Small Fiber Polyneuropathy Is Associated With Non-Bladder-Centric Interstitial Cystitis/Bladder Pain Syndrome Patients

Latent bladder hypersensitivity induced by neonatal cystitis in rats unmasked by segmental but not hetero-segmental inflammation

Rats which experienced neonatal bladder inflammation (NBI) have been demonstrated to exhibit latent bladder hypersensitivity with a nociceptive component that becomes unmasked by a second inflammatory insult as an adult. Manifested as augmented reflex and neuronal responses to urinary bladder distension (UBD), these NBI-induced changes are revealed by using inflammation of nearby structures as an adult pretreatment. The effect of inflammation in distant structures is not known. These studies examined visceromotor reflex responses and lumbosacral spinal dorsal horn neuronal responses to UBD in rats and compared effects of segmental (hindpaw) versus hetero-segmental (forepaw or face) inflammatory pretreatments in 192 female Sprague-Dawley rats raised from birth. On postnatal days 14-16 these rats underwent either NBI or control procedures. As adults, these rats received control injections or 0.1 ml Complete Freund's Adjuvant (CFA) injections into one of four sites. Three days later they were studied in reflex or spinal single-cell neuronal experiments where responses were evoked by UBD. Visceromotor responses to UBD were more robust in rats which had injections in the hindpaw (either side) but were not significantly affected by forepaw or facial injections. Similar results were identified in L6/S1 neurons with more robust UBD-evoked responses observed in rats receiving hindpaw CFA injections but not forepaw injections. These results indicate that latent bladder hypersensitivity induced by NBI is made manifest by segmental, but not hetero-segmental inflammatory stimuli. This observation correlates with pain in patients with interstitial cystitis who often have flares in symptoms associated with inflammation of nearby structures.

Small-Fiber Polyneuropathy Is Prevalent in Patients With Interstitial Cystitis/Bladder Pain Syndrome

IMPORTANCE

The pathophysiology of interstitial cystitis/bladder pain syndrome (IC/BPS) is imperfectly understood. Recent studies reported that small-fiber polyneuropathy (SFPN) is common in fibromyalgia, a condition commonly comorbid with IC/BPS.

OBJECTIVE

The objective of this study was to determine the prevalence of SFPN in a large cohort of IC/BPS patients.

METHODS

Adults diagnosed with IC/BPS scheduled to undergo either therapeutic hydrodistention (n = 97) or cystectomy with urinary diversion (n = 3) were prospectively recruited to this study. A skin biopsy obtained from the lower leg was used for intraepidermal nerve fiber density measurement. Small-fiber polyneuropathy (+/-) status was determined by comparing linear intraepidermal nerve fiber density (fibers/mm2) with normative reference values. Demographic information, medical history, and diagnoses for 14 conditions (both urologic and nonurologic) known to co-occur with IC/BPS were documented from self-report and electronic medical record.

RESULTS

In this large cohort of patients with IC/BPS, 31% (31/100) were positive for SFPN. Intraepidermal nerve fiber density was below the median for age and sex in 81% (81/100) of patients. Approximately one-third (31%) of SFPN+ patients reported co-occurring chronic fatigue syndrome, compared with 10.6% of the SFPN- group (P = 0.034). Small-fiber polyneuropathy-positive patients reported significantly fewer allergies than SFPN- patients (37.9% vs 60.6%; P = 0.047). There were no significant differences in bladder capacity or Hunner lesion status between the SFPN+ and SFPN- subgroups.

CONCLUSIONS

Small-fiber polyneuropathy is a common finding in patients with IC/BPS, and SFPN status is significantly correlated with co-occurring chronic fatigue syndrome and negatively correlated with the presence of allergies in this population.

Small Fiber Polyneuropathy May Be a Nexus Between Autonomic Nervous System Dysregulation and Pain in Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a highly heterogeneous chronic and debilitating condition which effects millions of women and men in the United States. While primarily defined by urinary symptoms and pain perceived to be emanating from the bladder, IC/BPS patients frequently have co-occurring conditions and symptoms, many of which affect diverse body systems related to autonomic nervous system function. The impact on the autonomic system appears to stem from increased sympathetic innervation of the urinary tract, along with increased systemic sympathetic tone and decreased parasympathetic tone. Concurrent with these findings is evidence for destruction of peripheral sympathetic innervation to the sweat glands which may relate to small fiber polyneuropathy. It is unknown to what degree the wider alterations in autonomic function are also related to destruction/alterations in the small fibers carrying autonomic innervation. This potential nexus is an important point of investigation to better understand the unclarified pathophysiology of interstitial cystitis/bladder pain syndrome, the numerous co-occurring symptoms and syndromes, and for the identification of novel targeted therapeutic strategies.

