Spinal-cord syndrome due to non-compressive Paget's disease of bone: a spinal-artery steal phenomenon reversible with calcitonin.

A 76-year-old man had progressive low back pain, leg weakness, and sensory loss. Radiology showed changes consistent with wide-spread Paget's disease, but no cord compression or involvement of nerve roots was detected by myelography or computerised axial tomography. His symptoms were relieved within 12 days of starting 100 MRC units of subcutaneous salmon calcitonin and recurred when calcitonin was discontinued for 5 days. The improvement continued on calcitonin treatment for 1 year, with falls in serum alkaline phosphatase and urinary hydroxyproline excretion. It is suggested that calcitonin treatment, in reducing the abnormally high metabolic activity of the diseased bone, and hence its vascular perfusion, allows more blood to reach the spinal cord.