dyssynergia (DSD). The lack of co-ordination between the bladder and the external urethral sphincter muscle (EUS) in DSD can result in poor bladder emptying and high bladder pressures, which may eventually lead to progressive renal damage. OBJECTIVES To assess the effectiveness of different surgical therapies for the treatment of functional bladder outlet obstruction (i.e. DSD) in adults with neurogenic bladder dysfunction. SEARCH METHODS We searched the Cochrane Incontinence Group Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, and handsearching of journals and conference proceedings (searched 20 February 2014), and the reference lists of relevant articles. SELECTION CRITERIA Randomised controlled trials (RCTs) or quasi-RCTs comparing a surgical treatment of DSD in adults suffering from neurogenic bladder dysfunction, with no treatment, placebo, non-surgical treatment, or other surgical treatment, alone or in combination. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trial quality and extracted data. MAIN RESULTS We included five trials (total of 199 participants, average age of 40 years). The neurological diseases causing DSD were traumatic spinal cord injury (SCI), multiple sclerosis (MS), or congenital malformations.One trial compared placement of sphincteric stent prosthesis with sphincterotomy. For urodynamic measurements, results for postvoid residual urine volume (PVR) and cystometric bladder capacity were inconclusive and consistent with benefit of either sphincteric stent prosthesis or sphincterotomy at three, six, 12, and 24 months. Results for maximum detrusor pressure (Pdet.max) were also inconclusive at three, six, and 12 months; however, after two years, the Pdet.max after sphincterotomy was lower than after stent placement (mean difference (MD) -30 cmH2O, 95% confidence interval (CI) 8.99 to 51.01).Four trials considered botulinum A toxin (BTX-A) injection in the EUS, either alone or in combination with other treatments. The comparators included oral baclofen, oral alpha blocker, lidocaine, and placebo. The BTX-A trials all differed in protocols, and therefore we did not undertake meta-analysis. A single 100 units transperineal BTX-A injection (Botox®) in patients with MS resulted in higher voided urine volumes (MD 69 mL, 95% CI 11.87 to 126.13), lower pre-micturition detrusor pressure (MD -10 cmH2O, 95% CI -17.62 to -2.38), and lower Pdet.max (MD -14 cmH2O, 95% CI -25.32 to -2.68) after 30 days, compared to placebo injection. Results for PVR using catheterisation, basal detrusor pressure, maximal bladder capacity, maximal urinary flow, bladder compliance at functional bladder capacity, maximal urethral pressure, and closure urethral pressure at 30 days were inconclusive and consistent with benefit of either BTX-A injection or placebo injections. In participants with SCI, treatment with 200 units of Chinese manufactured BTX-A injected at eight different sites resulted in better bladder compliance (MD 7.5 mL/cmH2O, 95% CI -10.74 to -4.26) than participants who received the same injections with the addition of oral baclofen. Results for maximum uroflow rate, maximal cystometric capacity, and volume per voiding were inconclusive and consistent with benefit of either BTX-A injection or BTX-A injection with the addition of oral baclofen. However, the poor quality of reporting in this trial caused us to question the relevance of bladder compliance as an adequate outcome measure.In participants with DSD due to traumatic SCI, MS, or congenital malformation, the results for PVRs after one day were inconclusive and consistent with benefit of either a single 100 units transperineal BTX-A (Botox®) injection or lidocaine injection. However, after seven and 30 days of BTX-A injection, PVRs were lower (MD -163 and -158 mL, 95% CI -308.65 to -17.35 and 95% CI -277.57 to -39.03, respectively) compared to participants who received lidocaine injections. Results at one month for Pdet.max on voiding, EUS activity in electromyography, and maximal urethral pressure were inconclusive and consistent with benefit of either BTX-A or lidocaine injections.Finally, one small trial consisting of five men with SCI compared weekly BTX-A injections with normal saline as placebo. The placebo had no effect on DSD in the two participants allocated to the placebo treatment. Their urodynamic parameters were unchanged from baseline values until subsequent injections with BTX-A once a week for three weeks. These subsequent injections resulted in similar responses to those of the three participants who were allocated to the BTX-A treatment. Unfortunately, the report presented no data on placebo treatment.Only the trial that compared sphincterotomy with stent placement reported outcome measures renal function and urologic complications related to DSD. Results for