G Model
YPRRV-957; No. of Pages 10 Paediatric Respiratory Reviews xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Paediatric Respiratory Reviews
CME article
Chest Wall Abnormalities and their Clinical Significance in Childhood Anastassios C. Koumbourlis M.D. M.P.H.* Professor of Pediatrics, George Washington University, Chief, Pulmonary & Sleep Medicine, Children’s National Medical Center
EDUCATIONAL AIMS 1. 2. 3. 4.
The The The The
reader reader reader reader
will will will will
become familiar with the anatomy and physiology of the thorax learn how the chest wall abnormalities affect the intrathoracic organs learn the indications for surgical repair of chest wall abnormalities become familiar with the controversies surrounding the outcomes of the VEPTR technique
A R T I C L E I N F O
S U M M A R Y
Keywords: Thoracic cage Scoliosis Pectus Excavatum Jeune Syndrome VEPTR
The thorax consists of the rib cage and the respiratory muscles. It houses and protects the various intrathoracic organs such as the lungs, heart, vessels, esophagus, nerves etc. It also serves as the so-called ‘‘respiratory pump’’ that generates the movement of air into the lungs while it prevents their total collapse during exhalation. In order to be performed these functions depend on the structural and functional integrity of the rib cage and of the respiratory muscles. Any condition (congenital or acquired) that may affect either one of these components is going to have serious implications on the function of the other. Furthermore, when these abnormalities occur early in life, they may affect the growth of the lungs themselves. The following article reviews the physiology of the respiratory pump, provides a comprehensive list of conditions that affect the thorax and describes their effect(s) on lung growth and function. ß 2014 Published by Elsevier Ltd.
INTRODUCTION The thorax comprises the upper body and it consists of multiple independent bony parts (spinal vertebrae, sternum, ribs) that form the rib cage, and several muscles that cover it from the outside and separate it from the abdominal cavity. The rib cage provides the ‘‘scaffolding’’ on which the muscles lay and connect, whereas the muscles provide stabilization and movement to the rib cage. Although, it is often viewed as just a ‘‘protective case’’ for the various intrathoracic organs (lungs, heart, vessels, esophagus, nerves etc), the thorax is in fact a dynamic apparatus (the so-called ‘‘respiratory pump’’) that performs the actual function of breathing by, generating the movement of air in and allowing or forcing the movement of air out of the lungs). Thus, any condition that results in its malfunction will have significant repercussions on the function of the respiratory system and frequently on other intrathoracic organs as well.
* Division of Pulmonary & Sleep Medicine, Children’s National Medical Center, 111 Michigan Ave N.W., Washington DC 20010 Tel.: +001-202-476-3519; fax: +001-202-476-5864. E-mail address: [email protected].
‘‘Chest wall abnormalities’’ refer to any abnormality that affects the normal structure and/or limit the function of the thorax. Chest wall abnormalities are often referred to as chest or thoracic dysplasias or dystrophies. Although there is a certain overlap between these terms, in this article, dysplasia refers to abnormal anatomic structures that result from the abnormal growth or development of cells or tissues, and it is primarily used for bony abnormalities (e.g. Spondyloepiphyseal dysplasia). The term dystrophy is conventionally used for muscle abnormalities (e.g. muscular dystrophy). This article reviews in detail the common types of chest wall abnormalities and the effects they have on the respiratory system. TYPES OF CHEST WALL ABNORMALITIES Many of the chest wall abnormalities (especially the dysplasias) are congenital but they can also develop later in life as a result of a disease (e.g. ankylosing spondylitis) or injury that can be accidental (e.g. flail chest secondary to trauma), or iatrogenic (e.g. thoracotomy). Specific genes and modes of inheritance have been identified for many of the congenital dysplasias, whereas others are assumed to be caused by accidental exposures. The chest wall abnormalities are either primary or part of a syndrome
1526-0542/$ – see front matter ß 2014 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.prrv.2013.12.003
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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YPRRV-957; No. of Pages 10 A.C. Koumbourlis / Paediatric Respiratory Reviews xxx (2014) xxx–xxx
2
