The heatmaps give a visual representation of how closely concentrations of different mediators correlate in the samples by nearest neighbour correlation.

<p>Using a hierarchical cluster analysis the mediators are listed in the same order for each of the three aetiological groups to allow a visual comparison of the pattern between the groups. In the serum (a) the pattern of mediator correlations is similar for all three aetiological groups, where-as in the cerebrospinal fluid (b) the pattern differed between immune-mediated and infectious aetiologies, and the pattern for those of unknown aetiology is closer to that seen with infection.