The basics behind bladder pain: A review of data on lower urinary tract sensations

Urothelial ATP exocytosis: regulation of bladder compliance in the urine storage phase

The bladder urothelium is more than just a barrier. When the bladder is distended, the urothelium functions as a sensor to initiate the voiding reflex, during which it releases ATP via multiple mechanisms. However, the mechanisms underlying this ATP release in response to the various stretch stimuli caused by bladder filling remain largely unknown. Therefore, the aim of this study was to elucidate these mechanisms. By comparing vesicular nucleotide transporter (VNUT)-deficient and wild-type male mice, we showed that ATP has a crucial role in urine storage through exocytosis via a VNUT-dependent mechanism. VNUT was abundantly expressed in the bladder urothelium, and when the urothelium was weakly stimulated (i.e. in the early filling stages), it released ATP by exocytosis. VNUT-deficient mice showed reduced bladder compliance from the early storage phase and displayed frequent urination in inappropriate places without a change in voiding function. We conclude that urothelial, VNUT-dependent ATP exocytosis is involved in urine storage mechanisms that promote the relaxation of the bladder during the early stages of filling.

Purinergic signalling in the urinary tract in health and disease

Purinergic signalling is involved in a number of physiological and pathophysiological activities in the lower urinary tract. In the bladder of laboratory animals there is parasympathetic excitatory cotransmission with the purinergic and cholinergic components being approximately equal, acting via P2X1 and muscarinic receptors, respectively. Purinergic mechanosensory transduction occurs where ATP, released from urothelial cells during distension of bladder and ureter, acts on P2X3 and P2X2/3 receptors on suburothelial sensory nerves to initiate the voiding reflex, via low threshold fibres, and nociception, via high threshold fibres. In human bladder the purinergic component of parasympathetic cotransmission is less than 3 %, but in pathological conditions, such as interstitial cystitis, obstructed and neuropathic bladder, the purinergic component is increased to 40 %. Other pathological conditions of the bladder have been shown to involve purinoceptor-mediated activities, including multiple sclerosis, ischaemia, diabetes, cancer and bacterial infections. In the ureter, P2X7 receptors have been implicated in inflammation and fibrosis. Purinergic therapeutic strategies are being explored that hopefully will be developed and bring benefit and relief to many patients with urinary tract disorders.

Descriptors of sensation confirm the multidimensional nature of desire to void

AIMS

To collect and categorize descriptors of "desire to void" sensation, determine the reliability of descriptor categories and assess whether descriptor categories discriminate between people with and without symptoms of overactive bladder.

METHODS

This observational, repeated measures study involved 64 Australian volunteers (47 female), aged 50 years or more, with and without symptoms of overactive bladder. Descriptors of desire to void sensation were derived from a structured interview (conducted on two occasions, 1 week apart). Descriptors were recorded verbatim and categorized in a three-stage process. Overactive bladder status was determined by the Overactive Bladder Awareness Tool and the Overactive Bladder Symptom Score. McNemar's test assessed the reliability of descriptors volunteered between two occasions and Partial Least Squares Regression determined whether language categories discriminated according to overactive bladder status. Post hoc Chi squared analysis and relative risk calculation determined the size and direction of overactive bladder prediction.

RESULTS

Thirteen language categories (Urgency, Fullness, Pressure, Tickle/tingle, Pain/ache, Heavy, Normal, Intense, Sudden, Annoying, Uncomfortable, Anxiety, and Unique somatic) encapsulated 344 descriptors of sensation. Descriptor categories were stable between two interviews. The categories "Urgency" and "Fullness" predicted overactive bladder status. Participants who volunteered "Urgency" descriptors were twice as likely to have overactive bladder and participants who volunteered "Fullness" descriptors were almost three times as likely not to have overactive bladder.

CONCLUSIONS

The sensation of desire to void is reliably described over sessions separated by a week, the language used reflects multiple dimensions of sensation, and can predict overactive bladder status.

Retinoid signaling in progenitors controls specification and regeneration of the urothelium

The urothelium is a multilayered epithelium that serves as a barrier between the urinary tract and blood, preventing the exchange of water and toxic substances. It consists of superficial cells specialized for synthesis and transport of uroplakins that assemble into a tough apical plaque, one or more layers of intermediate cells, and keratin 5-expressing basal cells (K5-BCs), which are considered to be progenitors in the urothelium and other specialized epithelia. Fate mapping, however, reveals that intermediate cells rather than K5-BCs are progenitors in the adult regenerating urothelium, that P cells, a transient population, are progenitors in the embryo, and that retinoids are critical in P cells and intermediate cells, respectively, for their specification during development and regeneration. These observations have important implications for tissue engineering and repair and, ultimately, may lead to treatments that prevent loss of the urothelial barrier, a major cause of voiding dysfunction and bladder pain syndrome.

