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An in-depth analysis of the embryonic development of the sternum and explains the pathogenesis of cleft sternum (fissura sterni congenita), a rare congenital anomaly. the layers of the embryo, the formation of the coelom, and the development of the ventral body wall, highlighting the role of the somites and the formation of the sternum. The document also explores the origin of the precostal process and the development of the manubrium, as well as the therapeutic consequences of congenital sternal fissures.
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Thorax (1970), 25, 490.
Department of Thoracic Surgery of the Surgical Clinic, and Department of Embryology of the Anatomical Laboratory, State University, Groningen, The Netherlands
in some detail.
Total or partial fissure in the middle of the
chest wall (^) gives rise to a (^) severely paradoxical movement of this part of the thorax (Figs 1 and
only by soft tissues. The anomaly is caused by a disturbance in
fissure the^ two^ halves^ of the^ sternum^ are^ entirely separated. In^ the^ more^ severe^ cases^ of^ partial fissure takes the shape of a triangle with the apex fissure, only the xiphoid process is^ fused, and this^ in a caudal direction;
Congenital perforations of the sternal body also
EMBRYOLOGICAL INTRODUCTION
sternal anomalies the development of the human embryo has^ first^ to^ be^ considered. Until the (^) beginning of the third week, the embryonic primordium lies^ practically^ flat^ on^ the
..-. - -. - (^) -.--.-C, --, -^ ---- --
Congenital cleft sternum
third week. Development of the three germ layers.
week (Fig. 4). Towards the end of the third week the paraxial
HEAD FOLO
FIG. 4. Schematic representation of a median section through an embryo at the beginning of the fourth week.
X1'-^ HEAO FOLD NEURAL TUBE
0 0-SOMI ITEECTOORECTM
-r-- -- (^) TAIL FOLD ATE i-</ COELOM SPLANCHNIC MESOOERM LATERAL PLATE MES SOERMSOMATIC MESODERM
A B
through the same embryo.
Congenital cleft sternum
the ventral body wall far from the mid-line. That
yolk sac. In all animal species, whose embryos
bands are formed independently of the ribs, which
embryos as well.^ In^ human^ embryos^ the^ two mesenchymal sternal bands are present in the
from two mesenchymal condensations, which not
advanced to allow conclusions concerning the first
In the^ development of^ the^ sternum,^ the
Apart from the sternal bands a few blastemas of different nature participate in this anlage. In the human embryo, too, these structures are
chymal blastemas. Between the ventral ends of
described them as 'suprasternal structures'. These
time only.
"SUPRASTERNAL SrRUcTuRE" "PRECOSTAL PROCESS'
X,.
.....
A
..
FIG. 8. Development of the sternum: A. After Klima (1968); B. After Reiter^ (1942).
A. Eijgelaar and J.^ H.^ Bijtel
The origin of the precostal process is^ even^ more difficult to^ explain. Both sternal^ primordia,^ each^ consisting^ of^ a sternal band^ with^ a^ suprasternal^ structure^ at^ its cranial end, have^ their^ first^ contact^ at^ the cranial end of the thorax. Klima^ demonstrates^ the^ start of the fusion in a reconstruction^ of^ the^ sternum of an embryo of 17 mm.^ This implies^ that^ the fusion starts in about the seventh^ week.^ At^ this stage each of the sternal bands^ has^ begun^ to
the fusion of the left and the right sternal primor- dium proceeds in a caudal direction the more^ ven- trally localized unpaired^ precostal^ process^ is enclosed by them. Klima^ depicts^ this^ enclosure in sections of embryos of^21 and^27 mm.^ The fusion of^ the^ more^ caudal^ parts^ of^ the^ sternal
(Muller, 1906; Patten, 1968). The question which now^ arises^ concerns^ the
on phylogenetic grounds,^ that^ the^ material^ of which the sternum is^ made^ up^ originates^ from two different sources. In the older view^ the^ sternal^ bands,^ as^ a^ pro- duct of union of the ribs^ (Muller,^ 1906),^ are^ sup- posed to derive their material from the^ somites by way of the sclerotomes. However, since it^ has been established that the sternal bands^ develop
whether their^ material^ derives^ from^ the^ somites. This question has been^ explicitly expressed^ by
and Pinot (1969). As a result of experiments which^ were^ per- formed in different ways on^ chick^ embryos,^ these authors came to the^ conclusion^ that^ it^ is^ the lateral plate that^ gives^ rise^ to^ the^ sternum. According to Seno, not only the^ sternum^ arises from the lateral plate but the^ skeleton^ of^ the
Seno, Murillo-Ferrol nor^ Pinot^ have^ investigated the early stages of^ the^ development^ of^ the^ cervical
sternum and^ the^ skeleton^ of the^ wing,^ arise^ from the cervical^ somites.^ In this^ connection^ it is^ worth noting that Fell (1939) as^ well^ as^ Chen^ (1952a,^ b) began their experiments on^ the^ origin^ of^ the sternum by a study of^ its normal^ development.
ment of^ the^ sternal^ bands-which^ occurs^ in^ the
body wall in a ventral direction.^ They^ do not
Huizinga (1954):
tures and as the precostal process prevents^ the
abnormal course^ of^ development^ leads^ to^ a^ total sternal fissure.
