Evaluation of outcomes for patients with nitrous oxide-related myeloneuropathy treated with self-injection of hydroxocobalamin versus nurse-led injections on an ambulatory care pathway

Abstract

Background Nitrous oxide (N2O)-related neurotoxicity is a significant public health concern among young people in the UK. Recognition necessitates timely diagnosis, abstinence from N2O consumption and replacement of vitamin B12, usually via intramuscular (IM) hydroxocobalamin. This service development project evaluated a self-injection programme (SIP) compared with a nurse-led approach, within an established ambulatory care pathway, with the aim of improving treatment adherence and completion. Methods Between June and December 2024, a total of 46 patients presenting with N2O-induced neurological symptoms were included in the evaluation. Patients were given the choice of self-injecting (SIP, n=25) or attending the hospital for nurse-led administration (non-SIP, n=21). Clinical outcomes, adherence and functional improvement (including the 10 metre walk test (10MWT)) were assessed. Results Most patients were young (median age of 23), male (n=29, 63%), of Asian or Asian British ethnicity (n=29, 63%), and regularly using N2O (n=32, 70%). SIP patients had higher adherence, missing fewer IM B12 doses compared with non-SIP (79.7% vs 20.3%, p<0.001). Clinical recovery rates were comparable, with 74% achieving full or substantial improvement across both groups. Walking speed (10MWT) improved across both groups following treatment and did not differ between groups. Conclusion Self-injection of IM hydroxocobalamin is a feasible and likely cost-effective alternative to nurse-led administration while maintaining clinical efficacy.Copyright © Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.