Induction of inflammatory cytokines and alteration of urothelial ATP, acetylcholine and prostaglandin E2 release by doxorubicin

Intravesical treatment with cytotoxic drugs such as doxorubicin is associated with local adverse effects in bladder cancer patients. Here we investigate the effects of doxorubicin on urothelial release of ATP, acetylcholine and prostaglandin E(2), and production of inflammatory cytokines. Urothelial cells were treated with doxorubicin for 1h at 37 °C. Immediately or 24 h following treatment the level of ATP, acetylcholine and prostaglandin E(2) released under basal and stimulated conditions was measured and compared to release from vehicle treated control cultures. The presence of inflammatory cytokines, in culture medium was also assessed 24 h after doxorubicin pre-treatment. Immediately following treatment, stimulated ATP release was inhibited at doxorubicin concentrations ≥1 μg/ml and showed partial recovery at 24 h. Immediately following treatment, basal acetylcholine release was increased by doxorubicin at its clinical concentration (1 mg/ml), while a concentration-dependent decrease in stimulated acetylcholine release was observed. Twenty four hour after treatment, basal acetylcholine release was increased in culture treated with 0.01 mg/ml doxorubicin while stimulated acetylcholine release remained depressed. A significant increase in prostaglandin E(2) release was observed in cells immediately and 24 h after treatment with doxorubicin. A 5.5- and 2-fold increase in interleukin -8 and -1β secretion, respectively was detected 24 h following doxorubicin treatment. These findings indicate that inflammatory cytokines interleukin-8 and -1β are induced and urothelial mediator release is affected by treatment with doxorubicin at clinically relevant concentrations and durations of treatment. These changes may play a role in the adverse effects associated with intravesical doxorubicin treatment.

Morphologic indication for proprioception in the human ciliary muscle

PURPOSE

To search for proprioceptive nerve terminals in human ciliary muscle.

METHODS

In 48 human donor eyes, histologic and ultrathin sections cut in different planes and wholemounts of the ciliary muscle were studied. Immunohistochemical staining with antibodies against pan-neuronal antigens and antigens reported as markers for sensory terminals in other organs was performed.

RESULTS

Among the markers for proprioceptive terminals, only calretinin was present in the ciliary body. Calretinin-immunoreactive (IR) nerve terminals surrounded the posterior and reticular ciliary muscle tips and their elastic tendons. Terminals in that region contained mitochondria and neurofilaments. At the anterior tips larger terminals with numerous membrane-filled vesicles were located between the muscle fibers. The most elaborate network of calretinin-IR nerve fibers was present in the ground plate covering the circular muscle portion. Here calretinin-IR neurons with morphologic features of mechanoreception were present. Within the circular muscle portion numerous calretinin-IR ganglion cells were found. Their processes were connected to the calretinin-IR network but also surrounded ciliary muscle cells and NADPH-diaphorase-positive ganglion cells.

CONCLUSIONS

These morphologic findings indicate that there are proprioreceptors in the ciliary muscle that morphologically and presumably functionally differ at different locations. At the posterior muscle tips, the receptors could measure stretch of the tendons, whereas the large receptor organs located at the anterior muscle tips morphologically resemble mechanoreceptors measuring shear stress. The presence of the numerous intrinsic nerve cells indicates that contraction of the circular muscle portion can be modulated locally via a self-contained reflex arc.

Biofilm and other causes of pain in catheterization

This article looks at the anatomy of the bladder and how sensations, including pain, are transmitted to the brain. The use of urinary catheters is discussed and initially, the development of biofilm is addressed, from its cause, structure and effect, to how it can be treated. Many of the problems arising from biofilm and the resulting encrustation, can lead to pain, and the causes of this are discussed. Other problems which can cause patients to experience pain are also considered, and where there are possible solutions, these have been put forward. However, even when good practice is carried out, there will still be problems encountered, and further research is needed.

Brain responses during the first desire to void: a positron emission tomography study

OBJECTIVES

First desire to void (FDV) is defined as the first feeling that would lead the patient to pass urine. The aim of the present study is to identify the brain regions activated during FDV.

