MP77-04 SENSATION DURING FILLING CYSTOMETRY CORRELATES WITH DETRUSOR WALL TENSION IN PATIENTS WITH OVERACTIVE BLADDER

INTRODUCTION AND OBJECTIVES: Overactive bladder (OAB) pathophysiology may be related to increased afferent nerve activity and altered central nervous system processing of excitatory signals. Central sensitization, which is an induced state of spinal hypersensitivity and a well-recognized mechanism of centrally amplified pain perception underlying many chronic pain conditions, may play a role in the pathophysiology of OAB and can be indexed by measuring temporal summation (TS) or 00wind-up00 (i.e. an increased neuronal response to a given constant stimulus) during quantitative sensory testing (QST). The study aim was to compare TS of evoked thermal pain stimuli in women with and without OAB. METHODS: We recruited women with medication-refractory OAB who were electing either sacral neuromodulation or onabotulinumtoxin A to undergo QST to the forearm. A Medoc Thermal Sensory Analyzer was used to apply a controlled heat stimulus to the forearm using a Peltier thermistor probe. Wind-up trials were performed using TPS-CoVASv3.19, MedocInc. software that administered a standardized oscillating thermal stimulation at a frequency of 0.5Hz, a frequency known to elicit C-fiber mediated wind-up in the dorsal horn of the spinal cord. During TS trials, a sequence of 10 heat pulses (0.5s duration) was administered from 40-49 Celsius. At the peak of each pulse, subjects rated their pain intensity on a 0-100 scale (01⁄4No Pain, 1001⁄4Worst Possible Pain). A standardized slope was calculated for each subject to reflect the degree of TS. Analyses compared study subjects with healthy controls using t-test statistics. RESULTS: We included 32 subjects, 17 women with OAB [mean age 58.5 years (range 39-71)] and 15 controls [mean age 34 years (range 22-55)]. The calculated average slope in controls for the TS trials was 0.75 (standard deviation 1⁄4 0.32) compared to 2.23 (standard deviation 1⁄4 1.28) for women with OAB (p<0.001), suggesting that women with OAB have higher degrees of TS. CONCLUSIONS: In this pilot study, women with OAB demonstrated heightened TS on thermal QST compared to controls, suggesting that central sensitization may contribute to OAB pathophysiology in some women. Further study will elucidate the use of TS as an objective marker for OAB treatment outcomes.