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Li TF, Fan H, Wang YX. Epidural sustained release ropivacaine prolongs anti-allodynia and anti-hyperalgesia in developing and established neuropathic pain. PLoS One 2015; 10:e0117321. [PMID: 25617901 PMCID: PMC4305322 DOI: 10.1371/journal.pone.0117321] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 12/23/2014] [Indexed: 01/08/2023] Open
Abstract
Ropivacaine is a local anesthetic widely used for regional anesthesia and epidural analgesia, but its relatively short duration limits its clinical use. A novel sustained release lipid formulation of ropivacaine has been recently developed to prolong its duration. We examined the epidural anti-hypersensitivity and preemptive effects of ropivacaine in mesylate injection and sustained release suspension forms in a rat model of neuropathy produced by peripheral nerve injury. Epidural administration of ropivacaine mesylate injection specifically blocked mechanical allodynia and thermal hyperalgesia by approximately 50% with a biological half-effective duration of approximately 3 hrs. The equivalent dose of ropivacaine free-base in sustained release suspension significantly prolonged the duration of anti-allodynia and anti-hyperalgesia by approximately 2 times. Multiple daily epidural injections of ropivacaine in both the mesylate injection and sustained-release suspension forms did not induce tolerance or potentiation to anti-allodynia or anti-hyperalgesia. Moreover, the single or multiple daily administration of ropivacaine mesylate injection before surgery in particular, markedly blocked the initiation and development of neuropathic pain, increasing the biological half-effective duration from less than 4 hrs up to 1 or 2 days. The single and multiple daily epidural injection of ropivacaine sustained release suspension further delayed the biological half-lives to 2 and 3 days, respectively. Our results indicate that the epidural administration of ropivacaine effectively blocks neuropathic pain without the induction of analgesic tolerance, and significantly delays the development of neuropathy produced by peripheral nerve injury. Epidural ropivacaine sustained release suspension produces much longer blockade effects of mechanical allodynia and heat hyperalgesia, and more significantly delays the development of neuropathic pain.
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Affiliation(s)
- Teng-Fei Li
- King’s Lab, Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - Hui Fan
- King’s Lab, Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - Yong-Xiang Wang
- King’s Lab, Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
- * E-mail:
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Abstract
Overactive bladder and urgency incontinence are common conditions generally treated with oral anticholinergic therapy. Despite the development of new antimuscarinic agents, many patients do not tolerate or fail to respond to oral therapy. Intravesical instillation therapy can provide an alternative method of managing bladder overactivity. Intravesical instillation of anticholinergics such as oxybutynin and atropine can achieve cholinergic blockade without producing systemic side effects. Botulinum A toxin injected directly into the detrusor has been shown in preliminary studies to increase bladder capacity and decrease uncontrolled bladder contractility for up to 6 months. Intravesical local anesthetics such as lidocaine and bupivacaine block the conduction of unmyelinated C fibers and when administered into the bladder, lead to an increase in functional bladder capacity. Intravesical capsaicin and resiniferatoxin also affect afferent innervation by blocking C-fiber afferents, leading to decreased bladder contractility and increased bladder capacity. Intravesical instillation therapy can provide an alternative treatment for the management of overactive bladder.
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Affiliation(s)
- Robert J Evans
- The Urology Center, 509 North Elam Avenue, Greensboro, NC 27403, USA.
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Komai H, McDowell TS. Differential effects of bupivacaine and tetracaine on capsaicin-induced currents in dorsal root ganglion neurons. Neurosci Lett 2005; 380:21-5. [PMID: 15854744 PMCID: PMC2046220 DOI: 10.1016/j.neulet.2005.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 12/29/2004] [Accepted: 01/05/2005] [Indexed: 11/25/2022]
Abstract
Capsaicin opens the TRPV1 channel, a cation channel that depolarizes and activates nociceptive neurons. Following this initial activation, neurons become desensitized to subsequent applications of capsaicin as well as to other noxious stimuli, a phenomenon attributed primarily to the entry of Ca2+ ions through the open TRPV1 channel. This ability of capsaicin to desensitize nociceptors has led to its use as an analgesic in the treatment of a variety of chronic pain states. Because treatment with capsaicin is initially quite painful, local anesthetics are sometimes used to block axonal conduction in nociceptive neurons and thus minimize pain. However, local anesthetics might also block TRPV1 and prevent the Ca2+ entry required for capsaicin-induced desensitization. We have studied the direct effect of local anesthetics on currents induced by capsaicin (1 microM) in acutely isolated rat dorsal root ganglion neurons using the whole cell patch clamp technique. At the highest concentration tested (1 mM), bupivacaine only moderately inhibited the capsaicin-induced current to 55 +/- 27% of control (mean +/- S.D.; n=12, p<0.01). Tetracaine (1 mM), on the other hand, enhanced the capsaicin-induced current to 151 +/- 34% of control (mean +/- S.D.; n=7, p<0.01). These results show that local anesthetics can be used to prevent the initial pain induced by application of capsaicin without abolishing, and perhaps even enhancing, its desensitizing actions.
