Madsen MH, Christiansen CB, Mølleskov E, et al. - Since the reported variation in nerve block duration is noteworthy and it is important to acquire knowledge of the intra- vs inter-individual variability in order to individualize nerve block therapy, therefore, researchers focused on the relative contribution of these two parameters to the overall nerve block duration variability in this randomised cross-over trial. On four consecutive days, they administered eight common peroneal nerve blockades with lidocaine 0.5% in 20 healthy volunteers. Allocations were five millilitres to either the right or left side and ten millilitres to the opposite side on day one and two and vice versa on day three and four. For each blockade, local anaesthetic deposition was repeated, with fixed needle entry and nerve target. According to the findings, the mean sensory block of 380 minutes on day one was 55 minutes longer than on day two, but no variations were seen in mean duration between days two, three and four. The chances of inter- to intra-individual variation-ratios > 1 were 96% and 97%. Experts concluded a substantially minor contribution of intra-individual variability, vs inter-individual variability, to the overall variability in sensory nerve block duration.