Effects of acute bolus and chronic continuous intrathecal baclofen on genitourinary dysfunction due to spinal cord pathology

Systemic and intrathecal baclofen produce bladder antinociception in rats

BACKGROUND

Baclofen, a clinically available GABAB receptor agonist, produces non-opioid analgesia in multiple models of pain but has not been tested for effects on bladder nociception.

METHODS

A series of experiments examined the effects of systemic and spinally administered baclofen on bladder nociception in female anesthetized rats. Models of bladder nociception included those which employed neonatal and adult bladder inflammation to produce bladder hypersensitivity.

RESULTS

Cumulative intraperitoneal dosing (1-8 mg/kg IP) and cumulative intrathecal dosing (10-160 ng IT) of baclofen led to dose-dependent inhibition of visceromotor responses (VMRs) to urinary bladder distension (UBD) in all tested models. There were no differences in the magnitude of the analgesic effects of baclofen as a function of inflammation versus no inflammation treatments. Hemodynamic (pressor) responses to UBD were similarly inhibited by IT baclofen as well as UBD-evoked excitatory responses of spinal dorsal horn neurons. The GABAB receptor antagonist, CGP 35,348, antagonized the antinociceptive effects of IT baclofen on VMRs in all tested models but did not affect the magnitude of the VMRs by itself suggesting no tonic GABAB activity was present in this preparation. Tolerance to a seven day continuous IT infusion of baclofen was not observed.

CONCLUSIONS

These data provide support for a clinical trial of baclofen as a non-opioid treatment of human bladder pain.

Viral Vector-Mediated Gene Transfer of Glutamic Acid Decarboxylase for Chronic Pain Treatment: A Literature Review

Chronic pain is long-lasting nociceptive state, impairing the patient's quality of life. Existing analgesics are generally not effective in the treatment of chronic pain, some of which such as opioids have the risk of tolerance/dependence and overdose death with higher daily opioid doses for increasing analgesic effect. Opioid use disorders have already reached an epidemic level in the United States; therefore, nonopioid analgesic approach and/or use of nonpharmacologic interventions will be employed with increasing frequency. Viral vector-mediated gene therapy is promising in clinical trials in the nervous system diseases. Glutamic acid decarboxylase (GAD) enzyme, a key enzyme in biosynthesis of γ-aminobutyric acid (GABA), plays an important role in analgesic mechanism. In the literature review, we used PubMed and bioRxiv to search the studies, and the eligible criteria include (1) article written in English, (2) use of viral vectors expressing GAD67 or GAD65, and (3) preclinical pain models. We identified 13 eligible original research articles, in which the pain models include nerve injury, HIV-related pain, painful diabetic neuropathy, and formalin test. GAD expressed by the viral vectors from all the reports produced antinociceptive effects. Restoring GABA systems is a promising therapeutic strategy for chronic pain, which provides evidence for the clinical trial of gene therapy for pain in the near future.

Effects of Dietary Vitamin E Supplementation in Bladder Function and Spasticity during Spinal Cord Injury

Traumatic spinal cord injury (SCI) results in debilitating autonomic dysfunctions, paralysis and significant sensorimotor impairments. A key component of SCI is the generation of free radicals that contributes to the high levels of oxidative stress observed. This study investigates whether dietary supplementation with the antioxidant vitamin E (alpha-tocopherol) improves functional recovery after SCI. Female adult Sprague-Dawley rats were fed either with a normal diet or a dietary regiment supplemented with vitamin E (51 IU/g) for eight weeks. The rats were subsequently exposed either to a contusive SCI or sham operation, and evaluated using standard functional behavior analysis. We report that the rats that consumed the vitamin E-enriched diet showed an accelerated bladder recovery and significant improvements in locomotor function relative to controls, as determined by residual volumes and Basso, Beatie, and Bresnaham BBB scores, respectively. Interestingly, the prophylactic dietary intervention did not preserve neurons in the ventral horn of injured rats, but it significantly increased the numbers of oligodendrocytes. Vitamin E supplementation attenuated the depression of the H-reflex (a typical functional consequence of SCI) while increasing the levels of supraspinal serotonin immunoreactivity. Our findings support the potential complementary use of vitamin E to ameliorate sensory and autonomic dysfunctions associated with spinal cord injury, and identified promising new cellular and functional targets of its neuroprotective effects.

Investigational Drug Therapies for Overactive Bladder Syndrome: The Potential Alternatives to Anticolinergics

Background

Overactive bladder is a high prevalent and quality of life affecting disease. The mainstay of the medical therapy is represented by antimuscarinic drugs, but their side effects markedly affect patient compliance and prompt studies on novel investigational drugs.

Methods

A systematic literature search of peer-reviewed papers and meeting abstracts published by December 2008 was performed. PubMed databank was searched for original English articles, by using the following search terms: “overactive bladder” or “detrusor overactivity” or “urinary incontinence” and “treatment”, alone and linked to any potential molecular target or novel drug cited in the literature.

Results

Effective alternative pharmacological treatments are currently scarce, but many new promising compounds are emerging which target key molecular pathways involved in micturition control. The most promising potential therapeutic targets include central nervous system GABAergic inhibitory pathway, dopaminergic and serotoninergic systems, b-adrenoceptors and cAMP metabolism, nonadrenergic-noncholinergic mechanisms such as purinergic and neuropeptidergic systems, vanilloid receptor, bladder sensory nervous terminals, nonneuronal bladder signalling systems including urothelium and interstitial cells, prostanoids, Rho-kinase and different subtypes of potassium and calcium channels.

Conclusions

Despite the enormous amount of new biologic insight, very few novel pharmacological therapies seems to have passed the proof-of-concept clinical stage. The ultimate clinical utility of new drugs will depend on the ability to exploit tissue-specific differences and disease-related changes in molecular expression/function and to improve storage phase dysfunctions without interfering with the emptying phase. Further preclinical investigations and controlled clinical trials are urgently needed in this challenging field.

Severe, Protracted Spasm of Urinary Bladder and Autonomic Dysreflexia Caused by Changing the Suprapubic Catheter in a Cervical Spinal Cord Injury Patient: Treatment by a Bolus Dose and Increased Total Daily Dose of Intrathecal Baclofen

BACKGROUND

Intrathecal administration of baclofen by implanted pump reduces rigidity and muscle spasms. Its use specifically to control bladder spasms has not been reported.

CASE REPORT

A tetraplegic patient developed severe, protracted, bladder spasms, abdominal muscles spasms, and high blood pressure after change of suprapubic catheter; nifedipine, diazepam, and paracetamol did not control spasms; bolus dose of baclofen intrathecally produced prompt relief via baclofen pump.

CONCLUSION

Severe, protracted bladder spasms, abdominal muscles spasms, and autonomic dysreflexia, induced by change of suprapubic catheter in a spinal cord injury patient, were treated successfully by a bolus dose and increased total daily dose of intrathecal baclofen.

