C-tactile Fibers Contribute to Cutaneous Allodynia After Eccentric Exercise

Abstract We recently showed that during acute muscle pain, C-tactile (CT) fibers mediate allodynia in healthy human subjects. In this study, we pursued the following questions: Do CTs contribute to allodynia observed in delayed onset muscle soreness (DOMS)? Is CT-mediated allodynia reproducible in a...

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Bibliographic Details
Published in:The journal of pain 2013-05, Vol.14 (5), p.538-548
Main Authors: Nagi, Saad S, Mahns, David A
Format: Article
Language:English
Subjects:
Adolescent
Adult
allodynia
Analysis of Variance
Anesthesia & Perioperative Care
C fiber
Chronic Pain - pathology
Chronic Pain - physiopathology
delayed onset muscle soreness
eccentric exercise
Exercise - physiology
Female
hairy skin
Humans
Hyperalgesia - diagnosis
Hyperalgesia - physiopathology
intradermal anesthesia
Male
Myalgia - etiology
Nerve Fibers, Unmyelinated - physiology
Neural Conduction
Pain Measurement
Pain Medicine
Pain Threshold - physiology
pressure pain threshold
Skin - innervation
Skin - pathology
Touch
Vibration
Young Adult
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Summary:Abstract We recently showed that during acute muscle pain, C-tactile (CT) fibers mediate allodynia in healthy human subjects. In this study, we pursued the following questions: Do CTs contribute to allodynia observed in delayed onset muscle soreness (DOMS)? Is CT-mediated allodynia reproducible in a clinical pain state? In 30 healthy subjects, DOMS was induced in anterior compartment muscles of the leg by repeated eccentric contractions. DOMS was confirmed by mapping the emergence of tender points (decreased pressure pain thresholds). Furthermore, we measured pressure pain thresholds in a clinical subject who presented with activity-triggered heel pain but no resting pain. Cutaneous vibration (sinusoidal; 200 Hz–200 μm)—an otherwise innocuous stimulus—was applied to anterolateral leg before exercise, during DOMS, and following recovery from DOMS. The peripheral origin of allodynia was determined by employing conduction blocks of unmyelinated (intradermal anesthesia) and myelinated (nerve compression) fibers. In DOMS state, there was no resting pain, but vibration reproducibly evoked pain (allodynia). The blockade of cutaneous C fibers abolished this effect, whereas it persisted during blockade of myelinated fibers. In the clinical subject, without exposure to eccentric exercise, vibration (and brushing) produced a cognate expression of CT-mediated allodynia. These observations attest to a broader role of CTs in pain processing. Perspective This is the first study to demonstrate the contribution of CT fibers to mechanical allodynia in exercise-induced as well as pathological pain states. These findings are of clinical significance, given the crippling effect of sensory impairments on the performance of competing athletes and patients with chronic pain and neurological disorders.
ISSN:1526-5900
1528-8447
DOI:10.1016/j.jpain.2013.01.009