Table 1 Conditions associated with abnormalities of the thorax CONDITION Aarskog syndrome Achondrogenesis Achondroplasia Allagile Syndrome (arteriohepatic dysplasia) Beals syndrome Camptomelic Dysplasia Cerebro-Costo-Mandibular syndrome Chondroectodermal dysplasia Chondroplasia punctate CHARGE syndrome CHILD syndrome Cleidocranial dysostosis Coffin-Lowry syndrome Cohen syndrome Diastrophic dysplasia Down syndrome Dyggve-Melchior-Clausen syndrome Early Amnion Rupture sequence Ehlers-Danlos syndrome Escobar syndrome Fetal Hydantoin Effects Fetal Alcohol syndrome Fetal Aminopterin Effects Fetal Valproate Effect Fibrochondrogenesis Frontometaphyseal dysplasia Generalized Gangliosidosis syndrome, Type I Gorlin syndrome Haldu-Cheney syndrome Homocystinuria syntrome Hunter syndrome Hurler syndrome Hypophosphatasia Incontinentia PPigmenti syndrome Jarcho-Levin syndrome Jeune syndrome Klippel-Feil sequence Kniest Dysplasia Kozlowski spondyloepiphyseal dysplasia Langer-Giedion syndrome Lenz-Majeswski hyperostosis syndrome Lethal multiple pterygium syndrome Marfan syndrome Marinesco-Sjogren syndrome Maroteaux-mucopolysaccharidosis Melnick-Needles syndrome Meningomyelocele Metaphyseal chondrodysplasias Metatropic Dysplasia Morquio syndrome Mucopolysaccharidosis VII Multiple synostosis Multiple Lentigines syndrome Multiple neuroma syndrome MURCS association Neurofibromatosis syndrome Noonan syndrome Osteogenesis imperfect Oto-Palato-Digital syndrome Pallister Hall syndrome Partial Trisomy 10q syndrome Poland anomaly Progeria syndrome Proteus syndrome Pseudoachondroplasia Sponyloepiphyseal dysplasia Pyle Metaphyseal Dysplasia Rhizomelic Chondroplasia Punctuta Robinow syndrome Rokitansky sequence Rubenstein-Taybi syndrome Ruvalcaba syndrome Sanfilippo syndrome Seckel syndrome Short rib syndrome Shprintzen syndrome Shwachman syndrome Sponyloepiphyseal dysplasia congenita
THORACIC SHAPE
STERNUM
RIBS
PE/PC
SPINE
VERTEBRAE
(X)
(X) X X X X X X
Small thoracic cage Small thoracic cage X Small thoracic cage Small thoracic cage Small thoracic cage
X X
X (X)
X
(X)
X X X
X X
(X) (X) (X)
Small thoracic cage PE/PC Small thoracic cage (PE/PC) PE/PC
(X)
X X (X) (X) (X)
X X (X) (X)
PE/PC
X (X)
Small thoracic cage X X
(X) X
(X) X (X) X
X X
X X X X (X) X
X
Small thoracic cage X Small thoracic cage Small thoracic cage (X)
(X) X
PE/PC X X
(X) X X X X X X
Small thoracic cage PE/PC PE/PC Small thoracic cage
PE/PC
X X
PE/PC
X X
Small thoracic cage Small thoracic cage
PE/PC PE/PC
Small thoracic cage (Small thoracic cage)
PE/PC PE/PC PE/PC PE/PC
X (X) X
X X
(X) X X X X X X (X) X
(X) (X) (X) (X) X (X) X X
(X) (X)
X
(Small thoracic cage) (X) Small thoracic cage X
X X (X)
(X)
PE/PC
X X X
X (X) X X X X (X) (X) X (X) X X X X X (X) X X
(X)
Small thoracic cage
X (X) PE/PC
X
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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YPRRV-957; No. of Pages 10 A.C. Koumbourlis / Paediatric Respiratory Reviews xxx (2014) xxx–xxx
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Table 1 (Continued) CONDITION
THORACIC SHAPE
Thanatophoric dysplasia Trich-Rhino-Pharyngeal syndrome Trisomy 8, 9, 9p Mosaic syndrome Trisomy 4p, 13 Trisomy 18, 20 Vater syndrome Waardenburg syndrome Williams syndrome XO, XYY, 18p, XXXXY syndromes
Small thoracic cage
STERNUM
RIBS
SPINE
VERTEBRAE X
PE/PC Small thoracic cage X (X) X (X) (PE/PC) PE/PC
(X)
X X X (X)
X (X) X X (X)
(X)
(X)
Adapted from: Smith’s Recognizable Patterns of Human Malformation / Edition 5., Jones KL Elsevier Saunders, Philadelphia, PA, USA 1988 PE: Pectus Excavatum; PC: Pectus Carinatum; (X): abnormality only occasionally present
Table 2 Chest wall abnormalities on each of the components of the thorax Abnormalities of the Sternum
Abnormalities of the Ribs
Abnormalities of the Spine
Abnormalities of the Muscles
Pectus Excavatum Pectus Carinatum
Fused ribs (e.g. Jarcho-Levin syndrome) Narrow chest (e.g.Asphyxiating Thoracic Dystrophy) Fractured ribs (e.g. Flail chest)
Scoliosis Kyphosis
Absent muscles (Poland Syndrome) Muscle weakness (e.g. spinal muscular atrophy)
Lordosis
Absent ribs (e.g. resection of tumors)
Abnormal vertebrae
Defects (e.g. Congenital diaphragmatic hernia); gastroschisis) Paralysis (e.g, diaphragmatic paralysis)
Bifid Sternum
(Table 1). Most of the syndromes initially affect a specific component of the thorax but because of the interrelationship between the various components eventually the entire thorax may become deformed. From a clinical standpoint the chest wall abnormalities can be categorized according to the part of the thorax that is primarily affected (Table 2) and/or according to the causes as follows: Congenital chest wall abnormalities a) Anomalies of the sternum (e.g. Pectus excavatum, bifid sternum) b) Anomalies of the ribs (e.g. Jarcho-Levine Syndrome) c) Anomalies of the spine (e.g. Scoliosis) d) Anomalies of the respiratory muscles (e.g. Poland syndrome, neuromuscular disorders)
spondylitis (that may cause ossification of the ligaments in the spine and in the rib cage); fibrothorax (that causes fibrosis of the pleura that in turn limits the expansion of the rib cage), and scleroderma (that limits the expansion of the rib cage due to the thickening of the skin that covers the thorax). Abdominal conditions Conditions such morbid obesity, accumulation of large amounts of fluid or air in the peritoneal cavity (e.g. ascites or pneumoperitoneum) or organ enlargement (e.g. significant hepatosplenomegaly) may cause severe limitation in the function of the thorax by impeding the function of the diaphragm. Defects of the abdominal wall (e.g. gastroschisis, giant omphalocele) also impede diaphragmatic function, thus limiting the normal expansion of the thorax. One could also include the normal pregnancy (although it obviously can ‘‘affect’’ only women of reproductive age) as a cause of temporary dysfunction of the thorax due to the pressure that the fetus and the amniotic sac exert on the diaphragm.
