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KYPHOSCOLIOSIS

Epidemiology and Pathobiology

Kyphoscoliosis, which is a common spinal disorder, affects approximately 1

in 1000 individuals, and about 1 in 10,000 affected individuals has a severe

spinal deformity. Deformities include excessive spinal curvature in the

coronal (scoliosis) and sagittal (kyphosis) planes as well as rotation of the

spinal axis. Kyphoscoliosis can be idiopathic or can be secondary

(paralytic) and associated with neuromuscular diseases, such as muscular

dystrophy and polio.

Idiopathic kyphoscoliosis, in which there may be a familial

predominance, usually manifests in late childhood or early adolescenceand involves females more than males with a ratio of 4:1. Although a defect

in the chromatin-remodeling gene family (CHD7 ) has been associated with

idiopathic kyphoscoliosis, other genes have also been identified.

Kyphoscoliosis produces one of the most severe restrictive

impairments of all the chest wall diseases. Total lung capacity and vital

capacity may be reduced to as low as 30% of predicted values. This

restrictive pathology becomes most severe as the degree of spinal

angulation increases. The patient’s age, degree of spinal rotation, presenceof respiratory muscle weakness, and involvement of the thoracic vertebrae

are all factors that promote the restrictive process. Respiratory failure is a

common cause of morbidity and mortality in patients with kyphoscoliosis.

Clinical Manifestations

Individuals with mild to moderate kyphoscoliosis may have complaints of

back pain and have psychosocial problems as a result of their deformity.

Adolescents with mild idiopathic kyphoscoliosis usually have normalexercise capacity, whereas those with moderate idiopathic kyphoscoliosis

have reduced exercise capacity with additional exercise limitation due to

deconditioning. With severe deformities, patients may experience dyspnea

with minimal exertion or at rest.

Severe kyphoscoliosis can be readily diagnosed on physical

examination. Typical findings are the dorsal hump, which is due to the



angulated ribs and shoulder asymmetry, as well as the hip tilt that is related

to the spinal rotation. In younger individuals with milder spinal deformities,

the initial changes may be subtle. The Adams forward bend test, in which

the examiner observes for thoracic or lumbar region asymmetry while the

patient bends forward at the waist until the spine becomes parallel to the

floor, can help detect minor deformities. With severe kyphoscoliosis, signs

of right heart failure may be present such as cyanosis, distended neck

veins, peripheral edema, and hepatomegaly.

Individuals with kyphoscoliosis are particularly prone to hypoventilation

during sleep, especially REM sleep. Because sleep-related abnormalities

and their effects on cardiorespiratory function are potentially treatable,

individuals with kyphoscoliosis should be evaluated for nocturnalhypoventilation well in advance of the development of daytime

hypercapnia.

Diagnosis

Although spinal deformity is often readily apparent on physical examination,

the degree of spinal deformity should be assessed by calculation of the

angle of spinal curvature (the Cobb angle) from radiographs. This angle is

formed by the intersection of lines parallel to the top and bottom vertebraeof the scoliotic or kyphotic curves (Fig. 99-1). Angles more than 100

degrees are usually associated with respiratory symptoms, and angles

more than 120 degrees with respiratory failure. Factors associated with

progression of the spinal deformity include inspiratory muscle weakness, a

large spinal curvature at the time of presentation, skeletal immaturity, and a

thoracic location of the curve apex. Individuals with inspiratory muscle

weakness and kyphoscoliosis are more prone to develop respiratory failure

than those with normal inspiratory muscle strength.



TREATMENT

Patients should be encouraged to remain physically active to minimize

peripheral muscle deconditioning. In addition, general supportive measures

including immunizations against influenza and pneumococci, smoking

cessation, maintenance of a normal body weight, and treatment of

respiratory infections in a timely fashion should be instituted. Patients with

severe kyphoscoliosis and Cobb angles of more than 100 degrees should

be monitored closely for respiratory complications. Respiratory failure may

be precipitated by respiratory infections or by medications that produce

central nervous system depression.

Nocturnal hypoventilation typically precedes findings of daytime hyper-

capnia and hypoxemia and should be treated with NPPV. Indications for



instituting NPPV include symptoms of nocturnal hypoventilation or signs of

cor pulmonale with either an elevated daytime PaCO2 or nocturnal oxygen

saturation of less than 89% for 5 consecutive minutes. Supplemental

oxygen will be needed if hypoxemia persists despite correction of

hypoventilation. NPPV can reduce the number and duration of

hospitalizations and improve gas exchange, daytime blood gases, quality of

life, and survival (see Table 99-2).

Surgical and nonsurgical (back-brace) treatments have been used in

skeletally immature patients with idiopathic kyphoscoliosis in an effort to

correct or prevent progression of the spinal deformity. Braces have been

used for growing children with Cobb angles between 25 and 40 degrees,

whereas surgery has been used for adolescents with a Cobb angle of morethan 45 degrees. The overall role of surgical management in restoring

function to that of nonscoliotic individuals and minimizing the possibility of

respiratory failure is not clear.

Prognosis

Idiopathic kyphoscoliosis has a better prognosis than kyphoscoliosis

secondary to neuromuscular diseases. In general, individuals with mild

idiopathic kyphoscoliosis have an overall benign course. Patients withmoderate or severe deformities are at higher risk of developing respiratory

complications.

In secondary kyphoscoliosis, factors such as an early age of onset,

rapid curve progression during growth, progression of scoliosis after

skeletal maturity, large curves at the time of presentation, and a thoracic

rather than a thoracolumbar or lumbar location of the curve apex are risk

factors for respiratory complications. Respiratory failure may occur in

individuals with mild or moderate kyphoscoliosis owing to concurrent

respiratory muscle dysfunction. Muscle strength should be evaluated in

individuals with respiratory failure and Cobb angles of less than 100

degrees. When cor pulmonale develops, the prognosis is poor, and death

may occur within 1 year without therapy.

kyp ho scoliosis

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