Consequences of myeloma bone disease

Myeloma bone disease has a number of potentially traumatic and debilitating consequences. Although it may occur at almost any skeletal site, areas most commonly affected are those of active haematopoiesis such as the spine, skull, pelvis, ribs, humeri, femora and mandible.

The most common clinical consequences of myeloma bone disease include:

• Severe and unremitting bone pain
• Pathological fractures
• Vertebral collapse, kyphosis, height loss
• Spinal cord compression
• Hypercalcaemia

Some of these skeletal-related events can cause other complications such as poor circulation, breathing difficulties, muscle wasting and renal insufficiency.

The impact of myeloma bone disease can therefore be devastating. Quality of life is often compromised by pain, decreased mobility and inability to carry out activities of daily living.

The following section describes the most frequent symptoms and complications of myeloma bone disease in more detail:

Bone pain

Bone pain is present at diagnosis in around 80% of myeloma patients and is most commonly felt in the mid and lower back, ribs, hips, shoulder, or wherever there are areas of bone damage due to myeloma bone disease. The severity and intensity of pain varies from individual to individual but most patients report that their pain is usually aggravated by movement but relieved by lying down.

Bone pain can become progressively worse over time or occur suddenly or severely. The latter is often a sign of a fractured bone. Increasing pain, especially on movement is a red flag for an impending fracture and warrants urgent imaging, ideally by CT.

Pathological Fracture

The term pathological fracture refers to a fracture in an area of weakened bone. It can occur spontaneously or through a small injury, most often in the ribs, sternum and long bones of the arms and legs. A significant number of patients are diagnosed with myeloma when they develop this type of fracture – the spine and ribs the most common locations affected.

Vertebral compression fracture

Vertebral compression fracture occurs when the vertebral body collapses into itself, producing a “wedged” vertebra (see Figure 3). When several vertebrae become wedge-shaped, patients can develop a humped spine, known as kyphosis, which can result in height loss.

Activities such as lifting a heavy object, sneezing or coughing may cause fractures. Vertebral compression fractures can lead to severe back pain sometimes of sudden onset, reduced physical activity, immobility loss of independence, decreased lung capacity, depression and difficulty sleeping.

Spinal cord compression

Spinal cord compression is the term used to describe pressure on the spinal cord as a result of a vertebral compression fracture. It presents most commonly as pain (both local and radicular – from the nerve root), weakness, paraesthesia (tingling sensation), loss of bladder or bowel function or ataxia (affecting balance and coordination)

Spinal cord compression is a medical emergency that requires prompt investigation, preferably with MRI scans, and treatment if function is to recover. Treatment often includes steroids and radiotherapy. Delay in treatment can be result in permanent paralysis (paraplegia, quadriplegia) and devastating loss of independence and quality of life. Patients may present in a number of settings including emergency departments. Following an urgent MDT review by spinal surgeons, it may be suggested to follow strict spinal precautions including flat bed rest, log rolling and a cervical collar if cervical spine involvement is suspected, and a multidisciplinary team approach including the acute oncology team implemented for ongoing monitoring and treatment.

Hypercalcaemia

Hypercalcaemia occurs in approximately 15% of myeloma patients at diagnosis as a consequence of the release of calcium due to myeloma bone disease. In a minority of patients, increased production of the hormone, parathyroid hormone-related protein (PTH-rP), by myeloma cells can also cause hypercalcaemia.

Early signs and symptoms of hypercalcaemia include dehydration, nausea, vomiting, lethargy, constipation and polyuria.

Prompt management of hypercalcaemia with intravenous fluid replacement or intravenous bisphosphonates is imperative to preventing cardiac arrhythmias and permanent renal damage.