Preliminary results of chronic intrathecal therapy in treatment of spastic syndromes of various etiologies

OBJECTIVE

To estimate the effectiveness of the chronic intrathecal baclofen infusion (ITB) for the treatment of botuloresistant spastic disorders.

MATERIAL AND METHODS

ITB have been performed in 15 cases of spastic disorders. In 8 cases spasticity was the result of cerebral palsy, 5 - spinal cord injure, 1 - cerebral injure, 1 - pyogenic spinal epiduritis. The results of surgical treatment were estimated with the Ashworth, GMFM-88 and Arens scales. These data have been exposed statistically analysis.

RESULTS

Significantly decrease of spasticity have been revealed in most cases: from 4.26±0.7 points before the operation to 1.8±0.67 points after the operation (p<0.004). In 8 cases we have observed improvement in motor functions.

CONCLUSION

ITB is an effective procedure which leads to decreasing of spasticity, incree of movement volume and improvement in motor functions in patients with spastic disorders.

Surgical management of functional bladder outlet obstruction in adults with neurogenic bladder dysfunction

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.

Central nervous targets for the treatment of bladder dysfunction

BACKGROUND

The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the urinary bladder, urethra, and external urethral sphincter. This activity is in turn controlled by neural circuits in the brain, spinal cord, and peripheral ganglia.

AIMS

This paper will review recent advances in our understanding of the pathophysiology of voiding disorders, especially focusing on the central nervous system.

METHODS

Various neurotransmitters, including acetylcholine, norepinephrine, dopamine, serotonin, excitatory and inhibitory amino acids, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in the neural regulation of the lower urinary tract.

RESULTS

Injuries or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce voiding dysfunctions such as urinary frequency, urgency, or incontinence.

CONCLUSION

We discuss the potential targets in the central nervous system and new modalities for the treatment of voiding dysfunction.

Neurotrophins in bladder function: what do we know and where do we go from here?

AIMS

Neurotrophins (NTs) have attracted considerable attention in the urologic community. The reason for this resides in the recognition of their ability to induce plastic changes of the neuronal circuits that govern bladder function. In many pathologic states, urinary symptoms, including urgency and urinary frequency, reflect abnormal activity of bladder sensory afferents that results from neuroplastic changes. Accordingly, in pathologies associated with increased sensory input, such as the overactive bladder syndrome (OAB) or bladder pain syndrome/interstitial cystitis (BPS/IC), significant amounts of NTs have been found in the bladder wall.

METHODS

Here, current knowledge about the importance of NTs in bladder function will be reviewed, with a focus on the most well-studied NTs, nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF).

RESULTS

Both NTs are present in the bladder and regulate bladder sensory afferents and urothelial cells. Experimental models of bladder dysfunction show that upregulation of these NTs is strongly linked to bladder hyperactivity and, in some cases, pain. NT manipulation has been tested in animal models of bladder dysfunction, and recently, NGF downregulation, achieved by administration of a monoclonal antibody, has also been tested in patients with BPS/IC and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). NTs have also been found in high quantities in the urine of OAB and BPS/IC patients, raising the possibility of NTs serving as biomarkers.

CONCLUSIONS

Available data show that our knowledge of NTs has greatly increased in recent years and that some results may have future clinical application.

Neurophysiology of the lower urinary tract

The lower urinary tract (LUT) has two functions: (1) the storage of waste products in the form of urine and (2) the elimination of those wastes through micturition. The LUT operates in a simple "on-off" fashion, either storing urine or releasing it during voiding. While this activity may seem simple, micturition is controlled by a complex set of peripheral neurons that are, in turn, coordinated by cell groups in the spinal cord, brainstem, and brain. When this careful coordination is interrupted, the control of the bladder is lost, resulting in incontinence or retention of urine. The purpose of this chapter is to review how the neural systems coordinating the activity of the lower urinary tract form neural circuits that are responsible for either maintaining continence (the storage reflex) or inducing micturition (the voiding reflex). We will also discuss the brain centers that enable higher organisms to voluntarily choose the time and place for voiding. Finally, we will discuss how defects in the pathways controlling micturition can lead to urinary incontinence and which treatments may normalize LUT function.

Suppression of detrusor-sphincter dyssynergia by herpes simplex virus vector mediated gene delivery of glutamic acid decarboxylase in spinal cord injured rats

PURPOSE

We investigated whether replication defective herpes simplex virus vectors encoding genes of glutamic acid decarboxylase, the gamma-aminobutyric acid synthesis enzyme, could suppress detrusor-sphincter dyssynergia in rats with spinal cord injury.

MATERIALS AND METHODS

One week after spinalization herpes simplex virus vectors expressing glutamic acid decarboxylase and green fluorescent protein were injected into the bladder wall. Spinal cord injured rats without herpes simplex virus injection (sham treated) and those injected with LacZ encoding herpes simplex virus vectors served as controls. Three weeks after viral injection we simultaneously recorded urethral and intravesical pressure in awake rats.

RESULTS

In the glutamic acid decarboxylase group the urethral pressure increase during bladder contraction was significantly decreased by 77% to 79% compared with that in the sham treated and LacZ groups. Bladder activity and urethral baseline pressure did not differ among the 3 groups. Intrathecal application of the gamma-aminobutyric acid-A receptor antagonist bicuculline almost completely reversed the decrease in the urethral pressure increase during bladder contractions while intrathecal saclofen (Tocris Cookson, Ellisville, Missouri), a gamma-aminobutyric acid-B receptor antagonist, partially reversed it. In the glutamic acid decarboxylase group the mRNA of glutamic acid decarboxylase 67 was significantly increased in L6-S1 dorsal root ganglia, which is where bladder afferents originate, compared with that in the LacZ group.

CONCLUSIONS

Herpes simplex virus based glutamic acid decarboxylase gene transfer to bladder afferent pathway may represent a novel approach to detrusor-sphincter dyssynergia in cases of spinal cord injury.

Neural control of the female urethral and anal rhabdosphincters and pelvic floor muscles

The urethral rhabdosphincter and pelvic floor muscles are important in maintenance of urinary continence and in preventing descent of pelvic organs [i.e., pelvic organ prolapse (POP)]. Despite its clinical importance and complexity, a comprehensive review of neural control of the rhabdosphincter and pelvic floor muscles is lacking. The present review places historical and recent basic science findings on neural control into the context of functional anatomy of the pelvic muscles and their coordination with visceral function and correlates basic science findings with clinical findings when possible. This review briefly describes the striated muscles of the pelvis and then provides details on the peripheral innervation and, in particular, the contributions of the pudendal and levator ani nerves to the function of the various pelvic muscles. The locations and unique phenotypic characteristics of rhabdosphincter motor neurons located in Onuf's nucleus, and levator ani motor neurons located diffusely in the sacral ventral horn, are provided along with the locations and phenotypes of primary afferent neurons that convey sensory information from these muscles. Spinal and supraspinal pathways mediating excitatory and inhibitory inputs to the motor neurons are described; the relative contributions of the nerves to urethral function and their involvement in POP and incontinence are discussed. Finally, a detailed summary of the neurochemical anatomy of Onuf's nucleus and the pharmacological control of the rhabdosphincter are provided.

