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Severe birth defects due to Rubella infection during pregnancy, especially before week 12 of gestation.
History:
In 1941, an Australian ophthalmologist, Norman Gregg, first reported the association between congenital cataracts and a rubella infection during pregnancy in an article entitled “Congenital cataract following German measles in the mother”. This condition is now referred to as congenital rubella syndrome (CRS). It occurs as a result of a maternal rubella infection during the first trimester of pregnancy when organogenesis is occurring and is most commonly associated with hearing impairment (60%), congenital heart disease (45%), microcephaly (27%) congenital cataracts (25%) and mental retardation (13%). During the early 1960s, there was a worldwide pandemic of CRS. In the United States alone, 20 000 children were born with CRS between 1962 and 1965. In 1969, a live attenuated rubella vaccine was licensed in the US, and widespread vaccination of children was initiated. As a result, CRS has almost been eradicated from the US. Between 2001 and 2004, there were only 4 reported cases of CRS in the US, of which 3 were born to mothers who had immigrated to the US.
In India, CRS is the second leading cause of non‐traumatic childhood cataracts exceeded only by hereditary cataracts. The visual outcome of children with cataracts secondary to CRS is generally quite poor. In a recent report from India, 50% of children with bilateral cataracts secondary to CRS remained legally blind following cataract surgery. The poor visual outcomes were ascribed to amblyopia, glaucoma, cornea opacities, optic atrophy and pupillary membranes. The poor visual outcomes were particularly tragic, since more than 50% of these children had a hearing impairment.
Pathophysiology
Clinical features
Triad of Gregg:
- Sensorineural hearing loss (SNHL) (58% cases)
- Eye abnormalities (43% cases): Salt-and-pepper chorioretinopathy, cataract, and microphthalmia
- Congenital heart disease (50% cases): Patent ductus arteriosus (PDA) (M/C) > pulmonary artery stenosis > VSD > ASD
Other manifestations:
- Hepatosplenomegaly & jaundice
- CNS manifestations: Deafness, microcephaly, panencephalitis, brain calcification & psychomotor disorders
- Low birth weight
- Thrombocytopenic purpura
- Extramedullary hematopoiesis (characteristic blueberry muffin rash)
- Hepatomegaly
- Micrognathia
Case studies:
Diagnosis
CRS is defined by:
- Presence of IgM antibody in neonatal serum shortly after bith (since IgM doesn’t cross placenta, thus presence indicates thay were sythesized in-utero)
- Persistence of IgG antibodies beyond 6 months (maternal antibodies dissapear by then)
Management
Prenatal management of the mother and fetus depends on gestational age at onset of infection.
Infection before 18 weeks gestation:
- Termination of pregnancy (as fetus is at high risk for infection and severe symptoms)
- Detailed USG and assessment of viral RNA in amniotic fluid recommended.
Infections after 18 weeks gestation:
- Pregnancy continued with USG monitoring followed by neonatal physical examination and testing for RV-IgG