Common Pain Syndromes in Older Adults

During his presentation "Common Pain Syndromes in Older Adults" Saturday at PAINWeek, Paul J. Christo, MD, MBA, provided an overview of the prevalence of pain in older adults, discussed several physiological age-associated changes in pain processing, and described the clinical characteristics of four common pain syndromes commonly seen in elderly patients.

Christo noted that the prevalence of chronic painful conditions will increase as the US population ages. Current figures show that chronic pain is present in 25-50 percent of the elderly population, with prevalence increasing with age. He noted that people age 60 or older are twice as likely to have chronic pain as younger patients; patients age 80 or older are three times as likely to experience chronic pain. Although chronic pain is not a normal part of aging, Christo noted that one study found that up to 80 percent of residents in nursing homes report they experience chronic pain.

As people age, they experience a range of physiological changes that alters the way they process pain, said Christo, including a decrease in density of myelinated and unmyelinated fibers, an increased number of damaged or degenerated sensory fibers, reduced nerve conduction velocity, and impairment of myelinated fiber function. Older adult also have an increased pain threshold, coupled with a reduced tolerance for pain.

Christo reviewed the clinical characteristics of osteoarthritis, low back pain, neuropathic pain, and post-operative pain, noting that although older adults experience a wide range of painful conditions, these four are the most common causes of chronic pain in this population.

Osteoarthritis is present in 10-20 percent of older adults, with an average age at onset of 50 years or so, said Christo, with some degree of osteoarthritis being "nearly universal" in patients age 65 and older. The condition is seen in women more often than in men and pain associated with osteoarthritis is the leading cause of disability in seniors. He said that the history and physical exam are the most important aspect of diagnosis. Pharmacologic management options include acetaminophen, low-dose anti-inflammatory drugs, and topical agents. Interventional treatment options include glucocorticoid injections and hyaluronic injections. Christo also briefly reviewed joint replacement surgery as a last resort, as well as several other treatment modalities, including patient education, physical therapy, and aqua therapy.

Low back pain is the most common musculoskeletal disorder in older adults, and there is often more than one pathological contributor to low back pain, including osteoarthritis, spinal stenosis, degenerative disc disease, and others. One study found that 36 percent of older adults reported having experienced low back pain in the prior year; one in five older patients report experiencing moderate to severe frequent low back pain. Christo said that low back pain can be classified temporally (how often it occurs and duration) or structurally (according to physical cause). Causes include a range of conditions, but low back pain can also be caused by visceral or referred pain. Christo also identified several less prominent and less frequent non-mechanical causes such as infections, tumors, and various inflammatory processes.

The majority of older adults have mechanical lower back pain. Christo said that there are many possible etiologies of low back pain, including herniated disc, lumbar spondylosis, and arthritis. When evaluating older adults for low back pain, clinicians should look for evidence of neurological compromise, psychosocial stressors, and "elements suggestive of underlying systemic disease," said Christo. The physical exam should incorporate a broad range of tests and assessments and focus on specific areas, including the sacroiliac joint, the paraspinal muscles, the fibromyalgia tender points, the piriformis, and the iliotibial band. Christo said that imaging is not recommended when evaluating a patient for low back that lasts for less than 4-6 weeks unless the clinician suspects a recent traumatic event that may be the cause. If pain persists for more than three months then use plain radiography, MRI, and/or CT. Christo said that EMG/nerve conduction tests are not ordered often but can be useful if neuroimaging differs from the patient's radicular symptoms. Although Christo noted that there is "no definitive treatment for low back pain," management options include exercise and other self-care, physical therapy, and pharmacologic agents for short-term relief (NSAIDs, acetaminophen, etc). Christo mentioned that there is some data supporting the use of tricyclic antidepressants, but he recommends avoiding amitriptyline. Muscle relaxants "are overused and less effective," said Christo, but should be considerd if the patient has true muscle spasms.

"Neuropathic pain is a complex process that is not well elucidated," said Christo. A new definition for neuropathic pain has been proposed that would describe it as "pain arising as a direct consequence of a lesion or disease that affects the somatosensory system." Neuropathic pain affects up to 7-8 percent of the older adult population and includes many conditions, with diabetic peripheral neuropathy (DPN) and post-herpetic neuralgia (PHN) common in older adults. PHN, which results from herpes zoster (HZ), is classified as pain that persists for four months after the HZ rash dissipates. There is a 20 percent lifetime risk of developing HZ (increasing to 50 percent in adults age 85 and over) and the incidence increases with increasing age. Clinical features of PHN include vesicular rash, unilateral, dermatonal, in the thoracic region and ophthalmic branch of the trigeminal nerve, and other prodromal symptoms. Prompt treatment (within 72 hours, ideally) of HZ with an antiviral can reduce symptoms of acute pain and may decrease progression to PHN. There are several FDA-approved drugs for treatment (gabapentin, lidocaine patch, etc) and there is mounting evidence supporting the use of opioids in PHN.

With one third of all inpatient surgeries performed on adults over age 65, postoperative pain is a common source of chronic pain in older adults and, if not relieved, can cause a wide range of health problems. Postoperative pain has many causes, but one contributing factor is that older adults receive less analgesia and are often given less pain medication than younger patients. Treatment for postoperative pain includes multimodal analgesia, including NSAIDs and acetaminophen for mild to moderate postoperative pain. Christo said that opioids "are the cornerstone for moderate to severe postoperative pain." Clinicians who prescribe opioids for postoperative in older adults should decrease the starting dose by 25-50 percent and titrate slowly, said Christo. They should also monitor the patient for opioid-induced side effects and treat aggressively.

Christo closed the session by reminding the audience that patients' tolerance to pain decreases with age. Clinicians should be aware of the specific painful conditions that occur frequently in older adults, manage their chronic pain using a multi-modal approach, and tailor treatments according to recent guidelines and evidence.