Urodynamic autonomic bladder dysfunction in women with complex chronic pelvic pain is associated with small fiber polyneuropathy

AIMS

Small fiber neuropathy/polyneuropathy (SFN) has been found to be present in 64% of complex (refractory or multisystem) chronic pelvic pain (CPP) patients. The small fiber dysfunction seen in SFN can negatively impact autonomic control of micturition in addition to pain. This study investigated the clinical association of autonomic dysfunction (detrusor underactivity and primary bladder neck obstruction [BNO]) on video urodynamics (VUDS) with SFN in patients with CPP.

METHODS

This was a retrospective observational study, querying data from patients with complex CPP. Inclusion criteria were: the presence of complex (refractory or multisystem) CPP, and completion of both (1) subspecialty autonomic neurology evaluation for SFN and (2) high-quality VUDS performed according to ICS standards. Autonomic bladder dysfunction (BNO or detrusor underactivity) on VUDS was compared to the presence of SFN.

RESULTS

Thirty-two female patients with complex CPP met criteria. Of the 32, 23 (72%) were found to have SFN. Patient with autonomic bladder dysfunction (BNO or detrusor underactivity) were more likely to have SFN (OR = 9.5 [95% CI: 1.641, 55.00], p = 0.007). Post-void residual volume was higher in the SFN group (p = 0.011 [95% CI: 13.12, 94.0]) and symptoms of urge urinary incontinence were more likely to be present (p = 0.000 [95% CI: -3.4, -1.25]).

CONCLUSIONS

Patients with complex CPP with autonomic bladder dysfunction are more likely to have SFN. This suggests patients with complex CPP should be considered for diagnosis and treatment of SFN, particularly if BNO or detrusor underactivity is noted on VUDS evaluation.

[Interstitial cystitis: the latest findings on its aetiopathogenesis]

New findings provide progress in the understanding of the complicated aetiopathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS), whose causalities have only been deciphered in fragments so far. An increasingly complex network of pathomechanisms is emerging, in which the frequently mentioned mast cells and urothelial changes seem to be only a fragment of the pathological changes. The latest findings regarding a possible genetic and epigenetic predisposition are based on pedigree analyses, detection of single nucleotide polymorphisms and significant changes in differentially expressed genes. Multiple alterations can be detected at the molecular level. Platelet-activating factor, VEGF, corticotropin-releasing hormone and the inflammasome are important players in understanding the disease, but the pathomechanism underlying the "activation" of IC remains unclear. New starting points could be the detection of viruses (Epstein-Barr virus, BK polyomaviruses) or bacterial inflammation by pathogens that cannot be detected in standard cultures.

Trigone as a diagnostic and therapeutic target for bladder-centric interstitial cystitis/bladder pain syndrome

The pathophysiology of interstitial cystitis/bladder pain syndrome (IC/BPS) may be bladder-centric, with afferent nerve hyperexcitability and/or due to neural central sensitization. In bladder-centric disease, the trigone's unmyelinated nociceptive C-fibers are thought to be upregulated, suggesting this as a potential target for diagnostic modalities and for treatment with local anesthetics and chemodenervation. We propose that the transvaginal trigone treatment (T3) route of administration of such treatments should be considered in women with IC/BPS, as this approach is easier and less invasive than cystoscopy. For T3, or other bladder-centric treatments to be successful, patient selection should attempt to exclude patients with predominantly neural central sensitization.

Pulsed electromagnetic field (PEMF) as an adjunct therapy for pain management in interstitial cystitis/bladder pain syndrome

INTRODUCTION AND HYPOTHESIS

Patients with interstitial cystitis/bladder pain syndrome (IC/BPS) often experience chronic pelvic and even systemic pain that can be difficult to clinically manage. Pulsed electromagnetic field (PEMF) therapy, a non-invasive strategy that has shown significant efficacy for pain reduction in other chronic pain conditions, may provide benefit for pain management in patients with IC/BPS.

METHODS

PEMF delivery to patients occurs via a bio-electromagnetic-energy device which consists of a flexible mat (180 × 50 cm) that the patient lies on for systemic, full-body delivery and/or a flexible pad (50 × 15 cm) for targeted delivery to a specific body region (e.g., pelvic area). The duration of individual sessions, number of sessions per day, total number of sessions, and follow-up observation period vary between previously published studies. Positive outcomes are typically reported as a significant reduction in visual analog scale (VAS) pain score and functional improvement assessed using validated questionnaires specific to the condition under study.

RESULTS AND CONCLUSIONS

The use of PEMF has been evaluated as a therapeutic strategy for pain management in several clinical scenarios. Randomized, double-blinded, placebo-controlled trials have reported positive efficacy and safety profiles when PEMF was used to treat non-specific low back pain, patellofemoral pain syndrome, chronic post-operative pain, osteoarthritis-related pain, rheumatoid arthritis-related pain, and fibromyalgia-related pain. Based on these positive outcomes in a variety of pain conditions, clinical trials to evaluate whether PEMF can provide a safe, non-invasive therapeutic approach to improve symptoms of chronic pain and fatigue in patients with IC/BPS are warranted.