Temporal summation to thermal stimuli is elevated in women with overactive bladder syndrome

Abstract

Introduction This study sought to provide a preliminary assessment of whether spinally-mediated afferent hyperactivity (i.e. central sensitization) might contribute to manifestations of Overactive Bladder Syndrome (OAB) in women as indexed by elevated temporal summation of evoked heat pain stimuli. Methods We recruited 20 adult women with OAB who were planning to undergo interventional therapy for OAB with either onabotulinumtoxinA injection or sacral neuromodulation and 23 healthy controls without OAB symptoms to undergo quantitative sensory testing with cutaneous thermal pain temporal summation. The primary study outcome was the degree of temporal summation, as reflected in the magnitude of positive slope of the line fitted to the series of 10 stimuli at the 49°C target temperatures. Linear regression and analysis of covariance were utilized to compare the degree of temporal summation between study groups. Results The standardized slope of temporal summation trials for women with OAB was significantly higher than for Controls (beta = 3.43, 95% confidence interval = 0.6 – 6.2, p = .017). The adjusted means ± SE of the standardized temporal summation slopes for the full OAB and Control groups were 3.0 ± .5 (95% confidence interval = 2.0, 4.1) and 1.7 ± .5 (95% confidence interval = .7, 2.7), respectively. Conclusion In this preliminary study, we demonstrated that women with OAB refractory to primary and secondary therapies exhibited greater thermal cutaneous temporal summation than women without OAB symptoms. This suggests that central sensitization, indexed by temporal summation, may be an underlying factor contributing to OAB in some women.

Painful Bladder Symptoms Related to Somatic Syndromes in a Convenience Sample of Community Women with Overactive Bladder Symptoms

“…Temporal summation, which is an indicator of central sensitization, is measured by an increase in pain perception to a series of stimuli delivered a constant intensity and frequency, such as heat. A group of women undergoing third-line therapy for OAB demonstrated higher pain intensity scores and greater temporal summation compared to controls 20 . On sub-analysis, women with self-reported IC/BPS exhibited the greatest degree of temporal summation, although it was not statistically significantly higher than the OAB group.…”

The LURN Research Network Neuroimaging and Sensory Testing (NIST) Study: Design, protocols, and operations

“…Given the potential roles that the brain and the somatosensory and viscerosensory system might play in processing, interpreting, and modulating normal and abnormal lower urinary tract symptoms (e.g., urinary urgency), it is surprising that there have been few neuroimaging and sensory testing studies. [7–16, 61, 62] The NIST Study brings the following innovations and uniqueness to OAB research by:…”

“…[11, 12, 14, 15] To our knowledge, only one study used quantitative sensory testing (QST) to measure sensory processing in a small sample of females with urinary urgency. [16] The NIST Study is designed to overcome these limitations by being the first study to enroll a large population of both men and women from multiple clinical centers, and to compare urinary urgency, urgency incontinent, and control participants using both brain magnetic resonance imaging (MRI) and QST.…”

Women Undergoing Third Line Overactive Bladder Treatment Demonstrate Elevated Thermal Temporal Summation

“…4 Briefly, we administered a sequence of 10 successive 0.5 second heat pulses to the forearm, during which the temperature rapidly increased and decreased from a temperature of 40°C to 49°C at a frequency of 0.4 Hz, a frequency known to elicit C-fiber mediated temporal summation in the dorsal horn of the spinal cord. Immediately after the peak of every heat pulse, subjects provided a verbal numeric pain intensity rating using a 0 – 100 visual analog scale (VAS) anchored with 0 = “No Pain or Warmth” and 100 = “Worst Possible Pain.” The standardized slope of change in pain ratings over the series of 10 stimuli was derived for each patient as an index of TS.…”

“…4 Because elevated TS is believed to be a marker for CS, 5,6 this finding suggested elevated CS in OAB patients when compared to non-OAB controls. Our present hypothesis is that the presence of CS may contribute to why some women with OAB are more likely to be refractory to first- and second-line OAB therapy than others.…”