Spinal cord embolism syndrome is a common and complex condition in pediatric neurosurgery that causes distress to many children and families. Spinal cord embolism syndrome accounts for a large portion of the inquiries I receive. I think it is necessary to write a popular article to talk about my understanding of this disease in simple and simple words, and I hope it will be helpful to the families of children with spinal cord tethering syndrome.
1.What is spinal cord tethering syndrome?
We know that the spinal cord is located in the spinal canal of the spine. In early fetal life, the length of the spinal cord and the length of the spinal canal are approximately the same. As the fetus grows, the spinal canal grows faster than the spinal cord, so the lower end of the spinal cord rises in relation to the lower end of the spinal canal. By the time the baby is born the lowermost part of the spinal cord (what we call the conus) is located at or slightly above the second lumbar vertebra, and by the end of puberty our conus rises to the level of the 12th thoracic vertebra and the first lumbar vertebra and continues throughout life. Spinal cord tethering syndrome is essentially the affliction that comes with growing up.
Then when the spinal cord cannot rise properly for various reasons due to the wall of the spinal canal, the resulting series of clinical manifestations is called spinal cord tethering syndrome, or as some call it, spinal cord tethering syndrome. This problem is like the name of an American drama “Growing pains” (Growing pains).
2.What are the causes of spinal cord tethering syndrome in babies?
Various congenital abnormalities of the spinal cord and spinal ends can lead to spinal cord tethering, the most common being lipoma-type spinal bulge, others being spinal bulge, spinal cord spondylolisthesis, spinal end filament lipoma, spinal longitudinal bifida, teratoma congenital cysts and latent hair sinus. Sometimes a small percentage of occult spina bifida may also be tethered.
In addition to the aforementioned congenital factors, surgery can also cause spinal cord tethering syndrome, for example, postoperative adhesions in lumbosacral spinal bulge can also lead to spinal cord tethering. After release of spinal cord tethering, adhesions between the trauma and dura mater or artificial dura mater can cause re-tethering.
3, the embryological basis of spinal cord tethering syndrome – how did the baby embolize in the mother’s womb?
This is difficult to understand, but particularly important. When a child is still unformed in the mother’s womb, it is initially composed of three germ layers: generally speaking, the ectoderm forms the epidermis and neural tissue, the endoderm forms the epithelium of the intestinal lumen and the epithelium of the digestive glands, and the mesoderm forms the bones, muscles, blood, lymph, fat, and other connective tissues. Nerve tissue, although located in the interior of the body, comes from the ectoderm. That is, the nerve plate has to be curled and wrapped to get from the outer layer to the inner layer. Normally, the neural tube should be completely closed at the end of embryonic week 4. If the induction of the notochord is lost or if it is affected by environmental teratogenic factors, the neural sulcus does not close properly as a neural tube. If the neural sulcus on the cephalic side closes at the end, anencephaly is formed; if the neural sulcus on the caudal side does not close, spina bifida is formed.
Spina bifida is often accompanied by spina bifida of the corresponding segment, with the spine most commonly located in the lumbosacral region. The degree of spina bifida varies. In mild cases, a few vertebral arches do not heal in the dorsal midline, leaving a small gap, and the spinal cord, spinal membrane and nerve roots are normal, called occult spina bifida. Most of them have no symptoms. Moderate spina bifida is more common and often forms a pocket of skin of varying size at the affected area. If the pouch contains only spinal membrane and cerebrospinal fluid, the pouch is called a spinal expansion; if the pouch contains both spinal membrane and cerebrospinal fluid, as well as the spinal cord and nerve roots, the pouch is called a spinal cord spondylolisthesis. Severe spina bifida can be extensive undeveloped vertebral arches with spina bifida, with skin splitting on the surface and nerve tissue exposed, which we call spinal ectasia.
Due to incomplete closure, skin tissue from the ectoderm enters the spinal canal, forming spinal cord dermatomal cysts and latent hair sinuses, which themselves form emboli and often cause infection. If fat from the mesoderm grows into the spinal canal, it forms a lipoma-type spinal bulge, and the lipoma itself causes tethering of the spinal cord, preventing it from moving up with development. Other tissues retain the ability to differentiate and form teratomas.
