Amniotic Band Syndrome (Streeter Dysplasia) 

Updated: Sep 10, 2020
Author: Twee T Do, MD; Chief Editor: Jeffrey D Thomson, MD 

Overview

Practice Essentials

Streeter dysplasia is a term that historically has been used to describe a complex disorder characterized by constricting rings, acrosyndactyly, or, often, amputations of the extremities of neonates. It is analogous to constriction band syndrome or amniotic band syndrome (ABS; also referred to as amniotic band sequence[1] ), which was recognized as early as 300 BCE.

Depending on the severity of the constriction, the defect may be as minimal as a merely cosmetic band. Deeper bands may cause lymphatic obstruction leading to edema and vascular compromise that necessitates immediate release. Pressure from the bands may potentially cause abnormalities distal to the constriction, such as hemihypertrophy, anterolateral bowing, pseudarthrosis, leg-length discrepancy, and resistant teratologic clubfeet. These conditions may lead to limited function and difficulty with ambulation.[2, 3, 4]

Constriction bands across the head and face may lead to facial clefts. If the cleft extends into the cranium, encephaloceles may result. Bands that cross the body may compromise the chest (thoracoschisis or extrathoracic heart) or abdomen (gastroschisis).

Because ABS is an intrauterine phenomenon probably caused by the rupture of amniotic membranes and constriction of the developing tissue, no medical treatment exists for the condition. (See Treatment.) Indications for intervention depend on the medical stability of the child and on the neurovascular status of the limb. Anencephaly usually is incompatible with life, but the other deformities can be triaged for correction and reconstruction. Of all the deformities, only the tight constriction bands with gross lymphedema, vascular compromise, or both necessitate immediate surgical release.

Anatomy

The anatomy relevant to surgery for ABS depends on the area of the body affected. Most bands are superficial, and only the skin and subcutaneous tissue are involved. However, the neurovascular bundle may be displaced near areas of banding. Therefore, this possibility must be taken into consideration with dissection for excision in order to avoid devascularization or denervation of the involved body segments.

Pathophysiology

The developing embryo sits within two cavities, the amnion and the chorion. As development occurs, the amnion presses against the extracoelomic space, eventually obliterating it and bringing the amnion up to and supported by the chorion. This phenomenon occurs on or about week 12 of gestation. Incomplete obliteration of the extracoelomic space renders the amnion fragile and subject to spontaneous or traumatic rupture.[5] After the rupture, a transient oligohydramnios occurs due to extravasation of amniotic fluid. Until the chorion adjusts to the permeability, the developing fetus has very little room in which to move. This may contribute to the severity of clubfeet deformities seen with ABS.

This decrease in space also allows the resultant floating amniotic bands to easily ensnare a developing body part. Early in gestation, the encircling bands may result in spontaneous abortions. If the constriction occurs after development is nearly complete, only fissures, acrosyndactylization, and intrauterine amputation are noted on the extremities as typical manifestations. If the amniotic bands are swallowed while still partially attached to the placenta, the tether may lead to bizarre facial clefts and palate deficiencies.[6]

Etiology

Two main lines of thought have been followed regarding the etiology of ABS, attributing the condition either to intrinsic or to extrinsic causes.

Hippocrates suggested that extrinsic pressures from a ruptured amniotic membrane lead to the formation of bands or digital amputations. In 1652, van Helmont reported on intrauterine amputations, which he attributed to the pregnant mothers having looked upon maimed soldiers. Montgomery[7] in 1832 and Simpson[8] in 1836 subsequently described series of amniotic band–associated deformities and discussed the differences between agenesis- and amniotic band–induced amputations.

The condition was not referred to as Streeter dysplasia until 1930, when Streeter postulated a germ plasm defect as one plausible etiology.[9] At that time, this theory was well accepted because of the associated anomalies, which occurred far from the site of the constriction bands. Streeter proposed that a disruptive event occurs during blastogenesis, leading to an intrinsic germ plasm defect.[9] This causes the soft tissue to slough. External healing of the slough leads to the constricting rings and the resultant localized developmental defects. Cases of ABS in which the amnion is intact supported this theory, as did the frequently associated renal abnormalities (37% of cases) and occasional cardiac abnormalities.

