CONGENITAL CONSTRICTION BANDS (AMNIOTIC BANDS)

Amniotic band syndrome (ABS)—also known as amniotic band constriction; congenital constriction bands; constrictive ring syndrome; Streeter dysplasia; and amniotic deformity, adhesions, and mutilations (ADAM) complex—is a rare, congenital, nonhereditary disorder in which fetal parts become entangled in the amniotic membrane, leading to constriction, deformation, and deletion. Although the pathogenesis of ABS is still not clear, the leading theory proposes that a rupture of the amnions during early pregnancy allows the fetus to enter the chorionic cavity and causes fetal structures to be trapped by amniotic bands. The defects that result from these bands range in severity from mild constriction to complete digital and/or limb amputation, anencephaly, and fetal demise. ABS most commonly affects the upper extremities, with a predilection for the distal segments of the hand. Treatment may not be necessary for very shallow constriction rings, but surgery is often needed for many other cases.^1,2

Pathophysiology

• Extrinsic model theory
  • More widely accepted and recently confirmed by medical imaging, proposes that amniotic rupture during early pregnancy allows the embryo/fetus to enter the chorionic cavity and contact the chorionic side of the amnions; this causes fetal structures to be trapped by the fibrous septum that protrudes into the chorionic cavity
  • Compression and adhesion of these free-floating amniotic bands may cause disruption of fetal structures and may lead to the fetus’ arms and legs becoming tangled and amputated during intrauterine development owing to loss of blood flow²
  • Intrinsic model theory
    • Suggests the existence of an early embryo lesion with alterations of the germinal disc that produce an inflammatory response of the adjacent amnions, which then develop a fibrous band²
    • This mechanism was thought to be similar to the process involved in the development of normal skin folds, which appear very similar histologically¹
    • No autosomal inheritance pattern has been identified for ABS, and no connection has been made to any infectious agent¹
    • The onset of ABS is somewhat later than that of other limb malformations³

Related Anatomy

• Fetal membrane
  • Chorion
  • Amnion
    • Inner amnion
      • Inner layer
      • Mesenchymal layer
      • Outer layer
      • The inner and mesenchymal layers secrete collagen, fibronectin, and lamin to provide a strong elastic and tensile layer
      • The outer layer, or spongy layer, is adjacent to the chorion and can swell to accommodate sliding of the amnion across the chorion
      • Patterson’s classification system for constriction rings⁴
        • Simple: mild ring with no distal deformity or lymphedema
        • Distal deformity: ring may or may not also cause lymphedema
        • Associated with acrosyndactyly  (fusion between more distal portions of the digits, with the space between the digits varying in size)
          • Type I: conjoined fingertips with well-formed webs of the proper depth
          • Type II: tips of digits are joined, but web formation is incomplete
          • Type III: joined tips, sinus tracts between digits, and absent webs
• Causing intrauterine amputation loss of limb distal to constriction ring
• Protruding fetal structures are more vulnerable and more likely to be entrapped; involvement is common in the upper extremities, with a predilection for the distal segments of the hand, particularly the middle digits; the thumb is less vulnerable and often spared because it lies protected within the palm of the hand in utero^1,5

Incidence and Related Conditions

• Incidence estimates are ~1 in 1,200–15,000 live births⁶
• ABS does not appear to affect any gender or race more frequently than others, although some studies report a slightly higher incidence in Afro-Caribbean individuals^6,7
• Prenatal diagnosis of ABS as early as 12 gestational weeks is performed in 29–50% of cases, depending on the severity of the disorder and the time when the lesions appear²
• Risk factors include prematurity, maternal illness, low birth weight, and drug exposure
• Cleft lip, cleft palate, and other craniofacial defects
• Hemangioma
• Meningoceles
• Visceral and body wall defects
• Digital hypoplasia
• Dactylys: acrosyndactyly, camptodactyly, polydactyly, pseudosyndactyly, symbrachydactyly, syndactyly
• Clubfoot
• Leg length discrepancies
• Bone anomalies
• Anencephaly
• Congenital heart defects
• Renal anomalies
• Supernumerary nipples
• Skin tags

Differential Diagnosis

• Vasculocutaneous catastrophe of the newborn
• Brachysyndactyly
• Transverse growth arrest
• Limb-body wall complex
• Short umbilical cord syndrome
• Pentalogy of Cantrell

The typical patient is a newborn baby of either gender. An examination after the infant is born will reveal constriction bands around the arms and/or digits, and possibly other signs of vascular, lymphatic, and/or neural damage. The constriction bands may or may not have also caused an intrauterine amputation.

