Comparison of LC heavy metal staining between MND patients and controls. (A) The number of MND patients having any heavy metal staining neurons in their LC was greater than in controls (chi square p = 0.002). (B) LC neurons containing heavy metal staining were present in both MND and control groups, but were significantly higher in the MND group (Mann–Whitney p = 0.0006). Bars = median values. (C) When the percentages of LC neurons containing heavy metals were divided into high (upper 50% of range) and low (lower 50% of range) categories, MND patients were predominantly in the high category, significantly different to the mirror-image result in controls (chi-square p = 0.0012).