Applying Kinesiology as a Multipronged Approach to Pain Management: Part 2
In the first installment of this article in the June issue of Practical Pain Management, the authors introduced the field of kinesiology as a key component of an effective biopsychosocial model for an interdisciplinary pain management program. In this installment, the role of kinesiology will be examined. In particular, the role of improving balance will be highlighted—an important area of research due to the ever-increasing population of Americans over 65 who have chronic pain and are at risk of falls and injury.
Exercise and Pain’s Effects on Balance
Under normal circumstances, the body uses 3 primary systems to maintain balance: the visual system, the vestibular system, and the proprioceptive system (Figure 1).
Kinesiologists have long studied these important areas of balance because:
- The visual system provides information about the environment that can be seen with the eyes
- The vestibular system provides information about motion, equilibrium, and spatial orientation
- The proprioceptive system provides information about the position of the limbs and the amount of force being exerted during movement through sensors in the skeletal muscles, joints, and skin
All 3 of these systems provide information to the central nervous system, which then sends signals to the skeletal muscles with instructions on what movements are required to maintain posture, and therefore balance.
How Does Pain Impact Balance?
Understanding how the body works to maintain postural control is necessary to allow a clinician to piece together how pain might have a detrimental effect on balance. Postural control has been defined as the act of maintaining, achieving, or restoring a state of balance during any posture or activity. Unfortunately, the 3 systems that work together to maintain balance can become impaired for a variety of reasons. For example, removal of visual input (due to blindness, cataracts, etc) can increase reliance on the proprioceptive and vestibular systems.1 Impairments in the proprioceptive system (due to chronic musculoskeletal pain or neuropathy), for example, might limit range of motion, forcing an increased reliance on the visual and vestibular systems to maintain postural control.2
One way that pain impacts balance indirectly, especially in the elderly, is through self-imposed restriction on physical activity in order to avoid pain. The Fear-Avoidance Model3 suggests that people who suffer from chronic pain may avoid movements or activities for fear of inducing pain.
This self imposed restriction on physical activity contributes to deconditioning and skeletal muscle atrophy and stiffness, further decreasing the body’s ability to maintain core strength and good postural control (ie, increasing frailty).4 Patients who are deconditioned or have poor postural control are at an increased risk of falling, which increases their risk of sustaining a hip, wrist, or ankle fracture. Fractures account for 61% of the $19 billion spent annually to treat nonfatal falls in the US.5
Pain and the Visual System
Various types of chronic pain can impact vision. For example, fibromyalgia deteriorates the nervous system (central sensitization), which can include the nerves leading to the eyes. This can result in blurred vision, sensitivity to light, double vision, and loss of peripheral vision.6
A vast majority of individuals with multiple sclerosis (75%) can have a condition known as optic neuritis, which is characterized by an inflammation of the optic nerve.7 This can result in blurred vision or even blindness. Another condition associated with multiple sclerosis is nystagmus, which is uncontrolled eye movements. The severity of nystagmus typically dictates whether or not vision is impaired.4
Individuals diagnosed with rheumatoid arthritis can also have vision impairments. Twenty-five percent of patients with rheumatoid arthritis will have vision problems, including pain with sensitivity to light, blurred vision, and pain with eye movement.8 Dry eye, which is increasingly becoming a public health problem, is associated with multiple symptoms, including blurred vision, irritation, and pain.9
Pain and the Vestibular System
A number of chronic pain conditions can impact the vestibular system, which can lead to an increased risk of falling. These include patients with chronic, non-cancer related pain or underlying neurologic disorders such as spinal stenosis (usually secondary to degenerative disc disease and spondylosis), ruptured disc, spinal instability, spondylolisthesis, spinal cord injury or disorder (ie, multiple sclerosis, myelopathy, and syrinx), peripheral nerve injury or disorder, or brain injury or disorder (eg, stroke, multiple sclerosis, Chiari malformation).10
Cervical vertigo (dizziness) can be induced by neck pain or stiffness, arthritis, and other causes.11 Dizziness in the elderly can be a result of problems with the vestibular, central nervous system, and vision systems. However, approximately 50% of reported dizziness in the elderly is thought to be caused by vestibular disorders.12
Individuals with migraines often complain of vestibular problems, such as vertigo, unsteadiness, and head motion intolerance.13 According to the Vestibular Disorders Association, vestibular hyperacusis, which is the perception of an unusual auditory sensitivity to certain sounds, occurs when “the complex electrical signals generated by sound vibrations are misinterpreted, confused, or exaggerated. With cochlear hyperacusis, subjects feel ear pain, discomfort, annoyance, or some other emotional reaction when certain sounds are heard. In vestibular hyperacusis, exposure to sound can result in falling or a loss of balance.”12
Another interesting phenomenon is medication-induced vestibular dysfunction. A recent study found that 66.9% of subjects who were prescribed a chronic non-cancer pain medication or a medication for a neurological condition had vestibular dysfunction, which was significantly higher than the 35.4% incidence among the general population.10 The type and dosage of medications were not provided in the article. Physician-recommended therapy included neurologic examination and possible magnetic resonance imaging (MRI) or computed tomography (CT) of the brain, vestibular rehabilitation therapy, and related balance-
function rehabilitation therapy.
This warrants particular consideration in patients at higher risk for falls, and it may benefit clinicians to counsel patients on balance strategies to counteract any vestibular dysfunction that may be impacted by pain or pain medications.