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.

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.