Keywords
sternal cleft - chest wall malformation - infant - pericardial patch
New Insights and the Importance for the Pediatric Surgeon
Sternal cleft is a rare congenital malformation that should be recognized by every
pediatrician, pediatric surgeon and gynecologist, as its simple diagnosis can avert
severe long-term consequences. Undiagnosed gas exchange impairment and respiratory
dysfunction can result in i.a. respiratory distress and recurrent infections of the
respiratory tract in the growing child. Pre-eminently the knowledge of its correlation
with associated malformations like cardiac defects is of vital importance as specific
diagnostics can be life-saving. By presenting our case of surgical repair of a superior
sternal cleft in an infant we are able to recall our colleagues of this important
malformation and issue instructions for diagnosis and surgical treatment.
Introduction
Sternal cleft (SC) is a rare congenital malformation that results from the defective
embryologic fusion of mesenchymal cells in the ventral midline. The first case was
reported in 1739 by De Torres.[1] Since then data from little more than 100 cases have been published worldwide. Based
on the clinical manifestation, the SC is classified into complete or incomplete, and
the incomplete form being further subdivided in a superior and inferior type. At present
2 in 100,000 newborns are diagnosed with SC.[2] In 67% of cases the SC is incomplete and two-thirds are female. Therefore, incomplete
sternal clefting in a female is the more common anomaly.[3]
Associated malformations such as cardiovascular anomalies, midline fusion defects,
hemangioma, maxillofacial defects, and pectus excavatus are common. Syndromic malformations
coinciding with sternal clefting include PHACES (posterior fossa malformations–hemangiomas–arterial
anomalies–cardiac defects–eye abnormalities–sternal cleft and supraumbilical raphe
syndrome) or Cantrell pentalogy syndrome.[3]
The fusion defect leaves the mediastinal viscera unprotected, resulting in an increased
risk of harmful events to the underlying mediastinal organs. To restore the protective
function of the skeleton by establishing bony integrity as soon as possible and to
benefit from the high flexibility of the chest wall in newborns, surgical repair should
be performed in the first weeks of life.[3]
[4]
[5]
Different surgical techniques such as primary closure, bone graft interposition, prosthetic
closure, muscle flap interposition, and others have been described.[3]
[4]
[5]
[6]
[7]
[8]
We present the case of a 4-month-old male infant with a superior SC.
Case Report
At 4 months, a male infant was referred to our department with the clinical diagnosis
of a superior SC ([Fig. 1A]). The SC was diagnosed postnatal by clinical examination in the maternity hospital
and any associated cardiac anomalies had already been excluded. The clinical examination
and ultrasound study ([Fig. 2]) done in our hospital confirmed the diagnosis of SC and no further examinations
were performed.
Fig. 1 Surgical closure of a superior sternal cleft in a 4-month-old male infant. (A) Preoperative.
(B) SC after detachment of the subcutaneous tissue. (C) Placement of a bovine pericardial
patch. (D) Approximation of the sternal bars. (E) Fibrin glue and bone insertion.
(F) Postoperative result.
Fig. 2 Clinical examination and ultrasound study. A, ascending aorta; LPA, left pulmonary
artery, R, ribs; T, thymus; VCS, vena cava superior. *Absence of superior part of
the sternum. **Regular inferior part of the sternum.
Surgical Treatment
After a vertical midline skin incision subcutaneous tissues were detached carefully.
The two sternal bars were released from the underlying pericardium, thymus and mediastinal
tissues and freed from the sternoclavicular joint ([Fig. 1B]). A midline osteotomy was performed to separate the fused inferior part of the sternal
bone. To facilitate closure of the SC wedge, excision at the bottom of the V-formed
defect was performed. A bovine pericardial patch (Peri-Guard, Synovis, St. Paul, Minnesota,
United States,) was placed posteriorly before approximating the separated sternal
bars in the midline applying PDS (polydioxanone) sutures ([Fig. 1C, D]). A small residual gap was filled with fibrin glue and bone remnants collected during
the osteotomy ([Fig. 1E]). Wound closure was performed in two layers ([Fig. 1F]). Neither a drain nor a chest tube was placed. Perioperative antibiotic treatment
with cefuroxime was started and continued for 7 days.
