In the United States, back pain is the most common reason for limiting physical activity in people younger than 45 years; it is the second most frequent cause of visits to a physician, the fifth cause of hospital admissions, and the third leading cause of surgery. In many countries, it is the most common cause of absenteeism from work, accounting for more than 12% of sick days. The aggregate economic cost in the Netherlands in 1991 was estimated to be 1.7% of gross national product. This figure likely represents the typical cost incurred by developed nations. In the United States, the aggregate cost of lower back pain is estimated to exceed $100 billion per year.

According to Andersson, “Chronic low back pain has become a diagnosis of convenience for many people who are actually disabled for socioeconomic, work-related, or psychological reasons.” The complexity of the problem is measured in a lengthy literature and a long list of approaches to therapy. Medications and other therapies include nonsteroidal anti-inflammatory drugs, opiates, and antidepressants; extradural injection of steroids; decompressive surgery; physical therapy, including massage and exercise; chiropractic treatment; and acupuncture. In Finland, a third of the direct costs were spent on complementary therapies. Multidisciplinary spine centers and pain centers may be sources of the most effective approach to management.

Root syndromes of intervertebral disk disease are often episodic, so remissions are characteristic. The pain may be restricted to the back or follow a radicular distribution in one or both legs. Lumbar pain may increase after heavy lifting or twisting of the spine. No matter how severe the pain is when the patient is erect, characteristically, it is relieved when the patient lies down. Some patients, however, are more comfortable sitting and many find no comfortable position.

Physical examination often reveals loss of lumbar lordosis or flattening of the lumbar spine with splinting and asymmetric prominence of the long erector muscles. Range of motion of the lumbar spine is reduced by the protective splinting of paraspinal muscles, and attempted movement in some planes induces severe back pain. There may be tenderness of the adjacent vertebrae. When the patient is erect, one gluteal fold may hang down and show added skin creases because the gluteus is wasted—evidence of involvement of the S1 root. Passive straight leg raise is reduced in range and increases back and leg pain. Muscle atrophy and weakness or sciatic tenderness and discomfort may occur on direct pressure at some point along the nerve from the sciatic notch to the calf. This is particularly true in older patients.

The typical syndromes of root compression at lumbar levels are described in Table 109.1. Importantly, clinical signs may not be as distinct in actual practice as the table implies. More than 80% of syndromes affect the L5 or S1 nerve roots (Table 109.2). Compression of the nerve root at these levels results in “sciatica,” a sharp and burning pain that radiates down the posterior/lateral aspect of the leg to the foot or ankle (Fig. 109.3). When the lesion affects L4 or higher roots, straight leg raise does not stretch the roots above L5. The affected roots may be tensed, however, by extension of the limb with the knee flexed when the patient is prone, thus reproducing the typical radicular spread of pain. Nerve root compression is often associated with numbness and tingling. Radicular pain resulting from disk disease classically intensifies with Valsalva (coughing, defecating, sneezing).

The thoracic spine is designed for rigidity rather than excursion, thus wear and tear from motion and stress may not cause thoracic disk protrusion, and clinical disorders are rare. Thoracic disk disease may result from chronic vertebral changes incident to Scheuermann disease or juvenile osteochondritis with later trauma. The radiographic changes of Scheuermann disease, when seen with thoracic cord compression, should raise the possibility of disk protrusion (Fig. 109.4). The small capacity of the thoracic spinal canal makes this region vulnerable to cord compression from disk herniation. By the same token, decompressive operations are more precarious and require meticulous care to avoid damaging the spinal cord. Calcific changes are common in pathologic thoracic intervertebral disks, which pose additional challenges when performing diskectomy. The lower thoracic levels, however, are more capacious, and although the conus medullaris or cauda equina may be damaged by disk protrusions, surgical approaches are less hazardous compared to higher levels.