Rise of online risk mitigation strategies in recreational nitrous oxide use

<h3></h3> A 20-year-old man was referred to the outpatient clinic with a clumsy gait. On assessment he was found to have an ataxic gait, pseudoathetosis and bilateral foot drop. Direct questioning revealed regular recreational nitrous oxide use. In view of the history, he was admitted for treatment of presumed nitrous oxide induced subacute cord degeneration (N2O-SACD) and started on intensive B12 injections. At present there is no national guideline for the investigation and treatment of N2O- SACD. However, consensus guidance has recently been published in practical neurology. Prior to treatment, it is recommended that homocysteine and/or methylmalonic acid (MMA) levels are measured, as elevated levels can help secure the diagnosis. Interestingly, in this case the homocysteine level was found to be normal at 10mcmol/l (0 – 20mcmol/l). MRI spine was consistent with SACD. The patient later disclosed that he had read about N2O harm reduction strategies online, and that he takes over the counter B12 supplementation prior to N2O use. A cursory search on several social media platforms reveals multiple forum posts discussing N2O harm reduction strategies. Despite the normal homocysteine level, the patient’s neurological state improved with three times weekly B12 injections. It is suspected that the patient’s own B12 use conflated the interpretation of the homocysteine level. B12 injections continued until the patient’s neurological state plateaued.