Constriction ring syndrome | |
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Other names | ADAM Complex, amniotic band sequence, amniotic band syndrome, amniotic disruption complex, amniochorionic mesoblastic fibrous strings, congenital amputation, constriction band syndrome, congenital constriction bands, Streeter bands, tissue bands, Pseudoainhum [1] |
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An infant's hand affected by constriction ring syndrome | |
Specialty | Pediatrics ![]() |
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 give deep grooves in, most commonly, distal extremities like 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. [2] [3] [4] CRS can be associated with other malformations with club foot being most common. [5] [6] [7] 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. [2] [3] [8] [9]
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, implicates an anomaly in germ plasm resulting in the defects. [10] This theory is reinforced by the clinical presentation of the constriction rings with other internal visceral and systematic anomalies. [10] 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. [10] [11] Later, as the fetus grows but the bands do not, the bands become constricting. This constriction reduces blood circulation, hence causes congenital abnormalities. In some cases a complete "natural" amputation of a digit(s) or limb may occur before birth or the digit(s) 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. [10] [12]
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. It could be 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. [13] However, not every patient will be diagnosed at that moment; most will be diagnosed at birth.[ citation needed ]
Individual strands are small and hard to see on ultrasound, so bands are detected indirectly because of the constrictions and swelling upon limbs or digits. Misdiagnosis is also common, so if there are any signs of amniotic bands, further detailed ultrasound tests should be done to assess the severity. 3D ultrasound and MRI can be used for more detailed and accurate diagnosis of bands and the resulting damage/danger to the fetus.
Decreased fetal movement could be a sign of a serious problem which may include ABS. It is rare but possible for the membrane to become wrapped around the placenta or the neck of the baby in the womb causing strangulation and death.
There is a strong relationship between ABS and clubfoot (also called talipes). 31.5% of clubfoot cases can be correlated with ABS, with 20% occurring bilaterally. Other abnormalities found with ABS include: clubhands, cleft lip, and/or cleft palate, and hemangioma.
The differential diagnosis includes:[ citation needed ]
ADAM Complex; CRS is sometimes mislabeled as ADAM complex. ADAM is an abbreviation for amniotic deformity, adhesions mutilations . CRS is the malformation due to a constriction ring around mostly a limb. ADAM complex is the association of limb defects (caused by constriction rings) and certain craniofacial clefts [8] [14] [15]
"Adams–Oliver syndrome is often mislabeled as CRS and consists of cutis aplasia of the scalp in which a longitudinal defect can vary in size and can often be associated with full-thickness skullcap loss. The distal digital or toe hypoplasia-aplasia is often confused with CRS. Constriction rings with or without edema are not present. The digital or toe hypoplasia-aplasia usually contains diminutive nails or nail folds". [8]
The constriction ring syndrome is a complex collection of asymmetric congenital anomalies, in which no two cases are exactly alike. [16] This is why a classification is difficult to make.
The most widely used classification system was proposed by Patterson. This classification system is based on the severity of the syndrome and is useful because, the different types require different treatments. Other clinicians have amended this scheme by separating the depth of the ring into mild, moderate, severe, and amputation [3] [17] [18] and by further defining the presence or absence of lymphedema or soft tissue loss distal to the ring. [4] Expanding over subdivision in depth of the clefts for every classification is not necessary because the principles of treatment and technique for correction are the same. [8]
There are four categories:
Patterson divided the constriction ring associated with acrosyndactyly into three types:
There are simple constriction rings which are strands most commonly around the distal extremities as fingers and toes. In general, the thumb is not likely to be affected by a constriction ring because the fetus typically holds the thumb in tight adduction flexion, making entanglement with strands less likely. [2] These malformations need to be surgically removed which must be executed in different stages and can done by different techniques (see also treatment).
The CRS involves strands which obstruct the lymphatic vessels and thus causing fluid retention, distal of the affected extremity. This utters itself with swollen parts distal of the constriction.
In this form there is a complex form of syndactyly named acrosyndactyly, the fingers (or toes) were initially separated but due to the constriction they are formed back together. Sometimes multiple fingers can be involved. The distal fusion between digits or toes never initially involves a skeletal coalition. [8] The digits are usually hypoplastic if multiple digits are involved. When the constriction cuts off the blood supply to the fingers, the fingers can form a peak with the most palmar digit being the index finger. Normal neurovascular bundles are not present in the distal parts. [8] Hands with fused fingers need to be released in phases to preserve the distal blood supply.
