| History: Individuals may complain of stiffness, local tenderness, generalized discomfort, and weakness of the lower back. Pain that radiates to the posterior thigh may reflect referred pain from myofascial, sacroiliac, or facet joint involvement. Pain that radiates to the leg, in the distribution of a nerve root (radiculopathy), may indicate nerve involvement. Pain that gets little relief from rest may suggest compression fracture or malignancy. Dramatic symptoms of neural compromise may imply uncommon conditions such as an epidural abscess or cauda equina tumor. More often, low back pain is aggravated by activity and improved by rest. Certain types of back pain do not originate in the back at all but from other tissues or organs. This is called referred pain, and the individual's history may provide information about the affected structure.
Most episodes of low back pain have no apparent cause. It is, however, important to rule out those causes of low back pain that require more urgent attention, including fracture, infection, tumor, or systemic conditions. The history may focus on when and under what circumstances the pain began. Information may be gathered regarding a possible precipitating incident such as a fall or an episode of heavy lifting. Questions may be asked regarding the pain: Has it worsened or improved? Are there any activities that aggravate or diminish it? Is it intermittent? Is it worse at a particular time of the day? Has the quality of the pain changed?
Perhaps one of the most important questions is whether this is the first episode of this particular type of pain. Recurrent low back pain is very common, and back pain is an episodic condition. With over 80% of adults having experienced low back pain, a complaint that this episode of pain is different from prior episodes or more persistent may be cause for more extensive testing. Physical exam: Individuals are examined in three positions: lying flat (supine), sitting, and standing. The exam includes visual inspection for obvious asymmetry, deformities, or accentuated spinal curves. Posture, gait, and range of motion are evaluated. Neurological examination assesses reflexes, muscle strength, sensation, and gait. Palpation along the spine, muscles, and tendon insertions can reveal areas of localized tenderness. Examination of the circulation in the lower extremities is important to exclude vascular causes of leg pain. Tests: In many cases, testing is not needed for simple low back pain. When testing is required, the type and amount are determined by the severity of the pain, whether it is chronic, and the individual's history of trauma or signs or symptoms (frequently called "red flags") suggesting the possibility of serious disease like spinal infection or tumor. In order to be considered diagnostic, test results must closely correlate with symptoms.
Plain x-rays reveal most fractures and deformities (e.g., scoliosis, spondylolisthesis) and may reveal more advanced spinal infections or tumors. Aside from these conditions, the age-related changes and/or anomalies visible on x-ray are not specific and do not generally correlate with the individual's symptoms.
Bone scans, MRI, and CT scans are used to rule out infection or tumor, if musculoskeletal pain is not the obvious diagnosis. In general, in the absence of specific symptoms or signs to suggest fracture, infection, or tumor, no imaging studies or tests are indicated initially. If tumor or infection is suspected, blood (complete blood count and erythrocyte sedimentation rate) and urine tests will generally be performed. Neurological testing may include electromyography (EMG) and nerve conduction studies if radiculopathy is suspected.
Provocative tests, such as discography or analgesic injections, are extremely controversial tests believed by proponents to help identify whether a specific disc or nerve root is the source of pain. These tests are not usually performed until the individual has failed a course of nonoperative care. Discography is usually performed in anticipation of surgery; nerve root injections may be both diagnostic and therapeutic. |