Fetal aqueductal stenosis diagnosed sonographically: how grave is the prognosis?

Aqueductal stenosis is a common cause of fetal hydrocephalus. Published studies of neonates with aqueductal stenosis have noted variable outcomes, with normal development seen in 24-86% of cases. In an attempt to better assess long-term outcomes in cases diagnosed in utero and to determine what prenatal sonographic findings might be used to predict prognosis, a retrospective analysis of patients with aqueductal stenosis was done.

Fifty-three consecutive cases of aqueductal stenosis discovered in utero at two high-risk obstetrical centers in Seattle between 1980 and 1993 were studied. Parents elected to continue pregnancy in 39 of these cases. Two months to 10 years of long-term follow-up was available in 30 patients, who form our study group. Prenatal sonograms, postnatal cranial ultrasound, and head CT and MR were evaluated. Prenatal sonographic data collected included the biparietal diameter, size of the lateral and third ventricles, the ratio of the two, and thickness of the frontoparietal cortical mantle. Medical records provided an assessment of development based on physical examination, meeting of major milestones, and neuropsychological testing. The in utero diagnosis of aqueductal stenosis was confirmed by postnatal CT, MR imaging, sonography, or autopsy.

Within the study group of 30 patients, eight died in the postnatal period and four died subsequently. Of the 22 patients with adequate postnatal follow-up, moderate or severe developmental delay was present in 16 (73%). Normal developmental milestones were met in only three (10%) of all 30 patients and in 14% of those surviving the neonatal period. Although size of the lateral and third ventricles was not a useful predictor of long-term prognosis, the ratio of the two, as well as thickness of the frontoparietal cortical mantle, was weakly associated with long-term prognosis. No correlation was found between biparietal diameter and outcome.

As compared with previous reports, prenatal diagnosis of aqueductal stenosis carries a grave prognosis. Twelve of the 30 patients died, for an overall mortality of 40%. Normal development was seen in only 10%, significantly less than in prior studies.