Changes in afferent activity after spinal cord injury

AIMS

To summarize the changes that occur in the properties of bladder afferent neurons following spinal cord injury.

METHODS

Literature review of anatomical, immunohistochemical, and pharmacologic studies of normal and dysfunctional bladder afferent pathways.

RESULTS

Studies in animals indicate that the micturition reflex is mediated by a spinobulbospinal pathway passing through coordination centers (periaqueductal gray and pontine micturition center) located in the rostral brain stem. This reflex pathway, which is activated by small myelinated (Adelta) bladder afferent nerves, is in turn modulated by higher centers in the cerebral cortex involved in the voluntary control of micturition. Spinal cord injury at cervical or thoracic levels disrupts voluntary voiding, as well as the normal reflex pathways that coordinate bladder and sphincter function. Following spinal cord injury, the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. The recovery of bladder function after spinal cord injury is dependent in part on the plasticity of bladder afferent pathways and the unmasking of reflexes triggered by unmyelinated, capsaicin-sensitive, C-fiber bladder afferent neurons. Plasticity is associated with morphologic, chemical, and electrical changes in bladder afferent neurons and appears to be mediated in part by neurotrophic factors released in the spinal cord and the peripheral target organs.

CONCLUSIONS

Spinal cord injury at sites remote from the lumbosacral spinal cord can indirectly influence properties of bladder afferent neurons by altering the function and chemical environment in the bladder or the spinal cord.

Normalization of central cord syndrome spinal cord injury urodynamics after intrathecal baclofen therapy: a case report

Objective. To report a case of improved urodynamics in a central cord syndrome spinal cord injury after intrathecal baclofen therapy. Methods. A 47-year-old man fell resulting in C4-C5 disc herniation with ventral spinal cord compression and cord edema. Results. He underwent an anterior cervical discectomy and fusion. Postoperatively, his examination revealed a C4 ASIA D injury in a central cord syndrome pattern. Cystometrogram (CMG) revealed a hyperactive detrusor with sphincter dyssynergia managed with intermittent self-catheterization. One and a half years later, he was impaired by severe lower limb spasticity, despite oral medications and botulinum toxin injections. After intrathecal pump therapy, CMG revealed relatively normal detrusor and minimal sphincter tone. He volitionally voids with urgency but improved continence, which was maintained in one-year follow-up. Conclusion. Although the main indication for intrathecal baclofen therapy is spasticity, improved urodynamics can be an additional benefit in central cord syndrome spinal cord injury.

Roles of Glycinergic and Gamma-aminobutyric-ergic Mechanisms in the Micturition Reflex in Rats

The micturition reflex is one of the autonomic reflexes mediated by the spinobulbospinal reflex pathway that passes through the pontine micturition center. In the central nervous system, glutamate is a major excitatory amino acid, while glycine and gamma-aminobutyric acid (GABA) are major inhibitory neurotransmitters and act to inhibit the micturition reflex at supraspinal and/or spinal sites. Glycine and GABA have additive or synergistic inhibitory effects on bladder activity. Hypofunction of glycinergic/GABAergic mechanisms in the lumbosacral spinal cord induces voiding dysfunctions, such as detrusor overactivity (DO) or detrusor-sphincter dyssynergia (DSD) after spinal cord injury (SCI) or bladder outlet obstruction in rats. Intrathecal, intravenous, or dietary glycine inhibits both bladder and urethral activity in normal and spinal cord injury (SCI) rats. Therefore, glycine might be a useful agent for the treatment of DO. Intrathecal muscimol and baclofen (GABA(A) and GABA(B) agonists, respectively) also inhibit non-voiding bladder contractions by suppressing C-fiber bladder afferents in SCI rats. They also improve DSD by suppressing Onuf's nucleus and C-fiber bladder afferents. Baclofen is approved for the treatment of DO in SCI patients, but this agent has not been widely used because the therapeutic window of the drug is modest and the dose is limited by side-effects. Glutamic acid decraboxylase (GAD), the GABA synthesis enzyme, gene delivery by using non-replicating herpes simplex virus (HSV) vectors inhibits DO by suppressing C-fiber bladder afferents without affecting voiding contraction in SCI rats. Therefore, GAD gene therapy can restore urine storage function without affecting voiding function; it would be more beneficial than drug therapy for the treatment of urinary problems in SCI patients.

Herpes simplex virus vector-mediated gene delivery of glutamic acid decarboxylase reduces detrusor overactivity in spinal cord-injured rats

We examined whether replication-defective herpes simplex virus (HSV) vectors encoding the 67 kDa form of the glutamic acid decarboxylase (GAD(67)) gene product, the gamma-aminobutyric acid (GABA) synthesis enzyme, can suppress detrusor overactivity (DO) in rats with spinal cord injury (SCI). One week after spinalization, HSV vectors expressing GAD and green fluorescent protein (GFP) (HSV-GAD) were injected into the bladder wall. Rats with SCI without HSV injection (HSV-untreated) and those injected with lacZ-encoding reporter gene HSV vectors (HSV-LacZ) were used as controls. Three weeks after viral injection, continuous cystometry was performed under awake conditions in all three groups. In the HSV-GAD group, the number and amplitude of non-voiding contractions (NVCs) were significantly decreased (40-45% and 38-40%, respectively) along with an increase in voiding efficiency, compared with HSV-untreated and HSV-LacZ groups, but micturition pressure was not different among the three groups. Intrathecal application of bicuculline partly reversed the decreased number and amplitude of NVCs, and decreased voiding efficiency in the HSV-GAD group. In the HSV-GAD group, GAD(67) mRNA and protein levels were significantly increased in the L6-S1 dorsal root ganglia (DRG) compared with the HSV-LacZ group, while 57% of DRG cells were GFP-positive, and these neurons showed increased GAD(67)-like immunoreactivity compared with the HSV-LacZ group. These results indicate that GAD gene therapy effectively suppresses DO after SCI predominantly through the activation of spinal GABA(A) receptors. Thus, HSV-based GAD gene transfer to bladder afferent pathways may represent a novel approach for treatment of neurogenic DO.

