Scoliosis and Kyphoscoliosis

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Chapter 63 Scoliosis and Kyphoscoliosis

Anita K. Simonds

Scoliosis refers to lateral curvature of the spine (Figure 63-1), a well-recognized clinical entity that was described by Hippocrates as early as 500 BCE. Kyphosis indicates backward and lordosis forward curvature in an anteroposterior (medial) plane. Many patients who have a thoracic scoliosis are mistakenly described as having a kyphoscoliosis, because the rib angle prominence is misinterpreted as a kyphotic component. In fact, most instances of idiopathic thoracic scoliosis incorporate a lordotic and a rotatory element. The degree of lateral curvature is expressed by the Cobb angle, which is calculated from radiograph-based measurements, as shown in Figure 63-2.

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Figure 63-1 Radiograph showing lateral curvature of the spine in a patient with congenital idiopathic scoliosis.

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Figure 63-2 Method of calculating the Cobb angle.

Epidemiology, Risk Factors, and Pathophysiology

Spinal curvature is the most common cause of chest wall deformity. The causes of chest wall deformity are shown in Box 63-1. By far, the most frequently found scoliosis is the idiopathic variety, which accounts for approximately 80% of cases. Idiopathic scoliosis is defined as lateral curvature for which no cause can be identified; congenital forms of scoliosis are related to a developmental abnormality of the spine, as in failure of segmentation (e.g., fused vertebrae), failure of formation (e.g., hemivertebrae), or genetic syndromes (e.g., spondylocostal dysostosis or Klippel-Feil or Goldenhar syndrome).

Box 63-1

Classification of Spinal Deformity

Idiopathic Deformities

Idiopathic scoliosis

Idiopathic kyphosis

Congenital Deformities

Bone

Scoliosis

Kyphosis

Cord

Myelodysplasia

Syndromes in Which Scoliosis Is Common

Neurofibromatosis

Marfan syndrome

Osteogenesis imperfecta

Klippel-Feil syndrome

Mucopolysaccharidoses

Treacher Collins syndrome

Goldenhar syndrome

Apert syndrome

Ehlers-Danlos syndrome

Vertebral and epiphyseal dysplasias

Arthrogryposis

Deformity Associated With Neuromuscular Disease

Cerebral palsy

Poliomyelitis

Muscular dystrophies

Myopathies

Hereditary sensory motor neuropathies

Friedreich ataxia

Syringomyelia

Acquired Deformity Secondary to Insult or Disease

Surgery/trauma

Infection

Pyogenic
Tuberculosis (Pott kyphosis)

Radiotherapy

Tumor

Neuroblastoma
Osteoma
Hemangioma
Chordoma
Eosinophilic granuloma

Scoliotic curves of more than 35 degrees are present in 1 in 1000 population, and those that exceed 70 degrees are estimated to occur at a rate of 0.1 in 1000. A gender predilection for more pronounced deformity has been recognized: Females are at greater risk for severe curvature. It has been estimated that approximately 500,000 persons with a scoliotic curve of greater than 30 degrees are living in the United States. Approximately 3 or 4 children per 1000 will require specialist supervision for their spinal curvature, and a third of these will require intervention (e.g., corrective surgery or bracing). Idiopathic scoliosis occurs more often with increasing maternal age and in higher socioeconomic groups, but no association has been found between the incidence of scoliosis and birth order or season of birth. A subclassification of idiopathic scoliosis is based on age at onset of the spinal changes resulting in curvature—infantile (birth to age 3 years), juvenile (3 to 11 years), and adolescent (11 years and older).

Scoliosis is associated with a variety of congenital syndromes. Marfan syndrome affects 1 in 5000 of the population, and approximately 70% of these patients develop a spinal deformity. Diagnosis can be confirmed by linkage to the Marfan syndrome gene MFS1, the protein product of which produces fibrillin. Marfan genotype-phenotype correlations show association with severe mutations in 25% of persons with the syndrome, with 50% of those in the latter half of the exon (exons 33 to 63). Related syndromes may result from mutations in microfibrils that interact with fibrillin in the extracellular matrix. Congenital contractual arachnodactyly (Beals syndrome), in which scoliosis is common, also has been shown to be caused by fibrillin deficiency.

