Nitrous oxide-induced neurological disorders: an increasing public health concern

Neurological presentations resulting from nitrous oxide (N₂ O) abuse are increasing in Australia and worldwide. Despite known neuropsychiatric sequelae, N₂ O canisters remain readily available and its use unregulated.

To examine the demographics, clinical and electrophysiological findings of patients presenting with neurological complications of N₂ O abuse, and thus inform clinicians and public health decision-makers of the significant public health concerns of this increasing practice.

Consecutive patients presenting to a tertiary referral metropolitan hospital were included in this series. Patients were identified by a search of discharge summaries of patients admitted with acute or subacute neuropathy or myelopathy and a history of N₂ O abuse, and from the electrophysiology database.

Thirteen patients were identified, most presenting with subacute paraesthesia, sensory ataxia and lower limb weakness. Eleven had low serum vitamin B₁₂ . Spinal magnetic resonance imaging was consistent with subacute combined degeneration in eight. Nerve conduction studies revealed a motor or sensorimotor axonal neuropathy (three with motor predominance). There was a bimodal demographic distribution consisting of socially isolated, international university students and local residents with a history of mental illness and polydrug abuse.

Recreational N₂ O use is an emerging health problem in Australia. International university students and patients with pre-existing mental illness or polydrug use appear to be at increased risk. A severe motor neuropathy may emerge following vitamin B₁₂ replacement. Public health measures are required to limit the availability of N₂ O and to educate adolescents and young adults about the potential for significant harm.