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. Author manuscript; available in PMC: 2015 Sep 1.
Published in final edited form as: Pain. 2014 Jun 28;155(9):1878–1887. doi: 10.1016/j.pain.2014.06.019

Figure 6.

Figure 6

Evoked spike activity in the dorsal horn on day 7 after facet capsule injury varies with timing of intra-articular bupivacaine. (a) Neuronal firing evoked by light brush is significantly higher when bupivacaine is administered at time later than 4 hours after injury than when it is given immediately (inj-BP0h) (*p<0.0001) or at 4 hours (inj-BP4h) (#p<0.0001). Firing during a noxious pinch is increased in the inj-BP8h and inj-BPd1 groups compared to the inj-BP0h (*p<0.0001), inj-BP4h (#p<0.002), and inj-BPd4 (^p<0.018) groups. (b) Similarly, firing evoked by stimulation by all of the magnitudes of von Frey filaments is significantly greater when bupivacaine is administered 8 hours (inj-BP8h), 1 day (inj-BPd1), or 4 days after injury (inj-BPd4) than when it is given immediately (inj-BP0h) (*p<0.0001) or at 4 hours (inj-BP4h) (#p<0.045). Firing is also greater after treatment given at 4 hours (inj-BP4h) than it is when given at the time of injury (inj-BP0h) for all von Frey filament stimuli (*p<0.0001). There is also significantly more evoked firing in the inj-BP8h group than the inj-BPd1 group for stimulation by the 1.4g and 26g filaments (†p<0.0003) and the inj-BPd4 group for the 4g, 10g, and 26 filaments (^p<0.0001).