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Ultrasound screening for spina bifida: cranial and cerebellar signs
Insights
Ultrasound can identify key fetal abnormalities in open spina bifida cases. Specific cranial measurements and signs like the lemon and banana signs are crucial for diagnosis.
Area of Science:
- Medical Imaging
- Fetal Medicine
- Neurology
Background:
- Open spina bifida is a serious congenital condition.
- Early diagnosis is critical for management and outcomes.
- Prenatal ultrasound is a primary diagnostic tool.
Purpose of the Study:
- To evaluate the utility of specific ultrasound markers for diagnosing open spina bifida.
- To identify characteristic sonographic findings in fetuses with open spina bifida.
Main Methods:
- Retrospective analysis of ultrasound records from 70 fetuses diagnosed with open spina bifida.
- Examination of fetal head measurements (biparietal diameter, head circumference).
- Assessment of ventriculomegaly and specific cranial signs (lemon sign, banana sign).
Main Results:
- 61% of fetuses showed biparietal diameter below the 5th centile.
- 77% exhibited an enlarged anterior horn to hemisphere ratio, and 86% had posterior horn ventriculomegaly.
- The lemon sign was observed in 54 fetuses, and the banana sign in 12 of 21.
- None of these findings were present in the control group of 100 fetuses.
Conclusions:
- Specific ultrasound findings, including cranial measurements and the lemon and banana signs, are highly indicative of open spina bifida.
- These sonographic markers aid in the prenatal diagnosis of open spina bifida.
- Routine second-trimester ultrasound can detect these abnormalities.
Abstract:
Ultrasound records were examined retrospectively in the cases of 70 fetuses with open spina bifida diagnosed by ultrasonography at 16-23 weeks' gestation. Biparietal diameter was below the 5th centile for gestation in 61% and head circumference measurements in 26%. The anterior horn of the lateral cerebral ventricle to hemisphere ratio was above the 95th centile in 77%, and ventriculomegaly of the posterior horn of the lateral venricle was observed in 86%. In the 54 fetuses for which pictures were taken at the level of the biparietal diameter a scalloping of the frontal bones (the lemon sign) was seen. In 12 of 21 fetuses for which a suboccipital bregmatic view of the cranium had been obtained, the cerebellar hemispheres were curved anteriorly with simultaneous obliteration of the cisterna magna (the banana sign); in a further 8 cases the cerebellum was not displayed. None of these changes was seen in 100 patients presenting consecutively for routine ultrasound examination in the second trimester.