One of the most severe consequence of constriction strains is probably intrauterine amputations, this is where the constriction goes as deep as the bone and cuts off the blood supply of the proximal extremity. The result will be that the developing toe or finger will become ischemic and fall off. Because the result is a transverse amputation that cuts off the vascular supply to the developing extremity, [2] the actual constriction ring is not seen. [8] This can result in different outcomes:
In extremely rare cases a strain can form around the umbilical cord and cut off the blood supply to the fetus which will result in intrauterine death.
The percentage of associated anomalies varies from 40% to as high as 80% [16] [17] [19] Constriction ring deformities are as common on the lower extremity as on the upper, almost all of these involve the musculoskeletal system, with clubbed feet being the most common in up to 30% of reported cases. [7] [12] [17] [20] Large reported series reveal an incidence between 5% and 15% of craniofacial malformations with clefting of the lip or palate. [14] [21] [22] [23] [24] [25] [26]
Amniotic band syndrome is considered an accidental event and it does not appear to be genetic or hereditary, so the likelihood of it occurring in another pregnancy is remote. The cause of amnion tearing is unknown and as such there are no known preventative measures.[ citation needed ]
Surgical correction is recommended when a constriction ring results in a limb contour deformity, with or without lymphedema. [27]
At the beginning of the surgery a tourniquet will be applied to the limb. A tourniquet compresses and controls local arterial and venous circulation for about two hours. The constriction band must be dissected very carefully to avoid damaging the underlying neurovasculature. When the constriction band is excised, there will be a direct closure. This allows the fatty tissue to naturally reposition itself under the skin. [28]
"With complete circumferential constriction bands, it is recommended that a two-stage correction approach be used. At the first operation, one-half of the circumference is excised and the other one-half can be excised after three to six months. This will avoid any problems to the distal circulation in the limb, which may already be compromised. Lymphedema, when present, will significantly improve within a few weeks of the first surgery." [28]
For the direct closure of the defect after dissecting a constriction band there are two techniques:
In rare cases, if diagnosed in utero, fetal surgery may be considered to save a limb that is in danger of amputation or other deformity. This operation has been successfully performed on fetuses as young as 22 weeks. [29] Monash Medical Centre in Melbourne, Australia, as well as multiple facilities in the United States, have performed successful amniotic band release surgery.
Treatment usually occurs after birth and where plastic and reconstructive surgery is considered to treat the resulting deformity. [30] Plastic surgery ranges from simple to complex depending on the extent of the deformity. Physical and occupational therapy may be needed long-term.[ citation needed ]
Prosthetics may help some people with ABS to live more functional lives. The price and complexity of these prosthetics vary dramatically, but advances in 3-D printing have helped to increase the availability of artificial fingers while reducing their cost of production. [31]
The prognosis depends on the location and severity of the constricting bands. Every case is different and multiple bands may be entangled around the fetus.
Bands which wrap around fingers and toes can result in syndactyly or amputations of the digits. In other instances, bands can wrap around limbs causing restriction of movement resulting in clubbed feet. In more severe cases, the bands can constrict the limb causing decreased blood supply and amputation. Amniotic bands can also sometimes attach to the face or neck causing deformities such as cleft lip and palate. If the bands become wrapped around the head or umbilical cord it can be life-threatening for the fetus.
The number of cases of miscarriage that can be attributed to ABS is unknown, although it has been reported that it may be the cause of 178 in 10,000 miscarriages. Up to 50% of cases have other congenital anomalies including cleft lip, cleft palate, and clubfoot deformity. Hand and finger anomalies occur in up to 80%.
The reported incidence of constriction ring syndrome varies from 1/1200 and 1/15,000 live births. [19] The prevalence is equal in male and female. [12]
Fetomaternal factors like prematurity, maternal illness, low birth weight, and maternal drug exposure are predisposing factors for the constriction ring syndrome. [12]
No positive relationship between CRS and genetic inheritance has been reported. [8]
Notable people living with ABS include:
Polydactyly or polydactylism, also known as hyperdactyly, is an anomaly in humans and non-human animals resulting in supernumerary fingers and/or toes. Polydactyly is the opposite of oligodactyly.
Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology caused by teratogens. Teratogens are substances that may cause non-heritable birth defects via a toxic effect on an embryo or fetus. Defects include malformations, disruptions, deformations, and dysplasia that may cause stunted growth, delayed mental development, or other congenital disorders that lack structural malformations. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental insult. The extent to which teratogens will impact an embryo is dependent on several factors, such as how long the embryo has been exposed, the stage of development the embryo was in when exposed, the genetic makeup of the embryo, and the transfer rate of the teratogen.
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders.
Arthrogryposis (AMC) describes congenital joint contracture in two or more areas of the body. It derives its name from Greek, literally meaning 'curving of joints'.