Acquired chest wall abnormalities Trauma Traumatic injuries to the thorax such as fractures of the ribs, the sternum or the spine will affect the normal function of the thorax not only at the time of the injury but potentially in the long-term as well, due to potentially abnormal healing. Similar short and longterm effects may be produced by accidental trauma to the muscles (e.g. extensive burns) Or after iatrogenic injuries (e.g. rib and/or muscle resection due to tumours, sternotomy for cardiac surgery) Neurologic conditions Partial or complete paralysis of the respiratory muscles due to injuries (e.g. spinal cord injury) or diseases (e.g. Guillain-Barre syndrome), not only prevent the normal breathing but eventually, can cause significant disfigurement of the thorax because the weak muscles cannot provide the necessary stability that is required to maintain its physiologic shape. Diseases affecting components of the thorax Various unrelated conditions may affect parts of the thorax causing significant limitation to its expansion. Typical examples (although generally rare in children) include ankylosing
Hypoplasia or absence of the lung Lung agenesis, severe lung hypoplasia (e.g. congenital diaphragmatic hernia), and pneumonectomy can cause significant disfigurement of the rib cage due to the ‘‘caving’’ of the rib cage on the affected side as well as due to the hyperinflation of the contralateral lung that usually herniates to the opposite side thus rotating the intrathoracic organs and the mediastinum. Severe upper airway obstruction Chronic significantly increased work of breathing (e.g. severe laryngomalacia or subglottic stenosis) may cause irreversible disfigurement of the chest wall, usually in the form of pectus excavatum. ANATOMY & PHYSIOLOGY OF THE THORAX To understand the effects of the thoracic dystrophies on the respiratory system, one has to understand the anatomy and physiology of the normal thorax. The rib cage is formed very early in fetal life. Primitive elements of the ribs, the clavicles and the sternum can be detected as early as 6 weeks of gestation (mesenchymal phase). When fully developed, the thorax resembles
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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a truncated cone formed by the sternum anteriorly, by the 12 thoracic vertebrae of the spine posteriorly, and by 12 pairs of ribs that connect the sternum and the spine in a complex way. Specifically, all 12 pairs of ribs are connected with the 12 thoracic vertebrae thus forming the posterior and lateral aspects of the rib cage. However, only 4 pairs (first, tenth, eleven and twelfth) are connected with the respective vertebrae, whereas the remaining pairs (ribs 2-9) are connected with two vertebrae each. The anterior wall of the thorax is formed by the sternum that is connected only to the first 7 seven pairs of ribs. Ribs 8-10 are attached only indirectly to the sternum by being attached to the cartilage of the rib above them, whereas the eleventh and twelfth ribs are not attached to the sternum at all. These articulations form a characteristic triangular opening in the anterior wall. [1] The ribs are attached to the vertebral bodies as well as to the sternum with true synovial joints consisting of articular cartilages, joint capsules and synovial cavities that allow freedom of movement of the ribs during the respiratory cycle. In neutral position, the ribs (especially the lower ones) lie in a downward fashion whereas during inspiration they assume a more horizontal position thus expanding the rib cage in an upward and outward fashion. However, not all ribs move the same way. The upper ribs move in a vertical plane that resembles the movement of an oldfashion pump (pulling the rib cage upwards). The middle ribs move in a way similar to the handle of a bucket, whereas the lower ribs move laterally, resembling the movement of a caliper. These complex movements allow the rib cage to increase significantly its cross-sectional area thus providing enough space for the lungs to expand. During infancy the ribs lie normally in an almost horizontal position, placing the infants at a mechanical disadvantage compared to older children and adults because they cannot expand their chest outward and so they rely almost exclusively on diaphragmatic breathing. The sternum is a few centimeters long at birth but it grows up to 20 cm in adults. It is comprised of three areas (manubrium, body, and xiphoid). The manubrium is connected via articulation with the clavicle and the first rib. It is also connected with the body of the sternum approximately at the level of the junction of the second rib (angle of Louis). Normally, the bifurcation of the trachea is located behind the angle of Louis. [1] The thorax is separated from the abdominal cavity by the diaphragm. As a result it is subjected directly to the pressures generated in the abdominal cavity, in part contributed to by the size of the abdominal organs. The diaphragm consists of two distinct muscular parts connected by a tendon. The tendon extends from the xiphoid process of the sternum to the second and third lumbar vertebral bodies, thereby placing the diaphragm in an angle in which its anterior portion lies higher than the posterior. The position of the diaphragm is not fixed and changes during the respiratory cycle, descending to the bottom of the rib-cage during inspiration, and ascending to almost half of the rib cage during maximal expiration. The thorax is covered by several muscles. The anterior part is covered by the pectoralis major and minor, the latissimus dorsi, the serratus anterior, and partially by the cervical muscles (the sternocleidomastoid and the scalene). The posterior part of the thorax is covered superficially by the trapezius and latissimus dorsi muscles whereas the serratus anterior and posterior, levatores and major and minor rhomboids form a deeper layer. The external muscles primarily stabilize and protect the thorax and they do not normally participate in the function of respiration. However, at times of extreme respiratory distress some of them (the deltoid, pectoralis, and latissimus dorsi muscles) can indirectly assist the respiration by ‘‘immobilizing’’ the upper extremities. Muscle injury or absence (as in the case of the pectoralis major muscle in Poland syndrome) may affect the physical integrity of the thorax.