METHODS

Six healthy right-handed male volunteers, aged 31-40 years, agreed to participate in this study. Rather than inserting a urethral catheter, we used a urinary volume monitoring unit and a self-adhesive external condom catheter for this study. Positron emission tomography (PET) scans obtained in the FDV and post-voiding (absence of urge to void) (REST) states were analyzed and compared.

RESULTS

First desire to void state was associated with increased blood flow in the right and left cerebellum, right parahippocampal gyrus (Brodmann area [BA] 30), left superior frontal gyrus (BA9), and left cingulate gyrus (BA32). Rest state was associated with decreased blood flow in the right superior temporal gyrus (BA22), right uncus (BA28), right cingulate gyrus (BA32), left middle temporal gyrus (BA21), and left medial frontal gyrus (BA25). According to region of interest analysis, regional cerebral blood flow of the periaqueductal grey and pons was significantly increased at FDV as opposed to REST.

CONCLUSIONS

We located possible brain activity associated with the FDV sensation. Combined activation of the right and left cerebellum, parahippocampal gyrus, superior frontal gyrus, and left cingulate gyrus could be associated with FDV.

The effects of tolterodine on bladder-filling sensations and perception thresholds to intravesical electrical stimulation: method and initial results

OBJECTIVES

To study the effects of the antimuscarinic agent tolterodine on the perception thresholds to intravesical electrical stimulation (IES) and the effects of the drug on subjective bladder sensation during normal filling cystometry in healthy female volunteers.

SUBJECTS AND METHODS

In seven healthy women IES was applied at 2.5 Hz (pulse width 10 ms, protocol 1), 2.5 Hz (pulse width 0.2 ms, protocol 2), and 250 Hz (pulse width 0.2 ms, protocol 3). Sensory perception thresholds were obtained using electric currents in 0.5 mA steps. Afterwards the bladder was filled and the first bladder-filling sensation, first desire to void, strong desire to void and urge to void were recorded. The bladder was then emptied, the volume measured and subjects were checked for residual urine by ultrasonography. The subjects then received 4 mg of tolterodine and the entire protocol was repeated 2 h afterward. The perception thresholds for IES and bladder sensation levels obtained at baseline were compared statistically with the corresponding values after tolterodine.

RESULTS

Tolterodine significantly increased perception thresholds to IES for all three protocols (P = 0.027, 0.018 and 0.018, respectively). The drug had no effect on the filling levels for the corresponding bladder sensation.

CONCLUSION

Oral tolterodine significantly increased the perception threshold to IES in healthy women; there was no effect on subjective bladder sensations during cystometry.

[Sensory innervation of the bladder: clinical and therapeutic implications]

Sensory impulses derived from the bladder and urinary sphincter system play an important role in the control of detrusor-sphincter function. Conscious sensation is essential to ensure the storage phase and to allow micturition at a functionally and socially acceptable time. Adequate sensation of the lower urinary tract requires an intact urothelium--peripheral nervous system--spinal cord--brain stem--midbrain--sensory cortex axis. This article reviews the current anatomical, physiological and pathophysiological knowledge concerning the afferent (sensory) nerve pathways of the bladder and urethra, with particular emphasis on their physiological and therapeutic implications.

Pain during ice water test distinguishes clinical bladder hypersensitivity from overactivity disorders

Background

The Bladder cooling reflex (BCR) i.e. uninhibited detrusor contractions evoked by intravesical instillation of cold saline, is a segmental reflex believed to be triggered by menthol sensitive cold receptors in the bladder wall, with the afferent signals transmitted by C fibres. The BCR is a neonatal reflex that becomes suppressed by descending signals from higher centres at approximately the time when the child gains full voluntary control of voiding. It re-emerges in adults with neurogenic detrusor overactivity as a consequence of loss of central descending inhibition, resulting from conditions such as spinal cord injury or multiple sclerosis. We have recently shown an increase of nerve fibres expressing the cool and menthol receptor TRPM8 in both overactive (IDO) and painful bladder syndrome (PBS), but its functional significance is unknown. We have therefore studied the bladder cooling reflex and associated sensory symptoms in patients with PBS and overactivity disorders.

Methods

The BCR, elicited by ice water test (IWT) was performed in patients with painful bladder syndrome (PBS, n = 17), idiopathic detrusor overactivity (IDO, n = 22), neurogenic detrusor overactivity (NDO, n = 4) and stress urinary incontinence (as controls, n = 21). The IWT was performed by intravesical instillation of cold saline (0 – 4°C). A positive IWT was defined as presence of uninhibited detrusor contraction evoked by cold saline, associated with urgency or with fluid expulsion. Patients were asked to report and rate any pain and cold sensation during the test.