Neurofibromatosis type 1 (NF) is a multisystem disease, with scoliosis being the most common bone manifestation, occurring in 10% to 30% of patients. Genome-wide scans have identified the likely chromosomal locus on 17q11.

Genetics of Idiopathic Scoliosis

The genetic basis of idiopathic scoliosis remains unclear, and causation may be multifactorial in that particular growth patterns may exacerbate a genetic predisposition. Support for an underlying genetic cause comes from data showing an incidence of idiopathic scoliosis in 6.94%, 3.69%, and 1.55% in first-, second-, and third-degree relatives, respectively, of 114 affected persons. These findings are consistent with either an autosomal dominant or a multifactorial mode of inheritance. A large kindred with autosomal dominant idiopathic scoliosis has been identified with a chromosomal locus on 17p11. By contrast, congenital scoliosis is relatively common among congenital malformations and is associated with congenital heart and renal tract anomalies. An autosomal recessive form of congenital scoliosis has been found in male and female sibships with consanguineous parents, associated with lack of vertebral segmentation and fused ribs. Mouse models for idiopathic scoliosis have been developed, and the list of candidate genes continues to grow, indicating the underlying etiologic complexity and probable interaction of genetic, environmental, and developmental factors.

Spinal curvature is acquired in neuromuscular disorders (Figure 63-3) that involve the chest wall and thoracic musculature before skeletal maturity occurs. Scoliosis develops in more than 50% of boys with Duchenne muscular dystrophy (DMD), and spinal curvature is common in many of the other congenital muscular dystrophies, myopathies, and conditions such as type I and type II spinal muscular atrophy. The introduction of steroid therapy in childhood in DMD may lessen the severity of scoliosis by reducing the rate of loss of muscle strength, such that wheelchair dependency occurs later in adolescence and peak vital capacity is increased, although the number of prospective randomized controlled trials has been limited.

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Figure 63-3 Radiograph showing extensive severe neuromuscular scoliosis in a patient with type II spinal muscular atrophy.

A scoliotic deformity often develops as a sequela of thoracotomy carried out in childhood or young adulthood.

Kyphosis

Idiopathic kyphosis is rare. An increase in thoracic kyphosis occurs with age and is exacerbated by factors that increase a tendency to osteoporosis, such as oral corticosteroid therapy. Pott’s disease, or tuberculosis (TB) of the spine, is still a common cause of acquired kyphosis in TB-endemic geographic regions.

Effects of Chest Wall Deformity on Respiratory and Cardiac Function

Chest wall disorders affect respiratory function and cause a restrictive ventilatory defect. Any significant scoliosis or kyphosis results in a loss of height, so arm span can be used to predict normal lung volumes. As a general rule, patients who have a thoracic curve of greater than 70 degrees are subject to significant ventilatory limitation.

Lung Volumes

Although both scoliosis and kyphosis diminish lung volumes, which results in a restrictive ventilatory defect, lateral curvature has a more profound effect on chest wall mechanics. Total lung capacity is reduced in all chest wall disorders. In a pure scoliosis, both vital capacity (VC) and expiratory reserve volume are decreased, with relative preservation of residual volume (Table 63-1). An obstructive ventilatory defect is rare in scoliosis and kyphosis, unless the individual is a smoker, has coexistent asthma, or the scoliosis results in bronchial torsion.

Table 63-1 Typical Results on Pulmonary Function Testing in Patients With Idiopathic Thoracic Scoliosis

Parameter Effect
Forced expiratory volume in 1 second (FEV1) Reduced
Forced vital capacity (FVC) Reduced
FEV1/FVC Normal
Residual volume Normal
Total lung capacity Reduced
Transfer factor for carbon monoxide—diffusion capacity (DLCO) Reduced
Transfer coefficient (KCO)—DLCO/accessible alveolar volume Supranormal*

* Transfer coefficient usually is supranormal, but it is reduced in the presence of pulmonary hypertension.

The relationship between pulmonary impairment and the deformity is complex and cannot be predicted accurately from the Cobb angle alone. The four major determinants of a reduced VC are the number of vertebrae involved in the curve, position of the curve closer to the head, Cobb angle, and the degree of loss of normal thoracic kyphosis.

