Diagnostic ultrasound ( PDFDrive )

CHAPTER 49 The Pediatric Spinal Canal 1685
A
B
C
D
E
F
G
H
FIG. 49.17 Lipomyelomeningocele. (A) Sagittal split-screen collage of the low spinal cord (arrow). (B) Transverse view shows the neural
placode posteriorly displaced (arrow) and the cerebrospinal luid (CSF)–illed meningocele surrounding the placode. (C) Distal end of the tethered
cord is incorporated into the lipoma (arrow). In another patient, (D) sagittal view shows a tethered cord (arrow) and a lipoma (L) that extends ventral
to the terminal placode. Note the small ventriculus terminalis. (E) Sagittal view of the spine demonstrates a low-lying cord (arrow) with a placode
that extends outside of the canal, luid that extends to the subcutaneous mass (small white arrow), and a large lipoma (L) that extends ventral to
the placode. (F) Sagittal view of the subcutaneous mass shows large amount of central luid and subcutaneous fat. (G) Sagittal T2-weighted,
fat-saturated image shows luid in the subcutaneous fat, the placode, and hypointense ventral lipoma extending outside the spinal canal. (H) Axial
T2 view of the pelvis shows the subcutaneous fatty and luid mass extending beyond the spinal canal through a defect in the posterior elements
of the sacrum. See also Video 49.7 and Video 49.8.
fatty tissue expands the ilum terminale beyond 2 mm. 21,67 On
ultrasound, this is seen as a thickened, echogenic ilum terminale,
sometimes with an undulating contour 68 (Fig. 49.19). In adults,
“incidental” fatty iniltration of the ilum has been found in 0.2%
to 4% of asymptomatic patients who had no evidence of cord
tethering and is considered a normal variant. 69,70
he abnormally long spinal cord is a variant in which the
conus medullaris does not taper and at the sacrum it connects
with the lower end of the thecal sac. It may occur with intradural
lipomas or lipomyelomeningoceles.
A persistent terminal ventricle (ith ventricle) is a small
ependyma-lined cavity in the conus medullaris. It is commonly
considered a normal variant. If large, it may cause symptoms
such as low back pain, sciatica, or bladder disturbance and it
should be distinguished from an intramedullary tumor by its
lack of enhancement and stable size.