Back pain, lumbar disc lesions

''Backache' is a common symptom. Your task, as often, is to sort out those patients who need specific and sometimes urgent treatment, from those whom you can only help symptomatically. ''Discs', together with osteorthritis and senile osteoporosis in the very old, make up most ''backaches'. The important backaches not to miss are the much less common infective ones, particularly in children: pyomyositis (7.1), osteomyelitis (7.15), septic arthritis (7.16) and tuberculosis (29.4). Other causes of back pain include malignant deposits in the spine, back injuries including ligamentous sprains (Chapter 64), spondylosis, spondylolysthesis and ankylosing spondylitis.

Lumbar disc lesions are due to the protrusion of the nucleus pulposus of an intervertebral disc through a weakened area in its annulus fibrosus. This is the ring of firm fibrous tissue that holds the softer nucleus pulposus in place. Prolapsed tissue from the nucleus pulposus presses on a nerve root, and causes pain down the leg. Almost all lumbar disc lesions occur in the spaces L[,4]/[,5] or L[,5]/S[,1]. Pressure on the S[,1] root causes pain down the back of the thigh, calf, and outer side of the foot. Pressure on the L[,5] root causes pain on the lateral aspect of the thigh and leg, and the dorsum of the foot. A protrusion from the L[,5]/S[,1] disc usually presses on the S[,1] root (not on L[,5]), but a protrusion from the L[,4]/L[,5] disc may press on the S[,1], or on the L[,5] root. Occasionally, when the protrusion is central, other roots are involved, and these may cause urinary problems. Disc protrusions are more likely to occur in a back which has been weakened by a sedentary occupation, and may follow sudden flexion of the spine, or bumping in a sedentary position, as with lorry drivers on bad roads.

The patient is usually a middle aged adult, or occasionally a younger one, who presents with sudden severe pain in the front of his thigh, the back of his thigh (sciatic pain, which is present in most patients), his calf, or his foot. Movement, coughing, or sneezing all make pain worse. The dorsum of his foot may be numb, and its dorsiflexors weak, occasionally on both sides. You can usually diagnose a disc lesion clinically without the use of X-rays; atypical cases are more difficult. Most disc lesions are benign and self-limiting, and can be managed non- operatively, although they often recur. Refer him for possible surgery on the indications given below[md]he probably has a central disc protrusion. At operation, the protruding disc material is removed, and his is disc scraped out.

Fig. 27-12a BACK PAIN. A, a normal disc. B, a ruptured annular ligament, with the nucleus protruding. C, an L[,5] lesion causes loss of sensation on the dorsomedial aspect of the foot, and weakness of the dorsiflexors of the ankle, with sparing of the ankle jerk. D, an S[,1] lesion causes loss of sensation on the lateral border of the foot, weakness of plantar flexors, a tender calf, and a diminished ankle jerk. E, a prolapsed disc pressing on the large L[,5] and S[,1] nerve roots; S[,2], S[,3], S[,4] and S[,5] are all small, control bladder function,, and are less often involved. F, a medial protrusion causes flexion of the lumbar spine, which tends to lift the root away from it. In this case the spine is convex to the left. G, a lateral protrusion causes flexion of the spine, which tends to lift the protrusion away from the disc. Here the spine is convex to the right. H, in severe osteoporosis X-rays show bulging of the discs into the demineralized vertebral bodies.

BACK PAIN EXAMINATION. Examine the patient's back as in Fig. 27-13. Examine a man's prostate rectally, and a woman's breasts.

LUMBAR DISC LESIONS EXAMINATION. His lumbar spine is flattened, with loss of its normal lumbar lordosis, and slight scoliosis. He may be tender over his interspinous ligaments, at the site of the lesion, or on gently tapping his spinous proceses. Movement of his lumbar spine is usually severely restricted. Forward flexion is always restricted, and is accompanied by spasm. Lateral flexion may be free, in one or both directions.

Lay him flat and raise his leg by his ankle. Straight leg raising is limited and flexing his ankle makes it worse. His ankle jerk (S[,1]) may be diminished or absent.

He may also have lost sensation in the relevant dermatomes, as shown in Figures 64-2, and A 6-8.

X-RAYS may or may not show confirmatory signs. Look for mild scoliosis, loss of his normal lumbar lordosis and narrowing of the disc space. The X-rays must be well centred to show this. If the film is taken obliquely, any disc space will look narrow.

THE DIFFERENTIAL DIAGNOSES include the following, and those listed below under ''Difficulties':

Suggesting bony secondaries[md]an older patient with persistent spinal pain, both when active and at rest. The X-rays of his spine may be normal initially. Typically, he has a patchy osteoporosis of the bodies, and/or the arches, of his vertebrae (some secondaries are sclerotic, especially those from the prostate). He may have a pathological fracture, especially of a vertebral body. His discs are spared. Look for the primary in the prostate (32.32), the breast (21.4), the bronchus (32.29), the thyroid (21.12), and the kidney (32.30),,,,,, and for signs of myelomatosis (32.17).

