Affections of the Spine and Thorax
Affections of the spine
Scoliosis is a lateral curvature of the spine. The curvature may be nonstructural, in which case the deformity is not fixed and the pathologic changes are usually outside the spine, or it may be structural. In structural scoliosis the deformity is associated with vertebral rotation and the curve cannot be completely corrected or maintained in a corrected position by the patient. Scoliosis is a deformity rather than a disease, and its causes are many. It is usually first detected during childhood, but, depending on the etiology it may have its onset at any time from infancy to the adult years.
Classification and etiology: The etiologic classification is necessarily imperfect, since our knowledge of the causes of scoliosis is incomplete. The Scoliosis Research Society has adopted a comprehensive classification of spinal deformities, of which the following is a modified and shortened version.
Nonstructural scoliosis: One large group of scoliosis patients is made up of those whose spinal curvatures are the result of temporary postural influences. Such functional or nonstructural scoliosis is not accompanied by rotational or asymmetric changes in the individual structures of the spine. The curve is not fixed, in that bending in the opposite direction is not restricted, and the patient can actively and completely correct the deformity by sitting erect. Functional scoliosis may result from poor posture or leg length discrepancies and usually poses no major therapeutic problem. An abduction or adduction contracture of the hip causes the pelvis to tilt when the patient stands with lower limbs parallel. This results in apparent rather than real leg length discrepancy and nonstructural scoliosis. A nonstructural scoliosis may also be caused by nerve root irritation such as the sciatic scoliosis seen in acute lumbar disk herniation. Only rarely does a functional curve progress to become a structural scoliosis.
Structural scoliosis: Structural scoliosis on the other hand, is characterized by definite morphologic abnormalities, and it is with this group of cases that therapeutic effort is most concerned. The causes of structural scoliosis are numerous. Congenital scoliosis is usually caused by a defect in embryologic development of the vertebrae or ribs, such as hemivertebra. Neuromuscular scoliosis is associated with a great variety of paralytic disorders that cause asymmetric paralysis of the trunk muscles. Structural scoliosis occurs also in neurofibromatosis; in skeletal diseases such as osteogenesis imperfecta, Marfan's syndrome, and osteomalacia; and, especially in children, after unilateral thoracic conditions such as thoracoplasty and chronic empyema. In the great majority of patients with structural scoliosis, however, the pathogenesis is unknown. Such cases are classified as idiopathic scoliosis. Because of the variety of disorders with which scoliosis may be associated, a thorough and detailed examination is required to establish the diagnosis. Important in the examination is a careful neurologic evaluation to detect the neuromuscular varieties of scoliosis.
Pathology: The extent of the pathologic changes varies with the degree of lateral curvature. All the structures of the concave side are compressed or shortened, whereas those of the convex side may remain normal or become lengthened. The apical vertebra, situated at the middle of the curve, shows the greatest change, being wedge shaped and most rotated. The vertebrae above and below it undergo similar but less pronounced changes. The intervertebral disks are compressed on the side of the concavity and may bulge on the opposite side as a result of the pressure; the nucleus pulposus migrates toward the convex side. The anterior longitudinal ligament is thickened on the concave side and thinned on the convex side. As the deformity increases, proliferation of bone takes place; later, ossification of the ligaments may occur. Malalignment of the spinal joints leads to degenerative arthritic changes in later life.
Rotation of the vertebrae in the axial plane invariably accompanies structural scoliosis. The rotation, which is greatest in the apical vertebra, is such that the vertebral body always turns toward the convex side of the curve, and the spinous process toward the concavity. This results, in the case of thoracic curves, in a posterior rotation of the chest wall, a posterior prominence of the rib cage (rib hump) on the convex side of the curve, and an anterior prominence of the thorax on the concave side. The vertebral rotation also leads to distortion of the posterior spinal elements and the neural canal. The deformity of the thorax results in a decrease in its volume, especially on the convex side. This impairment is accentuated by collapse of the spine to the point that the rib cage may rest on the pelvis, compressing both thoracic and abdominal viscera. Because of these anatomic changes in the chest, cardiopulmonary failure is a frequent cause of death in patients with severe scoliosis. Significant changes in pulmonary function are usually not apparent in curves under 55 degrees. As curvature increases above this level there is a progressive loss of pulmonary function, and at 100 degrees the patient often becomes symptomatic.
Roentgenographic picture: The pathologic changes described previously are reflected on the roentgenogram. Roentgenograms are not only important in establishing the diagnosis, but they are also essential in following the progress of scoliosis. Several types of curves can be identified. A major, or primary, curve, which is usually the largest and most rigid, is generally accompanied by minor or compensatory, curves above and below. The minor curves are more flexible and show fewer structural changes. Occasionally there are two major curves, forming a double major scoliosis. The location of a curve is of prognostic significance. Those in the thoracic and cervical regions tend to be most rigid and deforming.