Ainhum, a predominantly African syndrome in which progressive circumferential ulceration leads to eventual amputation of digits, is an inherited disease, thus further lending support to an intrinsic developmental defect as a cause of digit amputation. Streeter aggressively defended this theory for more than 35 years. For his long and avid support, many surgeons still describe this disorder as Streeter dysplasia.

In 1960, Patterson used histology to show how constriction bands look like normal skin creases. He hypothesized that the same lack of mesodermal development occurs in the area of the band, thereby making the bands simply abnormal creases.[10]

Patterson's theory was later refuted by Torpin, who examined many placentae and infants with the disorder.[11] In 1965, Torpin reintroduced the extrinsic theory originally held by Hippocrates. He proposed that maternal trauma leads to rupture of the amniotic membrane, which then forms into strands. These encircling strands cause extrinsic compression on the head or limb, leading to the formation of bands, vascular occlusion, and, eventually, amputations. This came to be the most widely supported hypothesis; therefore, ABS would be a more accurate name for this disorder than Streeter dysplasia.

The lack of family history or predictable recurrences in families of children born with ABS militated against the theory of an inherent or genetic component to the condition. Zionts et al[12] were able to demonstrate variable findings of the syndrome in monozygotic twins who each were affected by amniotic bands. These and other sporadic findings were more consistent with the view that external compression is the etiologic root of this syndrome.[13]

A sonographic study by Barzilay et al suggested that prior uterine surgery may be a risk factor for ABS.[14]

Epidemiology

The estimated frequency of ABS in the United States is 1 per 3000 pregnancies (if the potential miscarriages that occur from severe banding early in gestation are considered). More common statistics show an incidence of 1 case per 10,000-15,000 population. One of the few epidemiologic studies was a 1988 study from Atlanta that cited the incidence as 1.16 cases per 10,000 population. No sex predilection is recognized.

The incidence overseas is similar to that in the United States. The birth defect registry of Western Australia cited an incidence of 1.15 per 10,000 population.

Prognosis

The prognosis for patients with isolated superficial extremity bands is good (see the image below). Aside from cosmetic variability, no functional deficits remain.

Image shows the lower limb of a young child born w Image shows the lower limb of a young child born with moderate bands that extend deep to the fascia but do not compromise the neurovascular system.

Deeper bands may be associated with progressive problems leading to later lymphatic and neurovascular compromise that necessitates surgical intervention. For patients with acrosyndactyly, hand function is limited secondary to stiffness of the joints, but good prehension and grasp may be obtained with reconstructive procedures. Children who have had intrauterine amputations are usually well adapted to their physical limitations, and often little needs to be done. In children with a transverse deficiency proximal to the ankle joint, a prosthesis is required for full function.

 

Presentation

History and Physical Examination

Children born with amniotic band syndrome (ABS; also referred to as amniotic band sequence or Streeter dysplasia) are usually full-term or a few weeks premature; in most cases, the pregnancies were uncomplicated. In Light and Ogden's series, the average gestation was 37.5 weeks, with an average birth weight of 3.0 kg.[15]

Although the condition is quite variable in presentation, the most common clinical findings in ABS appear on the extremities (see the image below) and include amputation followed by constriction bands and then acrosyndactyly. Other associated findings include the following:

Image shows the lower limb of a young child born w Image shows the lower limb of a young child born with moderate bands that extend deep to the fascia but do not compromise the neurovascular system.

On the extremities, the distal portion is most often involved, especially the longer central digits of the hand (middle, long, and index fingers). The hands are affected in almost 90% of cases.[19] In rare cases, the thumb or small finger is involved, presumably because of their shorter lengths. The same rule holds true for the feet, where constriction bands most commonly involve the hallux.

Mild band pressure causes only indentations at the base of the phalanx, usually distal to the metacarpophalangeal (MCP) joints. Progressive constriction is the result of the maceration of the indentation and subsequent healing by scar tissue formation. If the compression from the band is severe, lymphatic and vascular compromise may ensue, and the child presents at birth with a swollen engorged digit or limb that may require immediate surgical release.[20]

More commonly, the digit has been amputated in utero. Acrosyndactyly occurs after digital separation is complete, but the fingers become twisted by bands and eventually coalesce. The peripheral digits are brought forward, and residual sinus tracts are usually present in the remnant web space where a probe can be placed—so-called fenestrated syndactyly.