Ainhum, also known as dactylolysis spontanea, is a painful constriction of the base of the fifth toe frequently followed by bilateral spontaneous autoamputation a few years later.
Apert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial arch, the precursor of the maxilla and mandible. Disturbances in the development of the branchial arches in fetal development create lasting and widespread effects.
Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, but is an unusual condition in humans. The term is from Greek σύν, syn 'together' and δάκτυλος, daktulos 'finger'.
Triploid syndrome, also called triploidy, is a chromosomal disorder in which a fetus has three copies of every chromosome instead of the normal two. If this occurs in only some cells, it is called mosaic triploidy and is less severe.
Dysmelia is a congenital disorder of a limb resulting from a disturbance in embryonic development.
Congenital amputation is birth without a limb or limbs, or without a part of a limb or limbs.
Frontonasal dysplasia (FND) is a congenital malformation of the midface. For the diagnosis of FND, a patient should present at least two of the following characteristics: hypertelorism, a wide nasal root, vertical midline cleft of the nose and/or upper lip, cleft of the wings of the nose, malformed nasal tip, encephalocele or V-shaped hair pattern on the forehead. The cause of FND remains unknown. FND seems to be sporadic (random) and multiple environmental factors are suggested as possible causes for the syndrome. However, in some families multiple cases of FND were reported, which suggests a genetic cause of FND.
Hanhart syndrome is a broadly classified medical condition consisting of congenital disorders that cause an undeveloped tongue and malformed extremities and fingers. There exist five types of Hanhart syndrome, with the severity and nature of the condition ranging widely on a case-by-case basis. Hanhart syndrome is classified as a rare disease, with approximately 30 known cases having been reported between 1932 and 1991. Early hypotheses believed that the disorder was caused by genetic conditions, with a more recent hypothesis demonstrating that the disorder may be caused by hemorrhagic lesions during prenatal development. The causal mechanism behind this vascular disruption is still unknown.
Fibular hemimelia or longitudinal fibular deficiency is "the congenital absence of the fibula and it is the most common congenital absence of long bone of the extremities." It is the shortening of the fibula at birth, or the complete lack thereof. Fibular hemimelia often causes severe knee instability due to deficiencies of the ligaments. Severe forms of fibula hemimelia can result in a malformed ankle with limited motion and stability. Fusion or absence of two or more toes are also common. In humans, the disorder can be noted by ultrasound in utero to prepare for amputation after birth or complex bone lengthening surgery. The amputation usually takes place at six months with removal of portions of the legs to prepare them for prosthetic use. The other treatments, which include repeated corrective osteotomies and leg-lengthening surgery, are costly and associated with residual deformity.
Malalignment of the nail plate, also known as congenital malalignment of the great toenails or congenital malalignment syndrome, is a congenital malalignment of the nail of the great toe, and is often misdiagnosed although it is a common condition. It most commonly affects the hallucices. The nail might be discolored and develop infections. If the misaligned nail becomes embedded in the lateral nail fold it can cause pain, inflammation and erythema.
Oligodactyly is the presence of fewer than five fingers or toes on a hand or foot.
Fryns syndrome is an autosomal recessive multiple congenital anomaly syndrome that is usually lethal in the neonatal period. Fryns (1987) reviewed the syndrome.
Roberts syndrome, or sometimes called pseudothalidomide syndrome, is an extremely rare autosomal recessive genetic disorder that is characterized by mild to severe prenatal retardation or disruption of cell division, leading to malformation of the bones in the skull, face, arms, and legs.
Triphalangeal thumb (TPT) is a congenital malformation where the thumb has three phalanges instead of two. The extra phalangeal bone can vary in size from that of a small pebble to a size comparable to the phalanges in non-thumb digits. The true incidence of the condition is unknown, but is estimated at 1:25,000 live births. In about two-thirds of the patients with triphalangeal thumbs, there is a hereditary component. Besides the three phalanges, there can also be other malformations. It was first described by Columbi in 1559.
Ectrodactyly, split hand, or cleft hand involves the deficiency or absence of one or more central digits of the hand or foot and is also known as split hand/split foot malformation (SHFM). The hands and feet of people with ectrodactyly (ectrodactyls) are often described as "claw-like" and may include only the thumb and one finger with similar abnormalities of the feet.
Neu–Laxova syndrome is a rare autosomal recessive disorder characterized by severe intrauterine growth restriction and multiple congenital malformations. Neu–Laxova syndrome is a very severe disorder, leading to stillbirth or death shortly after birth. It was first described by Dr. Richard Neu in 1971 and Dr. Renata Laxova in 1972 as a lethal disorder in siblings with multiple malformations. Neu–Laxova syndrome is an extremely rare disorder with fewer than 100 cases reported in medical literature.