Catalog

White matter disorder due to nitrous oxide toxicity

No MMS code

Link to WHO Definition

White matter disorder due to nitrous oxide toxicity – http://id.who.int/icd/entity/1905371082

Nitrous oxide causes irreversible inactivation of vitamin B12 by oxidation, and has been associated with myelopathy development in recreational users, and after its use for anaesthesia in patients with subclinical vitamin B12 deficiency. It results in an identical clinical pattern of toxicity to subacute combined degeneration with extensive spinal cord, brain and peripheral nerve demyelination. It causes a progressive distal sensory neuropathy, starting in the hands with proprioceptive loss secondary to involvement of large sensory nerves and dorsal columns. Progressive spasticity and hyper-reflexia then develops due to myelopathy. Neurologic impairment occurs due to functional vitamin B12 deficiency; therefore, measured serum vitamin B12 levels may appear normal.