Homotopic effect of 10 Hz CES on pain perception.

<p>A. Pain intensity evoked by SES. No changes were found after 10 Hz CES for the perception intensity of SES. No differences were found between the two sessions. B. HPT assessment. The HPT increased after 10 Hz CES (10 min and 20 min in the post conditioning period) then gradually returned to the baseline. The HPT in session one was higher than in session two.</p

Neurogenic inflammation.

<p>A. SBF changes caused by 10 Hz CES. An increase of SBF occurred 10 min after CES. Thereafter it declined. No difference was found between the two sessions. B. ST changes caused by 10 Hz CES. ST was found to be declined along the observation period when this decline was temporarily stopped 10 min and 20 min into the postconditioning period. No difference was found between sessions.</p

Experimental setup.

<p>(A) 10 Hz conditioning electrical stimulation was applied at the volar forearm 7 cm distal to the cubital fossa via a circular array of pin electrodes in two sessions. The single electrical stimulation was applied at the conditioned site by the same pin electrodes and the light stroking and pinprick stimuli were applied in the surrounding skin area. (B) Test stimulation series including SBF, ST, pain perception rating to pinprick and light-stroking stimuli, HPT and pain perception rating to SES was assessed with 10 min intervals three times before (pre-conditioning period) and six times after the CES (post-conditioning period). SBF: superficial blood flow; ST: skin temperature; HPT: heat pain threshold; SES: single electrical stimulation.</p

Pain experience induced by CES.

<p>A. Temporal changes during the conditioning process. The highest pain rating in each 10 s was chosen to compare the two sessions. The pain intensities declined in both sessions. B. Depiction of SF-MPQ scores for CES. The SF-MPQ scores and PPI were not found significantly different between the two sessions. PPI: present pain intensity; S: sensory; A: affective; E: evaluative overall intensity of total pain experience.</p

Bland-Altman plots for the effects after 10 Hz CES.

<p>Assessments were performed on the SBF, homotopic pain perception to SES, and heterotopic pain perception to light-stroking and pinprick stimulation (294 mN). The dashed line indicates the bias between sessions, whereas the dotted lines indicate the limits of agreement calculated as ±1.96×the standard deviation (SD) of the differences between measurements for the two sessions. Shaded areas indicate the confidence intervals of mean difference and limits of agreement.</p