Measurements of the curvatures are made on the roentgenograms in a standardized manner. The Cobb method of measurement is the most widely accepted technique. It is important that the same careful roentgenographic technique and measurements be applied each time the patient is examined, for major decisions concerning treatment will often be based on measured changes in the degree of curvature. Initial roentgenographic studies usually include an anteroposterior view of the entire spine made with the patient in the supine and standing positions. Views taken of the supine patient bending as far as possible to the left and to the right give evidence of the flexibility of major and minor curves. A lateral roentgenogram of the spine demonstrates kyphotic and lordotic curves and detects spondylolisthesis sometimes associated with scoliosis. Single anteroposterior films made in the standing position are usually sufficient to record the course of the scoliosis. Protective shields placed over the breasts and thyroid have been recommended by some to reduce repeated radiation exposure of these organs.
Idiopathic scoliosis: Of all the forms of structural scoliosis, the idiopathic scoliosis encountered in adolescents is the most common. Its cause is unknown. It is seen predominantly in girls (85%) and is associated with a significant familial occurrence (25%). Of the various hypotheses of etiology, including unrecognized paralysis, asymmetric growth of vertebral epiphyseal plates, and minor disorders of proprioception and balance associated with labyrinthine disorders, none has been proved. An infantile type of idiopathic scoliosis, uncommon in the United States, affects boys more frequently than girls and resolves spontaneously in most instances. A juvenile variety, of equal sex distribution and beginning between 3 years of age and the onset of puberty, is also recognized.
Clinical picture: As a rule there is no complaint until the deformity of the back is noticed, and since the deformity is of very gradual development, it may reach considerable proportions before its presence is observed. It is often first detected by a schoolteacher or health nurse, much to the surprise of the unsuspecting parents. The patient may be brought to the physician because of a high shoulder, a prominent hip, or a projecting shoulder blade. When the patient is a young girl, the fitting of a dress may first call attention to the deformity. Occasionally the child may complain of fatigue and backache before a deformity is noted. As the scoliosis increases, the discomfort bay become greater. In severe cases, pain developing in the lumbar region may be caused by pressure of the ribs on the crest of the ilium, but pain is generally not a prominent feature until the patient is well into adult life. There may be shortness of breath from diminished respiratory capacity, and gastrointestinal disturbances from crowding of the abdominal organs. In patients with only slight deformity, symptoms usually do not occur until middle age or later.
Physical examination should be conducted with the patient disrobed except for brief shorts. Viewed from the back, the most prominent features are the spinal curvature, asymmetric flank folds in the presence of a level pelvis, and prominence of the scapula and shoulder on the convex side of the curve. In adolescent idiopathic scoliosis the thoracic curve is usually convex to the right and the lumbar curve to the left. In the lumbar area, spinal rotation results in prominence of the paravertebral muscles on the convex side, while in the thoracic region rotation of the rib cage elevates the scapula and shoulder. The thoracic rotation, manifested by the rib hump, is best demonstrated by having the patient bend forward. With the patient erect, a plumbline dropped from the spinous process of C7 should pass through the intergluteal crease. If the line falls to one side of the crease, the scoliosis is uncompensated. In such instances the plumbline falls to the side of the major curve, indicating that there has been insufficient compensation by the minor curves to center the head over the pelvis. Flexibility of the curves may be evaluated by having the patient bend to each side or by supporting the patient briefly by the chin and occiput while noting the decrease in the spinal curvature. Standing and sitting heights as well as arm span should be recorded.
Diagnosis: Idiopathic scoliosis is diagnosed by exclusion, by eliminating from consideration other conditions that might cause spinal curvature. The neurologic findings should be normal, limb lengths equal, and manifestations of congenital disorders or systemic disease absent. Examination of siblings and other members of the family is advisable.
Prognosis: Among the large majority of adolescent children in whom structural scoliosis is detected in routine school screening programs, significant progression of the spinal curve does not occur. This is particularly true of children with minor curves who have nearly reached maturity. On the other hand, if the curve is greater than 20 to 30 degrees and the child still has several years to grow when the deformity is first detected, the chances of progression are increased. Thoracic and double primary curves are more likely to progress than are lower curves. In most cases of idiopathic scoliosis, significant progression of the curvature creases spontaneously with the cessation of vertebral growth at he age of 15 years in girls and 17 years in boys. Curves greater than 40 degrees at maturity , however, may continue to progress in adult life, although usually at a slower rate.
A useful roentgenographic guide, described by Risser, is the fact that idiopathic scoliosis increases little after the age at which the iliac crests have been fully capped by their apophyses. Fusion of the vertebral ring apophyses, which occurs a little later than capping of the iliac crests, is a more reliable indication of the completion of spinal growth. After skeletal maturity, structural curvatures may very gradually increase because of degenerative changes in the spine; this is often especially noticeable in paralytic scoliosis.