Underneath the external muscles lay the intercostal muscles (external, internal, and transverse or innermost). The intercostal muscles together with the diaphragm comprise the main muscles of respiration, whereas the sternocleidomastoid and the scalene muscles, as well as the serratus posterior and the levatores costarum muscles comprise the secondary muscles of respiration. The various respiratory muscles perform different functions. The diaphragm and the external intercostals (and in part the internal intercostals) are the primary inspiratory muscles during tidal breathing and during mild/moderate exercise. The scalene and the sternocleidomastoid muscles are also inspiratory muscles but they are used primarily at times of maximal exertion and/or during respiratory distress. The abdominal muscles enhance the inspiratory function of the diaphragm (especially in the upright and sitting position) during quiet breathing. When the diaphragm contracts, it slides downwards over the spine, effectively ‘‘scooping-out’’ the abdominal contents. The abdominal muscles create a ‘‘barrier’’ that prevents the outward movement of the abdominal contents which generates a high intrabdominal pressure that is transmitted back to the diaphragm causing its ‘‘flattening’’ that in turn causes the outward expansion of the rib cage. The interaction between the diaphragm and the abdominal muscles explains the difficulty in breathing or the respiratory failure that occurs when the abdominal muscles are defective (e.g. gastroschisis), weak (e.g. in neuromuscular diseases or normally in the neonatal period), or traumatized (e.g. in abdominal trauma or after major abdominal surgery). There are no pure expiratory muscles, because exhalation during tidal breathing is a passive movement produced by the elastic recoil of the lungs. However, forced exhalation depends on the internal intercostals and to a lesser degree on the abdominals. [1] EFFECTS OF CHEST WALL ABNORMALITIES ON THE RESPIRATORY SYSTEM In general, chest wall abnormalities affect the thorax by impairing or preventing its growth and/or by limiting its movement. In both cases the effects are not limited to the thorax but they extend to the intrathoracic organs as well. Effects on the growth of the thorax Similar to the overall somatic growth, the thorax grows in a gradual but not completely linear fashion that is characterized by growth spurts. Under normal circumstances, the thoracic volume in a newborn infant represents only a small fraction of the thoracic volume during adulthood. By 5 years of age, the thoracic volume increases to about 30% of the adult size, and by age 10 it reaches approximately 50% of its final volume. The remaining 50% develops during the prepuburtal period and early adolescence. [2] Thus, any process (congenital or acquired) that limits the growth of the thorax will have profound long-term effects on the thoracic volume and on the lungs. What actually limits the growth of the thorax (and possibly of the lungs) is unclear. In general, the more severe the abnormality, the more impaired is the thoracic volume and the lung volume. However, the effects are not linear and they seem to depend to a large extent on which component of the thorax (sternum, spine, ribs) is mostly affected. It appears that abnormalities affecting primarily or exclusively the sternum or the spine have relatively mild effects on the lung volume. For example the lung volume in patients with idiopathic pectus excavatum tends to be within the normal range (although at the lower levels of normal). [3] Similarly, a large prospective study comparing the growth of the thoracic volume in children and adolescents (4-16 years of age) with mild/moderate and severe scoliosis revealed that the thorax grew normally in patients with mild to moderate
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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scoliosis but it was lower in all age groups in patients with severe scoliosis (although the difference did not seem to be clinically very important). [4] In contrast, patients with spondyloepiphyseal dysplasia and fused ribs were found to have very severe restrictive lung disease with forced vital capacity
YPRRV-957; No. of Pages 10 Paediatric Respiratory Reviews xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Paediatric Respiratory Reviews
CME article
Chest Wall Abnormalities and their Clinical Significance in Childhood Anastassios C. Koumbourlis M.D. M.P.H.* Professor of Pediatrics, George Washington University, Chief, Pulmonary & Sleep Medicine, Children’s National Medical Center
EDUCATIONAL AIMS 1. 2. 3. 4.