renal function at 12 and 24 months, and urologic complications related to DSD at three, six, 12, and 24 months were inconclusive and consistent with benefit of either sphincteric stent prosthesis or sphincterotomy.Adverse effects reported were haematuria due to the cystoscopic injection and muscle weakness, of which the latter may be related to the BTX-A dose used.All trials had some methodological shortcomings, so insufficient information was available to permit judgement of risk of bias. At least half of the trials had an unclear risk of selection bias and reporting bias. One trial had a high risk of attrition bias, and another trial had a high risk of reporting bias. AUTHORS' CONCLUSIONS Results from small studies with a high risk of bias have identified evidence of limited quality that intraurethral BTX-A injections improve some urodynamic measures after 30 days in the treatment of functional bladder outlet obstruction in adults with neurogenic bladder dysfunction. The necessity of reinjection of BTX-A is a significant drawback; a sphincterotomy might therefore be a more effective treatment option for lowering bladder pressure in the long-term.However, because of the limited availability of eligible trials, this review was unable to provide robust evidence in favour of any of the surgical treatment options. More RCTs are needed, measuring improvement on quality of life, and on other types of surgical treatment options for DSD since these are lacking. Future RCTs assessing the effectiveness of BTX-A injections also need to address the uncertainty about the optimal dose and mode of injection for this specific type of urological condition.
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Affiliation(s)
- Elaine Utomo
- Erasmus Medical CenterDepartment of UrologyRoom Na‐1708's‐Gravendijkwal 230RotterdamZuid‐HollandNetherlands3015 CE
| | - Jan Groen
- Erasmus Medical CenterDepartment of UrologyRoom Na‐1708's‐Gravendijkwal 230RotterdamZuid‐HollandNetherlands3015 CE
| | - Bertil FM Blok
- Erasmus Medical CenterDepartment of UrologyRoom Na‐1708's‐Gravendijkwal 230RotterdamZuid‐HollandNetherlands3015 CE
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Hajebi N, Sadjedi H. Evaluating High-Frequency Nerve Conduction Block for Tinnitus Treatment Using SEF Model. ACTA ACUST UNITED AC 2010. [DOI: 10.1109/icbbe.2010.5515498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Joshi RP, Mishra A, Xiao S, Pakhomov A. Model study of time-dependent muscle response to pulsed electrical stimulation. Bioelectromagnetics 2010; 31:361-70. [DOI: 10.1002/bem.20566] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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8
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Transperineal Injection of Botulinum Toxin A for Treatment of Detrusor Sphincter Dyssynergia: Localization With Combined Fluoroscopic and Electromyographic Guidance. Arch Phys Med Rehabil 2009; 90:832-6. [DOI: 10.1016/j.apmr.2008.10.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 10/04/2008] [Accepted: 10/10/2008] [Indexed: 11/24/2022]
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Joshi R, Mishra A, Jiahui Song, Pakhomov A, Schoenbach K. Simulation Studies of Ultrashort, High-Intensity Electric Pulse Induced Action Potential Block in Whole-Animal Nerves. IEEE Trans Biomed Eng 2008; 55:1391-8. [DOI: 10.1109/tbme.2007.912424] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Joshi RP, Mishra A, Hu Q, Schoenbach KH, Pakhomov A. Self-consistent analyses for potential conduction block in nerves by an ultrashort high-intensity electric pulse. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:061906. [PMID: 17677299 DOI: 10.1103/physreve.75.061906] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Indexed: 05/16/2023]
Abstract
Simulation studies are presented that probe the possibility of using high-field (> 100 kV/cm) , short-duration ( approximately 50 ns) electrical pulses for nonthermal and reversible cessation of biological electrical signaling pathways. This would have obvious applications in neurophysiology, clinical research, neuromuscular stimulation therapies, and even nonlethal bioweapons development. The concept is based on the creation of a sufficiently high density of pores on the nerve membrane by an electric pulse. This modulates membrane conductance and presents an effective "electrical short" to an incident voltage wave traveling across a nerve. Net blocking of action potential propagation can then result. A continuum approach based on the Smoluchowski equation is used to treat electroporation. This is self-consistently coupled with a distributed circuit representation of the nerve dynamics. Our results indicate that poration at a single neural segment would be sufficient to produce an observable, yet reversible, effect.