Results

A positive IWT was observed in IDO (6/22, 27.3%) and NDO (4/4, 100%) patients, but was negative in all control and PBS patients. Thirteen (76.5%) PBS patients reported pain during the IWT, with significantly higher pain scores during ice water instillation compared to the baseline (P = 0.0002), or equivalent amount of bladder filling (100 mls) with saline at room temperature (P = 0.015). None of the control or overactive (NDO/IDO) patients reported any pain during the IWT.

Conclusion

The BCR in DO may reflect loss of central inhibition, which appears necessary to elicit this reflex; the pain elicited in PBS suggests afferent sensitisation, hence sensory symptoms are evoked but not reflex detrusor contractions. The ice water test may be a useful and simple marker for clinical trials in PBS, particularly for novel selective TRPM8 antagonists.

Regional Cancer Pain Syndromes

Cancer pain often presents in a body region. This review summarizes articles from 1999-2004 relevant to cancer pain syndromes in the head and neck, chest, back, abdomen, pelvis, and limbs. Although the evidence is limited, progress is being made in further development of the evidence base to support and guide current practice.

Sensory bladder disorders

Sensory bladder disorders include disorders involving abnormal sensations resulting from many diseases of the urinary bladder. In a proportion of patients no cause can be found and if pain or pelvic pressure is a part of the symptomatology, they are labelled as having painful bladder syndrome (PBS). In a subgroup of these patients abnormal findings can be demonstrated at cystoscopy and/or by histological examination of bladder biopsies. These patients are categorised as having interstitial cystitis (IC). This paper looks into the differential diagnosis, evaluation and treatment of patients with PBS.

Transient receptor potential vanilloid receptor subtype 1 in painful bladder syndrome and its correlation with pain

PURPOSE

Painful bladder syndrome is a chronic, debilitating bladder hypersensitivity disorder characterized by urinary frequency, urgency and bladder pain without an identifiable cause. Recent advances in understanding the molecular basis of hypersensitivity provide an opportunity to advance the understanding of and treatment for painful bladder syndrome. We studied the heat and capsaicin receptor transient receptor potential vanilloid receptor subtype 1 in the bladder in patients with painful bladder syndrome and their relationship to pain symptoms.

MATERIALS AND METHODS

Bladder biopsies were obtained from 20 characterized subjects with painful bladder syndrome and 25 with asymptomatic microscopic hematuria as controls. Specimens were immunostained using specific antibodies to transient receptor potential vanilloid receptor subtype 1 and neurofilaments as a structural maker. Nerve fiber and urothelial staining were quantified with computerized image analysis. The results of immunohistochemistry were correlated with the pain score.

RESULTS

There was a marked increase in suburothelial nerve fibers expressing transient receptor potential vanilloid receptor subtype 1 in painful bladder syndrome in comparison with that in controls (p <0.0001). The ratio of transient receptor potential vanilloid receptor subtype 1 fibers to neurofilaments was also significantly increased in painful bladder syndrome, suggesting over expression of transient receptor potential vanilloid receptor subtype 1 (p <0.0001). When all specimens studied were included, the pain score correlated significantly with the relative nerve fiber density of transient receptor potential vanilloid receptor subtype 1 in the suburothelium (r = 0.6862, p = 0.0002) as well as the ratio of transient receptor potential vanilloid receptor subtype 1 fibers to neurofilaments (r = 0.5554, p = 0.004). Urothelial transient receptor potential vanilloid receptor subtype 1 showed a tendency toward an increase in the painful bladder syndrome group but it did not achieve statistical significance. No correlation was found between transient receptor potential vanilloid receptor subtype 1 immunoreactivity of urothelium or neurofilament fibers and the pain score.

CONCLUSIONS

This study shows increased transient receptor potential vanilloid receptor subtype 1 in nerve fibers of the bladder in painful bladder syndrome and a correlation of the pain score with the relative density of transient receptor potential vanilloid receptor subtype 1 nerve fibers. Transient receptor potential vanilloid receptor subtype 1 may have a role in the pathophysiology of painful bladder syndrome and it is a potential target for novel therapeutic agents.