The The The The
reader reader reader reader
will will will will
become familiar with the anatomy and physiology of the thorax learn how the chest wall abnormalities affect the intrathoracic organs learn the indications for surgical repair of chest wall abnormalities become familiar with the controversies surrounding the outcomes of the VEPTR technique
A R T I C L E I N F O
S U M M A R Y
Keywords: Thoracic cage Scoliosis Pectus Excavatum Jeune Syndrome VEPTR
The thorax consists of the rib cage and the respiratory muscles. It houses and protects the various intrathoracic organs such as the lungs, heart, vessels, esophagus, nerves etc. It also serves as the so-called ‘‘respiratory pump’’ that generates the movement of air into the lungs while it prevents their total collapse during exhalation. In order to be performed these functions depend on the structural and functional integrity of the rib cage and of the respiratory muscles. Any condition (congenital or acquired) that may affect either one of these components is going to have serious implications on the function of the other. Furthermore, when these abnormalities occur early in life, they may affect the growth of the lungs themselves. The following article reviews the physiology of the respiratory pump, provides a comprehensive list of conditions that affect the thorax and describes their effect(s) on lung growth and function. ß 2014 Published by Elsevier Ltd.
INTRODUCTION The thorax comprises the upper body and it consists of multiple independent bony parts (spinal vertebrae, sternum, ribs) that form the rib cage, and several muscles that cover it from the outside and separate it from the abdominal cavity. The rib cage provides the ‘‘scaffolding’’ on which the muscles lay and connect, whereas the muscles provide stabilization and movement to the rib cage. Although, it is often viewed as just a ‘‘protective case’’ for the various intrathoracic organs (lungs, heart, vessels, esophagus, nerves etc), the thorax is in fact a dynamic apparatus (the so-called ‘‘respiratory pump’’) that performs the actual function of breathing by, generating the movement of air in and allowing or forcing the movement of air out of the lungs). Thus, any condition that results in its malfunction will have significant repercussions on the function of the respiratory system and frequently on other intrathoracic organs as well.
* Division of Pulmonary & Sleep Medicine, Children’s National Medical Center, 111 Michigan Ave N.W., Washington DC 20010 Tel.: +001-202-476-3519; fax: +001-202-476-5864. E-mail address: [email protected].
‘‘Chest wall abnormalities’’ refer to any abnormality that affects the normal structure and/or limit the function of the thorax. Chest wall abnormalities are often referred to as chest or thoracic dysplasias or dystrophies. Although there is a certain overlap between these terms, in this article, dysplasia refers to abnormal anatomic structures that result from the abnormal growth or development of cells or tissues, and it is primarily used for bony abnormalities (e.g. Spondyloepiphyseal dysplasia). The term dystrophy is conventionally used for muscle abnormalities (e.g. muscular dystrophy). This article reviews in detail the common types of chest wall abnormalities and the effects they have on the respiratory system. TYPES OF CHEST WALL ABNORMALITIES Many of the chest wall abnormalities (especially the dysplasias) are congenital but they can also develop later in life as a result of a disease (e.g. ankylosing spondylitis) or injury that can be accidental (e.g. flail chest secondary to trauma), or iatrogenic (e.g. thoracotomy). Specific genes and modes of inheritance have been identified for many of the congenital dysplasias, whereas others are assumed to be caused by accidental exposures. The chest wall abnormalities are either primary or part of a syndrome
1526-0542/$ – see front matter ß 2014 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.prrv.2013.12.003
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
G Model
YPRRV-957; No. of Pages 10 A.C. Koumbourlis / Paediatric Respiratory Reviews xxx (2014) xxx–xxx
2
Table 1 Conditions associated with abnormalities of the thorax CONDITION Aarskog syndrome Achondrogenesis Achondroplasia Allagile Syndrome (arteriohepatic dysplasia) Beals syndrome Camptomelic Dysplasia Cerebro-Costo-Mandibular syndrome Chondroectodermal dysplasia Chondroplasia punctate CHARGE syndrome CHILD syndrome Cleidocranial dysostosis Coffin-Lowry syndrome Cohen syndrome Diastrophic dysplasia Down syndrome Dyggve-Melchior-Clausen syndrome Early Amnion Rupture sequence Ehlers-Danlos syndrome Escobar syndrome Fetal Hydantoin Effects Fetal Alcohol syndrome Fetal Aminopterin Effects Fetal Valproate Effect Fibrochondrogenesis Frontometaphyseal dysplasia Generalized Gangliosidosis syndrome, Type I Gorlin syndrome Haldu-Cheney syndrome Homocystinuria syntrome Hunter syndrome Hurler syndrome Hypophosphatasia Incontinentia PPigmenti syndrome Jarcho-Levin syndrome Jeune syndrome