Neonatal Spine Imaging - SD

Introduction to Neonatal Ultrasound of the Spine

Hi, I'm Dorothy Blis.

I'll be talking about neonatal ultrasound of the spine.

Today we'll be talking about indications for spine ultrasound.

We'll become familiar with normal anatomy and review various spine anomalies that can be identified by ultrasound.

We'll also talk about the limitations of the exam and the pitfalls that may simulate disease ultrasound.

Evaluation of the spine in children is quite helpful because it's inexpensive, there's no need for sedation and allows for a clinical determination of abnormalities that may require urgent intervention.

MRI is the gold standard of assessing the spine but require sedation and is quite expensive and may not be available.

We'll talk about indications, the imaging strategy, and talk about normal anatomy and the embryology of the spine.

We'll then talk about normal variance, what the father cyst is, pseudo mass, coogal variations, and the pseudos sinus track.

Lastly, we'll talk about the actual pathologic entities that we use ultrasound for to look.

Indications for Spine Ultrasound

Why do we look at the spine?

We know that there are anomalies that are associated with tethered cord and spine abnormal maladies.

These include in peripheral anus.

We do know that with sacral dimples that are complicated, either they're above the gluteal crease, there is a very deep pit, there's drainage from the dimple or there's a soft tissue mask.

All of these have a higher incidence of cord anomalies.

Nice. We can also use spine ultrasound in patients who have a failed lumbar puncture.

You can differentiate high risk from low risk lesions if the mass is hyper hypopigmented midline with a deep pit above the intergluteal crease.

These are all considered high risk if it's simply a Mongolian spot or a hemangioma or port wine stain off midline a pit below the intergluteal crease.

These are considered low risk.

So here are examples of high risk midline lesions and this is a low risk lesion with a Mongolian spot and skin tag.

So MR is the gold standard for spine imaging, but we can look at the spine.

Um, as far as a year or two of age.

It becomes very difficult, however the more the spine is processes.

Ossify embryologically.

Embryology of the Spine

We'll talk a little bit about why different spine abnormalities occur.

Initially you have neural elation.

The neural plate begins to develop at the third weak gestation and they thicken and form the neural folds.

There's progressive development of the neural plate groove and neural tube canalization occurs when the distal end of the neural tube fuses with the neural epithelium.

It forms an impend line neural tube which unites with the rest of the spinal cord.

The cuddle mass distal to the neural tube coalesces and eventually fuses with the neural tube embryologically.

There's retro aggression differentiation, which causes cuddle cell mass and the coddle neural tube to become smaller.

Eventually the distal conus magis forms, there is a focal dilatation of the central spinal canal called the ventricular terminis and we also have the phylum terminality.

Spinal Dysraphism

Now spinal dysraphism can be separated into open and closed spinal dysraphism and in the closed spinal dysraphism you can separate them further between those that have a subcutaneous mass and those that do not with the open neural tube defects, these are not skin covered.

You'll have a meningo mye or a myelo cystocele with the closed subcutaneous masses.

If the masses present, it can be a lipo meningocele, a meningocele a C called myelo meningocele or myelo cysto seal.

If there's no mass, it can be a simple lipoma, tight phylum or it can be conal regression.

A split cord or a neuro enteric cyst.

Open Neural Tube Defects

This is an open neural tube defect where you have a translucent membrane with no skin covering.

These typically are separated into myo seals where the plaque code is elevated by the expansion of the subarachnoid space Or the myelo seal, which is a plaque of neural tissue that lies exposed to the same plane of the skin.

Neither of these are skin covered and both are associated with meningocele.

Um, sorry. Both are associated with chiari malformations.

Closed Dysraphism

With closed dysraphism, you have a skin covered mass that may have discoloration or hairy patch associated with it.

These can be separated into menig seals where again, this is skin covered but it's associated typically with a tethered cord but not associated with a Chiari malformation.

You can also have a lipo myel meningocele, which is also skin covered typically with a mass not associated with a Chiari malformation.

Myelo. Cysto seals is a dilated terminal ventricle that herniates through a spinal defect.

These typically herniate in the third trimester and may have some post posterior fossa herniation as well.

Lipomas persistent terminal ventricles are also closed spinal dysraphism that are skin covered.

Imaging Strategy and Technique

The most common abnormality that we look for by ultrasound however, is the tethered cord.

So how do we start? Will you have the child lying prone?

