CH 2 Cranial and Spine Protocols and Technique

Question 1

Excessive pressure on the anterior fontanelle will cause:

Answer 1

Bradycardia, slowing of the infants heart, and may put them in distress.

Question 2

In pre-term neonates an initial cranial ultrasound should be done:

Answer 2

Between the ages of 3 to 7 days, unless the neonate’s condition warrants otherwise.

Question 3

What are some benefits of using CT over a Ultrasound for cranial scanning?

Answer 3

Gray matter in infants is not as dense as the adult brain, therefore the difference between gray and white matter is better image on CT.

Birth asphyxia and birth trauma complications, neonatal seizures and tumors are best image with CT.

Question 4

Advantages of Ultrasound compared to CT:

Answer 4

No sedation

reveals excellent brain detail in coronal and sagittal planes

Not limited by bone interference on axial scan

Can show normal vascular structures pulsating

Question 5

Disadvantages of ultrasound compared to CT:

Answer 5

Increased/increasing head size

Infection

AV malformation

Clinical signs of CNS malformations

Question 6

The standard cranial exam includes:

Answer 6

Six coronal images and five sagittal images.

The anterior fontanelle is a primary imaging window.

Question 7

Anterior to posterior sweep in a coronal plane :

Answer 7

Anterior to the frontal horns and the lateral ventricles: interhemispheric fissure, frontal lobe and orbital ridge

Frontal horns: anterior frontal horns, corpus callosum, caudate nucleus, CSP

Third ventricle and thalami: lateral ventricles corpus callosum, CSP, thalami, third ventricle, pons, medulla

Level of the quadrigeminal cistern: lateral ventricles, choroidal fissure, Quadrigeminal cistern, Tentorium and cerebellar vermis

Choroid plexus in the atrium of the ventricle: periventricular halo, choroid plexus and lateral ventricles

Parietal and occipital cortex: parietal lobe, interhemispheric fissure , and parietal – occipital fissure

Question 8

Side to side sweeps sagittal views:

Answer 8

Midline through the third ventricle to include the CSP, Cerebellar vermis with the fourth ventricle and the foramen magnum, cavum septum Vergae, pericallosal artery, cingulate sulcus and gyrus, Massa intermedia, quadrigeminal cistern, brainstem ( Ponds and medulla ), cisterna magna.

Lateral ventricles to include the anterior horn occipital horn and body of vents, caudate nucleus, thalamus, choroid plexus, and caudophthalmic groove.

Out laterally to evaluate for any abnormalities of the sylvian fisher.

Question 9

Posterior fontanelle is used:

Answer 9

To evaluate the occipital horns of the lateral ventricles for intraventricular hemorrhage.

Usually only open until three months of age.

Useful and Imaging Chiari malformations.

Better visualize the occipital periventricular white matter.

Question 10

Spinal imaging of the neonate

Answer 10

Scanning of infants lesson than 6 months of age.

Normal movement and pulsations of the cord within the spinal canal should be seen, the sagittal method of scanning yields the most information.

By elevating the head, the hydrostatic pressure will increase in the fluid column of the spine. Any sacular abnormality in the spine will fill with fluid using this technique.

Question 11

Indications for spinal ultrasound may include:

Answer 11

skin dimples at the base of the spine
hemangioma
sinus tracts
hyper-pigmented plaques
hairy patches
bony spinal defects seen on x-rays
VADER syndrome (vertebral anomalies, anal treasure, TEF, Renal and radial and anomaly) lower extremity weakness and/or paralysis.

Question 12

Structures that can be imaged in the cervical spine include the:

Structures image in a lower spine include:

Answer 12

Cervical spine: cerebellum, brainstem, occipital bone, Cisterna magna, and the upper part of the spinal cord.

Lower spine: Spinal cord, conus medullaris, film terminale, and cauda equina

Question 13

Sonographic appearance of spine:

Answer 13

Transverse view : the spinal cord appears round in the cervical region and oval in the distal thoracic region. Appears Hypoechoic with an echogenic rim and a bright echogenic dot in the center.

Longitudinal plane: posterior and anterior aspects of the spinal cord will be seen at echogenic lines bordering a Hypoechoic canal with an echogenic center, the central spinal canal.

In lumbosacral area, the curved tip of the conus medullaris is seen with echogenic nerve rootlets inferiorly.

Question 14

Filum terminale:

Answer 14

Secures the lower end of the spinal cord, is seen as an echogenic strand with CSF pulstations.