On the first postoperative day the infant developed significant pleural effusion,
and chest tubes were placed bilaterally in the intensive care unit (ICU). Additionally,
a small pericardial effusion was present on the ultrasound examination. As a consequence
diuretic treatment was started. However, the patient was successfully extubated on
the forth postoperative day and complete oral intake was achieved the next day. On
day 6 the chest tubes were removed since the pleural effusion had resolved. The following
clinical course passed without complications. The infant was discharged home on the
12th postoperative day.
The first postoperative checkup after 2 months and the long-term follow-up after 1 year
showed very good cosmetic results and normal respiratory movements.
Discussion
SC is a rare congenital midline deformity of the chest wall. In regular embryologic
development, two sternal bars deriving from the somatopleure start merging around
the sixth week of gestation.[9] The reason for fusion failure in SC is not yet known. A link to a group of genes
that influence the body plan of the embryo along the anterior-posterior axis—the Hox
genes—is being discussed.[10]
Usually sternal clefting is initially noticed in postnatal clinical examination by
paradoxical respiratory movements in the newborn. Nevertheless some cases of late
diagnosis in adolescence are described in the literature.[4] Failure to diagnose the malformation in infants might be due to the absence of clinical
symptoms in most newborns.[3] If SC is not diagnosed and therefore not treated surgically in neonatal period,
gas exchange impairment and respiratory dysfunction can result in dyspnea, respiratory
distress, chronic coughing, or recurrent infections of the respiratory tract.[3]
Most patients with SC show associated malformations, in particular cardiac defects.[11] Therefore ultrasound and cardiologic examinations including electrocardiogram (ECG)
and echocardiography should be performed preoperatively. In our opinion radiologic
imaging of the bony defect in conventional X-rays or even computed tomographic (CT)
scans, as postulated obligatory by some authors,[3] is not necessary in most cases as no additional key information is gained and therefore
radiation can be avoided. If associated malformations are suspected, further specific
diagnostics are obligatory to prevent major complications during surgery. For example,
if PHACES syndrome is likely, magnetic resonance imaging (MRI) and ophthalmologic
or neurologic workup should be done. Laryngotracheal bronchoscopy is mandatory to
exclude a subglottic hemangioma in case of inspiratory stridor or patients presenting
with other signs of hemangiomatosis.
The first report of a successful surgical SC repair in a 11-week-old child was published
in 1947 by Burton.[11] Prevailing opinion in the literature is that primary surgical closure performed
in the neonatal age is the best treatment option.[3]
[4]
[12] Because of the high flexibility of the chest wall of newborns, the primary closure
is easier to perform and the risk for cardiovascular impairment is decreased.[3]
[5] Nevertheless, it is critically important to monitor the hemodynamic and respiratory
parameters closely during SC repair, as well as in the early postoperative phase.
To this point different surgical techniques have been described in literature, including
primary closure, sliding osteochondroplasty, and the use of periosteal or muscle flaps.[3]
[4]
[8]
[13] In older patients or to treat larger defects, the use of autologous grafts or prosthetic
material might be indicated as high pressure caused by reduced space and less compliance
of the thoracic wall could severely impair mediastinal organ function.[3]
[4] On the other hand, some authors claim the infection risk of artificial grafts might
be increased and the missing adaption to ongoing growth could have negative impact
on further development.[4] In our patient a bovine patch was placed to create a second layer in the case of
a diastasis of the two sternal bars postoperatively and to protect the underlying
pleura. The postoperative course was complicated by development of a small pericardial
effusion and pleural effusions, which had to be drained. We suggest that the pleural
effusion results from a pleural tear during the preparation of the two sternal bars.
In contrast to the complication seen in our case, the literature only reports the
development of postoperative seromas.[3]
[4] However, in different reports a drain was primarily placed to prevent fluid collections
regardless of the use of prosthetic material.[5]
[8] We didn't place drains to prevent infection such as mediastinitis in the postoperative
course. In a review of the literature and according to his own case series, Torre
et al found no negative effects on surgical outcome, stating that both techniques,
primary closure as well as prosthetic reconstruction, lead to satisfactory results.[3]
Throughout literature low complication rates are found. Intra- or postoperative mortality
is rarely reported and seems to be related to associated malformations rather than
to surgical intervention.
Conclusion
SC is a rare congenital chest malformation mostly diagnosed in newborns and infants.
Primary surgical closure performed in the neonatal period or in early infancy is agreed
upon as the therapy of choice. Ultrasound and cardiovascular examinations are obligatory
eventually followed by complementary specific diagnostic procedures to rule out associated
malformations prior to treatment. Overall the surgical repair of SC shows satisfying
functional and cosmetic results with low complication rates.