Intrathecal baclofen for autonomic instability due to spinal cord injury

Autonomic dysreflexia may occur following spinal cord injury above mid-thoracic level, commonly developing in the early posttraumatic period. Cardiovascular dysregulation is the most prominent feature, characterized by paroxysmal high blood pressure attacks, which are precipitated by distension of urinary bladder or bowels, skin wounds, or increased spastic muscle tone. Severe drops in blood pressure may occur in orthostatic conditions. Baclofen is effective for treating spasticity. While orally administered baclofen often fails to alleviate severe spasticity adequately, intrathecal baclofen (ITB) is more effective and thus is being used increasingly. A 61-year-old male sustained a cervical spinal cord injury, subsequently developing severe spastic tetraparesis, predominantly in the legs. Some 30 years later he experienced marked spasms of the muscles of the abdominal wall, leading to extreme fluctuations of blood pressure. After positive evaluation with ITB the patient underwent implantation of a pump-catheter-system for continuous ITB application. Abdominal wall spasms ceased entirely with a daily dose of 190 microg ITB, accompanied by a sustained normotensive blood pressure profile. However, spasms reoccurred after inadvertent reduction of ITB flow when increasing the pump's ITB concentration but subsided again when the optimal antispastic dose was reestablished. Baclofen per se has the potential of lowering blood pressure. In this patient, however, ITB treatment enabled permanent stabilization of insidious blood pressure fluctuations. It would appear that suppression of abdominal spasms prevented the triggering of dysautonomic crises. This case demonstrates that ITB administration may help to stabilize autonomic dysreflexia and orthostatic hypotension in patients with spinal cord lesions.

Intrathecal baclofen: Its effect on symptoms and activities of daily living in severe spasticity due to spinal cord injuries: A pilot study

BACKGROUND

Spasticity is a major problem related to spinal cord injuries. Use of intrathecal baclofen with an implanted pump seems a very useful mode of therapy in patients in whom oral antispasmodic agents are either not effective or produce intolerable side-effects.

MATERIALS AND METHODS

Twenty-four patients with mean age 50 years (range 32-72 years) had intrathecal baclofen pump implanted for the severe spasticity of spinal origin. One patient died following implantation of pump due to natural causes and was not included in the study. The patients were followed up for mean 22 months (range, one to five years).

RESULTS

All 24 patients showed improvement in their spasm following the procedure. Improvement was noted in pain (12), sleep disturbance (20) and sphincter control (14). Patients had improvement in activities of daily living such as feeding ability (10), self care (10), indoor and outdoor mobility (19), and driving (4). One patient had catheter leakage immediately after the surgery and required change of catheter. The radio telemetry allows very good adjustment of the dose according the individual patients needs.

CONCLUSION

Intrathecal baclofen pump improves the symptoms of spasm and also the quality of life. It helps the patient to live more independently. It is not an irreversible surgery for the patient and hence it is very useful in the changing the dynamics in this group of patients.

Acute anal stretch inhibits NMDA-dependent pelvic-urethra reflex potentiation via spinal GABAergic inhibition in anesthetized rats

The impact of acute anal stretch on the pelvic-urethra reflex potentiation was examined in urethane-anesthetized rats by recording the external urethra sphincter electromyogram activity evoked by the pelvic afferent stimulation. Test stimulation (1 stimulation/30 s) evoked a baseline reflex activity with a single action potential that was abolished by gallamine (5 mg/kg iv). On the other hand, the repetitive stimulation (1 stimulation/1 s) induced spinal reflex potentiation (SRP) that was attenuated by intrathecal 6-cyano-7-nitroquinoxaline-2,4-dione (a glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionat receptor antagonist, 100 μM, 10 μl) and d-2-amino-5-phosphonovalerate [a glutamatergic N-methyl-d-aspartate (NMDA) antagonist, 100 μM, 10 μl]. Acute anal stretch using a mosquito clamp with a distance of 4 mm exhibited no effect, whereas distances of 8 mm attenuated and 12 mm abolished the repetitive stimulation-induced SRP. Intrathecal NMDA (100 μM, 10 μl) reversed the abolition on SRP caused by anal stretch. On the other hand, pretreated bicuculline [γ-aminobutyric acid (GABA) A receptor antagonist, 100 μM, 10 μl] but not hydroxysaclofen (GABAB receptor antagonist) counteracted the abolition on the repetitive stimulation-induced SRP caused by the anal stretch. All of the results suggested that anal stretch may be used as an adjunct to assist voiding dysfunction in patients with overactive urethra sphincter and that GABAergic neurotransmission is important in the neural mechanisms underlying external urethra sphincter activity inhibited by anal stretch.

Limitations of Intrathecal Baclofen for Spastic Hemiparesis Following Stroke

Objective. Intrathecal baclofen (ITB) has become the first choice in the management of deleterious spasticity that does not respond to oral and intramuscular medications following spinal cord injury, traumatic brain injury, and cerebral palsy. The usefulness of ITB in severe spastic hemiparesis following stroke is studied. Methods. A total of 8 patients underwent clinical and video assessment following ITB bolus application (n = 5) and during continuous infusion via a temporary catheter system (n = 3). Results. The mean daily dosage alleviating spasticity on the hemiparetic side—without affecting the nonparetic side—was 119 μg/day (range 50 to 360 μg/day). However, 6 patients experienced functional deterioration as ITB weakened their paretic side such that the antigravity pattern they used for ambulation was suppressed. In 2 patients, spasticity-associated pain and spasms subsided and they underwent implantation of a long-term drug delivery system. Conclusions. ITB may reduce spasticity in a dose-dependent manner irrespective of its origin. Although not primarily antinociceptive in humans, ITB may alleviate pain if arising from increased muscle tone. A functional benefit may result if ITB can uncover “subclinical” motor control that had been suppressed by spasticity. However, when a patient uses antigravity patterns for ambulation in the absence of more complex motor control, ITB may cause the loss of residual walking ability, which becomes a major limitation for patients with hemiplegic stroke.

Suppression of detrusor-sphincter dysynergia by GABA-receptor activation in the lumbosacral spinal cord in spinal cord-injured rats

We investigated the effects of intrathecal application of GABAA- or GABAB-receptor agonists on detrusor-sphincter dyssynergia (DSD) in spinal cord transection (SCT) rats. Adult female Sprague-Dawley rats were used. At 4 wk after Th9-10 SCT, simultaneous recordings of intravesical pressure and urethral pressure were performed under an awake condition to examine the effect of intrathecal application of GABAA and GABAB agonists (muscimol and baclofen, respectively) or GABAA and GABAB antagonists (bicuculline and saclofen, respectively) at the level of L6-S1 spinal cord. In spinal-intact rats, the effects of bicuculline and saclofen on bladder and urethral activity were also examined. During urethral pressure measurements, DSD characterized by urethral pressure increases during isovolumetric bladder contractions were observed in 95% of SCT rats. However, after intrathecal application of muscimol or baclofen, urethral pressure showed urethral relaxation during isovolumetric bladder contractions. The effective dose to induce inhibition of urethral activity was lower compared with the dose that inhibited bladder contractions. The effect of muscimol and baclofen was antagonized by intrathecal bicuculline and saclofen, respectively. In spinal-intact rats, intrathecal application of bicuculline induced DSD-like changes. These results indicate that GABAA- and GABAB-receptor activation in the spinal cord exerts the inhibitory effects on DSD after SCT. Decreased activation of GABAA receptors due to hypofunction of GABAergic mechanisms in the spinal cord might be responsible, at least in part, for the development of DSD after SCT.