4. Is lipoma a tumor?
According to the above description, we understand that the spinal cord lipoma that the baby has is not a tumor, but a fatty tissue growing in the wrong place. The so-called lipoma is just a normal human tissue. It does not grow indefinitely, but grows in equal proportion to the growth of the person.
5. Is the spinal cord tethering caused by lipoma type spinal bulge caused by the compression of lipoma?
It is generally believed that spinal cord tethering syndrome in children is caused by the embolism that strains the spinal cord and causes impaired circulation, resulting in the corresponding neurological symptoms. The compression of the fat plays only a very minor role. This is the reason for not requiring 100% clean removal of the lipoma during surgery. However, it is more demanding to release the adhesions between the lipoma and the surrounding adhesions, and strive to completely release the adhesions.
6.What are the pathological types and common clinical manifestations of spinal cord tethering syndrome?
A. The pathological types causing spinal cord tethering syndrome include
a. Various congenital spinal developmental abnormalities, such as spondylolisthesis, spina bifida, and spinal cord spondylolisthesis caused by atresia of the neural tube ends.
b. Spinal cord lipomas and intradural and extradural lipomas
c. Subtle hair sinus
d. Longitudinal spinal cord fissure
e. Tension of the terminal filaments
f. neurogenic intestinal cysts
g. Teratoma
B. Common clinical manifestations that cause spinal cord embolism syndrome include
a. Skin changes in the lumbosacral region:bulging, depression, “small tail” of the skin in the lumbosacral region, which may be accompanied by discharge or infection; hirsutism; bulging masses, hemangiomas, etc.
b. Sensory disorders of the lower extremities:manifested as abnormal sensation and pain in the lower extremities, perineum and low back.
c. Motor disorders of lower limbs: manifesting as abnormal walking, weakness, deformation and pain of lower limbs, mostly starting from the side with severe tethering adhesions. Scoliosis may also be combined with scoliosis.
d. Urinary and fecal dysfunction: common manifestations are urinary retention, difficulty in urination, incontinence, more urination, less than normal volume each time, etc.; constipation, constipation, or incontinence.
e. Lower limb deformity: severe side leg thinning, neurogenic clubfoot.
7.What tests are usually needed for babies with spinal cord tethering syndrome?
a. MRI is the most effective and primary examination method. It can not only detect low spinal cones, but also clarify the cause of spinal cord tethering syndrome.
b. CT examination and 3D CT spine reconstruction are also required for children with combined spinal longitudinal bifurcation or scoliosis.
c. Ultrasound
Ultrasound can show the spinal cone in patients <1 year of age because the posterior spinal canal is not fully mature and ossified, and can determine whether there is postoperative re-tethering based on spinal cord pulsation. b. Ultrasound can also examine residual urine, understand bladder function, and estimate whether there is combined vesicoureteral reflux and its extent.
d.. Neurophysiological examination
Hanson et al. measured the electrophysiology of the sacral reflex in patients with spinal cord tethering syndrome and found that the shortened latency of the sacral reflex is one of the electrophysiological features of spinal cord tethering syndrome. The SSEPs of the posterior tibial nerve were found to be reduced or negative. SSEPs of the posterior tibial nerve were elevated after re-surgical release, confirming the recovery of nerve function after end-filament release.
e. X-ray plain film
X-ray plain radiographs and conventional spinal canalography are less commonly used because MRI and CT spinal canalography have become the main diagnostic methods for this disease. X-ray plain radiographs are only used to find out whether there is scoliosis deformity and preoperative vertebral body positioning.
f. Bladder function tests
These include intravesical pressure measurement, cystoscopy and urethral sphincter electromyography. Patients with spinal tethering syndrome may present with abnormalities such as sphincter-uretic muscle ataxia, increased (spasticity) or decreased (hypotonicity) intravesical pressure, and altered bladder residual urine volume. Preoperative and postoperative bladder function tests can help determine the efficacy of surgery.
8.Which cases of spinal cord tethering syndrome require surgery, and what are the principles and timing of surgery?
