Comparison of the effects of spinal administration of lacosamide and monosodium iodoacetate. These graphs show the effects of lacosamide (LCM; 10, 50 and 100 μg) on the evoked neuronal responses to electrical (a, b), dynamic brush (c, d), mechanical punctate (e, f) and thermal stimulation (g, h) of the peripheral receptive field in sham rats (n = 6, left panel) and monosodium iodoacetate (MIA) rats (n = 7, right panel). The neuronal responses evoked by Aβ-, Aδ- and C-fibres and the input measure of neuronal excitability, dynamic brush, von Frey (vF) 8 to 60 g and 45°C to 48°C heat stimulation were significantly reduced by LCM in the MIA group. LCM did not produce any significant effect on any neuronal measure in the sham group. Asterisks and bars denote statistically significant main effects (one-way repeated-measures analysis of variance (RM-ANOVA)). § denotes significance at 10 μg, + denotes significance at 50 μg and * denotes significance at 100 μg compared with baseline control data (P < 0.05 by one-way RM-ANOVA with Bonferroni-corrected paired t-test). Values are mean ± SEM. PD, Postdischarge; Input, Baseline C-fibre-evoked response measure of afferent input and the resultant spinal neuronal response prior to central neuronal hyperexcitability evoked by subsequent stimuli; W, Wind-up, a frequency-dependent incremental increase in neuronal response to repetitive stimulation of C-fibres (that is, a measure of central neuronal hyperexcitability).