An unusual cause of falls in a young woman.

Abstract

Nitrous oxide is commonly used as an analgesic and anaesthetic agent. Nitrous oxide is also in use in industry as an aerosol propellant and is now recognised as a recreational drug whose use is growing, especially among the young. Nitrous oxide from whipped cream canisters is inhaled to produce a dissociative, intoxicated state. Nitrous oxide is known to inactivate vitamin B12 via oxidation, which can precipitate a demyelinating myelopathy akin to the classical B12 deficiency syndrome, subacute combined degeneration of the spinal cord. This case describes a young woman with chronic pain and a poor nutritional state who took regular nitrous oxide as an opiate-sparing agent. She developed a progressive subacute myelopathy with a sensory level, profoundly impaired joint position sense, extensor plantars and required a wheelchair. Once diagnosed, she responded well to a regime of nitrous oxide withdrawal, high-dose B12 replacement and physiotherapy. The case illustrates the need for clinical teams to be able to dentify a nitrous oxide-precipitated myelopathy as its use as a drug of abuse increases; particularly in the case of malnourished patients who receive nitrous oxide surgically or obstetrically.