Diagnostic ultrasound ( PDFDrive )

1234 PART IV Obstetric and Fetal Sonography
Myelocystocele may occur at any level of the spine and is
oten associated with Chiari II malformation. 94-96 Prenatal and
postnatal sonography demonstrates a “cyst within a cyst” appearance
(Fig. 35.17). Splaying of the laminae and pedicles may or
may not be present. he prognosis for a myelocystocele is worse
than for a simple meningocele; infants with a simple meningocele
may remain normal neurologically ater surgical repair. he
prognosis with myelocystocele is worse because there is usually
some degree of associated myelodysplasia (i.e., dysplasia of spinal
cord). Although neurologic function is normal in the immediate
postoperative period, neurologic deicits oten become apparent
later in life.
A terminal myelocystocele occurs at the spinal cord termination.
he central canal of the spinal cord herniates with overlying
arachnoid and cerebrospinal luid through a defect in posterior
spinal elements and presents as a skin-covered mass along the
posterior aspect of the lumbosacral area. here may be associated
maldevelopment of the lower spine, pelvis, genitalia, bowel,
bladder, kidneys, and abdominal wall. MRI provides the best
imaging evaluation of the morphologic abnormalities ater
birth. 97-99
DIASTEMATOMYELIA
Diastematomyelia, also termed split-cord malformation, is a
partial or complete sagittal clet in the spinal cord, the distal
conus of the cord, or ilum terminale. Diastematomyelia is
characterized by a sagittal osseous or ibrous septum in the spinal
C
H
C
A
B
C
C
C
D
FIG. 35.17 Myelocystocele. (A) Coronal sonogram of thoracic spine at 18 weeks’ gestation demonstrates a double-walled cystic mass (arrows)
with inner cystic component (C) arising from the upper thoracic area. (B) Axial sonogram of the fetal chest 1 week later demonstrates a double-walled
cystic mass (arrows) arising along the posterior aspect of the fetal chest; H, fetal heart. The inner cystic component (C) is slightly smaller and
lattened compared to the irst scan. No abnormality was noted in the ossiied neural arch. (C) Sonogram of the specimen demonstrates the
double-walled cystic mass (white arrows) arising from the posterior thorax with a hypoechoic tract (black arrows) extending from the posterior
aspect of the spinal cord (curved arrow) toward the central cystic component (C) of the posterior mass. (D) CT scan of the specimen after injection
of water-soluble contrast material into the cyst demonstrates contrast within the cyst (C) and within a sinus tract (short arrows), leading to the
spinal cord (long arrow).
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