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A 53-year-old woman presented with insidiously progressive tetraparesis, C5 sensitive level and urinary incontinence for 16 months. Cervical MRI disclosed signal abnormalities consistent with subacute combined degeneration1 (SCD), associated with a hydromyelia (figure). Laboratory studies confirmed the diagnosis of SCD. Clinical and imagiologic remission occurred with vitamin B12 treatment. The MRI follow-up studies and the hydromyelia topography suggest that it was formed as a functional consequence of long-tract pathway demyelination. The presence of hydromyelia, when associated with the charac-teristic MRI, clinical and laboratorial features of SCD, may be attributed to vitamin B12 deficiency itself.2 1. Pittock SJ, Payne TA, Harper MC. Reversible myelopathy in a 34-year-old man with vitamin B12 deficiency. Mayo Clin Proc 2002;77:291–294