Extremity deformities in ABS are commonly classified into Patterson's four types, as follows:

  • Type I - Simple ring constriction
  • Type II - Ring constriction accompanied by fusion of the distal bony parts, with or without lymphedema
  • Type III - Ring constrictions accompanied by fusion of soft-tissue parts
  • Type IV - Intrauterine amputations

Clubfoot is seen in as many as 25% of cases. This is a mix of paralytic and idiopathic deformities. In 50% of clubfoot cases, a tight band is found around the peroneal nerve, which causes muscle imbalance and clubfoot.[21, 22] In the other 50%, no bands are visible anywhere on the limb. The deformity is thought to arise from lack of space due to oligohydramnios. The clubfoot deformity is typically rigid.

Clinically significant limb-length discrepancy may also be present, and patients need to be sequentially monitored, even after correction of bands and the clubfoot.

Other less common findings include the following:

  • Craniofacial abnormalities, [23, 24, 25] which may occur in as many as 5% of ABS cases
  • Acquired raised limb bands
  • Anterolateral bowing of the tibia with pseudarthrosis
 

Workup

Laboratory Studies

Because amniotic band syndrome (ABS; also referred to as amniotic band sequence or Streeter dysplasia) is an extrinsic yet spontaneous phenomenon, no good laboratory tests exist to detect its presence. Levels of α-fetoprotein have been shown to be elevated with normal acetylcholinesterase activity, but this elevation may be due to the anencephaly (with positive acetylcholinesterase isoenzymes) or fetal demise (negative acetylcholinesterase isoenzymes).

Imaging Studies

Serial ultrasonograms can show the gross lack of formation, such as anencephaly or intrauterine amputations, but earlier ultrasonographic (US) studies of monozygotic twins were disappointing.[26] One study reported evidence of ABS on US in both twins, but only one twin had clinical manifestations (and those were severe).

Advances in US technology and the availability of three-dimensional (3D) and four-dimensional (4D) US have allowed the defect to be characterized down to the level of how the nerves and muscles are affected distally.[27, 28, 29] The greater level of detail now available has made US a more reliable resource for identifying this disorder early in gestation, thereby allowing better prediction of the ultimate fetal prognoses.[30, 31, 14] This, in turn, may affect the outcome of antenatal counseling regarding the pregnancy. Antenatal diagnosis of atypical facial clefting should alert physicians to the possibility of ABS and other anomalies.[32, 33]

Magnetic resonance imaging (MRI) may be considered preoperatively on limbs with deep bands to evaluate the neurovascular status.[34] Magnetic resonance angiography (MRA) of limbs affected by ABS may reveal vessel deficiencies and variable anatomy that could affect the surgical outcome.

Procedures

Amniocentesis has been associated with membrane rupture after needle placement. Therefore, it has no significant place in the diagnosis or treatment of ABS.

 

Treatment

Approach Considerations

Indications for intervention to treat amniotic band syndrome (ABS; also referred to as amniotic band sequence or Streeter dysplasia) depend on the medical stability of the child and on the neurovascular status of the limb. Anencephaly usually is incompatible with life, but the other deformities can be triaged for correction and reconstruction. Of all the deformities, only the tight constriction bands with gross lymphedema, vascular compromise, or both necessitate immediate surgical release.

Clubfeet should be manipulated and put in casts early, as is the case for all idiopathic clubfeet. The paralytic feet in ABS, however, usually are severe and do not respond well to conventional treatment. Surgical correction is also associated with a high incidence of recurrence and complications due to neurovascular injury from proximal bands over the peroneal nerve.

Cleft lip and palate require reconstruction, but this is best done when the child is aged approximately 3-6 months, depending on the severity of the cleft and the infant's ability to feed.

Mild bands that only cosmetically affect the superficial skin, similar to the creases found in the Michelin tire baby syndrome (circumferential-ringed creases with specific histologic findings and/or karyotype abnormalities), do not require any intervention. As growth occurs, progressive constriction and edema may necessitate band excision and Z-plasty, but in general, excision is not indicated for superficial bands, because of the potential complications of wound infections and neurovascular compromise.