During childhood, however, the deformities of structural scoliosis may progress rapidly, constituting a serious therapeutic problem until the arrest of advancing curvature can be assured. Every case demands careful attention and supervision over a long period of time. In adult scoliosis pain is a common symptom, occurring in about two thirds of the cases, often in the fourth decade of life and in association with lumbar curves.
Without treatment, idiopathic curvatures in growing children may increase to cause severe deformity and disability. It is not possible to predict accurately how much an individual curve will increase. In general, the younger the patient and the earlier the onset, the more guarded must be the prognosis. Curves in the thoracic and cervicothoracic areas have poorer prognosis because of their tendency to become fixed and to cause sever deformity. Spinal curves that are severe at the time of first diagnosis naturally carry a poorer prognosis than those that are still mild. Curves of more than 100 degrees are likely to lead to cardiopulmonary disability.
Treatment: With these prognostic considerations in mind, the treatment of scoliosis must be suited to the individual patient. Many persons with idiopathic scoliosis will not require definitive treatment. Cosmetic considerations often influence the decision. As a general rule, thoracic curves that exceed 35 degrees are cosmetically unacceptable. However, the appearance of any given patient varies not only with the angular measurement but also with the spinal segment involved, the length of the curve, the patient's physique, and the degree of vertebral rotation.
In treating scoliosis the basic aims are to recognize curvature early, to evaluate its chance of progressing accurately, and insofar as possible to correct it and maintain its correction.
Nonsurgical measures. At the start of therapy for established scoliosis, nonsurgical treatment is used and, in the majority of patients, need not be followed by surgical measures. Two types of nonsurgical treatment are in general use. The first consists of exercises and observation. This treatment is reserved for mild cases with flexible curves under 20 degrees or perhaps a little more if the patient is near maturity. Exercises have not been shown to exert any lasting corrective influence on a structural cure, but they may serve to maintain spinal flexibility. Close observation by means of standing roentgenograms repeated faithfully every 3 to 6 months, with the more frequent observation being made during periods of rapid growth, is essential. If there should be any sign of progression, more aggressive treatment is indicated.
The second nonsurgical treatment is the use of braces. Of the many braces and jackets devised for treating scoliosis, that inmost effective use is the Milwaukee, or Blount, brace. It incorporates both active distraction, encouraged by adjustable uprights extending from head to pelvis, and adjustable posterolateral pressure over the thoracic prominence. In it the patient can lie down, sit, walk, carry out prescribed exercises, and engage in some sports. After initial passive lessening of the spinal deformity by the brace, further improvement is obtained by such activities and by special exercises taken under the direction of a physical therapist. As further correction occurs, the pads are advanced and the brace lengthened. The brace is worn for 23 hours a day and removed for 1 hour for bathing, skin care, and additional exercises.
In early progressive but flexible curves of young children of 20 to 40 degrees, the Milwaukee brace can be used to correct and maintain correction of the deformity. It is not effective in curves of over 40 or 50 degrees. During the period of spinal growth it may, by alleviating pressure on the concave side of the vertebral epiphyses, prevent and to some extent correct fixed deformity of the spine. The brace must be worn until all tendency toward increase of the curvature ahs ceased. Thus bracing must usually be continued until skeletal maturity, demonstrated by closure of the vertebral and iliac apophyses, has been reached. A gradual weaning rather than abrupt removal of the brace is recommended. In the final months the brace is worn only at night. During this critical period, frequent roentgenographic measurements of the curve are made to rule out any recurrence of the deformity.
If satisfactory correction can be maintained without need for extensive surgery, the effort is very worthwhile. Special training on the part of the physician and the brace-maker in the manufacture and adjustment of this brace is advisable. Since possible complications of wearing the brace include skin allergies, pressure sores, and emotional disturbance, the patient should be seen at frequent intervals. A cooperative patient and intelligent, understanding parents are essential to efficient brace treatment. Plastic braces that are shorter and less bulky than the Milwaukee brace are more readily accepted by young patients. The shorter braces are most effective in the treatment of flexible lower (thoracolumbar and lumbar) curves of less than 40 degrees.
Surgical Measures: Surgical treatment is indicated when curvatures of unacceptable degree cannot be satisfactorily improved or their improvement satisfactorily maintained by nonsurgical measures. In many clinics, operations advocated for all forms of paralytic scoliosis, for rapidly increasing idiopathic scoliosis, and for any other type accompanied by severe deformity in adolescence. In general, progressive curves of more than 45 degrees in children who are still growing are best treated surgically. As a rule, however, only about 5% of the cases of idiopathic scoliosis are severe enough to require spinal fusion.
Spinal arthrodesis, applies in the treatment of scoliosis by Hibbs in 1914, is the most effective means of permanently maintaining correction of the curvature. It may be done in one or more stages after maximum correction of the curvature by brace or cast has been obtained. Alternatively the arthrodesis may precede correction, since straightening of the curvature is facilitated.