Acromegaly causes a number of physical changes over time. Since growth hormone is responsible for organ, bone, and muscle development, overproduction leads to an abnormal growth of these tissues. People with acromegaly may have swelling in the hands and feet and develop a harsh facial appearance as the jawbone protrudes, the tongue enlarges, and the chest rounds. The heart grows, which impairs its function, and other tissue growth constricts the nerves, causing weakness, vision impairment, and headaches. In many cases, bone deformation causes joint pain, which can lead to severe arthritis.