Cover image: Figure 1 (A) Depicts 200 nitrous oxide canisters (the quantity consumed by this patient over 72 hours), purchased online by authors for illustrative purposes. 40 cm ruler included for scale. (B) MR scan of cervical spine (sagittal T2 image) showing mild expansion of the upper to mid cervical cord with posterior, longitudinally distributed T2 hyperintensity. (C) Axial T2 image shows the signal change localised to the dorsal columns. There was no enhancement or thoracic cord involvement shown on accompanying sequences (not shown). (see Southwell TG, et al. page 422, 505).