It's useful to have a towel rolled under the bed belly for better contact with the transducer and a linear five to 12 megahertz transducer should be used If there's a soft tissue mass.

That can be evaluated by ultrasound as well to see whether it's fatty or vascular for hemangioma.

If there's no connection of the mass to the spinal canal, the spine itself can then be looked at.

One starts with the vertebral body counting and it's very important to know what level of the conus the um, tip of the conus is.

And this can be done by counting from the ribs down or from counting from the cox up.

If there's confusion about where the actual level of the conus is, there may be some vertebral anomalies or it may be unclear whether the um, there are 11 ribs or 12 ribs.

One can identify where the conus is lying and put a marker on and get a radiograph to see the level of the conus.

So here we have an image of the spine.

This is a young infant in which the spine is processes are not ossified, so there is no shadowing.

These are the vertebral bodies, this is the conus, the central canal, and here are nerve roots.

Notice since this baby is prone that the nerve roots are lying close to the gravity driven positioning of the nerve roots.

And here's an image again of the spinous processes.

Dura cord and cardio equina and the transverse image.

We see the cord, central canal nerve roots.

By real time these will be pulsating.

And here again we have the transverse process, the core, the central canal, and the nerve roots.

When counting we start from below, the coccyx tends to be a more circular structure than the sacral elements.

Once the coys is identified, when can start from S 5, 4, 3, 2, 1, and count.

Generally the L five S one level has a mild transition where the bow bending is as you work your way up.

This is S 1, 5, 4, 3, 2.

So here the conus appears to be above the level of L two and that is considered normal.

The level of the conus should never be below L three.

Here again, this is a flat sacral element.

S 5, 4, 3, 2, and then you move your transducer up to start counting the lumbar elements.

Panorama is a very nice way of documenting how you're counting the elements.

Again, here we have this transition between L five S one and as we count high we see that this cord ns at L two which is normal.

Here's another case.

Is this in a normal level or abnormal level?

By counting, one can estimate that the tip is at L two, which is normal.

Below L three is abnormal.

The L two L three disc space is borderline and here you must be quite careful in making sure that your counting is correct.

This is when counting from the ribs down may be useful and if still in the in determinate range, putting a marker on and getting a radiograph may help confirm the position.

The transverse planes are helpful in identifying where the last rib is.

It allows us to look at the pulsation of the nerve roots, which should be normal if the cord is not tethered.

Here we're near the tip of the conus and these are all nerve roots which on real time will move with respiration ratio.

Normal Variants

The phylum terminality should measure be measured at about L five S one and should not measure greater than two millimeters when thicker than two millimeters.

It should be considered possibly having a fatty phylum with some lipoma associated with it.

There are several normal variants that we'll discuss.

The ventricular terminals as I had mentioned, is incomplete regression of the terminal ventricle and as long as it measures less than five millimeters, it may be considered a normal variant in children less than five years of age.

If it's larger, um, and way above the conus, you may worry that this is indeed a true sir.

Over time, the um ventricular terminal is remain stable and not enlarged.

This can also help differentiate it from a true srin.

A filer cyst is a cyst just distal to the conus.

This is also considered a normal variant and can be found with many other spine anomalies and can be seen in up to 3% of children with tethered cords.

This is however considered a normal variant and is not a true cyst.

It's felt to possibly be a collection of CSF between nerve roots that mimic a cyst.

And here's an example of another filer cyst.

These are difficult to see by MRI due to the high signal of the cyst and the very thin nerve roots surrounding it.

As mentioned, the file terminality should not measure more than two millimeters.

If it's thick it may be secondary to lipoma of the phylum.

We also look carefully for possible lipomas of the canal and sometimes clumping of the nerve loops can mimic a lipoma with repositioning of the infant.

If there's movement, this should be documented as a true nerve food clumping and not a true mass.

Pseudo sinus tracts can mimic tracts from the dimple into the canal.

But remember that these are so low at the conus, um, at the um, coccyx that these are simply cartilaginous um, areas that are not, do not have direct communication to the spinal canal.

These are several unusual, um, coys that seem to co to the skin can mimic a sinus tract but are simply cartilaginous.

Pathologic Entities

Lipomas and Tethered Cord

Let's talk about the pathology of the lumbar spine.

As mentioned, if the um, phyla measures more than two millimeters, there may be fat within the phylum.