Purinergic P2 receptors as targets for novel analgesics

Following hints in the early literature about adenosine 5'-triphosphate (ATP) injections producing pain, an ion-channel nucleotide receptor was cloned in 1995, P2X3 subtype, which was shown to be localized predominantly on small nociceptive sensory nerves. Since then, there has been an increasing number of papers exploring the role of P2X3 homomultimer and P2X2/3 heteromultimer receptors on sensory nerves in a wide range of organs, including skin, tongue, tooth pulp, intestine, bladder, and ureter that mediate the initiation of pain. Purinergic mechanosensory transduction has been proposed for visceral pain, where ATP released from epithelial cells lining the bladder, ureter, and intestine during distension acts on P2X3 and P2X2/3, and possibly P2Y, receptors on subepithelial sensory nerve fibers to send messages to the pain centers in the brain as well as initiating local reflexes. P1, P2X, and P2Y receptors also appear to be involved in nociceptive neural pathways in the spinal cord. P2X4 receptors on spinal microglia have been implicated in allodynia. The involvement of purinergic signaling in long-term neuropathic pain and inflammation as well as acute pain is discussed as well as the development of P2 receptor antagonists as novel analgesics.

Pathophysiology and therapeutic potential of purinergic signaling

The concept of a purinergic signaling system, using purine nucleotides and nucleosides as extracellular messengers, was first proposed over 30 years ago. After a brief introduction and update of purinoceptor subtypes, this article focuses on the diverse pathophysiological roles of purines and pyrimidines as signaling molecules. These molecules mediate short-term (acute) signaling functions in neurotransmission, mechanosensory transduction, secretion and vasodilatation, and long-term (chronic) signaling functions in cell proliferation, differentiation, and death involved in development and regeneration. Plasticity of purinoceptor expression in pathological conditions is frequently observed, including an increase in the purinergic component of autonomic cotransmission. Recent advances in therapies using purinergic-related drugs in a wide range of pathological conditions will be addressed with speculation on future developments in the field.

Intravesical instillation of human urine after oral administration of trospium, tolterodine and oxybutynin in a rat model of detrusor overactivity

OBJECTIVE

To study the effects of antimuscarinics excreted into human urine on normal bladder in a rat model of detrusor overactivity.

MATERIALS AND METHODS

Two 'normal' adult volunteers collected voided urine after taking trospium (20 mg, twice daily), tolterodine LA (4 mg, four times daily), or oxybutynin XL (10 mg, four times daily). The drugs were taken in a random order for 5 days with a 7-day washout period between the drugs. The urine collected from the two volunteers was mixed together and then blindly labelled and used for testing. Control human urine (no oral antimuscarinics) was also used. The effect of intravesical administration of human urine on carbachol-induced bladder overactivity was studied in female Sprague-Dawley rats anaesthetised with urethane. Cystometric variables during continuous infusion (0.04 mL/min) for >1 h each of saline, human urine, then a mixture of carbachol (30 microm) and human urine were compared in the four groups (control and the three different antimuscarinics tested; six rats per group).

RESULTS

Human urine, with or with no intake of antimuscarinic agents, had no effect on normal bladder function. Bladder capacity and intercontraction intervals were significantly decreased after adding carbachol to urine containing vehicle, tolterodine or oxybutynin. However, urine collected from the humans who had taken trospium prevented the carbachol-induced reduction in bladder capacity and intercontraction intervals. Maximum voiding pressure and pressure threshold were not changed in any case.

CONCLUSION

This is the first report that the urine excreted after oral ingestion of trospium (20 mg, twice daily) has a significant inhibitory effect in a rat model of detrusor overactivity. This suggests that antimuscarinic agents have a local bladder effect during the bladder-storage phase in addition to the smooth muscle-mediated voiding phase.

Peptidergic sensory and parasympathetic fiber sprouting in the mucosa of the rat urinary bladder in a chronic model of cyclophosphamide-induced cystitis

