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A previously healthy 30-year-old man developed limb paresthesias and incoordination. Initial magnetic resonance imaging of the spinal cord, performed 5 weeks after symptom onset, was normal (Figure, A). Over the subsequent 8 weeks, he developed a bandlike sensation across the torso and profound sensory ataxia. He was admitted to the neurology service for further evaluation. Motor examination showed mild (4+) weakness in the distal lower greater than upper extremities. Sensation to vibration and proprioception was absent in the lower extremities and markedly diminished in the distal upper extremities. There was no spinal sensory level to pinprick or temperature modalities. There was moderate dysmetria on heel-knee-shin greater than finger-nose-finger tests; the Romberg sign was present. Deep tendon reflexes were 2+ in the upper extremities and 3+ in the lower extremities. Plantar responses were extensor on the right and flexor on the left. Over 5 days of hospitalization, the patient became unable to walk or stand unsupported because of severe sensory ataxia.
Ernst LD, Brock K, Barraza LH, Davis A, Nirenberg MJ. Longitudinally Extensive Nitrous Oxide Myelopathy With Novel Radiographic Features. JAMA Neurol. 2015;72(11):1370-1371. doi:10.1001/jamaneurol.2015.2141