Patients with painful bladder syndrome have altered response to thermal stimuli and catastrophic reaction to painful experiences

Aims: To compare cutaneous sensory thresholds, habituation to somatic stimuli, and tendency towards catastrophic reaction to painful stimuli in patients with Painful Bladder Syndrome (PBS) to controls without PBS. Method: Thermal and vibratory sensory thresholds were established in 11 PBS patients and 10 controls at C5, T1, T12, and S3 dermatomes. Supra-threshold thermal stimuli were then applied at T12 and S3 for 60 sec while patients periodically rated the intensity of stimuli using a visual analog scale. A Pain Catastrophizing Scale (PCS) questionnaire was also completed by all participants before testing. Results: PBS patients were less sensitive to warm stimuli in the T12 dermatome than asymptomatic controls (thresholds 36.6 ± 1.10°C vs. 35.3 ± 1.0°C, P < 0.02) but otherwise had similar thermal and vibratory thresholds. Habituation to supra-threshold stimuli at T12 and S3 dermatomes was more common in controls than PBS subjects (7 (70%) vs. 2 (18%), P < 0.03 and 9 (90%) vs. 3 (27%), P < 0.008, respectively). The PCS score correlated with the duration of PBS symptoms and with thresholds to warm stimuli at T12 dermatome (ρ = 0.65, P < 0.03 and r = 0.5, P < 0.021, respectively). Conclusion: Our data suggests that habituation to stimuli may be impaired and that a catastrophic reaction to perceived stimuli may be involved in the sensory experience of PBS patients and facilitate chronic pain.