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Affiliation(s)
- R P Joshi
- Department of Electrical & Computer Engineering, Old Dominion University, Norfolk, Virginia 23529-0246, USA
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11
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Affiliation(s)
- Ja Hyeon Ku
- Department of Urology, Seoul Veterans Hospital, Seoul, Korea.
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Tai C, de Groat WC, Roppolo JR. Simulation of nerve block by high-frequency sinusoidal electrical current based on the Hodgkin-Huxley model. IEEE Trans Neural Syst Rehabil Eng 2005; 13:415-22. [PMID: 16200764 DOI: 10.1109/tnsre.2005.847356] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Nerve conduction block induced by high-frequency sinusoidal electrical current was simulated using a lumped circuit model of the unmyelinated axon based on Hodgkin-Huxley equations. Axons of different diameters (1-20 microm) can be blocked when the stimulation frequency is above 4 kHz. At higher frequency, a higher stimulation intensity is needed to block nerve conduction. Larger diameter axons have a lower threshold intensity for conduction block. High-frequency sinusoidal electrical currents are less effective in blocking nerve conduction than biphasic square pulses of the same frequency. The activation of potassium channels, rather than inactivation of sodium channels, is the possible mechanism underlying the nerve conduction block of the unmyelinated axon induced by high-frequency biphasic (sinusoidal or square pulse) stimulation. This simulation study, which provides more information about the axonal conduction block induced by high-frequency sinusoidal currents, can guide future animal experiments, as well as optimize stimulation waveforms for electrical nerve block in possible clinical applications.
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Affiliation(s)
- Changfeng Tai
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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Tai C, Roppolo JR, de Groat WC. Response of external urethral sphincter to high frequency biphasic electrical stimulation of pudendal nerve. J Urol 2005; 174:782-6. [PMID: 16006976 DOI: 10.1097/01.ju.0000164728.25074.36] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE We optimized the axonal blocking effect of high frequency, biphasic stimulation on neurally evoked contractions of the external urethral sphincter (EUS) and further investigated the repeatability of the blocking effect during relatively long periods to evaluate any acute nerve damage. MATERIALS AND METHODS Two stainless steel electrodes were positioned 5 to 10 mm apart on the decentralized pudendal nerve in alpha-chloralose anesthetized cats. The distal electrode was first tested at different frequencies (1 to 10 kHz) to search for the effective blocking frequency. At a fixed frequency (4, 6, 8 or 10 kHz) different stimulation intensities were then tested to evaluate their blocking effect. Sine waveform or biphasic pulses of a fixed pulse width were also tested. Finally, the proximal electrode was stimulated at 40 Hz for more than 40 minutes and during the same period the distal electrode (6 to 10 kHz) was repeatedly activated for 1-minute intervals in an attempt to block the EUS contraction induced by the proximal electrode. RESULTS High frequency, biphasic stimulation (6 to 10 kHz) with a pulse width dependent on frequency is optimal to block EUS contractions compared with sine waveform or biphasic pulses of a fixed pulse width. Acute nerve damage caused by blocking stimulation was not observed on neurally evoked urethral pressure. CONCLUSIONS Reversible block of EUS contractions by high frequency, biphasic stimulation of pudendal nerves is a potential method for suppressing detrusor-sphincter dyssynergia and improving voiding in spinal cord injured patients.
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Affiliation(s)
- Changfeng Tai
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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Tai C, de Groat WC, Roppolo JR. Simulation analysis of conduction block in unmyelinated axons induced by high-frequency biphasic electrical currents. IEEE Trans Biomed Eng 2005; 52:1323-32. [PMID: 16041996 PMCID: PMC2820275 DOI: 10.1109/tbme.2005.847561] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nerve conduction block induced by high-frequency biphasic electrical currents is analyzed using a lumped circuit model of the unmyelinated axon based on Hodgkin-Huxley equations. Axons of different diameters (5-20 microm) can not be blocked completely when the stimulation frequency is between 2 kHz and 4 kHz. However, when the stimulation frequency is above 4 kHz, all axons can be blocked. At high-frequency a higher stimulation intensity is needed to block nerve conduction. The larger diameter axon has a lower threshold intensity for conduction block. The stimulation waveform in which the pulsewidth changes with frequency is more effective in blocking nerve conduction than the waveform in which the pulsewidth is fixed. The activation of potassium channels, rather than inactivation of sodium channels, is the possible mechanism underlying the nerve conduction block of the unmyelinated axon. This simulation study further increases our understanding of axonal conduction block induced by high-frequency biphasic currents, and can guide future animal experiments as well as optimize stimulation waveforms that might be used for electrical nerve block in clinical applications.