GABA receptor activation in the lumbosacral spinal cord decreases detrusor overactivity in spinal cord injured rats

PURPOSE

We investigated the effects of intrathecal application of gamma-aminobutyric acid A and B receptor agonists on detrusor overactivity in spinal cord injured rats.

MATERIALS AND METHODS

Adult female Sprague-Dawley rats were used. At 4 weeks after Th9-10 spinal cord transection awake cystometry and recordings of external urethral sphincter electromyogram were performed to examine the effect of intrathecal application of the gamma-aminobutyric acid A and B agonists muscimol and baclofen or the gamma-aminobutyric acid A and B antagonists bicuculline and saclofen (Tocris Cookson, Ellisville, Missouri), respectively, at the level of the L6-S1 spinal cord. The expression of glutamate decarboxylase 67 mRNA in the L6-S1 spinal cord and dorsal root ganglia was also assessed.

RESULTS

Muscimol and baclofen produced a dose dependent inhibition of the number (51% to 73% decrease) and amplitude (35% to 93% decrease) of nonvoiding bladder contractions and a decrease in micturition pressure. The effects of muscimol and baclofen were antagonized by bicuculline and saclofen, respectively. Bursting activity of external urethral sphincter electromyogram was inhibited, corresponding to the inhibition of bladder activity by muscimol and baclofen. Glutamate decarboxylase 67 mRNA levels in the spinal cord and dorsal root ganglia were decreased after spinal cord transection (55% and 84%, respectively).

CONCLUSIONS

These results indicate that gamma-aminobutyric acid A and B receptor activation in the spinal cord inhibits detrusor overactivity. The decrease in glutamate decarboxylase 67 mRNA suggests hypofunction of GABAergic inhibitory mechanisms in the spinal cord. Therefore, stimulation of spinal GABAergic mechanisms could be effective for the treatment of detrusor overactivity after spinal cord injury.

Emerging pharmacological targets in overactive bladder therapy: experimental and clinical evidences

Antimuscarinics are the mainstay of the medical therapy for overactive bladder, but their side effects and often modest success have prompted studies on novel pharmacological approaches. In this paper, we give a systematic literature review of peer-reviewed papers on the subject. Effective nonantimuscarinic treatments are currently scarce, but many new promising compounds are emerging, which target key molecular pathways involved in micturition control. The most promising potential therapeutic targets include: nervous GABAergic, glycinergic, dopaminergic, and serotonergic systems; b-adrenoceptors and cAMP metabolism; nonadrenergic-noncholinergic mechanisms such as purinergic and neuropeptidergic systems; vanilloid receptors; bladder afferent nerves; nonneuronal bladder signaling systems including urothelium and interstitial cells; prostanoids; Rho-kinase; and different subtypes of potassium and calcium channels. Despite the enormous amount of new biologic insight, very few drugs with mechanism of action other than antimuscarinics have passed as yet the proof-of-concept stage. Further preclinical and clinical studies are urgently needed in this rapidly moving field.

Effects of intrathecal baclofen on perceived sexual functioning in men with spinal cord injury

BACKGROUND/OBJECTIVE

Reports in the literature suggest that administration of intrathecal baclofen to control spasticity may have deleterious effects on erectile function in men with spinal cord injury (SCI). A prospective study was conducted to document any changes in perceived sexual function after implant of a baclofen pump.

METHODS

Seven adult men with SCI (ASIA A or B) who received intrathecal baclofen through an implantable pump for treatment of severe spasticity were followed for an average of 670 days (22.4 months) after implant. Perceived sexual function was assessed using the Brief Sexual Function Inventory. Severity of spasticity and overall health-related quality of life were also assessed.

RESULTS

Participants reported improvements in spasticity severity and overall health-related quality of life. Two of 7 participants reported some negative changes in perceived sexual function after baclofen pump implant, noted in the areas of reduced sex drive and problems with erections (frequency, rigidity, difficulty in achieving). However, most participants reported minimal effects on sexual function, and 2 participants reported marked improvement in perceived sexual function from pre- to post-implant. Analysis of changes in perceived sexual function over time suggest that problems may be associated with an increase in baclofen dose and may be reversible with a reduction in dose.

CONCLUSIONS

Intrathecal baclofen may impact perceived sexual function particularly at higher doses. However, the effects seem to be reversible with withdrawal or reduction of baclofen administration.

Sexual dysfunction associated with intrathecal baclofen use: a report of two cases

BACKGROUND/OBJECTIVE

Intrathecal baclofen is considered standard treatment for severe spasticity of spinal cord and cerebral origin. Recognized side effects include fatigue and constipation. There are few reported findings of sexual dysfunction in men and none in women.

METHODS

Two case reports.

RESULTS

A male and a female patient with spasticity treated with intrathecal baclofen were recognized to have sexual dysfunction side effects from treatment. On reduction of the intrathecal baclofen dose, complete return to baseline sexual function was achieved for both subjects.

CONCLUSIONS

Intrathecal baclofen can impair sexual function and ejaculation in some patients. Clinicians should be aware of this risk and ask about it during routine clinic follow-up for spasticity. Dosing adjustments need to be considered in these patients.

[Disorders of bladder compliance and neurogenic bladder]

Bladder compliance is defined as the relationship between change in bladder volume and change in detrusor pressure (DV/DP). The pathophysiology of neurogenic disorders of bladder compliance is still poorly understood. Experimental reduction of blood flow in the bladder wall, bilateral hypogastric nerve section in rats, the study of spinalized rat bladders, and reduction of oestrogen impregnation show that these conditions induce loss of the viscoelastic properties of the bladder. With the arrival of new treatments active on afferent and/or efferent pathways or on the central nervous system, it is very important to improve our understanding of the pathophysiology of neurogenic disorders of bladder compliance. The reversibility of these disorders constitutes a major therapeutic challenge and their functional consequences constitute a crucial prognostic element of neurogenic bladder. Disorders of bladder compliance can be assessed clinically from two points of view: 1) The natural history of onset of these disorders in neurogenic bladder. Clinical experience demonstrates certain risk factors for the development of these disorders, such as the voiding mode (intermittent self-catheterization or by a carer versus indwelling catheter), the level of the spinal cord lesion (suprasacral versus sacral, incomplete versus complete, and cauda equina lesions), and the presence of myelomeningocele. 2) Data derived from conservative management of these disorders in patients with neurogenic bladder: urethral dilatation, various types of sphincterotomy, vesical denervation, alpha-blockers, sympatholytics, vanilloids (resiniferatoxin and capsaicin), intra-detrusor botulinum toxin and intrathecal baclofen have been shown to improve disorders of compliance of neurogenic bladder.