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Affiliation(s)
| | - Thomas S. McDowell
- * Corresponding author. Tel.: +1 608 265 3186 (Lab)/1 608 263 8698 (Hospital); fax: +1 608 263 0737 (Lab)/1 608 263 0575 (Hospital). E-mail address: (T.S. McDowell)
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Abstract
OBJECTIVE Pain management following bladder surgery in children is often complicated by bladder spasm. The overall severity of spasm can be reduced with opioids, anticholinergic medication and sedatives, although breakthrough spasms often occur. At the Royal Children's Hospital, Melbourne, intravesical bupivacaine has been used to manage postoperative bladder spasm to good effect. The administration of intravesical bupivacaine is analysed in this prospective audit of locally applied intravesical anaesthetic and compared with other methods. METHOD From February to August 2003, histories of 58 patients who had intravesical bupivacaine were studied and compared with six other methods of management of postoperative bladder spasm. CONCLUSION Data showed that epidural anaesthesia was the most effective treatment of pain, with a pain score reduction of 6.6, compared with a reduction of 6.1 with intravesical bupivacaine, and 4.5 using intravenous morphine. However, intravesical bupivacaine was the most effective method for the relief of bladder spasm.
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Affiliation(s)
- D Chiang
- Paediatric Urology Unit, Sunshine Hospital, and Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
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Abstract
STUDY DESIGN Review article. SETTING Neuro-Urology, Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland. OBJECTIVES This review considers intravesical treatment options of neurogenic detrusor overactivity and discusses the underlying mechanism of action, clinical safety and efficacy, and the future trends. METHODS The available literature was reviewed using medline services. RESULTS Oral anticholinergic drugs are widely used to treat detrusor overactivity, but they are ineffective in some patients or cause systemic side effects such as blurred vision or dry mouth. As an alternative, topical therapy strategies have been suggested to achieve a profound inhibition of the overactive detrusor and to avoid high systemic drug levels. Currently available intravesical treatment options either act on the afferent arc of the reflex such as local anaesthetics or vanilloids or on the efferent cholinergic transmission to the detrusor muscle such as intravesical oxybutynin or botulinum toxin. Although an established and effective therapy, intravesical oxybutynin is not widely used. Evidence for clinical significance of intravesical atropine and local anaesthetic is missing. Intravesical capsaicin has been shown to improve clinical and urodynamic parameters, but cause pain in some patients. The intravesical instillation of resiniferatoxin and the injection of botulinum-A toxin into the detrusor muscle are promising new options; however, randomised placebo-controlled studies to prove their safety and efficacy are still missing. CONCLUSION Intravesical treatment strategies in patients with neurogenic detrusor overactivity may provide alternatives to established therapies such as oral anticholinergics. The selectivity of the intravesical treatment and the reduction or even the absence of side effects are major advantages of this topical approach.