In paralytic scoliosis, lung volumes are reduced not only by chest wall restriction but also by inspiratory muscle weakness.

Chest Wall Mechanics

Chest wall compliance (CCW) is an important determinant of lung volumes and the work of breathing. Patients with a Cobb angle of less than 50 degrees experience a minimal reduction in CCW, whereas CCW is likely to be significantly reduced if the Cobb angle is greater than 100 degrees. A direct relationship between Cobb angle and CCW is not seen in patients with neuromuscular disorders, because respiratory muscle weakness contributes independently to chest wall stiffness. Alteration in chest wall properties cannot be attributed solely to the mechanical deformity of scoliosis, because a decrease in CCW has been found in patients affected by chronic respiratory muscle weakness in the absence of a scoliosis.

Lung Compliance

Although lung expansion is compromised by chest wall properties, primary pulmonary pathology is unusual in patients who have idiopathic scoliosis. Lung compliance is reduced, however, because of a shift in the pressure-volume curve to the right. These changes in pulmonary characteristics arise largely from an alteration in alveolar forces caused by chronic hypoventilation. In patients with neuromuscular disease, microatelectasis and macroatelectasis may complicate the picture. Microatelectasis seems relatively rare, however, because fine-section (thin-slice) CT scans have shown areas of atelectasis in only a minority of patients affected by respiratory muscle weakness. Patients with neuromuscular disease who exhibit bulbar weakness or an ineffectual cough are at increased risk for recurrent pneumonia. Severe lateral curvature of the spine in a minority of patients can produce bronchial torsion, and obstruction of the bronchus by this mechanism may lead to recurrent distal infection. Pulmonary fibrosis also is a histopathologic feature in patients who have “old” TB, in whom areas of bronchiectasis may be seen. Cystic lung changes may be noted in some patients with neurofibromatosis.

Gas transfer coefficient tends to be raised in patients with scoliosis in the presence of a low transfer factor (see Table 63-1), because extrathoracic compression squeezes more air than blood out of the lungs, thereby decreasing accessible alveolar volume.

Respiratory Muscles/Thoracic Pump During Sleep

Impaired respiratory muscle function might be expected in idiopathic scoliosis, because the respiratory muscles work at a mechanical disadvantage when chest wall shape is altered. A reduction in transdiaphragmatic pressure and static respiratory mouth pressures have been demonstrated in patients who have scoliosis or a thoracoplasty. These findings tend to support the contention that the efficiency of the respiratory muscles may be affected by relatively small degrees of chest wall deformity. Respiratory muscle action is further reduced by the loss of intercostal muscle tone during rapid eye movement (REM) sleep and a reduced ability to compensate for added respiratory load. The effect of these changes explains why early features of ventilatory failure during sleep predate the development of daytime ventilatory failure.

Control of Breathing

Impaired hypercapnic ventilatory drive usually is secondary to chronic CO2 retention in patients with scoliosis. However, primary drive disorders may complicate some neuromuscular conditions (e.g., myotonic dystrophy) and may be acquired in patients in whom poliomyelitis has compromised brain stem control mechanisms. Generally, however, ventilatory drive is increased in patients with neuromuscular disease, to compensate for respiratory muscle insufficiency.

Pulmonary and Cardiac Hemodynamics

Cor pulmonale is the end-stage result of severe, untreated chest wall deformity. Pulmonary artery pressure becomes elevated at rest with an inverse correlation between pulmonary artery pressure and arterial oxygen tension. In some patients with severe scoliosis, a disproportionate rise in pulmonary artery pressure on exercise can be seen in the absence of hypoxemia, because the restricted thorax is unable to accommodate the increase in cardiac output on exertion.

An additional stress on hemodynamics is the effect of nocturnal hypoventilation on pulmonary artery pressure. The exact level of nocturnal hypoxemia that generates pulmonary hypertension is unknown, but if it is severe, nocturnal arterial blood gas disturbances inevitably lead to daytime problems if the condition is left untreated.

