Pre-natal diagnosis of occult spinal dysraphism by ultrasonography and post-natal evaluation by MR scanning

Eight children born with occult spinal dysraphism were diagnosed in utero b y ultrasonography. Post-natally, they were evaluated by MR scans. The ultra sound scans in all 8 fetuses revealed a spina bifida: the spinal cord was l ong in 5 and in 3a meningocele was thought to be present, however, in 1, a post-natal MR scan revealed a lipomeningocele instead of a simple meningoce le. In 3 fetuses an echogenic area was seen on the ultrasound scan which ra ised the possibility that an intradural lipoma was present, and was confirm ed by post-natal MR scans. In 3 fetuses vertebral body anomalies and an add itional ossification centre in a midline bony spur together with widening o f the spinal canal were seen in the lower lumbar region. The lesions in all 8 fetuses were skin-covered, None had ventriculomegaly or an Arnold-Chiari malformation. The prognosis for fetuses with spina bifida aperta is well documented in co ntrast to that for those with spina bifida occulta. The ability to identify a spinal dysraphic lesion pre-natally allows a more accurate assessment to be made of the likely outcome for an individual fetus.