Abnormal gyration of the temporal lobe and megalencephaly are typical features of thanatophoric dysplasia and can be visualized prenatally by ultrasound
Article first published online: 22 JUN 2012
Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound in Obstetrics & Gynecology
Volume 40, Issue 2, pages 230–234, August 2012
How to Cite
Blaas, H.-G. K., Vogt, C. and Eik-Nes, S. H. (2012), Abnormal gyration of the temporal lobe and megalencephaly are typical features of thanatophoric dysplasia and can be visualized prenatally by ultrasound. Ultrasound Obstet Gynecol, 40: 230–234. doi: 10.1002/uog.11127
- Issue published online: 30 JUL 2012
- Article first published online: 22 JUN 2012
- Accepted manuscript online: 28 FEB 2012 09:58AM EST
- Manuscript Accepted: 17 JAN 2012
- abnormal gyration;
- temporal lobe dysplasia;
- thanatophoric dysplasia
Autopsies of fetuses with thanatophoric dysplasia (TD) have shown abnormal gyration of the temporal lobes. In addition, the head is relatively large compared with the abdomen. We evaluated by ultrasound six consecutive cases of TD at 19 + 0 to 19 + 6 gestational weeks based on last menstrual period. We observed abnormal and deep transverse sulci in the temporal lobes in all cases; these features were confirmed at autopsy. We performed biometric assessment, including biparietal diameter (BPD) and mean abdominal diameter (MAD). For each MAD value in the TD fetuses, we computed mean and SD of the corresponding BPD values from a population-based registry in the relevant age range, and used them to calculate Z-scores for each BPD/MAD ratio. In the general population, the average BPD/MAD ratio was 1.05. In the TD fetuses, the mean BPD was 51.5 (range, 49–54) mm, the MAD was 45 (range, 41–47) mm and the BPD/MAD ratio was 1.15 (range, 1.09–1.20). The average Z-score of the ratios for TD fetuses was 2.44 (range, 1.05–3.39). The ratios for the TD fetuses were significantly higher than were the population ratios (P = 0.016). At autopsy, the mean brain-to-body weight ratio was 20.6% (range, 15.4–24.1%), which was greater than the corresponding mean ratio of 14.9% in normal fetuses. We conclude that abnormal and deep transverse gyration of the temporal lobes can be visualized by ultrasound in mid-second-trimester fetuses with TD. Due to megalencephaly, fetuses with TD have significantly different body proportions, with a larger BPD compared with normal fetuses. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.