Back pain is extremely common. It can be mild and transient, or chronic and disabling. In many cases, the exact cause is not established. In Britain 375000 people lose some time from work each year because of back pain, an annual loss of 11.5 million working days, and back pain accounts for 6% of general-practice consultations. Back pain is not usually serious and mostly resolves; in one survey 44% of cases resolved within a week and 12% within 2 months.
Most back pain can be readily diagnosed from a simple clinical history and physical examination. A diagnostic approach to back pain. In many patients (30%) no cause will be found. It is foolish to label such patients as having ‘spondylosis’ or arthritis of the spine, terms that merely cause anxiety. It is better to use a term such as non-specific low back pain and explain to the patient what this means. The back is a common site of psychogenic pain. If possible a positive diagnosis of psychogenic back pain, rather than a diagnosis by exclusion, should be made. Supportive treatment can then be given.
The following factors should be considered.
LUMBAR PAIN. This is usually due to degenerative disease, disc prolapse and OA, which are almost never seen in the thoracic spine.
THORACIC PAIN. This is a characteristic site of osteoporotic crush fractures.
Sciatic radiation of pain suggests root compression; however, sacroiliac pain can also radiate down the back of the thigh to the knee.
• Sudden, e.g. disc prolapse or mechanical injury
• Gradual, e.g. ankylosing spondylitis
Pain in the back and leg on walking and relieved by stopping, suggestive of intermittent claudication, can be due to spinal stenosis.
• Disc disease is recurrent.
• Ankylosing spondylosis is chronic.
Inflammatory vs. mechanical
The differences in the history given in inflammatory and in mechanical back pain are shown.
Examination of the patient is summarized.
In back pain, investigations are less important than the history and examination. They can also be misleading; for example, degenerative changes on X-ray are virtually always present in older people and may not be the cause of the pain.
X-rays are particularly useful for excluding serious bone disease. Normal X-rays usually exclude metastases but not invariably. They are of little value in acute disc disease, although a narrowed disc space may suggest a prolapse.
Bone scans are useful to detect metastases; a slightly increased uptake in areas of degenerative disease is usually easily distinguished. MRI scans are now the investigation of choice in disc disease. Abnormal discs are distinguished on MRI scans because of changes in their water content. Impingement of disc material on the nerve roots is usually well seen and it is seldom neccesary to undertake the old-fashioned and invasive radiculogram.
ESR 0R C RP is a particularly useful investigation. A normal ESR or CRP makes serious disease unlikely. A very high ESR suggests myeloma.
CALCIUM, PHOSPHATE AND ALKALINE PHOSPHATASE LEVELS are measured to look for metabolic bone
disease such as osteomalacia.
ACID PHOSPHATASE AND PROSTATE-SPECIFIC ANTIGEN are measured to look for metastases from prostatic carcinoma.
PROTEIN ELECTROPHORESIS, IMMUNOGLOBULINS
(AND BONE MARROW ASPIRATION) are performed to look for myeloma.