Congenital contractures can be divided into two groups: isolated contractures and multiple contractures (Fig. 1). Isolated congenital contractures affect only a single area of the body; the most common isolated contracture is congenital clubfoot, which occurs in one of every 500 live births1.



Fig. 1 
Types of congenital contractures.



The term arthrogryposis is often used as shorthand to describe multiple congenital contractures that affect two or more different areas of the body. Arthrogryposis is not a specific diagnosis, but rather a clinical finding, and it is a characteristic of more than 300 different disorders2,3. The overall prevalence of arthrogryposis is one in 3000 live births4. The inheritance, natural history, treatment guidelines, and outcomes of arthrogryposis vary among disorders, underscoring the importance of making a specific diagnosis in each child1,5-10. The purpose of this article is to present the current state of knowledge about the classification, etiology, and management of children with various types of arthrogryposis.

To establish a differential diagnosis, it is important to first decide whether a child has normal neurological function. A normal neurological examination suggests that arthrogryposis is due to amyoplasia, a distal arthrogryposis, a generalized connective tissue disorder, or fetal crowding. In contrast, an abnormal neurological examination indicates that movement in utero was diminished as a result of an abnormality of the central or peripheral nervous system, the motor end plate, or muscle.

### Amyoplasia

Amyoplasia (A = no; myo = muscle; plasia = growth) is a distinct form of arthrogryposis with characteristic clinical features as shown in Figure 2: the shoulders are usually internally rotated and adducted, the elbows are extended, the wrists are flexed and ulnarly deviated, the fingers are stiff, and the thumbs are positioned in the palm. In the lower limbs, …

Arthrogryposis: A Review and Update

Autism together with Asperger syndrome and pervasive developmental disorder not otherwise specified form a spectrum of conditions (autism spectrum disorders or ASD) that is characterized by disturbances in social behavior, impaired communication and the presence of stereotyped behaviors or circumscribed interests. Recent estimates indicate a prevalence of ASD of 1 per 150 (Kuehn, 2007). The cause(s) of most cases of ASD are unknown but there is an emerging consensus that ASD have multiple etiologies. One proposed cause of ASD is exposure of the fetal brain to maternal autoantibodies during pregnancy [Dalton, P., Deacon, R., Blamire, A., Pike, M., McKinlay, I., Stein, J., Styles, P., Vincent, A., 2003. Maternal neuronal antibodies associated with autism and a language disorder. Ann. Neurol. 53, 533–537]. To provide evidence for this hypothesis, four rhesus monkeys were exposed prenatally to human IgG collected from mothers of multiple children diagnosed with ASD. Four control rhesus monkeys were exposed to human IgG collected from mothers of multiple typically developing children. Five additional monkeys were untreated controls. Monkeys were observed in a variety of behavioral paradigms involving unique social situations. Behaviors were scored by trained observers and overall activity was monitored with actimeters. Rhesus monkeys gestationally exposed to IgG class antibodies from mothers of children with ASD consistently demonstrated increased whole-body stereotypies across multiple testing paradigms. These monkeys were also hyperactive compared to controls. Treatment with IgG purified from mothers of typically developing children did not induce stereotypical or hyperactive behaviors. These findings support the potential for an autoimmune etiology in a subgroup of patients with neurodevelopmental disorders. This research raises the prospect of prenatal evaluation for neurodevelopmental risk factors and the potential for preventative therapeutics.

Stereotypies and hyperactivity in rhesus monkeys exposed to IgG from mothers of children with autism

Objective: To investigate the effect of maternal myasthenia gravis (MG) on giving birth and on the newborn. Methods: A retrospective cohort study for 1967 through 2000 was undertaken, using data from the Medical Birth Registry of Norway, based on the compulsory notification of all births. The target group consisted of 127 births by mothers with MG. The reference group consisted of all 1.9 million births by mothers without MG. Results: Women with MG had a higher rate of complications at delivery (40.9% vs 32.9%, p = 0.05), and in particular the risk of preterm rupture of amniotic membranes was three times higher in the MG group compared to the reference group (5.5% vs 1.7%, p = 0.001). The rate of interventions during birth was raised (33.9% vs 20.0%, p Conclusions: MG is associated with an increased risk for complications during delivery. This is linked to a higher occurrence of interventions during birth.

