Severe microcephaly associated with congenital varicella infection.

A case of second-trimester congenital varicella infection, in association with isolated microcephaly and severe brain damage, is reported, and cases of classical congenital varicella syndrome are compared on a clinical and immunological basis. This case, together with others cited in the literature, suggests that congenital varicella infection may lead to microcephaly and neurological abnormalities, without the presence of skin lesions. Although first-trimester infection has been considered the most likely to produce congenital abnormalities, the second trimester may be more commonly implicated; indeed there may not be a critical period if varicella causes secondary disruption of differentiated tissues.