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Affiliation(s)
- André Reitz
- Neuro-Urology, Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland
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el-Mahrouky AS, Elashry OM, Emran MA. The effect of intravesical capsaicin and resiniferatoxin in neurogenic bladder dysfunction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 539:359-79. [PMID: 15088918 DOI: 10.1007/978-1-4419-8889-8_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
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Zhou Y, Wang Y, Abdelhady M, Mourad MS, Hassouna MM. Change of vanilloid receptor 1 following neuromodulation in rats with spinal cord injury. J Surg Res 2002; 107:140-4. [PMID: 12384077 DOI: 10.1006/jsre.2002.6481] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Neuromodulation has been used to treat voiding dysfunction caused by spinal cord injury (SCI). However, the underlying mechanism of this technique is not well understood. Recently, vanilloid receptor 1 (VR1) has been recognized as a capsaicin receptor and an agent for noxious stimuli. The purposes of this study were to evaluate whether development of bladder hyperreflexia after SCI involves VR1 upregulation and whether VR1 is involved in the process of neuromodulation. MATERIALS AND METHODS Sprague-Dawley rats (n = 20) were divided into five groups: sham control (n = 4); 3 days after SCI (n = 4); 7 days after SCI (n = 4); 14 days after SCI (n = 4), and 14 days after SCI with neurostimulation (n = 4). Bilateral electrode wires were implanted into S1 dorsal foramina and electrical stimulation was performed 8 h/day for 2 weeks. Spinal segments of L6, S1, and dorsal root ganglia were removed and cut into sections. The intensity of VR1 staining was evaluated by image analysis. RESULTS VR1-positive staining was confined to the superficial dorsal horn of the spinal cord. The staining was weak in the sham group (1/luminosity: 0.0050 +/- 0.0006), but the staining intensity was significantly increased in three SCI groups (3 days, 7 days, and 14 days) when compared with that in the sham group (P < 0.05). After neuromodulation, the staining intensity was reduced. CONCLUSIONS VR1 expression in the spinal cord is up-regulated after SCI. Sacral nerve root stimulation can down-regulate the VR1 expression.
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Affiliation(s)
- Yuan Zhou
- Division of Urology, Toronto Western Hospital, University Health Network, University of Toronto, Ontario, Canada
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Abstract
Very recently, a membrane receptor (vanilloid receptor type 1 [VR-1]) sensitive to capsaicin or resiniferatoxin (RTX) was identified in small- and medium-sized dorsal root ganglion neurons that give rise to most unmyelinated sensory fibers. After vanilloid binding to VR-1, these neurons remain transiently desensitized; that is, less reactive to natural stimuli. It is this effect of vanilloid substances that is being investigated for its potential therapeutic utility. In the urinary bladder, VR-1-expressing fibers are extremely abundant in the mucosa and in the muscular layer. In the latter, VR-1 fibers are intimately apposed to smooth muscle cells. The demonstration, several years ago, that these fibers were involved in detrusor hyperreflexia of spinal origin and in bladder pain processing, justified the clinical application of intravesical capsaicin or RTX in humans with these bladder diseases. More recently, the experimental and clinical evidence that the same type of bladder sensory fibers were also involved in detrusor instability made a strong case for intravesical RTX assay in patients with idiopathic detrusor instability.
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Affiliation(s)
- Francisco Cruz
- Department of Urology, Hospital de S. João, Porto, Portugal.
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Intravesical Capsaicin Versus Resiniferatoxin In Patients With Detrusor Hyperreflexia: A Prospective Randomized Study. J Urol 2002. [DOI: 10.1097/00005392-200204000-00029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Giannantoni A, Di Stasi SM, Stephen RL, Navarra P, Scivoletto G, Mearini E, Porena M. Intravesical Capsaicin Versus Resiniferatoxin In Patients With Detrusor Hyperreflexia: A Prospective Randomized Study. J Urol 2002. [DOI: 10.1016/s0022-5347(05)65183-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Antonella Giannantoni
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
| | - Savino M. Di Stasi
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
| | - Robert L. Stephen
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
| | - Pierluigi Navarra
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
| | - Giorgio Scivoletto
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
| | - Ettore Mearini
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
| | - Massimo Porena
- From the Department of Urology, University of Perugia, Perugia, Department of Urology “Tor Vergata,” University of Rome, Institute of Pharmacology Catholic University of Rome and IRCCS S. Lucia Rehabilitation Hospital, Rome and Physion Laboratories, Medolla, Italy