Impact of Adolescent Idiopathic Scoliosis on Exercise Capacity

In a recent case-control study, the relationship among pulmonary function, muscle strength, and exercise ability was explored in 60 patients with adolescent-onset scoliosis (AIS) and Cobb angles greater than 40 degrees, and the findings were compared with data for 25 control subjects. The patients with AIS had mild to moderate ventilatory limitation (FVC of 86% predicted), but both respiratory muscle and limb muscle strength together with exercise capacity were reduced in comparison with those in control subjects. In the AIS group exercise capacity was 58% predicted with a maximum oxygen uptake of 60% predicted. Arterial oxygen saturation values on exercise remained normal. Of note, no relationship was found between the Cobb angle and lung function, muscle function, or exercise capacity. Exercise ability, however, was correlated with inspiratory, expiratory, and limb muscle function, with the main contributor on multiple regression analysis found to be limb muscle function. This finding suggests that generalized muscle dysfunction is key to explaining exercise limitation in the absence of severe ventilatory impairment and underscores the point that AIS may be a systemic disease process.

Clinical Features

Spinal abnormalities are best evaluated by ascertaining the age at onset, etiology, and location of the curve (e.g., adolescent onset, idiopathic thoracic scoliosis). During physical examination, accompanying features should be sought, such as café-au-lait spots and neurofibromas. Marfan syndrome is a clinical diagnosis that requires the involvement of two of three main systems—ocular, cardiac, and skeletal. A careful search for cardiac lesions is mandatory in patients with early-onset scoliosis, which is associated with an increased incidence of congenital heart disease. Skeletal lesions demonstrated radiologically, such as hemivertebrae and rib fusion, suggest the presence of a congenital scoliosis.

Patients are observed in the standing position and then viewed bending forward, to obtain an indication of the degree of lateral rib hump deformity. Assessment of shoulder and pelvic symmetry, leg length, and gait is helpful. The lower back should be examined for hairy tufts and other cutaneous stigmata of spinal dysraphism, and a full neurologic examination should be performed.

Progression of Curvature

Detailed studies of the natural history of untreated idiopathic scoliosis are rare, but the younger the age at presentation, the greater the potential for progression, because more of the growth spurt needs to be accommodated, and spinal growth continues until at least the age of 25 years. High and low thoracic curves, together with thoracolumbar curves, seem to be more unstable than lumbar deformities. Curves most likely to progress include those caused by congenital failure of segmentation, infantile idiopathic scoliosis, the angular curve of neurofibromatosis, pronounced paralytic curves, and scoliosis associated with progressive childhood neuromuscular conditions.

In AIS, key determinants of progression are the growth potential of the child at presentation and the magnitude of the curve. On evaluation using standard indices of skeletal maturity, skeletally immature children with a more pronounced curve (20 to 29 degrees) at initial diagnosis had a 68% risk of curve progression, whereas more mature teenagers with similar curves showed a 23% risk of curve progression. Conversely, immature children with lesser curves (5 to 19 degrees) had a 22% chance of curve progression, whereas mature children had only a 1.6% chance of progression. It also has been shown that children with curves of less than 30 degrees at skeletal maturity did not experience curve progression in adulthood, whereas a majority of curves greater than 50 degrees progressed at a rate of approximately 1 degree per year.

Diagnosis

Cardiopulmonary Decompensation: Identification of High-Risk Cases

Most patients who have a thoracic spinal curvature do not develop cardiorespiratory problems and therefore do not require long-term respiratory follow-up evaluations. It is important to identify the minority at risk for such problems, however, so that appropriate monitoring and therapeutic intervention can be carried out.

Cor pulmonale was the primary cause of death in a series of 102 untreated patients with idiopathic thoracic scoliosis. Age at onset of the scoliosis is crucial to ascertain. Branthwaite showed that in patients in whom cardiorespiratory problems attributable to their scoliosis developed, 90% had an early-onset curvature (i.e., onset before the age of 5 years).

A VC of 50% predicted is an important cutoff value, because respiratory decompensation is much more likely to develop in patients with a VC of less than 50% predicted at presentation than in those with initially larger lung volumes.

