Subacute combined degeneration of the spinal cord after nitrous oxide anaesthesia: role of magnetic resonance imaging

Among all the possible causes of myelopathy, subacute combined degeneration of the spinal cord, neurological complication of vitamin B12 (cobalamin) deficiency, is one of the less often seen. GE T2 weighted images of the cervical spine in the midsagittal (380/18/18:TR/TE/FA) and axial (510/15/15:TR/TE/FA) planes at the level of C2 at admission (A, C) and 8 months later after replacement therapy with cobalamin (B, D). At admission cord swelling is evident;high intensity lesions involve the posterior (C, arrows), and to a lesser degree, also the lateral (C, arrowheads) columns of the entire cervical spinal cord. Control examination shows the persistence of only faint hyperintensities in the posterior columns (D, arrow); the volume of the spinal cord is normal. We report a case of subacute combined degeneration of the spinal cord occurring postoperatively after nitrous oxide anaesthesia in a patient previously undiagnosed to be vitamin B12 deficient. A 73 year old woman underwent surgery for knee prothesis; forty days later she suffered a femoral fracture due to an accidental fall. Two weeks after surgical stabilisation performed under general anaesthesia with nitrous oxide, the patient complained of gradual onset of loss of gait and weakness of the upper limbs …