Diagnostic ultrasound ( PDFDrive )

CHAPTER 49 The Pediatric Spinal Canal 1697
myelopathy and radiculopathy. hey can be congenital or associated
with trauma, surgery, arachnoiditis, neural tube defects, or
neurocutaneous melanosis.
Arachnoid cysts can be intradural or less commonly extradural.
Intradural cysts result from alterations of the arachnoid trabeculae,
and extradural cysts from a defect in the dura that allows the
subarachnoid space to herniate. hey can occur in areas of prior
surgery from arachnoid adhesions or abnormal CSF low. hey
are most common in the thoracic spine (Fig. 49.33). When there
are symptoms of cord compression, they should be treated with
excision of the cyst wall. Widening of the spinal canal, bone
erosion, displacement of the epidural fat, displacement of the
thecal sac, and anterior compression of the cord can occur. he
cysts are posterolateral to the spinal cord, and the walls can be
diicult to diferentiate from the luid. 124-126
decompression. 132 Masses can be precisely localized, and optimal
position of the cervical cord can be determined before cervical
vertebral fusion. Ultrasound has successfully guided ine-needle
aspiration biopsy of lytic vertebral body and paraspinal mass
lesions. 133 Deinition of postoperative collections is also possible
(Fig. 49.34). In general, the supericial sot tissues of the back
are well deined by ultrasound. Supericial hemangiomas of the
back, frequently the impetus to perform spine sonography, are
well delineated on ultrasound (Fig. 49.35).
INTRAOPERATIVE AND OTHER USES
OF SPINAL SONOGRAPHY
Real-time ultrasound guidance is a valuable resource used by
neurosurgeons during spine surgery to guide procedures and
assess results in the setting of conined surgical ields. Many
authors have described the use of intraoperative spinal sonography
in minimizing surgical invasion of the vulnerable spinal cord
and in analyzing normal and abnormal cord motion. 127-130 Once
a laminectomy has been performed, the extended window into
the vertebral canal makes highly detailed imaging possible, even
in older patients. 131 Posterior fossa decompression for Chiari 1
malformation can be assessed intraoperatively with ultrasound
if a water bath is created in the surgical bed ater suboccipital
craniectomy. Adequate cerebellar tonsillar motion and CSF
pulsation is valuable information that can determine the need
for dural incision without compromising the outcome of the
FIG. 49.34 Seroma. Transverse view of the back in a 6-year-old
child after posterior spinal fusion for scoliosis. Cursors indicate the
presence of a seroma.
A
B
FIG. 49.35 Subcutaneous Hemangiomas. (A) Transverse ultrasound of a palpable, red mass adjacent to the coccyx (C) in a newborn. There
is no extension into the vertebral canal, and the underlying spinal cord (arrow) is normal. (B) Sagittal ultrasound view of another infant shows an
echogenic lesion (calipers) that does not distort the skin surface. The standoff pad is helpful to demonstrate or exclude changes in skin contour.