Chapitre C-1 B - Traitement pharmacologique de l’hyperactivité détrusorienne neurologique : drogues intrathécales

Intrathecal clonidine has been tested in spinal cord injury patients not supporting or resistant to anticholinergic drugs. Although the acute effect of clonidine on urodynamic parameters was satisfactory, cardiovascular adverse effects limited the long-term efficacy of this treatment. Intrathecal baclofen has a limited effect on overactive bladder in patients with spinal spasticity, but can modify the quality of erections and induce an incapacity to trigger ejaculation by vibratory penile stimulation.

Intrathecal baclofen in the treatment of spasticity

Spasticity is a disorder of the sensorimotor system resulting in velocity-dependent increased muscle tone and tendon reflexes. Intrathecal baclofen is currently the most effective means of treating diffuse abnormal spasticity of both cerebral and spinal origin in the adult and pediatric patient. Careful patient assessment, selection and continued therapies are essential to a successful intrathecal baclofen management program. Once a patient receives a baclofen pump, close monitoring is needed for dose adjustment and pump problems. Baclofen overdose and withdrawal by either system failure or human error can cause significant side effects and be life threatening. Excellent understanding of the baclofen delivery system, programming and dose effects are needed to evaluate any patient complaints. Future uses of intrathecal pump therapy includes use of other intrathecal drugs besides baclofen (or in combination with baclofen) and the effects of placing the catheter tip at various spinal levels. At the University of Minnesota, Sister Kenny Institute and Gillette Children's Specialty Healthcare our experience has shown excellent results with this form of therapy over the last 12-16 years.

Symptomatic treatment of multiple sclerosis. Multiple Sclerosis Therapy Consensus Group (MSTCG) of the German Multiple Sclerosis Society

Besides immunomodulation and immunosuppression, the specific treatment of symptoms is an essential component of the overall management of multiple sclerosis (MS). Symptomatic treatment is aimed at the elimination or reduction of symptoms impairing the functional abilities and quality of life of the affected patients. Moreover, with symptomatic treatment the development of a secondary physical impairment due to an existing one may be avoided. Many therapeutic techniques as well as different drugs are used for the treatment of MS symptoms, but only a few of them have been investigated, especially in MS patients, and are approved by the national health authorities. Despite an overwhelming number of publications, only a few evidence-based studies exist and consensus reports are very rare, too. Therefore, it seemed necessary to develop a consensus statement on symptomatic treatment of MS comprising existing evidence-based literature as well as therapeutic experience of neurologists who have dealt with these problems over a long time. This consensus paper contains proposals for the treatment of the most common MS symptoms: disorders of motor function and coordination, of cranial nerve function, of autonomic, cognitive, and psychological functions as well as MS-related pain syndromes and epileptic seizures.

Mechanisms underlying the recovery of lower urinary tract function following spinal cord injury

The lower urinary tract has two main functions, the storage and periodic expulsion of urine, which are regulated by a complex neural control system in the brain and lumbosacral spinal cord. This neural system coordinates the activity of two functional units in the lower urinary tract: (1) a reservoir (the urinary bladder) and (2) an outlet (consisting of bladder neck, urethra and striated muscles of the pelvic floor). During urine storage the outlet is closed and the bladder is quiescent, thereby maintaining a low intravesical pressure over a wide range of bladder volumes. During micturition the outlet relaxes and the bladder contracts to promote the release of urine. This reciprocal relationship between bladder and outlet is generated by visceral reflex circuits, some of which are under voluntary control. Experimental studies in animals indicate that the micturition reflex is mediated by a spinobulbospinal pathway passing through a coordination center (the pontine micturition center) located in the rostral brainstem. This reflex pathway is in turn modulated by higher centers in the cerebral cortex that are presumably involved in the voluntary control of micturition. Spinal cord injury at cervical or thoracic levels disrupts voluntary control of voiding as well as the normal reflex pathways that coordinate bladder and sphincter functions. Following spinal cord injury, the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. Studies in animals indicate that the recovery of bladder function after spinal cord injury is dependent in part on plasticity of bladder afferent pathways and the unmasking of reflexes triggered by capsaicin-sensitive C-fiber bladder afferent neurons. The plasticity is associated with changes in the properties of ion channels and electrical excitability of afferent neurons, and appears to be mediated in part by neurotrophic factors released in the spinal cord and the peripheral target organs.

Urinary incontinence in schizophrenic patients treated with atypical antipsychotics: urodynamic findings and therapeutic perspectives

Objective The present study was a urodynamic evaluation of schizophrenic patients with urinary incontinence occurring during treatment with atypical antipsychotics Methods A total of 12 schizophrenic patients (mean age = 30.7 years, SD = 6.5) presenting urinary incontinence during treatment with atypical antipsychotics at stable doses underwent urodynamic evaluations. Clinical assessment included the administration of Positive and Negative Syndrome Scale (PANSS) Results Four patients out of 12 presented urodynamic patterns consistent with an overactive bladder, while five patients presented reduced bladder compliance; only three patients showed normal urodynamic patterns Conclusion Detrusor overactivity is a condition associated with urinary incontinence in schizophrenic patients treated with atypical antipsychotics. Urodynamic evaluations can improve our knowledge of the mechanisms that subtend atypical antipsychotic-induced incontinence, an invalidating side-effect with strong repercussion on compliance and rehabilitation in schizophrenic patients.