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de Sèze M, Wiart L, de Sèze MP, Joseph PA, Brochet B, Ferrière JM, Mazaux JM, Barat M. [Reiterated intravesical instillation of capsaicin in neurogenic detrusor hyperreflexia: a 5-years experience of 100 instillations]. ANNALES DE READAPTATION ET DE MEDECINE PHYSIQUE : REVUE SCIENTIFIQUE DE LA SOCIETE FRANCAISE DE REEDUCATION FONCTIONNELLE DE READAPTATION ET DE MEDECINE PHYSIQUE 2001; 44:514-24. [PMID: 11788114 DOI: 10.1016/s0168-6054(01)00156-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Capsaicin is a topic and specific C-fiber afferent neurotoxic. After spinal-cord injury, C-fiber afferent proliferate in the bladder mucosae and are involving in detrusor hyperreflexia AIM OF THE STUDY To investigate middle-term efficacy and tolerance of intravesical instillation of capsaïcin in spinal-cord injured patients presenting severe urinary incontinence refractory to usual therapy due to detrusor hyperreflexia. METHODS Thirty patients receveid a first intravesical instillation of 1mMol/L Capsaïcin solution in 30% alcohol. The efficacy (voiding diary, pads, quality of life, maximum cystometric capacity, maximum detrusor pressure, first and normal desire to void) and tolerance were evaluated before, 1 month and 3 months after each instillation, completed by anual cystoscopy. In patients who responded favorably to this instillation, repeated instillations were proposed when symptoms recurred. RESULTS 25 patients (83.3%) were improved after the initial instillation (decrease of incontinence-frequency-urgency, best quality of life, rise on maximal cystometric capacity), since the 15(th) day and for 3.2 months. 76 reiterative instillations were performed in 22 patients (2 to 9 instillations per patient). 91.2% of them remained successfull, during an average period of 4.2 months. It does not appear loss of benefits after iterative instillations. Transient and moderate adverse effects followed 86% and 79% of the first and reiterated instillation (exacerbation of incontinence, supra-pubic pain). Two patients have presented a begnin and transient inflammatory cystitis after reiterated instillation. DISCUSSION-CONCLUSION Intravesical instillation of capsaïcin are an effective treatment for incontinence and associated symptoms caused by neurogenic detrusor hyperactivity. Propositions to improve immediate tolerance are debated.
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Affiliation(s)
- M de Sèze
- Service de médecine physique et réadaptation, centre hospitalier universitaire de Bordeaux, hôpital Pellegrin Tastet-Girard, 33076 cedex, Bordeaux, France.
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Lapointe SP, Wang B, Kennedy WA, Shortliffe LM. The effects of intravesical lidocaine on bladder dynamics of children with myelomeningocele. J Urol 2001; 165:2380-2. [PMID: 11371945 DOI: 10.1097/00005392-200106001-00041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Other studies have suggested that intravesical lidocaine may temporarily improve bladder dynamics but details of these effects and their application to children have not been examined. We evaluated the effects of intravesical lidocaine on bladder urodynamics of children with myelomeningocele and tried to correlate these effects with subsequent clinical response to oral oxybutynin. MATERIALS AND METHODS Charts of children with myelomeningocele who had undergone urodynamic examinations from 1992 to 1998 were reviewed retrospectively. In children with uninhibited contractions or poor compliance 150 to 300 mg. lidocaine were instilled for 8 minutes and cystometry was repeated. Changes in bladder capacity and compliance, number of uninhibited contractions and bladder volume at which pressure of 40 cm. H2O was reached were recorded before and after the lidocaine instillation. Clinical response to subsequent treatment with oral oxybutynin was assessed from chart review. RESULTS A total of 48 urodynamic studies in 22 girls and 20 boys with a mean age plus or minus standard deviation of 8.3 +/- 5.7 years and myelomeningocele were evaluable. After instillation of lidocaine, urodynamics showed increased bladder capacity in 70.8% of studies (34 of 48), with an average increase in volume of 66% (p <0.05). No change or decreased bladder capacity occurred in 29.2% of studies. Bladder compliance improved in 61.7% of the studies (29 of 47, p <0.05) and worsened in 38.3%. Bladder volume at which the pressure of 40 cm. H2O was reached increased in 77.8% of studies (14 of 18, p <0.05). After lidocaine the number of uninhibited contractions decreased by 3.2 in 56.8% of studies (21 of 37, p <0.05). Correlation of lidocaine induced changes in bladder capacity, compliance and number of uninhibited contractions with improvement on oral oxybutynin was 70.6%, 64.3% and 66.7%, respectively. CONCLUSIONS Intravesical lidocaine can improve bladder capacity and compliance and decrease the number of uninhibited contractions in many children with neurogenic bladder caused by myelomeningocele. These observations suggest that intravesical lidocaine has effects on the neurogenic bladder that improve bladder dynamics. Although intravesical lidocaine testing may not reliably predict clinical response to oral oxybutynin at the prescribed dosages, a possible therapeutic role for intravesical lidocaine or similar agents should be explored further.