In a study by Braithwaite, the mean age of patients in respiratory failure who presented for ventilatory support was 49 years for those with idiopathic scoliosis, 51 years for those with previous poliomyelitis, and 62 years for those who had sequelae of pulmonary TB. Pehrsson and co-workers followed lung function over a period of 20 years in patients with idiopathic scoliosis. Respiratory failure occurred in 25%, all of whom had a VC of less than 45% predicted and a thoracic Cobb angle greater than 110 degrees.

Monitoring High-Risk Patients

Monitoring high-risk patients should include the following:

• Assessment for breathlessness, exercise intolerance and associated limiting factors, frequency of chest infections, and symptoms of nocturnal hypoventilation

• Clinical examination

• Pulmonary function testing

• Arterial blood gas analysis

• Measurement of respiratory muscle strength (e.g., mouth pressures, sniff inspiratory pressure)

• Spinal and chest radiology

Additional investigations may be indicated:

• MRI scanning may be required to delineate spinal cord and vertebral anomalies, and computed tomography may be needed to investigate abnormalities such as pulmonary hypoplasia or bronchial torsion.

• Echocardiography (ECG) is mandatory in all patients with congenital or early-onset scoliosis.

A fall in VC of more than 15% predicted on assuming the supine position indicates significant diaphragm weakness. Daytime hypercapnia is associated with an inspiratory mouth pressure of less than 30% predicted.

As noted, in addition to detecting breathlessness and exercise tolerance, the assessment should identify any symptoms of nocturnal hypoventilation (morning headache, poor sleep quality, frequent arousals, nocturnal confusion, and morning anorexia); if any of these is present, the patient should undergo monitoring of respiration during sleep. A characteristic picture of nocturnal hypoventilation, with episodes of desaturation and CO2 retention most pronounced in REM sleep, usually is revealed (Figure 63-4).

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Figure 63-4 Overnight recording of oximetry-determined oxygen saturation (SpO2) and transcutaneous carbon dioxide tension (TcCO2) in a patient with early-onset scoliosis. The initial clinical presentation was one of sleep disturbance and morning headaches. The tracings show three periods of dips in SpO2 and peaks of TcCO2 in rapid eye movement sleep.

Treatment

Management of Spinal Deformity

Conservative Management

The success of a conservative approach depends on the age of the patient, the severity of the curvature at presentation, and its propensity to progression. For example, an infantile idiopathic scoliosis may spontaneously regress, whereas a juvenile-onset scoliosis is more likely to progress.

Bracing

Devices such as the Milwaukee and Cotrell braces have been used extensively, and these continue to evolve. The mechanical aim of the brace is to re-create a normal thoracic kyphosis, hyperextend the spine, and limit forward flexion, all of which will act to derotate the scoliosis. Bracing probably works more effectively with a kyphosis than with a scoliosis. In paralytic disorders, a circumferential brace can support the trunk, thereby making sitting more comfortable. Vital capacity should always be measured with and without the brace in place.

Surgery for Scoliosis

In general, surgery is performed to correct unacceptable deformity and to prevent progression. It is not carried out to improve ventilatory function.

Thoracic scolioses with curves of more than 45 degrees usually are judged to be unacceptable. A lesser curve associated with a greater degree of rotation, however, may create a rib hump, which is just as concerning to the patient. It is a surgical maxim that even the best operative technique does not completely straighten a spine. An approximately 50% correction of the Cobb angle in smaller curves can be expected from an instrumentation procedure. The best guide to a successful result is the initial amount of spinal flexibility. Also, the greater the degree of rotation, the greater the inflexibility of the curve.

Spinal fusion followed by casting has now been superseded in many situations by rod instrumentation (Figure 63-5). The system provides distraction to the concave side of the spine and compression to the convex side, which enhances stabilization and reduces any rotational tendency. Instrumentation is used to stabilize the curve and spinal fusion to prevent growth. A posterior approach is used, but with a severe deformity or very rigid curvature, an anterior approach may be required to release the disk space. The combined anterior and posterior approach carries greater anesthetic and surgical risk. In patients with AIS, surgical complication rates are around 5% to 6%, with wound infections being more common after posterior fusion and pulmonary complications more frequent with use of an anterior approach. Weiss and colleagues have recently debated the pros and cons of surgical correction in AIS.

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Figure 63-5 Radiograph showing instrumentation in place in a patient with scoliosis treated with a Harrington rod.