Myasthenia gravis: Consequences for pregnancy, delivery, and the newborn

Hyperthermia has been shown to be a teratogenic agent in a number of animal species. We have attempted to determine if maternal hyperthermia during early gestation might also be responsible for problems in human development. Eight retrospectively ascertained cases, in which high fever had occurred at four to six weeks' gestation, revealed a similar clinical phenotype in the infants despite the fact that the maternal fever was caused by different infections. The most consistent manifestations were severe mental deficiency, seizures, hypotonia, microphthalmia, midface hypoplasia, and mild impairment of distal limb development. In five patients exposed to hyperthermia at seven to 16 weeks' gestation, predominant features were hypotonia, neurogenic arthrogryposis, and central nervous system dysgenesis. The cause of fever differed in each of these cases; in one, a patient with neurogenic arthrogryposis, the hyperthermia had been induced in a sauna bath. No apparent serious problem in morphogenesis was found following hyperthermia during the latter half of gestation. These findings are similar to those resulting from induced hyperthermia in animals. Further research on the effects of hyperthermia in the developing human being seems warranted.

Hyperthermia as a Possible Teratogenic Agent

Patients with autoimmune myasthenia gravis (MG) should be further classified before initiating therapy, as treatment response varies for ocular versus generalised, early onset versus late onset, and acetylcholine receptor antibody positive versus MuSK antibody positive disease. Most patients need immunosuppression in addition to symptomatic therapy. Prednisolone and azathioprine represent first choice drugs, whereas several second choice options are recommended and should be considered. Thymectomy should be undertaken in MG with thymoma and in generalised, early-onset MG. For MG crises and other acute exacerbations, intravenous immunoglobulin (IvIg) and plasma exchange are equally effective and safe treatments. Children and females in child bearing age need special attention regarding potential side effects of immunosuppressive therapy. MG pathogenesis is known in detail, but the immune therapy is still surprisingly unspecific, without a pin-pointed attack on the defined disease-inducing antigen-antibody reaction being available.

https://downloads.hindawi.com/journals/ad/2011/847393.pdf

Myasthenia Gravis: A Review of Available Treatment Approaches

Background: Arthrogryposis multiplex congenita (AMC) is defined as nonprogressive congenital contractures that generally result from lack of fetal movement in utero. AMC is a feature of many congenital disorders caused by genetic, environmental, or other factors. One rare cause of AMC is maternal myasthenia gravis (MG). This is an autoimmune disorder, caused by antibodies to the nicotinic acetylcholine receptor (AChR), and resulting in weakness of voluntary muscles. In 10 ‐15% of babies born to MG mothers, transient signs of MG are noted after placental transfer of anti-AChR antibodies. In a few cases, AMC predominates. Methods: We review the role of antibodies to AChR in MG and in AMC associated with maternal antibodies to AChR. Results: In anti-AChR antibody-associated AMC, fetal or neonatal death is common; other deformities or CNS abnormalities are common as well. The condition usually recurs in each pregnancy unless the mother is treated for MG, but some mothers are asymptomatic. The maternal antibodies cross the placenta and block the function of the fetal isoform of the AChR leading to fetal paralysis. Injection of maternal plasma into pregnant mice results in AMC in mouse fetuses. Some women with recurrent AMC in their babies have no detectable anti-AChR suggesting the presence of antibodies to other fetal muscle or neuronal proteins. Conclusions: Although rare, anti-AChR-associated AMC is potentially treatable and can be diagnosed by a routine antibody test. The mouse model can be used to investigate the role of these and other maternal antibodies in causing congenital conditions.

Teratogen update: maternal myasthenia gravis as a cause of congenital arthrogryposis.

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Teratogen update: maternal myasthenia gravis as a cause of congenital arthrogryposis.