Assessments performed by the physiatrists assist the oncologists in distinguishing between types of back pain, identifying neurologic impairments and spinal instability, and determining the etiology of symptoms.
Shilo Kramer, DO, and Lisa Marie Ruppert, MD (pictured)
The benefits of rehabilitation in traumatic spinal injuries are well established. Recently, studies have shown similarly positive results in cancer-related spinal injuries, indicating that rehabilitation can play a complementary role in the care management of this patient population.
Spinal metastases alter normal bone architecture and can result in deformity or collapse of the affected vertebral body, leading to pain and potential spinal instability by increasing strain on the support and stability elements of the spine, including muscles, tendons, ligaments, and joint capsules. This bony instability can also result in retropulsion of bone fragments into the epidural space, causing cord compression.1-3
Metastatic tumors may also grow into the epidural space, compressing spinal nerve roots and/or the spinal cord. This compression results in mechanical injury to axons and myelin as well as vascular compromise of the spinal arteries and epidural venous plexus and may lead to neurologic impairments.4
Oncologic treatment options, including chemotherapy, hormonal manipulation, and radiation therapy, result in tumor regression, but they may also result in peripheral neuropathies, myopathies, and osteoporosis, increasing the risk for skeletal-related complications. Corticosteroids, often used to palliate pain and reduce neurologic complications in individuals with spinal metastases, can accelerate bone loss and induce muscle weakness, further increasing this risk.
Because bone density begins to decrease after the age of 40, age-related changes and nonskeletal comorbidities also play a significant role in the development of skeletal complications in this population. With aging, there is also loss of intervertebral disk integrity, facet joint arthropathy, and weakness of the core musculature, further disrupting the integrity of the spine. Intervertebral disk disease and facet arthropathy often cause compression on spinal nerve roots and the spinal cord, resulting in neurologic impairments.
Nonskeletal comorbidities, such as neuropathies from diabetes mellitus and peripheral vascular disease, deconditioning, and immobility, can lead to sensory impairments, loss of proprioception, and weakness, impairing the spine’s ability to distribute force away from the vertebral bodies and increasing the risk for fractures. These nonskeletal comorbidities also decrease physical function and increase the risk of falls.5,6
Pain is a common initial symptom in patients with spinal metastases. Three classic pain types have been described in this setting: localized, mechanical, and radicular pain.
Localized pain is thought to be the result of periosteal stretching and inflammation caused by tumor growth. It is described as a deep “gnawing” or “aching” pain and is often nocturnal, improving with activity and anti-inflammatory medications.
Unlike localized pain, mechanical pain is often refractory to anti-inflammatory and pain medications and varies with position or activity. This pain is indicative of impending or established spinal instability. Mechanical pain characteristically occurs with transitional movements or axial loading of the spine. Alternatively, this pain may be elicited by lying prone or supine, particularly in the thoracic spine. Mechanical pain responds well to stabilization of the spine with bracing or surgical fixation.4,7
Radicular pain occurs in the setting of nerve root compression directly from tumor extension into the neuroforamen or with pathologic fractures that obliterate this space. This type of pain is often described as “sharp,” “shooting,” or “stabbing.” In the thoracic region, radicular pain is typically bilateral and described as a tight band around the chest or abdomen. In cervical or lumbar lesions, it is usually unilateral, radiating to the upper or lower extremity, respectively.4,7
Motor weakness is the next most common symptom of epidural spinal cord compression and is present in 35% to 85% of patients with metastatic disease at the time of presentation. This weakness may affect the upper motor neuron, lower motor neuron, or a combination of both depending on the area of the cord involved.3 Sensory symptoms or impairments are usually present at the time of diagnosis of epidural spinal cord compression (60%) but are rarely the initial symptom. Similar to weakness, the pattern of sensory impairments corresponds to the location of nerve injury.4
Autonomic symptoms, including neurogenic bowel and bladder, sexual dysfunction, loss of sweating below the lesion, and orthostatic hypotension, are unusual initial symptoms, but they may present at the time of diagnosis. Autonomic symptoms usually correlate with the degree of motor involvement.4,7