In this study, we used a well-established animal model to investigate changes in the peptidergic and parasympathetic innervation of the bladder following chronic bladder inflammation. Adult female Sprague-Dawley rats were injected with either 70 mg/kg cyclophosphamide diluted in saline, i.p., once every 3 days or saline. After 10 days, all animals were tested for urinary frequency and number of low volume voids, as well as symptoms of spontaneous pain. At the end of 12 days, all animals were perfused with histological fixatives and the urinary bladders processed for immunofluorescence using antibodies against calcitonin gene-related peptide and the vesicular acetylcholine transporter as markers, respectively, of peptidergic primary afferent fibers and parasympathetic efferent fibers. We show that animals treated with cyclophosphamide had inflamed bladders and displayed high urinary frequency as well as some indicators of spontaneous pain, such as piloerection and a rounded-back posture. Furthermore, they had a significant increase in the density of both parasympathetic and peptidergic sensory fibers in the bladder mucosa and an increase in peptidergic sensory fibers in the detrusor muscle. Based on these results, we suggest that peripheral sprouting of parasympathetic and peptidergic fibers could be a mechanism responsible for sensitization of the bladder, leading to urinary symptoms. Since we observed that the parasympathetic and peptidergic fibers often wrapped around one another and that their varicosities were very close, these two fiber populations may be interacting with each other to lead to and maintain sensitization. Future studies are required to establish the role of this fiber sprouting in bladder symptoms.

Peptidergic sensory and parasympathetic fiber sprouting in the mucosa of the rat urinary bladder in a chronic model of cyclophosphamide-induced cystitis

In this study, we used a well-established animal model to investigate changes in the peptidergic and parasympathetic innervation of the bladder following chronic bladder inflammation. Adult female Sprague-Dawley rats were injected with either 70 mg/kg cyclophosphamide diluted in saline, i.p., once every 3 days or saline. After 10 days, all animals were tested for urinary frequency and number of low volume voids, as well as symptoms of spontaneous pain. At the end of 12 days, all animals were perfused with histological fixatives and the urinary bladders processed for immunofluorescence using antibodies against calcitonin gene-related peptide and the vesicular acetylcholine transporter as markers, respectively, of peptidergic primary afferent fibers and parasympathetic efferent fibers. We show that animals treated with cyclophosphamide had inflamed bladders and displayed high urinary frequency as well as some indicators of spontaneous pain, such as piloerection and a rounded-back posture. Furthermore, they had a significant increase in the density of both parasympathetic and peptidergic sensory fibers in the bladder mucosa and an increase in peptidergic sensory fibers in the detrusor muscle. Based on these results, we suggest that peripheral sprouting of parasympathetic and peptidergic fibers could be a mechanism responsible for sensitization of the bladder, leading to urinary symptoms. Since we observed that the parasympathetic and peptidergic fibers often wrapped around one another and that their varicosities were very close, these two fiber populations may be interacting with each other to lead to and maintain sensitization. Future studies are required to establish the role of this fiber sprouting in bladder symptoms.

[Afferent pathways arising from the lower urinary tract. Physiology, pathophysiology, and clinical implications]

Voluntary control of bladder function is mainly influenced by sensations arising from the lower urinary tract. Conscious perception of these sensations is imperative for appropriate urine storage and voiding at a socially accepted time and place and depends on the integrity of the afferent axis urothelium -- peripheral nerves -- spinal cord -- pons -- mesencephalon -- sensory cortex. This review considers the current knowledge about normal and impaired sensations arising from the bladder and the sphincter and addresses their clinical significance.

Interstitial cystitis: how should we diagnose it and treat it in 2004?

PURPOSE OF REVIEW

During the last 2 years, two international and two European meetings have taken place and a European Society formed dealing only with interstitial cystitis. A separate committee for interstitial cystitis was formed during the last WHO International Consensus Meeting on urinary incontinence. As a consequence, new concepts and recommendations are evolving, for example the nomenclature is changing from interstitial cystitis to painful bladder syndrome/interstitial cystitis.

RECENT FINDINGS

At an international meeting in Kyoto, the scientific basis for diagnosis and treatment of painful bladder syndrome/interstitial cystitis was reviewed, confirming the poor evidence for many diagnostic procedures and treatments. There are two main reasons for this: an internationally accepted definition is lacking and the disease is rare, making clinical trials difficult. A meeting in Copenhagen resulted in a standardization of the procedures for evaluation and the creation of a European Society for the Study of Interstitial Cystitis. Increased concentration of nitric oxide in the urine of patients with Hunner's ulcer may help to separate ulcer from non-ulcer patients. A prospective, randomized, placebo-controlled multicenter study failed to show a statistically significant effect of the antihistamine hydroxine or pentosan polysulfate sodium compared with placebo. The study confirmed the difficulties in recruiting patients for large-scale trials, which could be one of the reasons for the negative result. The effect of the traditional treatment with amitriptyline was confirmed in a prospective, placebo-controlled study.

SUMMARY

Standardized evaluation of patients with painful bladder syndrome/interstitial cystitis will benefit both patients and science. An internationally accepted definition of the condition appears to be in sight, which will make epidemiological and research studies easier.