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Affiliation(s)
- Changfeng Tai
- Department of Pharmacology, University of Pittsburgh, W1354 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
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Chang HY, Cheng CL, Chen JJJ, Peng CW, de Groat WC. Reflexes evoked by electrical stimulation of afferent axons in the pudendal nerve under empty and distended bladder conditions in urethane-anesthetized rats. J Neurosci Methods 2005; 150:80-9. [PMID: 16039722 PMCID: PMC3119341 DOI: 10.1016/j.jneumeth.2005.06.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Revised: 05/27/2005] [Accepted: 06/01/2005] [Indexed: 10/25/2022]
Abstract
This study examined reflex mechanisms that mediate urinary bladder and external urethral sphincter (EUS) coordination in female Sprague-Dawley urethane-anesthetized rats under empty and distended bladder conditions. The bladder was distended either by a small balloon or a saline filled catheter inserted through the body of the bladder. Stimulation of the entire pudendal nerve elicited short latency (8-12 ms) responses in the EUS and short (3-8 ms) and long latency responses (16-20 ms) in contralateral pudendal nerve. The long latency pudendal-pudendal reflex was reduced by 36.7% in area during bladder distension with the balloon catheter. However, there was no significant change in the area of pudendal-EUS reflex during bladder distension. Peak amplitudes of both reflexes were reduced 32% by bladder distension. The effects of glutamatergic receptor antagonists on the reflexes were also examined. MK 801 (0.3-5mg/kg, i.v.), an N-methyl-d-aspartate glutamatergic receptor antagonist, markedly depressed the pudendal-pudendal reflex, but LY 215490 (3mg/kg, i.v.), an alpha-amino-5-methyl isoxazole-4-propionate antagonist, had a minimal inhibitory effect. Both glutamatergic receptor antagonists significantly suppressed the pudendal-EUS reflex. These results indicate that the EUS is innervated by multiple pathways and that glutamatergic excitatory transmission is important in the neural mechanisms underlying bladder-sphincter coordination in the rat.
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Affiliation(s)
- Hui-Yi Chang
- Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania, USA
| | - Chen-Li Cheng
- Division of Urology, Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Jia-Jin J. Chen
- Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
- Corresponding author. Tel.: +886 6 2757575x63423. (J.-J.J. Chen)
| | - Chi-Wei Peng
- Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - William C. de Groat
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania, USA
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Tai C, Roppolo JR, de Groat WC. Block of external urethral sphincter contraction by high frequency electrical stimulation of pudendal nerve. J Urol 2005; 172:2069-72. [PMID: 15540791 DOI: 10.1097/01.ju.0000140709.71932.f0] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE High frequency electrical stimulation (1 to 10 kHz) of the pudendal nerve was evaluated as a method to block the external urethral sphincter contractions and increases in intraurethral pressure induced by electrical stimulation of pudendal nerve efferent axons. MATERIALS AND METHODS Two stainless steel electrodes were positioned 5 to 10 mm apart on the decentralized pudendal nerve in alpha-chloralose anesthetized cats. The most central electrode was electrically stimulated (40 Hz) to activate the efferent input to the external urethral sphincter. The change in the neurally evoked urethral responses by high frequency electrical stimulation of the distal electrode using a sinusoidal waveform or biphasic charge balanced pulses was examined. RESULTS For the 2 waveforms stimulation frequencies between 6 and 10 kHz were most effective in blocking external urethral sphincter activation. Intraurethral pressures caused by contractions of the external urethral sphincter were decreased more than 90% by high frequency stimulation using effective frequencies. When high frequency stimulation was turned off, external urethral sphincter responses recovered rapidly. CONCLUSIONS Reversible block of the external urethral sphincter contractions by high frequency electrical stimulation of the pudendal nerves is a potential method for suppressing detrusor-sphincter dyssynergia and improving voiding in spinal cord injured patients.
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Affiliation(s)
- Changfeng Tai
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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