This may be associated with tethering, but the patient may be asymptomatic and could be considered a normal variant if isolated.

If the mass becomes very thick, you can call it a lipoma and again, the measurement should be at the level of the L five S one vertebra.

It is often associated with core tethering and mylo meninga seals Lipomas are secondary to premature separation of the neuroectoderm from the cutaneous tissues.

The mesen kind can be trapped between the neural folds.

They can be intradural be associated with lipo myeling seals or be associated with the lipo fibroma of the terminal.

Um, phylum Interestingly, the fat can get bigger and smaller and prognosis is varied due to the association of other anomalies.

It can be difficult to completely resect these so they can come back and re tether By ultrasound we see hyper coic mass with intra or extradural extension.

Very commonly it's in the dorsal aspect of the cord, most commonly seen in the lumbosacral area.

Often, um, we talk about tethered cord as the primary diagnosis when we're doing an ultrasound and a neonate by definition as mentioned, tethered cord is when the conus is below the L two L three disc space.

Its incomplete regression or failed involution of the terminal cord.

This traction causes the conus and the nerve roots to be dorsally positioned.

The nerves are tight and can get injured by the stretching of the cord.

These are often associated with a thickened phylum terminality or fibro lipoma.

Here we have an example of a tethered cord low down with the conus way below the L five vertebra.

Tethered cords as mentioned are associated with fatty phylums.

Here we see a very thickened fatty phylum at the S one level.

Tethered cord is associated with scoliosis, a**l atresia sinus tracts cyst.

Unfortunately the clinical presentation may be late with difficulty ambulating and bladder and bowel dysfunction.

This is secondary to the abnormal reflexes from stretching of the nerve roots.

Treatment is surgical release and it's important to recognize this early for improvement in function.

Prognosis varies dependent on the severity of the tethering and how long the damage has been occurring for before it's been identified.

Some children may re tether and require re-release surgery.

Lipo Meningoceles

Lipo myin and seals are defective disjunction with entrapment of meine in contact with the neural tube.

These are skin covered and may have DYS spinal lesions.

Here we have a case of a lipo meningocele with a large sack.

It's skin covered but has a large mass with surrounding CSF fluid.

On MR imaging, one can document the tethering of the cord in the complex fat that is both under the skin and in the intradural component.

Here we have another case of a cord that's tethered with a fatty lipo Myla and gracile distally.

Conal Regression

Co regression is secondary to abnormal mesodermal formation of co cell mass.

This is most commonly associated with mothers with diabetes, but has been described in children with a**l anomalies, GU anomalies and the V-A-T-E-R-L sequence.

Notice how the blunting of the cord is and this is low and tethered at L four when correlated with the MR.

When sees, again this blunted cord low at L four, typically they're associated with some sacral agenesis as well.

Hematomas and Other Abnormalities

Neonatologists may ask you to do an ultrasound of the spine to look for epidural or subdural hematomas.

These are fairly rare but can occur after a failed lumbar puncture.

Ultrasound can help to decide if a retet at a lumbar puncture can occur and can be used to guide where the needle is placed.

Here we have a normal transfer spine.

We have CSF surrounding the cord and the nerve roots with an epidural or subdural hematoma.

The CSF is obliterated by the blood here on a panorama.

We see no CSF fluid.

This is all filled with blood that is energetic, kind of compressing and pooling the nerve roots together that are now clumped.

Here's another case of a hematoma surrounding and and clumping the nerve roots.

And this is a normal comparison with some CSF noted this case but um, from Judy Estro from Boston Children's demonstrates an epigenic mass that mimics a hematoma.

However, it's quite expansile and there was no history of a lumbar tap.

This is a term infant who had decreased lower extremity tone and by ultrasound we see a mass essentially obliterating the spinal canal.

This turned out to be a neuroblastoma with intraspinal extension in the newborn period.

Here's a newborn with a skin covered mass but it's way low below the coccyx, it's cystic and there was no evidence of cord tethering.

This was a sacro coil teratoma Notice the normal position of the cord and the skin covered cystic mass at the coccyx Ultrasound was particularly helpful in following this case, even at surgery during the excision.

Conclusion

So ultrasound allows for accurate detection and characterization of spinal abnormalities in the first few weeks of life.

Familiarization with the ultrasound appearance of the normal anatomy pitfalls that simulate disease and com.

Understanding the common pathology is essential for successful, um, imaging of the knee needle spine.