Despite being less known, Paget's disease is the second most common metabolic bone disease after osteoporosis.
The causes of Paget's disease are not entirely clear. The disease is partly genetically determined, which corresponds to its frequent familial occurrence. In addition to genetics, there is probably influence of some outer factors. Higher incidence of the Paget's disease is reported in developed countries of Europe and USA. Under normal circumstances, bone tissue is a tissue undergoing permanent dynamic reconstruction of its structure. Special cells called osteoclasts break down the bone and other cells known as osteoblasts create a new tissue. In Paget's disease, the activity of osteoclasts is increased, it is chaotic, the bones disintegrate and this situation is followed with excessive bone formation. Accelerated bone formation is associated with thickening of bones, but the newly formed bone tissue is of a poor quality and easy to break.
The most commonly affected are bones of the skull, ribs, spine and long bones of the limbs. In the majority of people, the symptoms are mild and inconspicuous. However, some people suffer from bone pain and consequences of bone thickening and deformation. The thickening bones may narrow various openings and compress nearby running nerves. Typical complication is compression of the auditory and visual nerve resulting in impaired vision and hearing, but also other neurological symptoms may occur. The newly formed bone tissue is fragile and it may be accompanied with frequent formation of pathologic fractures.
In a patient suffering from the symptoms, we may do the blood tests where we find elevated concentrations of substances related to bone breakdown. X-ray of bones may confirm their thickening and neurological examination is necessary in any patient exhibiting neurological symptoms. The examination may be followed by bone scintigraphy that helps us to evaluate bone metabolic activity.
The therapy is quite difficult. We can treat the patient symptomatically using the painkillers and local surgical interventions in neural compression syndrome and in fractures. Some effect is reported in drugs known as bisphosphonates. They interfere with the bone metabolism and inhibit bone degradation. The bisphosphonates are usually used together with calcium and vitamin D.