Klippel-Feil sequence Kniest Dysplasia Kozlowski spondyloepiphyseal dysplasia Langer-Giedion syndrome Lenz-Majeswski hyperostosis syndrome Lethal multiple pterygium syndrome Marfan syndrome Marinesco-Sjogren syndrome Maroteaux-mucopolysaccharidosis Melnick-Needles syndrome Meningomyelocele Metaphyseal chondrodysplasias Metatropic Dysplasia Morquio syndrome Mucopolysaccharidosis VII Multiple synostosis Multiple Lentigines syndrome Multiple neuroma syndrome MURCS association Neurofibromatosis syndrome Noonan syndrome Osteogenesis imperfect Oto-Palato-Digital syndrome Pallister Hall syndrome Partial Trisomy 10q syndrome Poland anomaly Progeria syndrome Proteus syndrome Pseudoachondroplasia Sponyloepiphyseal dysplasia Pyle Metaphyseal Dysplasia Rhizomelic Chondroplasia Punctuta Robinow syndrome Rokitansky sequence Rubenstein-Taybi syndrome Ruvalcaba syndrome Sanfilippo syndrome Seckel syndrome Short rib syndrome Shprintzen syndrome Shwachman syndrome Sponyloepiphyseal dysplasia congenita
THORACIC SHAPE
STERNUM
RIBS
PE/PC
SPINE
VERTEBRAE
(X)
(X) X X X X X X
Small thoracic cage Small thoracic cage X Small thoracic cage Small thoracic cage Small thoracic cage
X X
X (X)
X
(X)
X X X
X X
(X) (X) (X)
Small thoracic cage PE/PC Small thoracic cage (PE/PC) PE/PC
(X)
X X (X) (X) (X)
X X (X) (X)
PE/PC
X (X)
Small thoracic cage X X
(X) X
(X) X (X) X
X X
X X X X (X) X
X
Small thoracic cage X Small thoracic cage Small thoracic cage (X)
(X) X
PE/PC X X
(X) X X X X X X
Small thoracic cage PE/PC PE/PC Small thoracic cage
PE/PC
X X
PE/PC
X X
Small thoracic cage Small thoracic cage
PE/PC PE/PC
Small thoracic cage (Small thoracic cage)
PE/PC PE/PC PE/PC PE/PC
X (X) X
X X
(X) X X X X X X (X) X
(X) (X) (X) (X) X (X) X X
(X) (X)
X
(Small thoracic cage) (X) Small thoracic cage X
X X (X)
(X)
PE/PC
X X X
X (X) X X X X (X) (X) X (X) X X X X X (X) X X
(X)
Small thoracic cage
X (X) PE/PC
X
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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YPRRV-957; No. of Pages 10 A.C. Koumbourlis / Paediatric Respiratory Reviews xxx (2014) xxx–xxx
3
Table 1 (Continued) CONDITION
THORACIC SHAPE
Thanatophoric dysplasia Trich-Rhino-Pharyngeal syndrome Trisomy 8, 9, 9p Mosaic syndrome Trisomy 4p, 13 Trisomy 18, 20 Vater syndrome Waardenburg syndrome Williams syndrome XO, XYY, 18p, XXXXY syndromes
Small thoracic cage
STERNUM
RIBS
SPINE
VERTEBRAE X
PE/PC Small thoracic cage X (X) X (X) (PE/PC) PE/PC
(X)
X X X (X)
X (X) X X (X)
(X)
(X)
Adapted from: Smith’s Recognizable Patterns of Human Malformation / Edition 5., Jones KL Elsevier Saunders, Philadelphia, PA, USA 1988 PE: Pectus Excavatum; PC: Pectus Carinatum; (X): abnormality only occasionally present
Table 2 Chest wall abnormalities on each of the components of the thorax Abnormalities of the Sternum
Abnormalities of the Ribs
Abnormalities of the Spine
Abnormalities of the Muscles
Pectus Excavatum Pectus Carinatum
Fused ribs (e.g. Jarcho-Levin syndrome) Narrow chest (e.g.Asphyxiating Thoracic Dystrophy) Fractured ribs (e.g. Flail chest)
Scoliosis Kyphosis
Absent muscles (Poland Syndrome) Muscle weakness (e.g. spinal muscular atrophy)
Lordosis
Absent ribs (e.g. resection of tumors)
Abnormal vertebrae
Defects (e.g. Congenital diaphragmatic hernia); gastroschisis) Paralysis (e.g, diaphragmatic paralysis)
Bifid Sternum
(Table 1). Most of the syndromes initially affect a specific component of the thorax but because of the interrelationship between the various components eventually the entire thorax may become deformed. From a clinical standpoint the chest wall abnormalities can be categorized according to the part of the thorax that is primarily affected (Table 2) and/or according to the causes as follows: Congenital chest wall abnormalities a) Anomalies of the sternum (e.g. Pectus excavatum, bifid sternum) b) Anomalies of the ribs (e.g. Jarcho-Levine Syndrome) c) Anomalies of the spine (e.g. Scoliosis) d) Anomalies of the respiratory muscles (e.g. Poland syndrome, neuromuscular disorders)
spondylitis (that may cause ossification of the ligaments in the spine and in the rib cage); fibrothorax (that causes fibrosis of the pleura that in turn limits the expansion of the rib cage), and scleroderma (that limits the expansion of the rib cage due to the thickening of the skin that covers the thorax). Abdominal conditions Conditions such morbid obesity, accumulation of large amounts of fluid or air in the peritoneal cavity (e.g. ascites or pneumoperitoneum) or organ enlargement (e.g. significant hepatosplenomegaly) may cause severe limitation in the function of the thorax by impeding the function of the diaphragm. Defects of the abdominal wall (e.g. gastroschisis, giant omphalocele) also impede diaphragmatic function, thus limiting the normal expansion of the thorax. One could also include the normal pregnancy (although it obviously can ‘‘affect’’ only women of reproductive age) as a cause of temporary dysfunction of the thorax due to the pressure that the fetus and the amniotic sac exert on the diaphragm.
