Bladder pain syndrome/interstitial cystitis response to nerve blocks and trigger point injections

Abstract Objectives Bladder pain syndrome (BPS)/interstitial cystitis (IC) is a debilitating condition characterised by bladder/pelvic pain and pressure as well as persistent or recurrent urinary symptoms in the absence of an identifiable cause. It is hypothesised that in addition to organ specific visceral hypersensitivity, contributions of the hypertonic pelvic floor, peripheral sensitisation, and central sensitisation exacerbate this condition. The aim of this paper is to investigate outcomes of treating underlying neuromuscular dysfunction and neuro‐plastic mechanisms in BPS/IC patients. Methods A retrospective chart review of 84 patients referred to an outpatient pelvic rehabilitation centre with a diagnosis of BPS/IC given to them by a urologist. All 84 patients failed to progress after completing 6 weeks of pelvic floor physical therapy and underwent an institutional review board approved protocol (IRB# 17‐0761) consisting of external ultrasound‐guided trigger point injections to the pelvic floor musculature, peripheral nerve blocks of the pudendal and posterior femoral cutaneous nerves and continued pelvic floor physical therapy once weekly for 6 weeks. Pelvic pain intensity and functionality were measured pretreatment and 3 months posttreatment using Visual Analogue Scale (VAS) and Functional Pelvic Pain Scale (FPPS). Results Pretreatment, mean VAS was 6.23 ± 2.68 (95% CI 5.65 to 6.80). Posttreatment mean VAS was 3.90 ± 2.63 (95% CI 3.07–4.74). Mean FPPS before treatment was 11.98 ± 6.28 (95% CI 10.63 to 13.32). Posttreatment mean FPPS was 7.68 ± 5.73 (95% CI 6.45–8.90). Analysis of subcategories within FPPS indicated highest statistically significant improvement in the categories of bladder, intercourse and working. Conclusions Analysis suggests the treatment was effective at ameliorating bladder pain and function including urinary urgency, frequency, and burning in BPS/IC patients.


| INTRODUCTION
Bladder pain syndrome (BPS)/interstitial cystitis (IC) is defined by the International Continence Society as 'Persistent or recurrent chronic pelvic pain, pressure or discomfort perceived to be related to the urinary bladder accompanied by at least one other urinary symptom such as an urgent need to void or urinary frequency'. 1 Accurate nomenclature is still being developed; its aetiology is unknown and treatments are empirical and unsatisfactory. For the purposes of this paper, BPS/IC will be the constant nomenclature.
Prevalence approximations differ depending on procedures chosen to classify BPS/IC and diagnostic criteria. In older studies, prevalence of BPS/IC was comparatively rare (18.1/100 000 women and 10.6/100 000 men), and newer studies demonstrate a greater occurrence (52-197/100 000 women and 40-70/100 000 men) when physicians made the diagnosis. Estimates of patient self-reports are much higher at 501-865/100 000 patients. 2 Diagnosis is challenging because patients presenting with BPS/IC experience other unrelated disorders such as irritable bowel syndrome, fibromyalgia, chronic fatigue syndrome, and anxiety disorders in addition to their urinary bladder symptoms. 3 Thus, selecting the appropriate treatment becomes difficult. Traditional treatments focus on the bladder, considering it as the source of pain and primary end organ. The multifaceted nature of BPS/IC however demands a systemic approach including non-pharmacological treatment, conservative treatments, neuromodulators, and anti-inflammatories to name a few. 4 Non-pharmacological treatments that utilise pelvic floor physical therapy and acupuncture to manage BPS/IC patients' hypertonic pelvic floor muscle dysfunction are traditionally recommended as first line treatments. 5 Conservative treatments include behavioural and diet improvements, psychological distress management, and urogynecological exercises. 6 Neuromodulators including tricyclic antidepressants alleviate bladder symptoms through their anticholinergic effects. 5 Anti-inflammatories like lidocaine control the pain and inflammation, allowing the neuropathic bladder to gradually return to its regular state by altering the neural pathways to prevent sending faulty signals. 7 This investigation aims to establish the efficiency of an outpatient ultrasound-guided peripheral nerve block and trigger-point injection protocol aimed at treating the central neuro-plastic mechanisms involved in BPS/IC known as (1) peripheral sensitisation and its associated neurogenic inflammation, (2) central sensitisation and (3) pelvic floor hypertonia. 8 Central sensitisation results from increased membrane excitability and synaptic efficacy. This indicates neuro-plastic changes in the central nervous system (CNS) and peripheral nervous system (PNS) in response to the inflammation, activity and potential neural injury seen in BPS/IC patients. 9 Therefore, decreasing ectopic peripheral nociceptor activity and neurogenic inflammation with serial peripheral nerve blocks will ultimately decrease excessive peripheral neuronal input to the CNS and reverse the central sensitisation process. Pelvic floor hypertonia in BPS/IC patients causes neural ischemia around the peripheral pelvic nerves that contributes to the peripheral neurogenic sensitisation process. 10 Therefore, it is essential to also address the pelvic floor hypertonia. This study was conducted to provide evidence for the efficacy of our outpatient neuromuscular protocol in treating patients with BPS/IC.  Table 1, and previous medica-   to progress after completing 6 weeks of pelvic floor physical therapy and underwent an institutional review board approved protocol (IRB# 17-0761) consisting of external ultrasound-guided trigger point injections using 1 cc of Lidocaine 1% to the pelvic floor muscular structure.

| Procedures
Once weekly, for 6 weeks throughout the protocol, a global injection was administered into the iliococcygeus, pubococcygeus and puborectalis one side at a time. 11 Therefore, each muscle of the leva-  The statistical significance between VAS and FPPS scores before and after our protocol was determined using a paired t test (Table 2) following a Shapiro-Wilks test for normality. Descriptive statistics data are presented as mean AE standard deviation with a 95% confidence interval. The sensitivity of our correlations is depicted via error bars in Figure 3.

| RESULTS
Eighty-four patients underwent ultrasound-guided, pelvic floor trigger point injections and peripheral nerve blocks; 41.1 AE 14.12 years was the average age of the 84 patients analysed, and 5.33 AE 5.58 years was the average period of pelvic pain. This is shown in Table 1. Statistically significant improvements were seen in all categories. Table 2 and Figure 3B summarise these results.    Multiple expert panels such as the American Urological Association, 7 International Consultation on Incontinence, 23 European Society for the Study of BPS (ESSIC) 24 and European Association of Urology 2 consider bladder pain and the existence of one other urinary symptom as diagnostic criteria for BPS/IC. 24 Our study indicated the bladder category achieved the highest statistically significant improvement demonstrating the effect our protocol has on bladder pain and function in BPS/IC patients. A potential reason for this is the bladder neck no longer sits on a spastic pelvic floor preventing dysfunctional voiding caused by a hypertonic pelvic floor. 25 In addition, there is noteworthy indication that afferent hyperexcitability due to neurogenic bladder inflammation and urothelial dysfunction is the source of pain sensation as the increased afferent activity demonstrates a major surge in the quantity of nerve fibres expressing substance P. 26 The substance P expression may decrease as we address underlying neurogenic inflammation. The recurring contact to the anaesthetic lidocaine 1% in our protocol successfully downregulated bladder sensory nerves. 26 Nocturia is one of the main symptoms that characterises BPS/IC, 26

| Limitations
A limitation of the study is the retrospective nature that prevents ran-