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Affiliation(s)
- S P Lapointe
- Department of Urology, Stanford University, Stanford, California, USA
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Lapointe SP, Wang B, Kennedy WA, Shortliffe LM. The effects of intravesical lidocaine on bladder dynamics of children with myelomeningocele. J Urol 2001; 165:2380-2. [PMID: 11371945 DOI: 10.1016/s0022-5347(05)66209-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Other studies have suggested that intravesical lidocaine may temporarily improve bladder dynamics but details of these effects and their application to children have not been examined. We evaluated the effects of intravesical lidocaine on bladder urodynamics of children with myelomeningocele and tried to correlate these effects with subsequent clinical response to oral oxybutynin. MATERIALS AND METHODS Charts of children with myelomeningocele who had undergone urodynamic examinations from 1992 to 1998 were reviewed retrospectively. In children with uninhibited contractions or poor compliance 150 to 300 mg. lidocaine were instilled for 8 minutes and cystometry was repeated. Changes in bladder capacity and compliance, number of uninhibited contractions and bladder volume at which pressure of 40 cm. H2O was reached were recorded before and after the lidocaine instillation. Clinical response to subsequent treatment with oral oxybutynin was assessed from chart review. RESULTS A total of 48 urodynamic studies in 22 girls and 20 boys with a mean age plus or minus standard deviation of 8.3 +/- 5.7 years and myelomeningocele were evaluable. After instillation of lidocaine, urodynamics showed increased bladder capacity in 70.8% of studies (34 of 48), with an average increase in volume of 66% (p <0.05). No change or decreased bladder capacity occurred in 29.2% of studies. Bladder compliance improved in 61.7% of the studies (29 of 47, p <0.05) and worsened in 38.3%. Bladder volume at which the pressure of 40 cm. H2O was reached increased in 77.8% of studies (14 of 18, p <0.05). After lidocaine the number of uninhibited contractions decreased by 3.2 in 56.8% of studies (21 of 37, p <0.05). Correlation of lidocaine induced changes in bladder capacity, compliance and number of uninhibited contractions with improvement on oral oxybutynin was 70.6%, 64.3% and 66.7%, respectively. CONCLUSIONS Intravesical lidocaine can improve bladder capacity and compliance and decrease the number of uninhibited contractions in many children with neurogenic bladder caused by myelomeningocele. These observations suggest that intravesical lidocaine has effects on the neurogenic bladder that improve bladder dynamics. Although intravesical lidocaine testing may not reliably predict clinical response to oral oxybutynin at the prescribed dosages, a possible therapeutic role for intravesical lidocaine or similar agents should be explored further.
