Low Back Pain: Evaluating Presenting Symptoms in Elderly Patients

The Evaluation of the Elderly Person With Acute Low Back Pain

Most of us will experience back pain, a chronic illness with a high likelihood of recovery and recurrence. Back pain is second only to upper respiratory infection as the symptom most likely to precipitate a clinic visit. The prevalence of back pain in the geriatric population is estimated to be more than 70%.^[1-3]

As with many other clinical conditions, the cause, course, and evaluation of back pain in elderly people is different than in younger people. An elderly patient with a very first episode of low back merits close evaluation.

Degenerative changes in the lower back constitute a normal feature of aging, but these changes by themselves do not cause back pain. In younger people, back pain may be caused by distortion of the gel-like disks sandwiched between the vertebrae of the lower back. With aging, these disks lose much of their water content and are less likely to become distorted. However, this disk desiccation allows adjacent vertebrae to approximate each other and increases the wearing of the articular cartilage. Osteophytes may compress nerve roots and encroach on the spinal canal.

A Framework to Obtaining the History

Look for Signs of Systemic Disease and Referred Pain. One basic strategy is to first search for worrisome symptoms of systemic disease or clues to referred low back pain that would require immediate, sometimes urgent, imaging and specialized evaluations and consultations. These conditions tend to be nonmechanical (referred) low back pain or mechanical back pain with 1 or more red flags.

Once systemic causes of low back pain have been ruled out, 2 subgroups remain: pure mechanical low back pain and acute radicular low back pain, also known as sciatica.

Uncomplicated Mechanical Low Back Pain. Elderly people with back pain most commonly have uncomplicated mechanical low back pain. The discomfort tends to localize to the lumbosacral area and worsens with stretching, twisting, walking, or bending. The pain may cause aching in the buttock or thigh and rarely radiates below the knee. It is relieved by rest if the person can find a comfortable position in bed. The patient may report being awakened from sleep when turning over or changing position.

Acute Radicular Back Pain (Sciatica). Acute radicular low back pain radiates or shoots down one leg. The discomfort is often characterized as sharp, tingling, shooting or "electrical" and may be exacerbated by coughing, straining, sneezing, or Valsalva maneuvers. It may occur in several ways, depending on the nerve roots affected. The pattern of weakness (if present) in the lower extremity is an important clue to the site of the neurologic dysfunction. Significant unilateral thigh and leg weakness suggests involvement by multiple nerve roots or peripheral nerves (although most peripheral nerve processes are not usually associated with back pain). These presentations will be discussed in more detail below.

Of note, common causes of sciatica in elderly people include the following:

• Spinal stenosis: Spinal stenosis, the narrowing of the spinal canal, typically develops as a person ages and the disks become drier and start to shrink. At some point in this process, any disruption, such as a minor injury that results in disk inflammation, can cause impingement on the nerve root and trigger pain. Pain from spinal stenosis can occur in both legs or can occur as sciatica.
  
  
• Spondylosis and spondylolisthesis. Spondylosis occurs when the fourth or fifth lumbar vertebrae degenerate or develop small fractures. As it progresses, the spine can become unstable, leading to spondylolisthesis, in which one vertebra slips forward over the other and causes sciatica. The condition occurs mostly in older individuals, with women having a higher risk than men.