OPERATIONS FOR CONGENITAL STERNAL^ FISSURE^ FROM THE LITERATURE
Patients Treated Author by Operation^ IndicationsVital No. Age Burton (1947) ..^2 7 wk^ Intermittent cyanosis 12 yr Maier and Bortone (1949) 1 2 mth^ Dyspnoea Klassen (1949) ..^1 1 dy^ - Longino and Jewett (1955) 1 6 dy^ Tachypnoea Sabiston (1958) ..^1 21 yr^ - Asp and Sulamaa (1960) (^2) 2 mth^1 dy^ Resp.circ.^ and symp- toms in both cases Keeley et^ al.^ (1960) ..^1 17 mth^ Recurrent resp. infection Chang and Davis^ (1966)^1 4 yr^ - Thompson (1961) ..^1 10 dy^ - Jewett et al. (1962). 1 6 wk^ - Martin and Helmsworth (1962) 1 8 mth^ - Ingelrans and Debeugny (1965) 1 4 wk^ - 14
A. Eijgelaar and J. H. Bijtel
FIG. 10. Sternal halves approximated; evident gain^ of^ space^ by the^ incision^ in the costal cartilage. (From Sabiston, D. C., J.^ thorac. Surg.,^ 35,^ 118, 1958.)
Diarrhoea and^ purulent^ conjunctivitis^ made^ it necessary to postpone^ the^ operation^ until^5 May^ 1967. At that time the two sternal^ halves^ were^ approxi- mated, as indicated by Sabiston^ (Figs^9 and^ 10).^ The post-operative course was uneventful apart^ from some slightly delayed healing of the wound. A few weeks later, venous congestion in the right arm was observed when the patient^ was^ resting^ on the right side (costoclavicular^ compression?).^ This venous congestion has^ not^ been^ observed^ since^ the child's discharge from the clinic. When seen^ two^ years^ after the operation^ the^ child had grown satisfactorily. The distal part of^ the sternum, however, shows an anomaly that^ causes^ a cleft-like excavation of the chest wall^ (Fig.^ 12). Probably a dissociation in^ the speed of^ the^ growth of the original caudal sternal^ bridge^ is^ the^ reason for this anomaly.
DISCUSSION
Operative correction of^ a^ sternal^ fissure,^ total^ or partial, is^ technically^ feasible^ in^ neonates^ as^ well
and Jewett, 1955; Martin^ and^ Helmsworth,^ 1962).
determined chiefly by the paradoxical movement of the anterior chest wall.^ However, the^ extent to
likely to^ produce vital^ symptoms^ is^ often^ un-
respiratory infections in^ somewhat^ older^ infants
arterial and venous^ blood^ gas^ values^ supplies^ a measurable indication^ of^ the^ influence^ of^ the
However, when a patient with^ a^ congenital cleft sternum shows no^ serious^ symptoms either shortly after birth^ or^ later, the^ necessity^ for
Congenital cleft sternum
and (^) Hug, 1962 ; Ingelrans and (^) Debeugny, (^) 1965).
Operative correction^ of^ a^ congenital sternal fissure is therefore (^) quite justifiable even in cases in which (^) there is only paradoxical movement of the (^) anterior chest wall. It must be pointed (^) out, however, that, (^) according to^ our^ experience, there may be^ two^ additions^ to^ the^ technique described by Sabiston: (1) the^ caudal^ bridge in the sternum (^) probably
approximated to^ prevent a^ later^ growth anomaly, as shown (^) by our (^) patient;
through the (^) thoracic outlet (Daum and (^) Heiss, 1970).
TIMING THE OPERATION When there are (^) vital indications, such as^ attacks of tachycardia and cyanosis, it is^ obvious^ that^ the^ operation must^ be performed as soon after birth as possible. In all other cases it is advisable to operate at an (^) early
FIG 11. Chest radiograph in which the retraction (^) in age, when the 'flexibility' of the chest (^) wall Fig. 2 is outlined (^) by lead wire (^) markers.
operative correction^ remains^ a^ moot^ point. This
asymptomatic (Szenes, 1922; Greig, 1926; de Groot and (^) Huizinga, (^) 1954; Meissner, (^) 1964). ' ll'. Magan (^) (1949) and Pfeiffer (^) (1956), for example, described a woman with a (^) congenital sternal
fact a total fissure. The (^) operative indication (^) in
metic. This is not a reason to omit the (^) operation, but its risk must (^) seriously be taken into considera-
The (^) literature shows that correction of a con-
facial (^) angiomatosis, with (^) angiomas also in (^) the