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Affiliation(s)
- S P Lapointe
- Department of Urology, Stanford University, Stanford, California, USA
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Wang Y, Zhou Y, Mourad MS, Hassouna MM. Neuromodulation reduces urinary frequency in rats with hydrochloric acid-induced cystitis. BJU Int 2000; 86:726-30. [PMID: 11069385 DOI: 10.1046/j.1464-410x.2000.00873.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the effect of sacral neuromodulation on interstitial cystitis (IC) and determine the underlying mechanism of neuromodulation in the treatment of IC. Materials and methods Twenty Sprague-Dawley rats (body weight 220-250 g) were randomly divided into four equal groups; normal controls, a sham treatment (IC induced by 0.4 mol/L HCl, + saline), a second sham treatment (HCl-induced IC + acetic acid) and a stimulated group (HCl-induced IC + acetic acid, with electrical stimulation). In the last group bilateral electrodes were implanted into the S1 dorsal foramina and electrical stimulation applied for 8 h/day for 3 weeks. Acetic acid was instilled into the bladder to induce c-fos expression. After 3 weeks the rats were perfused with 4% paraformaldehyde, spinal segments dissected out and an immunocytochemical method used to stain the segments for fos protein encoded byc-fos. RESULTS The mean (SEM) micturition frequency (voids/17 h) in the sham groups increased from 10.8 (2.7) to 23.4 (3.4) 3 weeks after the intravesical instillation of HCl. The micturition frequency in the stimulated group, at 16.2 (2.7), was significantly less than in the sham group (P = 0.04) after electrical stimulation for 3 weeks. There was no significant difference in the mean (SEM) number of fos-positive neurones in the L6 spinal cord segment between the stimulated and the sham + acetic acid group, at 43.6 (9.4) and 35.8 (7.8) cells/section, respectively (P = 0.32). CONCLUSIONS In rats with HCl-induced cystitis, electrical stimulation reduced the micturition frequency, but not by inhibiting afferent c-fibre activity.
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Affiliation(s)
- Y Wang
- Urology Research Laboratory, Division of Urology, Toronto Western Hospital, University of Toronto, Toronto, Canada
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Avelino A, Cruz F, Coimbra A. Intravesical resiniferatoxin desensitizes rat bladder sensory fibres without causing intense noxious excitation. A c-fos study. Eur J Pharmacol 1999; 378:17-22. [PMID: 10478560 DOI: 10.1016/s0014-2999(99)00451-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study the desensitizing power of increasing concentrations of resiniferatoxin applied topically to the bladder mucosa, and the irritating properties of the most effective desensitizing dose, were determined with the aid of the spinal expression of the proto-oncogene c-fos. Desensitization was assessed by the decrease in the number of Fos-immunoreactive spinal neurons induced by the intravesical instillation of 1% acetic acid, when the latter was preceded by resiniferatoxin in concentrations between 1 and 1000 nM. Irritation, as shown by the noxious excitation of vesical sensory innervation, was measured by the c-fos response evoked by a single application of resiniferatoxin. As to the desensitizing power, resiniferatoxin produced a dose-dependent effect with a maximum at 100 nM, which decreased Fos-immunoreactive cell numbers to less than 10% of controls. No further decrease of c-fos activation occurred at 1000 nM. As to the irritating power, the saturation dose of resiniferatoxin (100 nM) produced a very weak c-fos activation in lumbosacral spinal cord segments. These data show that in an effective desensitizing concentration, resiniferatoxin is virtually devoid of nociceptive effects, in agreement with current clinical observations.
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Affiliation(s)
- A Avelino
- Institute of Histology and Embryology, Faculty of Medicine of Oporto, IBMC of University of Oporto, Porto, Portugal
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Cruz F. Desensitization of bladder sensory fibers by intravesical capsaicin or capsaicin analogs. A new strategy for treatment of urge incontinence in patients with spinal detrusor hyperreflexia or bladder hypersensitivity disorders. Int Urogynecol J 1998; 9:214-20. [PMID: 9795827 DOI: 10.1007/bf01901607] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Recent experimental studies have identified a category of unmyelinated type C bladder afferent fibers in the pelvic nerves which are extremely sensitive to capsaicin. Sensory input conveyed by these fibers triggers a spinal reflex which, in chronic spinalized animals, facilitates and controls micturition. In addition, bladder C fibers were also shown to have a role in bladder pain perception. In humans capsaicin-sensitive afferent fibers also innervate the bladder and contribute to the reflexogenic control of the detrusor muscle and to bladder pain perception. Desensitization of such fibers by intravesical administration of capsaicin, presumably by blocking sensory transmission, has been shown to reduce involuntary micturition and to increase bladder capacity in patients with detrusor hyperreflexia of spinal origin, and to reduce the intensity of bladder pain in patients with bladder hypersensitivity. Very recently, resiniferatoxin, an ultrapotent capsaicin analog, was shown to have a similar clinical effect in this subset of patients. However, unlike capsaicin, resiniferatoxin did not evoke acute irritative urinary symptoms during bladder instillation.
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Affiliation(s)
- F Cruz
- Department of Urology, Hospital São João, Oporto, Portugal
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