Acquired chest wall abnormalities Trauma Traumatic injuries to the thorax such as fractures of the ribs, the sternum or the spine will affect the normal function of the thorax not only at the time of the injury but potentially in the long-term as well, due to potentially abnormal healing. Similar short and longterm effects may be produced by accidental trauma to the muscles (e.g. extensive burns) Or after iatrogenic injuries (e.g. rib and/or muscle resection due to tumours, sternotomy for cardiac surgery) Neurologic conditions Partial or complete paralysis of the respiratory muscles due to injuries (e.g. spinal cord injury) or diseases (e.g. Guillain-Barre syndrome), not only prevent the normal breathing but eventually, can cause significant disfigurement of the thorax because the weak muscles cannot provide the necessary stability that is required to maintain its physiologic shape. Diseases affecting components of the thorax Various unrelated conditions may affect parts of the thorax causing significant limitation to its expansion. Typical examples (although generally rare in children) include ankylosing
Hypoplasia or absence of the lung Lung agenesis, severe lung hypoplasia (e.g. congenital diaphragmatic hernia), and pneumonectomy can cause significant disfigurement of the rib cage due to the ‘‘caving’’ of the rib cage on the affected side as well as due to the hyperinflation of the contralateral lung that usually herniates to the opposite side thus rotating the intrathoracic organs and the mediastinum. Severe upper airway obstruction Chronic significantly increased work of breathing (e.g. severe laryngomalacia or subglottic stenosis) may cause irreversible disfigurement of the chest wall, usually in the form of pectus excavatum. ANATOMY & PHYSIOLOGY OF THE THORAX To understand the effects of the thoracic dystrophies on the respiratory system, one has to understand the anatomy and physiology of the normal thorax. The rib cage is formed very early in fetal life. Primitive elements of the ribs, the clavicles and the sternum can be detected as early as 6 weeks of gestation (mesenchymal phase). When fully developed, the thorax resembles
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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a truncated cone formed by the sternum anteriorly, by the 12 thoracic vertebrae of the spine posteriorly, and by 12 pairs of ribs that connect the sternum and the spine in a complex way. Specifically, all 12 pairs of ribs are connected with the 12 thoracic vertebrae thus forming the posterior and lateral aspects of the rib cage. However, only 4 pairs (first, tenth, eleven and twelfth) are connected with the respective vertebrae, whereas the remaining pairs (ribs 2-9) are connected with two vertebrae each. The anterior wall of the thorax is formed by the sternum that is connected only to the first 7 seven pairs of ribs. Ribs 8-10 are attached only indirectly to the sternum by being attached to the cartilage of the rib above them, whereas the eleventh and twelfth ribs are not attached to the sternum at all. These articulations form a characteristic triangular opening in the anterior wall. [1] The ribs are attached to the vertebral bodies as well as to the sternum with true synovial joints consisting of articular cartilages, joint capsules and synovial cavities that allow freedom of movement of the ribs during the respiratory cycle. In neutral position, the ribs (especially the lower ones) lie in a downward fashion whereas during inspiration they assume a more horizontal position thus expanding the rib cage in an upward and outward fashion. However, not all ribs move the same way. The upper ribs move in a vertical plane that resembles the movement of an oldfashion pump (pulling the rib cage upwards). The middle ribs move in a way similar to the handle of a bucket, whereas the lower ribs move laterally, resembling the movement of a caliper. These complex movements allow the rib cage to increase significantly its cross-sectional area thus providing enough space for the lungs to expand. During infancy the ribs lie normally in an almost horizontal position, placing the infants at a mechanical disadvantage compared to older children and adults because they cannot expand their chest outward and so they rely almost exclusively on diaphragmatic breathing. The sternum is a few centimeters long at birth but it grows up to 20 cm in adults. It is comprised of three areas (manubrium, body, and xiphoid). The manubrium is connected via articulation with the clavicle and the first rib. It is also connected with the body of the sternum approximately at the level of the junction of the second rib (angle of Louis). Normally, the bifurcation of the trachea is located behind the angle of Louis. [1] The thorax is separated from the abdominal cavity by the diaphragm. As a result it is subjected directly to the pressures generated in the abdominal cavity, in part contributed to by the size of the abdominal organs. The diaphragm consists of two distinct muscular parts connected by a tendon. The tendon extends from the xiphoid process of the sternum to the second and third lumbar vertebral bodies, thereby placing the diaphragm in an angle in which its anterior portion lies higher than the posterior. The position of the diaphragm is not fixed and changes during the respiratory cycle, descending to the bottom of the rib-cage during inspiration, and ascending to almost half of the rib cage during maximal expiration. The thorax is covered by several muscles. The anterior part is covered by the pectoralis major and minor, the latissimus dorsi, the serratus anterior, and partially by the cervical muscles (the sternocleidomastoid and the scalene). The posterior part of the thorax is covered superficially by the trapezius and latissimus dorsi muscles whereas the serratus anterior and posterior, levatores and major and minor rhomboids form a deeper layer. The external muscles primarily stabilize and protect the thorax and they do not normally participate in the function of respiration. However, at times of extreme respiratory distress some of them (the deltoid, pectoralis, and latissimus dorsi muscles) can indirectly assist the respiration by ‘‘immobilizing’’ the upper extremities. Muscle injury or absence (as in the case of the pectoralis major muscle in Poland syndrome) may affect the physical integrity of the thorax.