Defined as a loss of spinal integrity associated with movement-related pain, symptomatic and progressive deformity, and/or neurologic compromise under a normal physiologic load, spinal instability is a potential complication of spinal metastases. Factors considered for spinal instability include the location of the lesion, spinal alignment of the involved segments, extent of vertebral body involvement, involvement of posterior elements, bone lesion quality, overall spinal bone mineral density, and presence of mechanical pain.8
Lesions within the junctional (occiput–C2, C7–T2, T11–L1, and L5–S1) and mobile spine (C3–C6 and L2–L4) pose greater risks for spinal instability than those in the semirigid (T3–T10) and rigid spine (S2–S5). The junctional spine is of particular concern, as it is subject to translational forces and unique blood supply characteristics. The articulation of the semirigid region with the rib cage and the rigid region with the pelvis provides biomechanical protection against spinal instability.8
The tumor size and the cross-sectional area within the vertebral body have been shown to predict the risk of pathologic fractures. Involvement of more than 50% of the vertebral body could represent spinal instability. Posterior spinal elements, including the pedicles, facet joints, and costovertebral joints, should also be assessed, as involvement increases the risk for spinal instability, particularly when bilateral. The presence of spinal alignment deformities and possible progressive deformities at these involved segments has also been suggested to indicate spinal instability.8
In addition to the extent of vertebral body involvement, bone lesion quality must be assessed. Both osteolytic and osteoblastic lesions alter the normal bone architecture, increasing fracture risk. Lytic lesions are known to carry a greater risk of vertebral body collapse than are blastic lesions because of their relative lack of mineralization. General bone mineral density greatly impacts the integrity of the spine and how lesions in the spinal column behave. In patients with metastatic disease, low bone mineral density is associated with a greater risk of fracture.8
Multilevel contiguous and noncontiguous lesions, loss of intervertebral disk integrity, facet joint arthropathy, previous surgical intervention, and cancer treatments (such as radiation therapy and hormonal therapies) may also influence fracture risk and spinal stability.
In 2010, Fisher et al published the Spinal Instability Neoplastic Score (SINS), a classification system that utilizes these factors to guide evaluation and treatment of spinal instability in individuals with neoplastic spinal involvement.8
A Multidisciplinary Management Approach
At Memorial Sloan Kettering Cancer Center in New York, the Rehabilitation Medicine Service has collaborated with the Genitourinary Oncology Service to establish a multidisciplinary clinic. Assessments performed by the physiatrists assist the oncologists in distinguishing between types of back pain, identifying neurologic impairments and spinal instability, and determining the etiology of symptoms.
Recommendations made by the physiatrist focus on improving bone health, spinal stability, neurologic status, physical function, and quality of life. These recommendations include a referral to skilled physical and/or occupational therapies, correction of posture and body mechanics, education on safe exercise and precautions, bracing to promote neutral spine alignment or to compensate for neurologic impairments, bowel and bladder programs, and medical management of symptoms. When symptoms are believed to be cancer related or there is concern about bone instability, a discussion with the patient and his or her treating oncologist may prompt further workup or a referral for assessment by additional specialists, including a neurosurgeon, orthopedist, or radiation oncologist.
This multidisciplinary team collaboration allows for guidance on treatment decision-making and the addition of rehabilitation interventions to relieve symptoms, improve functional status and quality of life, and potentially prevent negative outcomes. It also allows for direct communication among the treating oncologist, physiatrist, and patient, ensuring a better understanding of spinal involvement, nonskeletal comorbidities, impacts of treatments, and outlined recommendations. ■
Disclosure: Drs. Kramer and Ruppert reported no potential conflicts of interest.
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8. Fisher CG, DiPaola CP, Ryken TC, et al: A novel classification system for spinal instability in neoplastic disease: An evidence-based approach and expert consensus from the Spine Oncology Study Group. Spine (Phila Pa 1976) 35:E1221-E1229, 2010.