Effects vary from undetectable to severe.
Approximately 80 percent of cases of kyphoscoliosis are idiopathic. Idiopathic kyphoscoliosis commonly begins in late childhood or early adolescence and may progress in severity during these years of rapid skeletal growth. The incidence among females is four times higher than among males. Of the various chest deformities that produce ventilatory failure, kyphoscoliosis is the most common. The degree to which ventilation is reduced is determined by the severity of deformity and the degree of neuromuscular weakness.