Diagnostic ultrasound ( PDFDrive )

1198 PART IV Obstetric and Fetal Sonography
A
B
C
D
FIG. 34.25 Polymicrogyria. (A) Irregular appearance to the cortex and cortical calciication (arrow) on coronal transvaginal sonogram at 25
weeks. (B) and (C) Axial (B) and coronal (C) T2-weighted magnetic resonance imaging (MRI) scans show sawtooth appearance of the cortex at
25 weeks. Note how the calciications were better visualized on the sonogram than on MRI. (D) Polymicrogyria at 30 weeks’ gestational age. Note
ventriculomegaly and prominent extraaxial cerebrospinal luid (CSF). The shrunken brain has fallen away from the skull, leaving a wide, CSF-illed
subarachnoid space (hydrocephalus ex vacuo). Note also the ine nodularity of the surface of the brain (arrow).
Tuberous Sclerosis
Tuberous sclerosis (TSC) is a multisystem, hamartomatous
condition involving abnormalities of the brain, skin, heart,
eyes, and kidneys. It is autosomal dominant related to abnormal
TSC1 and TSC2 genes; however, about 70% of cases
are a de novo mutation. Clinical diagnosis is made using a
combination of major and minor indings including cranial
indings of cortical tubers and white matter migration lines,
subependymal nodules, subependymal giant cell astrocytomas,
cardiac rhabdomyomas, renal angiomyolipomas, and
skin lesions. 217,218
Prenatal diagnosis usually is made in late pregnancy ater
discovery of echogenic cardiac rhabdomyomas and demonstration
of subependymal nodules or cortical tubers on neurosonography
or MRI (Fig. 34.28). MRI has shown lesions as early as 21 weeks
in fetuses known to be at risk. 219 If the gene abnormality is known,
prenatal diagnosis is possible using CVS or amniocentesis as
well as neurosonography and fetal MRI. Diagnosis in other
suspected cases may be aided by looking for subtle manifestations
of TSC in the parents. Epilepsy and neurologic impairment are
common. Morbidity and mortality predominantly relate to CNS
and renal disease. 218