In cases of spinal cord tethering, organic changes have already occurred by the time symptoms appear, and even if surgery is performed, it is sometimes not possible to restore complete normalcy. However, the use of more minimally invasive microsurgery with neurophysiological monitoring can improve incontinence in 30% of cases, scoliosis in children with mild to moderate scoliosis, and muscle strength and sensation in the lower extremities of some children.
We know that spinal cord embolization is a preventive procedure. For patients with spinal cord embolism who have normal bowel and urinary function, we recommend early systematic examination, evaluation and surgery; the recommended time of surgery for infants and children without significant limb dysfunction and bowel dysfunction is 2-3 months of age after birth. At this time, the surgical level is clear and the tolerance of anesthesia is much higher than that of newborns. There are, of course, exceptions to this rule, such as when a spinal bulge has ruptured or is about to rupture and should be operated on as early as possible. For patients who have developed urinary and fecal dysfunction, surgery should be chosen in conjunction with their general condition and relevant investigations, and the vast majority of such patients can and will require surgical treatment. The details are as follows.
a. Surgery is needed as soon as symptoms are present, regardless of age, even in newborns; b. Babies with abnormalities behind the waist found after birth but without symptoms can be operated on 3-6 months after birth; c. Children with spinal cord tethering who are not noticed after birth and are found by chance, but are still growing, should be operated on as early as possible; e. Children with combined scoliosis with spinal cord tethering syndrome manifestations, six months before surgery to correct the scoliosis f. Patients who are not growing after puberty and have no symptoms do not need surgery.
Another concept that may be difficult to understand is that spinal cord tethering actually occurs in the fetus. Tethering already occurs while the fetus is in utero and worsens as the fetal spine grows, often with dilatation of the central canal of the spinal cord as well as anal flaccidity and little movement of both lower extremities. Some doctors call this condition congenital neurodevelopmental dysplasia, but it is essentially a manifestation of spinal cord tethering syndrome. As I described in the previous articles, the original dysfunction may not be fully restored after surgery in such a child, but early surgery is understandable. After all, the child grows relatively quickly after birth.
For children with spinal cord tethering combined with scoliosis, if the child shows signs of tethering, the spinal cord tethering must be released first and then corrected for scoliosis six months later. Otherwise, catastrophic consequences may occur.
The patient should be operated with a minimally invasive concept, and neurophysiological monitoring should be performed in order to release the tethering as completely as possible, avoid nerve damage, and reduce re-tethering.
Therefore, the fundamental aim of surgical treatment of spinal cord embolism syndrome (spinal cord tethering syndrome) is to prevent further progression of the disease, and some patients may have improved motor and sensory functions of the lower extremities and even urinary and fecal functions as a result. The deformities of the lower extremities and feet can be partially improved with manual rehabilitation, and in severe cases, orthopedic surgery can be performed in the long term. Therefore, many patients with spinal cord tethering syndrome, especially children, require the joint treatment of neurosurgery, urology and orthopedics.
9.Why must neurophysiological monitoring be used in spinal cord tethering release?
Neurophysiological monitoring has been routinely used in spinal cord tethering in developed countries in Europe, America and Hong Kong. We know that microscopic observation is still only a morphological distinction between neural and non-neural tissues, and the doctor’s judgment is still a subjective speculation. However, the morphological structure of the spinal canal of a tethered baby is abnormal, and morphological observation by microscopy alone does not guarantee that there will be times when “the eye will be lost”. It is particularly important to determine functionally whether the tissue being measured is neural tissue. The application of neurophysiological monitors is a milestone advancement.
10. Are there any cases of spinal cord tethering in children that do not require a release procedure?
a. If the spinal cord tethering is detected at or near the end of adolescence and the spine has basically stopped growing, it can be observed if there are no symptoms and no surgery is required.
b. When an adolescent child with scoliosis issues an asymptomatic spinal cord tethering, scoliosis correction can be performed under electrophysiological monitoring, and if there is no abnormality in electrophysiology, no further spinal cord tethering release is required after surgery. The reason is simple: the length of the spine has been fixed by the built-in orthosis and is no longer growing, so the tethering will not progress naturally.
c. Severe bilateral lower extremity deformity combined with urinary and fecal dysfunction, it is estimated that the surgical results are not considered surgical treatment.