Kyphosis is rounding of the upper spine that causes the person to have a hunched back. In cases of severe kyphosis, which is also called Scheuermann's disease, the curvature can press against the nerve that runs through the spinal column and cause paralysis.
Kyphosis may be present at birth (congenital) or may be caused by injury, infection, or disease. Kyphosis associated with bone thinning (osteoporosis) in older people often is called a dowager's hump.
WebMD Medical Reference from Healthwise