Nitrous oxide anesthesia-associated myelopathy

Background: The role of nitrous oxide exposure in neurologic complications of subclinical cobalamin deficiency has been reported, but few cases are we ll documented. Observation: Two weeks after surgery for prosthetic adenoma. a 69-year-old man developed ascending paresthesia of the limbs, severe ataxia of gait, ta ctile sensory loss on the 4 limbs and trunk, and absent tendon reflexes. Af ter a second surgical intervention, the patient became confused. Four month s after onset, the patient had paraplegia, severe weakness of the upper lim bs. cutaneous anesthesia sparing the head, and confusion. Moderate macrocyt osis, low serum B-12 levels, and a positive Schilling test result led to th e diagnosis of pernicious anemia. Results of electrophysiologic examination s showed a diffuse demyelinating neuropathy. Magnetic resonance imaging of the spinal cord disclosed hyperintensities of the dorsal columns on T2-weig hted images. Conclusions: Pernicious anemia can result in severe neurologic symptoms wit h only mild hematologic changes. The role of nitrous oxide anesthesia in re vealing subclinical B-12 deficiency must be emphazised. Magnetic resonance imaging of the spinal cord might be helpful in making the diagnosis.