What is Sternal Cleft ?

Sternal cleft is a rare anomaly that can be described as defects on the midline of the sternum (breastbone) with different length and position. It is an idiopathic, in other words a congenital defect with unknown etiology. It develops as a result of impairment in the fusion of the sternum. Two types have been identified. It is a disease with a good prognosis due to the lack of cardiac anomalies. Surgical repair is performed in order to protect the heart and large veins, to improve respiratory dynamics and eliminate cosmetic concerns.

The most common types of Sternal cleft

Patient with Sternal cleft

Causes

Underlying factors are not exactly known. It is thought to develop as a result of a cause affecting the development of mesodermal (mesoderm in fetus) structures during Weeks 6-9 of the prenatal period. Cleft thoracic wall is the most common type. It occurs in one in every 50.000 to 100.000 live births and accounts for %0.15 of the all thoracic wall malformations. In mouse models, studies to determine the etiology could have revealed a few factors such as methyl cobalamin (Vitamin B12) deficiency, excessive alcohol consumption during pregnancy and a disruption in the HOX-B4 gene.

Signs

In sternal cleft, defect involves the superior sternum and the heart is at its normal position. The skin is usually intact. Cardiac dysfunction usually develops as the heart bulges from the cleft during crying of the infant. Less commonly, cleft is inferior or complete.

Diagnosis

Sternal cleft is usually diagnosed by physical examination during neonatal period. Imaging methods are useful in determining additional problems. Since the disease can be asymptomatic, monitoring can continue from neonatal period to adult period. Usually patients may consult their physician due to the pectus deformity. If the sternal cleft is not treated surgically, flail chest leading to impaired gas exchange is developed. Consequently, this leads to respiratory symptoms e.g. coughing and dyspnea or recurrent lung infections may develop.

Treatment

Cases where the skin is not intact must be surgically treated immediately. Cases with healthy skin can be repaired under elective conditions. Repair must be performed during neonatal period. In the repairs performed during this period the heart is not compressed. For the repairs at advancing ages, cartilage grafts can be used. First-line treatment is the surgical defect closure in the neonatal period. Presurgical examination should focus on common associated malformations, especially cardiac defects. Early repair gives better outcomes. Lack of bone protection of the structures on the midline of the chest makes the heart and large veins vulnerable to traumas. Appearance of protruding heart is discomforting for the patient and the parents. Enlargement of the defect over time deteriorates the appearance and repair becomes more difficult. In case of a damage to the skin, infections may develop. It affects the veins and cardiac functions negatively. Thus, it should be treated immediately. Surgical repair is more difficult at advancing ages since the chest loses its flexibility and the defect may require more complicated repair methods. Particularly, if the defect is too large, autologous grafts, patches or titanium plates can be used.