Variation in quantitative sensory testing and epidermal nerve fiber density in repeated measurements

• Published in: Pain (Amsterdam) Vol. 151; no. 3; pp. 575 - 581
• Main Authors: Selim, Mona M., Wendelschafer-Crabb, Gwen, Hodges, James S., Simone, Donald A., Foster, Shawn X.Y.-L., Vanhove, Geertrui F., Kennedy, William R.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Elsevier B.V 01.12.2010; Lippincott Williams & Wilkins, Inc; Elsevier
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; Clinical neurology examination; Cold Temperature; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Epidermal nerve fibers; Epidermis - innervation; Female; Hot Temperature; Human viral diseases; Humans; Infectious diseases; Male; Medical sciences; Nerve Fibers; Nervous system (semeiology, syndromes); Neurology; Pain Measurement; Pain Perception - physiology; Pain Threshold - physiology; Physical Stimulation; QST; Quantitative sensory testing; Sensory Thresholds - physiology; Sex Factors; Skin biopsy; Touch Perception - physiology; Viral diseases; Viral diseases of the lymphoid tissue and the blood. Aids; Clinical neurology examination; Skin biopsy; Epidermal nerve fibers; QST; Quantitative sensory testing; Neurology; Sensory nerve; Skin
• ISSN: 0304-3959; 1872-6623; 1872-6623
• DOI: 10.1016/j.pain.2010.06.034

Quantitative sensory testing (QST) is commonly used to evaluate peripheral sensory function in neuropathic conditions. QST measures vary in repeated measurements of normal subjects but it is not known whether QST can reflect small changes in epidermal nerve fiber density (ENFd). This study evaluated QST measures (touch, mechanical pain, heat pain and innocuous cold sensations) for differences between genders and over time using ENFd as an objective-independent measure. QST was performed on the thighs of 36 healthy volunteers on four occasions between December and May. ENFd in skin biopsies was determined on three of those visits. Compared to men, women had a higher ENFd, a difference of 12.2 ENFs/mm. They also had lower tactile and innocuous cold thresholds, and detected mechanical pain (pinprick) at a higher frequency. Heat pain thresholds did not differ between genders. By the end of the 24-week study, men and women showed a small reduction (p<0.05) in the frequency of sharp mechanical pain evoked by pinprick whereas tactile and thermal thresholds showed no change. This coincided with a small decrease in ENFd, 4.18 ENFs/mm. Variation in measurements over time was large in a fraction of normal subjects. We conclude that most QST measures detect relatively large differences in epidermal innervation (12.2 ENFs/mm), but response to mechanical pain was the only sensory modality tested with the sensitivity to detect small changes in innervation (4.18 ENFs/mm). Since some individuals had large unsystematic variations, unexpected test results should therefore alert clinicians to test additional locations.