Suggesting an acute infective cause, pyomyositis (7.1), or osteomyelitis of the spine (7.2, 7.16)[md]an acute onset with fever in a child or young adult, who is obviously very ill.

Suggesting tuberculosis[md]a slow onset with loss of weight, malaise, mild fever, and a gibbus.

CAUTION ! (1) Young children don't have disc lesions, so assume that all back pain in a young child is serious, until you have proved it is not. (2) Back pain and fever are a serious combination. (3) Don't forget the possibility of tuberculosis (29.4).

TREATMENT. Put him to bed in his most comfortable position, which is usually with his hips and knees flexed. Don't put pillows under his knees; they will immobilize his legs and promote deep vein thrombosis. Put fracture boards under the mattress. Give him an analgesic (if necessary pethidine or morphine for the first few days), and don't let him get up, even to go to the toilet.

Many patients improve without traction (70.9). If you apply it, tie a band round his pelvis, and apply a total of 7 to 10 kg to both sides of it for a maximum of 3 to 5 days. Raise the foot of his bed to apply counter traction. Alternatively, apply 4 or 5 kg of traction to each leg with adhesive strapping.

Start active and passive movements of his legs, as soon as his acute pain is over. When his pain is sufficiently improved, start back extension exercises.

If his symptoms improve, keep him in bed for 3 weeks. Then allow him up to go to the toilet, keeping his back straight. If he wants to stoop, he must do this with his hips and knees, and keep his back straight.

INDICATIONS FOR REFERRAL. (1) If he has perineal numbness or incontinence of urine or faeces, referral for probable surgery is urgent. If you fail to do this, incontinence may become permanent. (2) More than mild weakness of his dorsiflexors (L[,5]) or plantarflexors (S[,1]). (3) Failure of his pain to improve, despite 3 or 4 weeks in bed.

Fig. 27-13 EXAMINING THE SPINE. A, flexion from side to side. B, flexion and extension forwards and backwards. C, rotation. D, straight leg raising to test for sciatic irritation. E, if a patient has a disc lesion, and you raise his leg straight, and then press in his popliteal fossa, it may cause sciatic pain. F, if you raise his other leg, it may also cause pain if he has a disc lesion.

DIFFICULTIES [s7]WITH BACK PAIN If an OLDER PATIENT complains of PAIN WHEN SITTING OR STANDING, or following manual activities, he is probably suffering from OSTEOARTHRITIS. X-ray him to exclude other diseases. If necessary, give him analgesics and keep his spine as mobile as possible with exercises. If he is obese, reduce his weight.

If an old patient, especially an OLD WOMAN, has a MARKED KYPHOSIS, think of SENILE OSTEOPOROSIS, with a generalized loss of matrix and calcium, especially from the bodies of her vertebrae. Her discs expand and compress her weak vertebral bodies. Painful pathological fractures are common, and she may have root pain.

Treat her symptomatically with analgesics, and encourage her to keep moving, if necessary with the aid of a stick. Oestrogens are useful, if they are started soon after the menopause before the condition is established. This requires the identification of risk factors, such as her family history. Give her stilboestrol 1 mg daily. The effect of this on a possible increased incidence of carcinoma of the breast is not known.

If an adult or older child complains of BACK PAIN, WORSE ON STANDING, and often episodic, consider the possibility of SPONDYLOLITHESIS. In this condition the body of a vertebra (commonly L[,5]) slips forwards on the vertebra below it. It is often asymptomatic, and even if you find it, it may not be the cause of his pain, so exclude other causes. If you find it by chance, when there is no pain, do nothing. If he has pain, refer him.

If a YOUNG MAN complains of BACK PAIN and later STIFFNESS, perhaps with inflammatory involvement of his other joints, consider the possibility of ANKYLOSING SPONDYLITIS (common in in India, rare in Africa). Typically, the pain wakens him from his sleep in the early hours of the morning, is relieved by getting up and walking, and, unlike most other pains, is made worse by rest. His upper legs may ache, but radiating pain is unusual. He may be ill. Test for bilateral sacroiliac tenderness, and pain over his sarioiliac joints on springing his pelvis (both early signs). All movements of his lumbar spine are restricted, sometimes with muscle spasm. His chest expansion is also restricted (an objective early sign). Look for uveitis (24.4). His ESR is raised. The earliest X-ray sign is bony erosion of the lower third of both his sacroiliac joints (invariable), followed later by secondary ossification and ankylosis of the whole joint. Early, his lumbar X-rays are normal; later he has a calcification of his intervertebral ligaments (''bamboo spine').

Teach him exercises to help prevent severe curvature of his spine, and retain mobility. In the early painful stages anti- inflammatory drugs may help, especially indomethacin 25 mg three times daily. Keep his major joints mobile, and if they do become fixed, try to ensure that this happens in the position of function (7-16).

Fig. 27-13a ANKYLOSING SPONDILITIS. A, the characteristic ''question-mark' posture of ankylosing spondylitis. B, bony bridges forming between the patient's vertebrae. C, his sacroiliac joints have fused and only the ghost of the old joint line is visible. J Robins in ''The Independent', permission requested.