Quantitative assessment of nonpelvic pressure pain sensitivity in urologic chronic pelvic pain syndrome: a MAPP Research Network study

Abstract

Experimental pain sensitivity was assessed in individuals with urologic chronic pelvic pain syndrome (UCPPS) as part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. A series of computer-controlled pressure stimuli were delivered to the thumbnail bed, an asymptomatic site distant from the area of UCPPS pain that is considered to be indicative of overall body pain threshold. Stimuli were rated according to a standardized magnitude estimation protocol. Pain sensitivity in participants with UCPPS was compared with healthy controls and a mixed pain group composed of individuals with other chronic overlapping pain conditions, including fibromyalgia, chronic fatigue, and irritable bowel syndromes. Data from 6 participating MAPP testing sites were pooled for analysis. Participants with UCPPS (n = 153) exhibited an intermediate pain sensitivity phenotype: they were less sensitive relative to the mixed pain group (n = 35) but significantly more sensitive than healthy controls (n = 100). Increased pain sensitivity in patients with UCPPS was associated with both higher levels of clinical pain severity and more painful body areas outside the pelvic region. Exploratory analyses in participants with UCPPS revealed that pain sensitivity increased during periods of urologic symptom flare and that less pressure pain sensitivity at baseline was associated with a greater likelihood of subsequent genitourinary pain improvement 1 year later. The finding that individuals with UCPPS demonstrate nonpelvic pain hypersensitivity that is related to clinical symptoms suggests that central nervous system mechanisms of pain amplification contribute to UCPPS.

COMT gene variants and β-endorphin levels contribute to ethnic differences in experimental pain sensitivity

“…EPT and PPT are often used in quantitative assessment of pain sensitivity in clinical studies. [39][40][41] In this work, EPT and PPT, as the reliable tool of pain sensitivity measurement, were also employed to identify the race difference in mechanical pain threshold, by compression and electric current stimulation, which efficiently prevented pain stimulus error caused by the single repetitive stimulus.…”

The Multidisciplinary Approach to The Study of Chronic Pelvic Pain (MAPP) Research Network*: Design and implementation of the Symptom Patterns Study (SPS)

“…The SPS QST study includes four testing methods that assess generalized and segmental pain sensitivity and endogenous pain modulation. As in MAPP I, Generalized (global) Mechanical Sensitivity is evaluated using the computer‐controlled MAST system 15,23 As in MAPP I, generalized pain sensitivity is measured using the MAST system which delivers a series of increasing discrete pressures to the thumbnail bed, 15,23 and is terminated when participants reach their maximum tolerable pain level.…”

“…Key MAPP I findings include observations that (a) urologic pain and urinary symptoms covary, with only moderate correlation ( r = .5), and thus should be evaluated separately, 5 (b) UCPPS participants who report pain beyond the pelvis have more severe UCPPS symptoms and more symptom flares than those with pelvic pain only, 6,7 (c) UCPPS participants report more psychosocial difficulties than pain‐free Controls, and poor psychosocial functioning is associated with a lower likelihood of longitudinal symptom improvement, 8‐10 (d) UCPPS is associated with changes in structure and function of pain‐related neural networks, as well as brain‐level sensorimotor systems regulating urine storage, 11‐13 (e) UCPPS symptom profiles can be distinguished by biological correlates (eg, immune factors), 14 and (f) QST assessment reveals that UCPPS participants have significantly increased pressure pain sensitivity compared to healthy Controls, and higher sensitivity was associated with less likelihood of UCPPS symptom improvement 15 . These primary findings were generally consistent in both males and females, although some sex‐specific differences were observed 16 …”

Itch Processing in the Skin

“…It has been noted that patients with sensitive skin also report a sensitive cornea (69) and irritable bowel syndrome (70), that is also linked to interstitial cystitis (71), and fibromyalgia (72). Increased pain sensitivity is observed in all these conditions and central sensitization has generally been assumed as a common mechanism (73, 74). In this respect it is interesting that definitive small fiber neuropathy with pathologically reduced intraepidermal nerve fiber density has been reported in patients with fibromyalgia (75, 76) possibly indicating a special subpopulation with peripheral neuropathy.…”