A benefit-risk assessment of baclofen in severe spinal spasticity

Baclofen is used for treatment of the spasticity of spinal origin that is a common sequela of spinal cord injury and multiple sclerosis; spasticity occurs in about 50% of patients affected by these disorders. In open-label studies of oral baclofen, the drug improved spasticity in 70-87% of patients; additionally, improvement in spasms was reported in 75-96% of patients. In double-blind, crossover, placebo-controlled trials, baclofen was reported to be effective, producing statistically significant improvements in spasticity. Tizanidine is the antispasticity drug that has been most widely compared with oral baclofen; studies have generally found the two drugs to have equivalent efficacy. However, tizanidine has better tolerability, in particular weakness was reported to be occur less frequently with tizanidine than with baclofen. The main adverse effects of oral baclofen include: sedation or somnolence, excessive weakness, vertigo and psychological disturbances. The incidence of adverse effects is reported to range from 10% to 75%. The majority of adverse effects are not severe; most are dose related, transient and/or reversible. The main risks of oral baclofen administration are related to withdrawal: seizures, psychic symptoms and hyperthermia can occur. These symptoms improve after the reintroduction of baclofen, usually without sequelae. When not related to withdrawal; these symptoms mainly present in patients with brain damage and in the elderly. The limited data on baclofen toxicity in patients with renal disease suggest that administration of the drug in these persons may carry an unnecessarily high risk. Intrathecal baclofen is indicated for use in patients with spasticity of spinal origin unresponsive to treatment with maximum doses of oral baclofen, tizanidine and/or dantrolene. The benefits of continuous intrathecal baclofen infusion have been demonstrated: >80% and >65% of patients have improvement in tone and spasms, respectively. The main risks of intrathecal baclofen infusion are symptoms related to overdose or withdrawal; the latter is more important because of the associated severe effects on clinical status and the possibility of death, but it is responsive to rapid treatment. Overdose primarily arises from drug test doses or human error during refill and programming of the pump, and withdrawal most commonly occurs as a result of a problem with the delivery system. Since the adverse consequences do not exceed the benefits of oral and intrathecal baclofen for patients with spinal spasticity, the benefit/risk assessment is favourable.

Delayed complications of discontinuation of intrathecal baclofen therapy: resurgence of dyssynergic voiding, which triggered off autonomic dysreflexia and hydronephrosis

STUDY DESIGN

Case report.

OBJECTIVES

To report insidious development of autonomic dysreflexia and hydronephrosis due to dyssynergic voiding following discontinuation of intrathecal baclofen therapy.

SETTING

Regional Spinal Injuries Centre, Southport, UK.

METHODS

A male patient with paraplegia at T-5 (ASIA-A) had implantation of Medtronic Synchromed 8615 s programmable pump to control intractable spasms. After 4 years, the baclofen pump needed replacement because of battery exhaustion. At this time, he was taking oxybutynin 2.5 mg twice a day. He wore a penile sheath and performed intermittent catheterisation three times a day. Intravenous urography showed no dilatation of pelvicalyceal systems or ureters. During the course of the next 4 months, the dose of baclofen had to be increased gradually to 820 microg/day in order to control the spasms. Investigations revealed disconnection of the tube from the pump. The patient decided to undergo explantation of the pump and discontinue intrathecal baclofen therapy altogether. Following removal of the pump, he was prescribed baclofen 20 mg four times a day and diazepam 5 mg twice a day. He continued penile sheath drainage with oxybutynin 2.5 mg twice a day. Although spasms were controlled with oral baclofen and diazepam, he started getting transient, mild headache during reflex voiding. After nearly 2 years, he developed unbearable and pounding headache while passing urine.

RESULTS

The dose of oxybutynin was increased to modified release formulation, 20 mg, once daily. He was prescribed modified release alfuzosin 10 mg once a day. Indwelling urethral catheter drainage was instituted. Intravenous urography showed dilation of left renal pelvis and calyces, and left ureter. After a fortnight, the dose of modified release oxybutynin was increased further to 25 mg once a day. After a month, he started performing self-catheterisation every 3 h and symptoms of autonomic dysreflexia subsided completely. A follow-up intravenous urography performed 6 months later, showed normal appearances of the left kidney.

CONCLUSION

Spinal cord injury patients, in whom intrathecal baclofen therapy is terminated, need close monitoring of their urological status. Medications, which are prescribed for neuropathic bladder, and the method of bladder drainage, may need suitable changes, as discontinuation of intrathecal baclofen therapy can result in reappearance of detrusor-sphincter dyssynergia in previously susceptible patients.

CNS involvement in overactive bladder: pathophysiology and opportunities for pharmacological intervention

The pathophysiology of overactive bladder (OAB) syndrome is complex, and involves both peripheral and CNS factors. Several CNS disorders are associated with OAB, e.g. stroke, spinal cord injury, Parkinson's disease and multiple sclerosis, and in each disorder the pathophysiology of OAB can be multifactorial. Irrespective of cause or pathophysiology of OAB, antimuscarinic drugs are the first line of pharmacological treatment. However, adverse effects and limited efficacy makes alternative therapeutic principles desirable. Most alternative drugs used for the treatment of OAB have a peripheral site of action, mainly affecting efferent or afferent neurotransmission or the detrusor muscle itself. New targets for pharmacological intervention may be found in the CNS. Several CNS transmitters/transmitter systems are known to be involved in micturition control, but few drugs with a defined CNS site of action (e.g. baclofen, imipramine and duloxetine) have been used for the treatment of voiding disorders. GABA, glutamate, opioid, serotonin, noradrenaline (norepinephrine), and dopamine receptors and mechanisms are known to influence micturition, and drugs influencing these systems could potentially be developed for the treatment of OAB. Preclinical studies in different animal models have shown that modulation of normal micturition and detrusor overactivity by drugs acting within the spinal cord or supraspinally is possible. Promising results have been obtained in such models, e.g. with drugs interfering with GABA mechanisms, serotonin 5-HT1A receptors, mu-opioid receptors and alpha-adrenoreceptors. However, considering the limited predictability of existing animal models for efficacy in humans, positive proof of concept studies in humans are mandatory. Such studies are scarce and further investigations are needed.

Spinal cord neural organization controlling the urinary bladder and striated sphincter

The storage and elimination of urine requires the coordination of activity between the autonomic nervous system (thoracolumbar sympathetic and sacral parasympathetic divisions) controlling the urinary bladder and urethra and the lumbosacral somatic motoneurons innervating the striated sphincter and pelvic floor muscles. These three efferent systems involved in the control of lower urinary tract function receive segmental sensory information from various visceral organs and the perineum, as well as inputs from supraspinal regions. Ascending and descending connections between the various spinal segments levels and supraspinal regions provide the reflex substrates participating in normal bladder continence and micturition reflexes. Many of the actions of descending and segmental reflexes are mediated by excitatory and inhibitory sacral spinal interneurons located within the region of the parasympathetic preganglionic autonomic neurons and the sphincter ventral horn motoneurons. This review will: (1) discuss the basic organization and spinal elements of the reflex pathways subserving continence and micturition; (2) describe features of the identified sacral interneuronal circuitry contributing to the control of the bladder and sphincter function; and (3) discuss how changes in the control of these reflex pathways and neurons may contribute to abnormal patterns of bladder and sphincter function commonly observed following spinal cord injury.

Effects of gamma-aminobutyrate B receptor modulation on normal micturition and oxyhemoglobin induced detrusor overactivity in female rats

PURPOSE

Using baclofen (Sigma-Aldrich, Steinheim, Germany), a gamma-aminobutyrate B (GABA(B)) receptor agonist, and CGP62349 (AstraZeneca R & D Mölndal, Sweden), a GABA(B) receptor antagonist, in a rat model of conscious micturition we addressed certain questions, including whether there is a tonic GABA(B) receptor influence on normal bladder function, how baclofen affects normal and C-fiber activated micturition, and where the sites of GABA(B) receptor action are.