Question 15

Landmarks to identify T-12, L-5, L-2

Answer 15

T-12 = identified by tracing the lowest rib medially.

L-5 = identified by a line connecting the two iliac crest

L-2 = identified by a line connecting the lowest palpable rib on each side.

Question 16

Lateral ventricles normal dimensions and measurement techniques:

Old measurement for hydrocephalus

Answer 16

Normal ventricles are largest at the atrium. The left ventricle is usually slightly larger than the right ventricle.

The widest portion of the lateral ventricle is a Thalamo-occipital distance. The measurement is done from the outermost point of the Thalamus at the junction with the choroid to the outer most part of occipital horn posteriorly.

Thalamo-occipital distance = less than 16 mm

**Occipital horns dilate 1st and the frontal horns last.

A change in shape without a change in size occurs first in the frontal horns.

Question 17

Lateral ventricle ratio:

Answer 17

Distance measured from the middle of the falx cerebri to the lateral wall of the lateral ventricle and divided by the distance from the falx cerebri to the inner table of the skull. This measurement is done in the axial plane, to monitor hydrocephalus.

Lateral ventricular ratio = lateral ventricle width / by hemispheric width

Lateral ventricle ratios values: normal
24–30% in term infants
24 -34% in preemies

The body of the lateral ventricle less than 10 mm in preemies and 10 to 11 mm in term infants.

Question 18

Third ventricle measurement

Answer 18

Third ventricle can be measured in the axial plane, at the level just above the line from the outer canthus of the eye to the upper point of the insertion of the ear or coronally at the level of the body of the lateral ventricles.

Measurement is made between thalami and in line with the foramen of Monro. The caliper should be placed from inner wall to inner wall.

Third ventricle normal measurement 3–5 mm

Question 19

Fourth ventricle measurement

Answer 19

width and length of fourth ventricle should be measured.
The mastoid fontanelle is ideal for imaging the fourth ventricle. (palp behind pinna of the ear)

The lateral walls of the fourth ventricle are formed by the cerebellar peduncles.

width: <7mm
length: <6 mm

Question 20

Measurements of the frontal horns of the lateral ventricles:

Answer 20

width of the anterior (frontal) horn of the lateral ventricle is measured in the coronal plane at the level of the foramen of Monro (anterior to the choroid)
Measurement should be from medial wall of the ventricle to the floor of the lateral ventricle at its widest.

Normal: <4 mm
Mild enlargement: 4-6 mm
Moderate enlargement: 6-10 mm
Marked enlargement: > 10mm

Question 21

Brain mantle measurements:

Answer 21

are calculated from the lateral edge of the ventricle to the inner table of the skull in the axial plane.

A measurement of less the 1 cm in the presence of severe hydrocephalus indicates a poor prognosis.

Question 22

Depth of cisterna magna:

Answer 22

Measure in the axial plane at the inferior portion of the third ventricle.

A normal measurement of the cisterna magna in the absence of any type of neural tube defect is: 5-10 mm

Less than 2 mm in Chiari malformation. <2mm with ‘banana’ sign = spina bifida

> 10 mm Dandy-Walker complex

Question 23

Extra axial fluid:

Answer 23

Measurement done using a high frequency linear transducer imaging through the anterior fontanelles at the level of the foramen of Monro.

Measurements made at the following sites:
SCW- sinocortical width
CCW- Craniocortical width
IHW- interhemispheric width

Question 24

Extra axial fluid measurements:

Answer 24

SCW (sinocortical width)- shortest distance between the lateral wall of the triangular superior sagittal sinus and the surface of the cerebral cortex. *SCW= 3mm

CCW (craniocortical width)- shortest vertical distance between the calvarium and the surface of the cerebral cortex. *CCW= 4mm

IHW (interhemispheric width)- widest horizontal distance between the hemispheres. *IHW= 6 mm

Question 25

Chronic extra axial fluid

Answer 25

generally due to hematomas (chronic subdural), effusions or hygromas. Can be due to trauma, bacterial menigitis, status post shunt revisions, tumors, post-asphyxia, vitamin K deficiency, seizures, or unknown.

Question 26

Extra-axial fluid/sub-dural fluid clinical signs:

Answer 26

increase in head size, vomiting, lethargy, headache, respiratory arrest, full fontanel, fever, retinal hemorrhage, macrocrania, coma, and developmental delays.

Question 27

How to determine if extra-axial fluid is subdural or subarachnoid:

Answer 27

Subdural fluid: vessels are compressed onto the brain surface.

Subarachnoid fluid: vessels float in fluid.