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Constriction ring syndrome
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Constriction ring syndrome
Constriction ring syndrome (CRS) is a congenital disorder with unknown cause. Because of the unknown cause there are many different, and sometimes incorrect, names. It is a malformation due to intrauterine bands or rings that produce deep grooves in (most commonly distal) extremities such as fingers and toes. In rare cases the constriction ring can form around other parts of the fetus and cause amputation or even intrauterine death. The anatomy proximal to the site of constriction (or amputation) is developmentally normal. CRS can be associated with other malformations, with club foot being most common. The precise configuration of the bands, lymphedema, and character of the amputations are not predictable and vary with each individual patient. Also, more than one extremity is usually affected, and it is rare for only one ring to present as an isolated malformation with no other manifestation of this syndrome.
The constriction of appendages by amniotic bands may result in:[citation needed]
There are three different theories to the cause of the constriction ring syndrome.
The first is the intrinsic theory, which was proposed by Streeter in 1930. This theory implicates an anomaly in germ plasm resulting in the defects. This theory is reinforced by the clinical presentation of the constriction rings with other internal visceral and systematic anomalies. Because of these other anomalies, the names constriction ring syndrome, constriction band syndrome, and Streeter bands are given to this defect/disease. This is sometimes attributed to vascular disruption shared between cleft palate and other forms of cleft defects occurring together with ABS; this co-occurrence suggests an intrinsic defect of the blood circulation.[citation needed]
The second theory postulates the involvement of an intrauterine disruption during pregnancy followed by a cascade of events involving amniotic rupture. When spontaneous rupture of the amnion occurs early in the second trimester, the separation of amnion from chorion produces many small, thin strands that can become entangled within digits and toes. Later, as the fetus grows but the bands do not, the bands become constricting. This constriction reduces blood circulation, and hence causes congenital abnormalities. In some cases a complete "natural" amputation of one or more digits or limbs may occur before birth or the digits or limbs may be necrotic (dead) and require surgical amputation following birth. The names amniotic band syndrome (ABS), amniotic disruption complex, and amniochorionic mesoblastic fibrous strings are based on this theory.
The third theory postulates the involvement of intrauterine trauma. Intrauterine trauma could be something like amniocentesis, or something like a fetal surgery. An intrauterine trauma could result in hemorrhage leading to acrosyndactyly. One study also showed the presence of bands as confirmed by sonography after fetal surgery.
Because of these different theories, there are many names for this syndrome. For a long time people believed the second theory about the amniotic rupture and strands. In the research cases not every child had a real (amniotic) strand. This could mean that there has to be another explanation for the development of these anomalies.
Diagnosis of constriction ring syndrome can be confirmed with an ultrasonography. The clinical manifestations can be extremely variable. It could be a single or multiple manifestation. This can be confirmed at the end of the first trimester or at the beginning of the second trimester. However, not every patient will be diagnosed at that moment; most will be diagnosed at birth.[citation needed]
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Constriction ring syndrome
Constriction ring syndrome (CRS) is a congenital disorder with unknown cause. Because of the unknown cause there are many different, and sometimes incorrect, names. It is a malformation due to intrauterine bands or rings that produce deep grooves in (most commonly distal) extremities such as fingers and toes. In rare cases the constriction ring can form around other parts of the fetus and cause amputation or even intrauterine death. The anatomy proximal to the site of constriction (or amputation) is developmentally normal. CRS can be associated with other malformations, with club foot being most common. The precise configuration of the bands, lymphedema, and character of the amputations are not predictable and vary with each individual patient. Also, more than one extremity is usually affected, and it is rare for only one ring to present as an isolated malformation with no other manifestation of this syndrome.
The constriction of appendages by amniotic bands may result in:[citation needed]
There are three different theories to the cause of the constriction ring syndrome.
The first is the intrinsic theory, which was proposed by Streeter in 1930. This theory implicates an anomaly in germ plasm resulting in the defects. This theory is reinforced by the clinical presentation of the constriction rings with other internal visceral and systematic anomalies. Because of these other anomalies, the names constriction ring syndrome, constriction band syndrome, and Streeter bands are given to this defect/disease. This is sometimes attributed to vascular disruption shared between cleft palate and other forms of cleft defects occurring together with ABS; this co-occurrence suggests an intrinsic defect of the blood circulation.[citation needed]
The second theory postulates the involvement of an intrauterine disruption during pregnancy followed by a cascade of events involving amniotic rupture. When spontaneous rupture of the amnion occurs early in the second trimester, the separation of amnion from chorion produces many small, thin strands that can become entangled within digits and toes. Later, as the fetus grows but the bands do not, the bands become constricting. This constriction reduces blood circulation, and hence causes congenital abnormalities. In some cases a complete "natural" amputation of one or more digits or limbs may occur before birth or the digits or limbs may be necrotic (dead) and require surgical amputation following birth. The names amniotic band syndrome (ABS), amniotic disruption complex, and amniochorionic mesoblastic fibrous strings are based on this theory.
The third theory postulates the involvement of intrauterine trauma. Intrauterine trauma could be something like amniocentesis, or something like a fetal surgery. An intrauterine trauma could result in hemorrhage leading to acrosyndactyly. One study also showed the presence of bands as confirmed by sonography after fetal surgery.
Because of these different theories, there are many names for this syndrome. For a long time people believed the second theory about the amniotic rupture and strands. In the research cases not every child had a real (amniotic) strand. This could mean that there has to be another explanation for the development of these anomalies.
Diagnosis of constriction ring syndrome can be confirmed with an ultrasonography. The clinical manifestations can be extremely variable. It could be a single or multiple manifestation. This can be confirmed at the end of the first trimester or at the beginning of the second trimester. However, not every patient will be diagnosed at that moment; most will be diagnosed at birth.[citation needed]
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