combined system disease, a disorder of the nervous system caused by a deficiency of vitamin B12 that results in pernicious anemia and degeneration of the spinal cord and peripheral nerves, marked by increased difficulty in walking, spasticity in lower extremities, a feeling of vibration in the legs, and a loss of sense of position. Also called subacute combined degeneration of the spinal cord. See also cyanocobalamin, pernicious anemia.
