In children, enlarged adenoids and/or tonsils are the most common cause of obstructive sleep apnea (OSA), which is temporary blockage of breathing during sleep. Surgery to remove the tonsils and adenoids is the first-line treatment for disorder, and has been shown to cure the majority of children. However, for children with only a mild degree of OSA and few symptoms, surgery is less clear-cut, since two-thirds of these children do not develop worsening disease.