When a pregnant woman is exposed to varicella, she can contract the disease if she never had chickenpox as a child or if she has never received varicella vaccination as a child. Varicella in pregnant women is a serious illness because of the high risk of varicella pneumonitis. The fetus is also at risk of contracting an intrauterine varicella infection16
. However, the risk of a symptomatic infection is low, certainly less than 2%.
Chickenpox in the pregnant woman occasionally is followed by in utero infection of the fetus with VZ virus. The consequences of such an infection to the fetus may be minimal to inapparent; alternately the newborn may present multiple congenital abnormalities. Laforet and Lynch published the first report of a congenital defects syndrome in an infant who was born to a mother who had contracted chickenpox during week 8 of pregnancy17
. At birth the infant was noted to have a malformed right leg. Clinically, the right leg was shorter than the left and had obvious muscle atrophy. The toes of the right foot were described only as “small horny pegs.” Roentgenographic examination revealed underdeveloped long bones and absent phalanges. Knee and ankle jerks were also absent in the same leg. The left leg was normal in size, but reddish pigmented areas (3–5 mm in diameter) were observed on the medial aspect. The infant was also noted to have insufficiency of vesical and anal sphincters. Within the first 3 months of life, the baby manifested generalized cortical atrophy as well as chorioretinitis with bilateral optic atrophy.
Savage and colleagues reported another infant with congenital defects born to a mother with a history of chickenpox during week 11 of pregnancy18
. This full-term baby had a hypoplastic left arm with rudimentary digits. Cutaneous cicatrices (“zig-zag” scars) were prominent along the entire length of the left arm and were also present to a lesser degree on the scalp and the otherwise normal-appearing right leg. Ptosis and meiosis of the left eye indicated Horner’s syndrome, but there was no involvement of the retina. Electromyographic and nerve conduction studies of the affected arm gave evidence of denervation. A third case, reported by McKendry and Bailey during the same year, was remarkably similar to the previous two cases19
. Multiple congenital defects were noted in an infant born to a mother who also had chickenpox during week 11 of gestation. This baby girl had hypoplasia of the right arm and shoulder; radiographs revealed corresponding hypoplasia of the right scapula, clavicle, and humerus. The skin over the right shoulder contained four deep scars. Superficial scars were present on the knees, scalp, and left hip. Chorioretinitis and nystagmoid eye movements developed within a few months.
The congenital defects syndrome may occur following VZV infection during any stage of embryogenesis or fetal growth. However, the period of greatest risk is the first trimester. In order to understand the pathogenesis of the fetal malformations it is essential to be cognizant of certain aspects of intrauterine development of the nervous system, especially the spinal cord. In utero the cervical and lumbosacral cord comprise greater than 70% of the total weight, since these two areas innervate the developing upper and lower extremities, respectively, whereas the thoracic cord serves mainly as a conduit. Destruction of any of the cervical or lumbosacral plexi during embryogenesis would lead to denervation and subsequent hypoplasia of the corresponding limb bud.
In this regard, it is of interest to review the timetable of musculoskeletal development which has been constructed after examination of aborted fetuses. The major differentiation and innervation of the limb primordia occur between 6 and 12 weeks of gestation. This critical time interval correlates precisely with the chickenpox histories of mothers who delivered severely affected children. Thus the agenesis or hypoplasia of the extremities is most likely the result of viral localization and replication in areas of the cervical or lumbosacral cord. In a similar manner, optic atrophy and chorioretinitis would follow VZV infection of the developing optic tracts, while involvement of the sympathetic fibers in the cervical and lumbosacral cord would lead to such divergent effects as Horner’s syndrome and bladder or anal sphincter dysfunction. The commonly seen zig-zag cicatrices represent the cutaneous residua of viral infection of the sensory nerves. In summary it appears that after infection of the fetus, VZV often manifests its known neurotropic potential and preferentially localizes in the nervous system. In other words, the malformations associated with the congenital defects syndrome are the sequelae of neurologic damage following this viral infection ().
Sequelae of fetal Infection with varicella-zoster virus