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2000-10-23-14 Amyoplasia © Muñoz Rojas www.thefetus.net/


Amyoplasia 

Maria Verônica Muñoz Rojas, MD, Luís Flávio Gonçalves, MD

Florianopolis, Brazil

Synonyms: Arthrogryposis Multiplex Congenita (AMC)

Definition: Syndrome characterized by multiple specific congenital joint contractures, associated with substitution of muscular tissue by fibrosis and adipose tissue.1,2,4

Incidence: 1:10.000 (most common form of arthrogryposis)4

Etiology: Sporadic.3,4

Diagnosis: When the superior limbs are affected, there is symmetrical involvement with internal rotation of the shoulders, elbows in hyperextension and flexed wrists. Small feet with severe clubfeet are observed when the lower limbs are involved. The muscles are hypoplastic and replaced by a mixture of fat and fibrosis.
 

Figure 1. Clubfoot at 13 weeks

Figure 2. Longitudinal section through the right arm at 13 weeks showing permanent hyperextension.

Figure 3. Longitudinal section through the right arm at 33 weeks, showing persistence of the hyperextension demonstrated at 13 weeks.

Figure 4. Aspect of the newborn. Note the internal rotation of the shoulders and bilateral clubfeet

Complications: Breech presentation (30%); bone fractures at birth (10%)

Associated anomalies:  Capillary  hemangioma of the middle face (90%): facial asymmetry; hypoplastic external genitalia: undescended testicles; hernias; scoliosis; gastroschisis; abdominal wall defects.

Prognosis: Limb deformities change with growth during childhood. Decrease movements affect bone growth and affected limbs are usually shorter than normal in adult life. Therefore, early mobilization is important.2

Genetic counseling and recurrence risk: Contractures occur because of decreased limb movement in utero. Amyoplasia may also be associated to muscular tissue loss during fetal development, probably during the second trimester. A disruptive vascular event is suspected as the cause of these abnormalities. Recurrence risk for siblings or for future children is minimal. There is no case report of familiar recurrence in the literature.2,4

Treatment: Physiotherapy with emphasis in early mobilization of the limbs in order to prevent atrophy of the remaining musculature. Sells et al. did an excellent review about the results of therapy in patients with amyoplasia.2

References
1. Hall JG, Reed SD, Driscoll EP. Part 1. Amyoplasia: a common, sporadic condition with congenital contractures. Am J Med Genet 1983;15:571-590.
2. 2.Sells JM, Jaffe KM, Hall JG. Amyoplasia, the most common type of arthrogryposis: the potential for good outcome. Pediatrics 1996;97:225-231.
3. Gonzalez CH, Marques-Dias J, Kim CA, Suguyama SMM. Da Paz JZ, Huson SM, Holmes LB. Congenital abnormalities in Brazilian children associated with misoprostol misuse in first trimester of pregnancy. Lancet 1998;351:1624-1627.
4. Hall, JG. Arthrogryposis, amyoplasia type. In: Buyse, ML (ed). Birth Defects Encyclopedia. Blackwell, 1990.

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