Subacute combined degeneration of the spinal cord following recreational nitrous oxide use.

We describe a case of a young woman who developed myelopathy and peripheral neuropathy following 1 year of recreational nitrous oxide (N2O) use. She presented with uncomfortable tingling sensation in her feet and poor balance. Physical examination revealed mild weakness and hyper-reflexia in the lower limbs. Proprioception and vibration were absent in the lower limbs. Pinprick and light touch sensations were reduced below the sixth thoracic dermatome. A broad-based gait and a positive Romberg sign were noted. The level of vitamin B12 was low (76 pmol/l). T2-weighted MRI scans showed hyperintensity changes at the posterior column from the second to the fifth cervical vertebrae. She made a full recovery following injections of vitamin B12 and physiotherapy. This case discusses subacute combined degeneration of the spinal cord on a background of N2O abuse.