Medical Therapy

Because ABS is an intrauterine phenomenon probably caused by the rupture of amniotic membranes and constriction of the developing tissue, no medical treatment exists for the condition. Avoiding certain drugs that can lead to spontaneous rupture of membranes, such as cocaine and mifepristone, may help decrease the potential risk.

Surgical Therapy

Tight constrictions on the digits or extremities often render urgent surgical treatment necessary for patients with vascular compromise. Surgery also is indicated for patients with syndactyly or acrosyndactyly that compromises hand function. Thumb amputation (which is rare), clubfeet, cleft lip, and cleft palate also warrant reconstruction, but these procedures can be performed electively at a later time and at the discretion of the physician and family.[35]

In bands identified by three-dimensional (3D) ultrasonography (US) as causing neurovascular compromise, early in-utero fetoscopic surgery for release can be performed. Early studies in animal models yielded promising results.[36] Multiple series of case reports also documented the effectiveness of fetoscopic releases on the outcomes for the constrictions affecting the fetus and the relative safety of the procedure for the mothers.[37, 38, 39, 40, 41]

Early intervention for severe constriction bands after birth includes band excision with 1-2 mm of normal skin to avoid recurrence. The entire band must be excised. This is performed on a maximum of 65% of the ring (most authors recommend 50%) by Z-plasty for lesser constrictions and by V-Y plasty or W-plasty for tighter bands. A staged correction ensures adequacy of vascularity to the residual limb or digit. Additionally, debulking of the fibrofatty soft tissues followed by subcutaneous tissue advancement as described by Upton[42] may further improve the cosmetic appearance of the digits after band release.

For a study of the formation of phalanges and small joints through tissue engineering, see the work of Isogai et al.[43]

For severely constricted bands with wide tissue excision, W-plasty is preferred to provide additional skin for closure. In band excision, intraoperative consideration should be given to possible attenuation of the neurovascular bundle and its proximity to the surface of the band. Careful dissection under magnifying loupes prevents possible damage to these vital structures.

The first part of acrosyndactyly release consists of separation of the digits, especially if the constricting rings are not compromising circulation. Digits are separated when infants are aged 6 months to 1 year. Dobyns reported that the number of fingers is not as important as their length, bulk, stability, spacing, and control.[44]

The groin is prepared for skin graft harvest, which will be necessary for closure. Reconstruction typically is performed in a proximal-to-distal direction and requires complete removal of the sinus tracts, which tend to be located more distally than the normal web spaces are. If the thumb is severely shortened or its function is compromised, the on-top plasty or toe-to-thumb transfer may be considered. Despite cosmetic improvements, the digits will continue to be stiff.

Intrauterine amputations do not warrant intervention unless they involve the thumb at the metacarpophalangeal (MCP) joint. In these cases, the on-top plasty or toe-to-thumb transfer may improve function.

In the lower extremities, teratologic clubfeet associated with deep congenital constriction bands usually require constriction band excision, Z-plasty, and posteromedial release and casting. This is typically described as a staged procedure. The band excision and Z-plasty may be performed in parts (three-stage clubfoot release) or in full (two-stage clubfoot release).[45]

Performing the procedure in staged parts was previously considered necessary to avoid any vascular compromise with the clubfoot surgery, skin sloughing, and infection. Greene,[46] however, published good results in three patients with four affected clubfeet who were treated with band excision, Z-plasty, and posteromedial release in a single full procedure with no significant complications. The benefits of a single complete procedure include ease of postoperative patient care and reduced patient exposure to general anesthetics.

Complications

Complications from ABS include severe lymphatic or venous congestion at the time of birth due to tight bands. This congestion may lead to necrosis and gangrene[18] if not urgently treated with excision and release. Other potential complications include neurovascular compromise caused by release of the entire band at one sitting or lack of attention to the superficial level of the attenuated nerves and vessels.

Clubfeet are teratologic in 50% of cases and do not respond well to surgical posteromedial releases alone. The constriction bands often require excision, and tendon transfers may be required later because of peroneal nerve compromise.

Long-Term Monitoring

All patients with ABS should be monitored regularly until skeletal maturity because of the potential for recurrence of the rings and for secondary contractures that may develop and must be addressed on an individual basis.