Abstract
Background
Intramuscular injection of Nerve Growth Factor (NGF) may influence the responsiveness of active chemo‐sensitive channels affecting muscle pain sensitivity. This double‐blinded crossover study in healthy humans assessed contraction‐evoked pain responses and pain sensitivity during acute ischemia in the tibialis anterior (TA) muscle before and 24h after five distributed NGF injections (1μg, 4 cm interval) compared with control injections (isotonic‐saline).
Methods
Twenty‐one subjects participated in two experimental phases, each including 5 sessions over 7 days, with a gap of 4 weeks in‐between. Muscle pain intensity evoked with daily functional tasks (Likert scale score) was collected using a paper diary. Pain intensity evoked by ischemic and non‐ischemic contractions (numerical rating scale, NRS) was collected at Day0 and Day1. Pressure pain thresholds (PPTs) on the TA were recorded before (Day0), 3 hours, 1, 3, and 7 days post‐injection, and after the ischemic‐contractions and post‐cuff deflation at Day0 and Day1.
Results
Increased Likert scores of pain were present for 7 days after NGF compared to control injections (P<0.05). Higher NRS pain scores of ischemic‐contractions were seen when contracting the muscle injected with NGF compared to baseline (P=0.003) and control (P=0.012). Pain during non‐ischemic contractions was not significantly affected by NGF injections. Decreased PPTs were found at 3 hours, Day1 and Day3 post‐injection (P<0.05) in both conditions. Compared with pre‐contractions, PPTs were increased following ischemic contractions at Day0 (P<0.05) and Day1 (P<0.05) in both conditions.
Conclusion
This study showed that ischemic contraction‐evoked pain was facilitated in an NGF‐sensitized muscle.
This article is protected by copyright. All rights reserved.
from Wiley: European Journal of Pain: Table of Contents https://ift.tt/2XPc0ep
via IFTTT
No comments:
Post a Comment