Preoperative assessment should include the investigations listed previously. In persons with a VC less than 50% predicted, a sleep study should be considered. If there is evidence of nocturnal hypoventilation, use of noninvasive ventilation (NIV) in the perioperative period may be helpful.

A recent consensus conference of scoliosis surgery in patients with Duchenne muscular dystrophy (DMD) highlighted the fact that scoliosis surgery should be carried out in centers with full access to multidisciplinary respiratory and cardiac input. The key aim of scoliosis surgery in these neuromuscular conditions is not to improve lung function, because most studies show no major impact on postoperative lung volumes, but to prevent further progression of the curve and to improve comfort and sitting position in a wheelchair. Surgery should optimally be performed in DMD and other neuromuscular conditions when pulmonary function is not too compromised (as reflected in an FVC greater than 30% predicted) but has been carried out safely in patients with VC between 20% and 30% predicted as supportive care such as NIV in the postoperative period and cough assistance with a mechanical insufflator-exsufflator has become available. All patients with DMD are at risk for development of cardiomyopathy, and left ventricular function and ECG should be monitored closely. Surgery-associated risks are likely to increase if left ventricular fractional shortening is less than 25%, and these risks should be carefully balanced against the overall prognosis.

Management of Ventilatory Impairment

Optimization of Respiratory Function

Individuals should be advised of the adverse effects of smoking and obesity and encouraged to enroll in appropriate intervention programs. The influenza and pneumococcal vaccines are recommended for persons who have ventilatory limitations.

Bisphosphonate therapy reduces the risk of osteoporosis in postmenopausal women and also in men. Care should be taken not to miss the reactivation of TB in patients with a thoracoplasty. Patients who have Marfan syndrome may require β-adrenergic blocker therapy to reduce the risk of aortic dissection.

Exercise should be encouraged, other than for persons with pulmonary hypertension and patients with Marfan syndrome. Pulmonary rehabilitation programs suggest that exercise and a reduction in deconditioning is just as valuable in restrictive disorders as in chronic obstructive pulmonary disease.

Ventilatory Failure

The evidence now clearly shows that ventilatory failure in patients who have chest wall disease can be successfully treated by use of NIV at night. Negative-pressure devices are effective but have been supplanted by noninvasive positive-pressure ventilation systems. In patients with scoliosis who receive NIV, the 5-year survival rate is approximately 80%, with rates of 100% in patients with previous poliomyelitis and greater than 90% in those with post-TB conditions. It seems increasingly likely that persons who have nonprogressive disorders may live a normal or near-normal life span, provided that NIV is introduced before the development of intractable pulmonary hypertension. Patients report good quality of life with use of NIV, and many are able to return to work.

Of note, NIV produces a more favorable outcome than that achieved with long-term oxygen therapy (LTOT) in patients with scoliosis. In a retrospective analysis of consecutive patients with kyphoscoliosis who started LTOT alone or NIV in Belgium, 1-year survival was higher in the NIV treatment group (100% versus 66%), and NIV-managed patients demonstrated a greater improvement in PaO2 and PaCO2. More recently, these results have been confirmed in a larger Swedish cohort, for which the reported survival rate was three times higher in NIV users than in those receiving LTOT alone, and this was unrelated to baseline arterial blood gas tensions, gender, or respiratory comorbidity. In general, oxygen usually is combined with NIV at night if mean SaO2 on NIV alone is not above 90%, despite adequate control of PaCO2. Evidence that any one type of ventilator is superior in patients with scoliosis is lacking, although some patients with congenital or idiopathic scoliosis may require relatively high inflation pressures.

NIV also can be used to palliate symptoms of breathlessness and cor pulmonale in patients who have progressive disorders and will alter the natural history of these conditions. A 5-year survival as high as 73% can be achieved in DMD, and many patients with DMD are now surviving into their 30s and early 40s.

Controversies and Pitfalls

Clinical Signs in Scoliosis

In patients with severe scoliosis in whom asthma subsequently develops, an important consideration is that a characteristic wheeze may not be heard because of low airflow. Measurement of spirometry and home peak flow monitoring are useful in these cases.