Underneath the external muscles lay the intercostal muscles (external, internal, and transverse or innermost). The intercostal muscles together with the diaphragm comprise the main muscles of respiration, whereas the sternocleidomastoid and the scalene muscles, as well as the serratus posterior and the levatores costarum muscles comprise the secondary muscles of respiration. The various respiratory muscles perform different functions. The diaphragm and the external intercostals (and in part the internal intercostals) are the primary inspiratory muscles during tidal breathing and during mild/moderate exercise. The scalene and the sternocleidomastoid muscles are also inspiratory muscles but they are used primarily at times of maximal exertion and/or during respiratory distress. The abdominal muscles enhance the inspiratory function of the diaphragm (especially in the upright and sitting position) during quiet breathing. When the diaphragm contracts, it slides downwards over the spine, effectively ‘‘scooping-out’’ the abdominal contents. The abdominal muscles create a ‘‘barrier’’ that prevents the outward movement of the abdominal contents which generates a high intrabdominal pressure that is transmitted back to the diaphragm causing its ‘‘flattening’’ that in turn causes the outward expansion of the rib cage. The interaction between the diaphragm and the abdominal muscles explains the difficulty in breathing or the respiratory failure that occurs when the abdominal muscles are defective (e.g. gastroschisis), weak (e.g. in neuromuscular diseases or normally in the neonatal period), or traumatized (e.g. in abdominal trauma or after major abdominal surgery). There are no pure expiratory muscles, because exhalation during tidal breathing is a passive movement produced by the elastic recoil of the lungs. However, forced exhalation depends on the internal intercostals and to a lesser degree on the abdominals. [1] EFFECTS OF CHEST WALL ABNORMALITIES ON THE RESPIRATORY SYSTEM In general, chest wall abnormalities affect the thorax by impairing or preventing its growth and/or by limiting its movement. In both cases the effects are not limited to the thorax but they extend to the intrathoracic organs as well. Effects on the growth of the thorax Similar to the overall somatic growth, the thorax grows in a gradual but not completely linear fashion that is characterized by growth spurts. Under normal circumstances, the thoracic volume in a newborn infant represents only a small fraction of the thoracic volume during adulthood. By 5 years of age, the thoracic volume increases to about 30% of the adult size, and by age 10 it reaches approximately 50% of its final volume. The remaining 50% develops during the prepuburtal period and early adolescence. [2] Thus, any process (congenital or acquired) that limits the growth of the thorax will have profound long-term effects on the thoracic volume and on the lungs. What actually limits the growth of the thorax (and possibly of the lungs) is unclear. In general, the more severe the abnormality, the more impaired is the thoracic volume and the lung volume. However, the effects are not linear and they seem to depend to a large extent on which component of the thorax (sternum, spine, ribs) is mostly affected. It appears that abnormalities affecting primarily or exclusively the sternum or the spine have relatively mild effects on the lung volume. For example the lung volume in patients with idiopathic pectus excavatum tends to be within the normal range (although at the lower levels of normal). [3] Similarly, a large prospective study comparing the growth of the thoracic volume in children and adolescents (4-16 years of age) with mild/moderate and severe scoliosis revealed that the thorax grew normally in patients with mild to moderate
Please cite this article in press as: Koumbourlis AC. Chest Wall Abnormalities and their Clinical Significance in Childhood. Paediatr. Respir. Rev. (2014), http://dx.doi.org/10.1016/j.prrv.2013.12.003
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scoliosis but it was lower in all age groups in patients with severe scoliosis (although the difference did not seem to be clinically very important). [4] In contrast, patients with spondyloepiphyseal dysplasia and fused ribs were found to have very severe restrictive lung disease with forced vital capacity