MATERIALS AND METHODS

Nonanesthetized female Sprague-Dawley rats were used. The bladder was catheterized and other catheters were placed intravenously, intrathecally or intracerebroventricularly. At 3 days the rats underwent cystometric investigation in a metabolic cage. Micturition was stimulated by infusing saline intravesically. Overactivity caused by C-fiber activation was induced by intravesical oxyhemoglobin. Drugs were given intravenously, intrathecally or intracerebroventricularly. Micturition parameters were recorded and compared before and after drug administration.

RESULTS

Baclofen at doses of 0.5 microg. intrathecally and 0.3 microg. intracerebroventricularly increased bladder capacity and threshold pressure. Overflow incontinence developed in 4 of 7 rats after 0.5 microg. baclofen intrathecally and in 5 of 7 after 1 microg. baclofen intracerebroventricularly. CGP62349 at a dose of 30 microg. intrathecally and intracerebroventricularly had a stimulatory effect on micturition, which was attenuated by baclofen. While intravenous baclofen at 1 mg. (-1)kg. was devoid of effects, intravenous baclofen at 4 mg. kg. (-1)tended to decrease micturition pressure, bladder capacity and micturition volume. Infusion volume decreased significantly, demonstrating a diuretic effect, which was abolished by pretreatment with subcutaneous desmopressin at 25 ng. kg. (-1). CGP62349 at 2 mg. kg. (-1) intravenously had a stimulatory effect on micturition, which was inhibited by baclofen. Intravesical oxyhemoglobin at 250 microM. induced bladder overactivity, which was attenuated by baclofen at 4 mg. kg. (-1) intravenously and abolished by baclofen 0.5 microg intrathecally.

CONCLUSIONS

In the normal rat stimulation of GABA(B) receptors, mainly in the central nervous system, inhibits micturition. Antagonism of GABA(B) receptors stimulates micturition, suggesting that the receptors are under tonic GABAergic influence. Baclofen intrathecally attenuated oxyhemoglobin induced detrusor overactivity, suggesting that the inhibitory actions of GABA(B) receptor agonists in the spinal cord may be useful for controlling micturition disorders caused by C-fiber activation in the urothelium and/or suburothelium.

Treatment of the overactive bladder: possible central nervous system drug targets

The well-known side effects of antimuscarinic drugs have focused interest on other modalities of treatment of the overactive bladder. To effectively control bladder activity, identification of suitable targets for pharmacologic intervention is necessary. Such targets may be found in the central nervous system (CNS) or peripherally. Several CNS transmitters may modulate voiding, but few drugs with a defined CNS site of action have been developed for treatment of voiding disorders. Drugs affecting gamma-aminobutyric acid, opioid, serotonin, noradrenaline, dopamine, or glutamatergic receptors and mechanisms are known to influence micturition, and potentially such drugs could be developed for clinical use. However, a selective action on the lower urinary tract may be difficult to obtain.

Pharmacology of the lower urinary tract

The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the urinary bladder, urethra, and external urethral sphincter. This activity is in turn controlled by neural circuits in the brain, spinal cord, and peripheral ganglia. Various neurotransmitters, including acetylcholine, norepinephrine, dopamine, serotonin, excitatory and inhibitory amino acids, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in the neural regulation of the lower urinary tract. Injuries or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce voiding dysfunctions such as urinary frequency, urgency, and incontinence or inefficient voiding and urinary retention. This chapter will review recent advances in our understanding of the pathophysiology of voiding disorders and the targets for drug therapy.

Neurologic disorders affecting the anorectum

Neurologic disorders that affect the brain, spinal cord, or extrinsic innervation may present with similar symptoms and share common pathophysiology, such as rectal impaction, loss of an urge to defecate, inability to trigger a defecation sequence, obstructive defecation, or incontinence. If these symptoms are persistent or bothersome, they require treatment. The management of a patient with neurologic anorectal dysfunction depends on the underlying pathophysiologic mechanisms. Dietary advice, bowel training, pharmacotherapy, and rehabilitative treatment may be used alone or in combination.

Pharmacologic and potential biologic interventions to restore bladder function after spinal cord injury

Spinal cord injury disrupts voluntary control of voiding and the normal reflex pathways that coordinate bladder and urethral sphincter function. The present review addresses studies in animals and humans that have evaluated various therapeutic approaches for normalizing lower urinary tract function after spinal cord injury.

Treatment of overactive bladder: other drug mechanisms

The well-known side effects of antimuscarinic drugs have focused interest on other ways of treating overactive bladder. Targets for pharmacologic intervention may be found in the central nervous system (CNS) or peripherally. Several CNS transmitter systems can modulate voiding, but few drugs with a defined CNS site of action have been demonstrated to be clinically useful. The mechanism of action of imipramine, which may be effective in the treatment of overactive bladder, has not yet been clarified. Like imipramine, duloxetine is an inhibitor of serotonin (5-HT) and norepinephrine reuptake. Duloxetine has shown some promise in the treatment of urinary incontinence, but, as with the selective serotonin reuptake inhibitors, its effectiveness in the treatment of overactive bladder has not been proven. Drugs affecting norepinephrine, dopamine or gamma-aminobutyric acid (GABA) receptors and mechanisms may be useful. There is also evidence for a central site of action of alpha(1)-adrenoceptor (AR) antagonists. Traditionally, drugs for the treatment of overactive bladder have had a peripheral site of action. Drugs acting on ARs or membrane channels, as well as prostaglandin synthase inhibitors and several other agents, have been used with moderate success. However, recent developments may lead to more effective drugs, including potassium channel openers, prostaglandins, selective and nonselective inhibitors of cyclooxygenase and those acting on the beta(3)-ARs in the human detrusor. Drugs that reduce afferent activity represent an attractive therapeutic approach, and transmitters of afferent nerves and their receptors are possible targets for pharmacologic interventions.

Drug therapy for urinary incontinence

Drugs used for treatment of urinary incontinence may act on the central nervous system (CNS) or peripherally. Few drugs with a defined CNS site of action are available for treatment of urine storage disorders; most of those currently used have a peripheral site of action. To treat bladder overactivity associated with urgency and urge incontinence, antimuscarinic drugs, alpha-adrenoceptor antagonists, beta-adrenoceptor agonists, prostaglandin synthesis inhibitors, and several other agents most often developed for non-urological indications, are employed. Current treatment is based on the use of antimuscarinic drugs, and oxybutynin is, despite a high incidence of side-effects, the gold standard. Pharmacological treatment of stress incontinence has had limited success, and only alpha-adrenoceptor agonists, with and without combination with oestrogens have had a documented effect. New drugs, specifically directed at treatment of urine storage disorders, are desirable.