An isolated unifocal wheeze may indicate bronchial torsion or kinking, which can occur in patients with severe scoliosis and may be associated with bronchiectasis or hyperinflation in the distal lung lobe. Bronchial stenting has been successfully used in this situation. In the case shown in Figure 63-6, the right bronchus intermedius was partially obstructed by torsion and compression against the spine. The clinical consequence was development of a staphylococcal pneumonia with cystic changes affecting the right lower lobe.

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Figure 63-6 Computed tomography scan showing compression of right bronchial tree and hyperinflated right lower lobe with cystic change. The patient had a staphylococcal pneumonia that resulted from the ventilatory obstruction.

(Courtesy P. Rafferty.)

Pregnancy and Scoliosis

A successful outcome from pregnancy is usual in most patients who have adolescent-onset idiopathic scoliosis. In a survey of 118 pregnancies in 64 women who had thoracic scoliosis, no serious medical problems were encountered, with a cesarean rate of 17% for obstetric reasons. More recently, in a study of 142 pregnancies in women who had been treated with Harrington rod surgery, the proportion of cases requiring cesarean section was slightly higher than in the general population, but the rates of complications in pregnancy and delivery did not exceed those in the general population, and the offspring were healthy. About 40% of mothers developed low back pain during pregnancy, but this had resolved by 3 months after delivery in a majority. Likewise, a 2010 survey of cases of mostly idiopathic scoliosis in India shows a higher cesarean rate than for women without scoliosis, and no major problems with maternal health were reported.

However, cardiorespiratory complications can be expected in women with a VC less than 1.0 L. Stable curves are unlikely to progress during pregnancy. Prepregnancy counseling and assessment are sensible in patients with scoliosis, particularly those with congenital or early-onset curves or a VC less than 50% predicted. Assessment should include full pulmonary and cardiologic evaluation and genetic counselling. Pregnancy is contraindicated in the presence of pulmonary hypertension and hypoxemia. If ventilatory problems arise in pregnancy, the situation may be successfully managed by use of NIV.

Suggested Readings

Bergofsky EH. Thoracic deformities. In: Roussos C, ed. The thorax; part C: disease. New York: Marcel Dekker; 1995:1915–1949.

Branthwaite MA. Cardiorespiratory consequences of unfused idiopathic scoliosis. Br J Dis Chest. 1986;80:360–369.

Buyse B, Meersseman W, Demedts M. Treatment of chronic respiratory failure in kyphoscoliosis: oxygen or ventilation? Eur Respir J. 2003;22:525–528.

Chopra S, Adhikari K, Agarwal N, et al. Kyphoscoliosis complicating pregnancy: maternal and neonatal outcome. Arch Gynecol Obstet. 2011;284:295–297.

Giampietro PF, Blank RD, Raggio CL, et al. Congenital and idiopathic scoliosis: clinical and genetic aspects. Clin Med Res. 2003;1:125–136.

Gustafson T, Franklin KA, Midgren B, et al. Survival of patients with kyphoscoliosis receiving mechanical ventilation or oxygen at home. Chest. 2006;130:1828–1833.

Lowe TG, Edgar M, Margulies JY, et al. Etiology of idiopathic scoliosis: current trends in research. J Bone Joint Surg Am. 2000;82-A:1157–1168.

Martinez-Llorens J, Ramirez M, Colomina MJ, et al. Muscle dysfunction and exercise limitation in adolescent idiopathic scoliosis. Eur Respir J. 2010;36:393–400.

Orvoman E, Hiilesmaa V, Poussa M, et al. Pregnancy and delivery in patients operated by Harrington method for idiopathic scoliosis. Eur Spine J. 1997;6:304–307.

Pehrsson K, Bake B, Larsson S, Nachemson A. Lung function in adult idiopathic scoliosis: a 20 year follow up. Thorax. 1991;46:474–478.

Simonds AK. Home non-invasive ventilation in restrictive disorders and stable neuromuscular disease. In: Simonds AK, ed. Non-invasive respiratory support: a practical handbook. ed 3. London: Arnold; 2007:184–188.

Weiss HR, Bess S, Wong MS, et al Adolescent idiopathic scoliosis—to operate or not?. A debate article. Patient Saf Surg. 2008;2:25.

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