ECR 2018 / C-1245 | |
Ultrasound spinal cord of newborn and infants: normal radioanatomy and variant of normal. |
Congress: | ECR 2018 |
Poster No.: | C-1245 |
Type: | Educational Exhibit |
Keywords: | Neuroradiology spine, Ultrasound, Education, Education and training |
Authors: | B. Bannar1, D. BASRAOUI2, H. Jalal2; 1MARRAKECH/MA, 2Marrakesh/MA |
DOI: | 10.1594/ecr2018/C-1245 |
DOI-Link: | http://dx.doi.org/10.1594/ecr2018/C-1245 |
Findings and procedure details
Technique of spinal ultrasound
•Spinal cord is easily analysable until 3rd month
• Through the posterior arches incompletely ossified.
• Infant in prone, with pillow under the abdomen or lateral decubitus.
• Linear probe of high frequency (at least 7 MHz) with axial and longitudinal cuts from the occiput to the sacrum.
•Analysis of the bulbo-medullary junction: flexion of the neck oor phased-array that follows the physiological cervical lordosis of the infant.
Indications
- Clinical lumbosacral anomaly :
Cutaneous stigma at high risk of dysraphism:
- Angioma on the midline, nevus.
- Subcutaneous mass.
- Tuft of hair or a pigmented spot.
- Caudal appendix.
- Aplasia or cutaneous hypoplasia.
- Dermal sinus.
- Sacred agenesis.
- High-risk coccygeal fossa: atypical fossa,> 5 mm in size and more than 2.5 cm from the anus.
Cutaneous stigma at high risk of dysraphism:
- Simple coccygeal fossa, <5 mm and <2.5 cm from the anal margin.
- Or bony: hemi vertebrae, dehiscence of the posterior arch.
2. Anorectal malformation
3. Fight Bladder, unexplained bladder globe , or repetitive urinary tract infections.
4. Abnormal neurological examination of the lower limbs.
A normal spinal ultrasound eliminates severe dysraphism and provides an MRI.
Normal radio anatomy of spinal ultrasound :
1) The spinal cord:
- Marrow: hypoechoic tubular structure,
thicker in the cone region (about 5.5 mm)
thinner in the dorsal region (about 4.5 mm). - Centered by a hyperechoic echo"complex central echo" : at the acoustic interface between the anterior white commissure and the central part of the anterior median fissure.
- Laterally, the marrow is fixed by the serrated ligaments (arachnoidal duplications) which appear as fine linear echoes oriented transversely.

References: - MARRAKECH/MA
2) The cervico-occipital hinge
Sub-occipital sagittal section:
- Large cistern
- Cerebellar tonsils to eliminate a chiari malformation.
- Analyze the pons, bulb and cervical spine
- Within the subarachnoid spaces
3) terminal conus medullaris :
- Conus medullaris : ends above L3.
Its terminal portion gradually tapered continues with the terminal filum whose thickness varies from 0.5 to 2 mm. - Filum terminale visualized on the median line, behind the roots. Its thickness is = or less than 2 mm.
•Lumbar and sacral roots (ponytail): echoic features, arranged around and below the terminal cone.
•The ending of the space dural is in S2.
Simple clinical and ultrasound landmarks to identify vertebral bodies, and locate the terminal cone:
Clinical landmarks :
- The tip of the last rib is L2.
- The top of the iliac crest corresponds to L4.
Ultrasound landmarks :
- Follow the 12th coast until T12
- Visualization of the renal pedicle located at L2
- Possibly identifying the 1st sacral vertebra (in the absence of transitional anomaly).
The variants of the normal:
In about 10% of newborns.
1)The dilation of the terminal ventricle (rare):
- Anechoic formation,
- Ovoid v Clear limit
- Hyperechoic in the filum or in the conus medullaris
- Size <5mm
- Stability over time
2) Filum Terminale cyst:
- Origin discussed
- Arachnoid reflexion or embryonic remnant covered with ependymocytes.
- Less visible on MRI
- Strict criteria:
- Median line
- In the filum,
just below the spinal cone
- Fusiform
- Well limited
- Anechoic as a simple cyst.
3)Transient dilatation of terminal ependymal canal:
Differential diagnosis of syringomyelia and terminal ventricle.
4) Pseudo dermal sinus
- Fibrous tissue extended: cutaneous dimple → coccyx.
- Dermal sinus is rarely located at the tip of the coccyx and often more cranial.
- Search mass or liquid well along this fibrous tract.
5) Filum prominent
- More visible compared to nerve roots.
- Thickness> 1mm
- median
6) Coccyx:
•Many possible variations can be considered as a mass on palpation.