Altered Central Sensitization in Subgroups of Women With Vulvodynia

• Published in: The Clinical journal of pain Vol. 27; no. 9; pp. 755 - 763
• Main Authors: Zhang, Zheng, Zolnoun, Denniz A, Francisco, Eric M, Holden, Jameson K, Dennis, Robert G, Tommerdahl, Mark
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins, Inc 01-11-2011; Lippincott Williams & Wilkins
• Subjects: Adaptation, Physiological - physiology; Adult; Animal viral diseases; Biological and medical sciences; Case-Control Studies; Central Nervous System - physiopathology; Central Nervous System Sensitization - physiology; Discrimination (Psychology); Female; Fundamental and applied biological sciences. Psychology; Humans; Infectious diseases; Medical sciences; Neurology; Pain Threshold - physiology; Physical Stimulation - methods; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs; Viral diseases; Vulvodynia - classification; Vulvodynia - pathology; Vulvodynia - physiopathology; Human; Nociception; Nervous system diseases; Pain; central sensitization; Sensitization; Adaptation; Vulvodynia
• ISSN: 0749-8047; 1536-5409
• DOI: 10.1097/AJP.0b013e31821c98ec

OBJECTIVETo investigate the clinical correlates of central nervous system alterations among women with vulvodynia. Altered central sensitization has been linked to dysfunction in central nervous system-inhibitory pathways (eg, γ-aminobutyric acidergic), and metrics of sensory adaptation, a centrally mediated process that is sensitive to this dysfunction, could potentially be used to identify women at risk of treatment failure using conventional approaches.
METHODSTwelve women with vulvodynia and 20 age-matched controls participated in this study, which was conducted by sensory testing of the right handʼs index and middle fingers. The following sensory precepts were assessed(1) vibrotactile detection threshold; (2) amplitude discrimination capacity (defined as the ability to detect differences in intensity of simultaneously delivered stimuli to 2 fingers); and (3) a metric of adaptation (determined by the impact that applying conditioning stimuli have on amplitude discriminative capacity).
RESULTSParticipants did not differ on key demographic variables, vibrotactile detection threshold, and amplitude discrimination capacity. However, we found significant differences from controls in adaptation metrics in 1 subgroup of vulvodynia patients. Compared with healthy controls and women with a shorter history of pain [n=5; duration (y)=3.4±1.3], those with a longer history [n=7; duration (y)=9.3±1.4)] were found to be less likely to have adaptation metrics similar to control values.
DISCUSSIONChronic pain is thought to lead to altered central sensitization, and adaptation is a centrally mediated process that is sensitive to this condition. This report suggests that similar alterations exist in a subgroup of vulvodynia patients.