• Infection
• Hematoma
• Flap and/or graft necrosis
• Distal circulatory failure

• Web space deepening is effective in ABS cases with thumb involvement

• Constriction bands should be surgically released as soon as possible for satisfactory results, and emergency surgery should be reserved for patients with severe distal edema; this surgery comprises constriction band release and one-stage Z-plasty⁹
• Timing of repair is important. Release of bands associated with severe distal edema should be performed within the first few postnatal days; in infants with acrosyndactyly, repair in the first 3-6 months allows the best chance for proper longitudinal bone growth¹
• Urgent release of the ring is required in constriction bands with considerable distal lymphedema, cyanosis, and circulatory embarrassment that may progress quickly to ulceration or infection¹
• Simple excision without Z-plasty leaves a circular scar that may contract, producing a more noticeable defect than was present before repair; the Upton technique may be preferable when repairing moderate to severe rings presenting with or without edema¹
• Surgical planning should be guided by the dictum that the number of fingers is not as important as their spacing, length, bulk, stability, and control¹
• Magnetic resonance imaging - MRI without contrast
  • Intrauterine ABS diagnosis can be performed as early as 12 gestational weeks and is based on US visualization of amniotic bands in an asymmetric distribution or deformities in a “random” nonembryonic distribution
  • Findings may be confirmed by fetal MRI, which is often ordered as a complementary measure when considering fetal surgery^2,5
• The mere presence of amniotic bands is not considered sufficient to diagnose ABS, as several types of membranes may be seen in normal pregnancies⁸

Cited

1. Moran SL, Jensen M, Bravo C. Amniotic band syndrome of the upper extremity: diagnosis and management. J Am Acad Orthop Surg 2007;15(7):397-407. PMID: 17602029
2. Cortez-Ortega C, Garrocho-Rangel JA, Flores-Velázquez J, et al. Management of the Amniotic Band Syndrome with Cleft Palate: Literature Review and Report of a Case. Case Rep Dent 2017;2017:7620416. PMID: 28246561
3. Miura T. Congenital constriction band syndrome. J Hand Surg Am 1984;9A(1):82-8. PMID: 6319481
4. Light TR, Ogden JA. Congenital constriction band syndrome. Pathophysiology and treatment. Yale J Biol Med 1993;66(3):143-55. PMID: 8209551
5. Rezai S, Faye J, Chadee A, et al. Amniotic Band Syndrome, Perinatal Hospice, and Palliative Care versus Active Management. Case Rep Obstet Gynecol 2016;2016:9756987. PMID: 28025631
6. Doi Y, Kawamata H, Asano K, Imai Y. A case of amniotic band syndrome with cleft lip and palate. J Maxillofac Oral Surg 2011;10(4):354-6. PMID: 23204754
7. Koskimies E, Syvänen J, Nietosvaara Y, et al. Congenital constriction band syndrome with limb defects. J Pediatr Orthop 2015;35(1):100-3. PMID: 24787313
8. Pant R, Singh H, Narula G. AMNIOTIC BAND SYNDROME. Med J Armed Forces India 2001;57(2):172-3. PMID: 27407331
9. Visuthikosol V, Hompuem T. Constriction band syndrome. Ann Plast Surg 1988;21(5):489-95. PMID: 3232940

New Articles

1. Cortez-Ortega C, Garrocho-Rangel JA, Flores-Velázquez J, et al. Management of the Amniotic Band Syndrome with Cleft Palate: Literature Review and Report of a Case. Case Rep Dent 2017;2017:7620416. PMID: 28246561
2. Rezai S, Faye J, Chadee A, et al. Amniotic Band Syndrome, Perinatal Hospice, and Palliative Care versus Active Management. Case Rep Obstet Gynecol 2016;2016:9756987. PMID: 28025631

Reviews

1. Moran SL, Jensen M, Bravo C. Amniotic band syndrome of the upper extremity: diagnosis and management. J Am Acad Orthop Surg 2007;15(7):397-407. PMID: 17602029

Classics

1. Cockayne EA. Constriction of Arm by Amniotic Bands. Proc R Soc Med 1914;7:4-5. PMID: 19978341