Spinal cord tethering syndrome in children is a distressing condition for many children and families, and the consultation process can be very difficult. The most worrying thing for parents is the occurrence of postoperative complications, among which spinal cord re-tethering (often accompanied by incomplete release of the embolus) is the most common and has the most serious consequences.
1. What is spinal cord embolism syndrome and what is spinal cord reattachment?
We know that as the fetus develops, the spinal canal grows faster than the spinal cord, so the lower end of the spinal cord gradually rises in relation to the lower end of the spinal canal. At 40 weeks of embryonic life the lowermost part of the spinal cord (what we call the conus) is at about the level of the third lumbar vertebra, by the time the baby is born the conus is at or slightly above the second lumbar vertebra, and by the end of puberty our conus rises to the level of the 12th thoracic and first lumbar vertebra and continues throughout life. Then, when the spinal cord cannot rise properly due to various constraints on the wall of the spinal canal, its position is lower than normal, resulting in a series of clinical manifestations called spinal cord embolism syndrome.
The spinal cord re-embolism means that the child has scar adhesions after the spinal cord embolism release, and the spinal cord is still not able to move up normally with the development, causing the symptoms to worsen or new symptoms to appear. To put it bluntly, this means that the spinal cord and the surrounding tissues are still adhered to each other, while the child continues to grow. As soon as the child grows, the spinal cord is inevitably stretched tightly. It’s really worrying for the mother when her child doesn’t grow, and for the mother when she grows.
2.What are the causes of spinal cord re-embolism in babies?
Re-tethering is caused by adhesions between the trauma surface and the dura mater or artificial dura mater after spinal cord tethering release; adhesions caused by arachnoid thickening due to sterile inflammation in the spinal canal after spinal cord tethering surgery.
3.What are the clinical conditions that are prone to re-tethering?
We know that the spinal cord grows inside the dura mater of the spinal canal, and the spinal cord and the dura mater are often not in direct contact with each other, and the two are filled with a fluid. We call this the cerebrospinal fluid. If the trauma to the spinal cord is obvious after separation, the dura and the spinal cord can easily grow together. When the child grows, the spinal cord is stretched tight again, and the blood flow to the spinal cord becomes impaired, showing signs of spinal cord tethering syndrome. When the spinal cord (including lipomas) is relatively large and the spinal canal is relatively narrow, the striated surface of the spinal cord and the dura are more likely to grow together in intimate contact. Tethering due to thickened arachnoid adhesions is often not the primary cause of re-tethering.
The spinal cord is not necessarily tethered by adhesions alone, but the child’s size is growing, and this dynamic process causes the spinal cord to become tighter and tighter, resulting in spinal cord tethering syndrome.
4. Since the consequences of spinal cord tethering are so serious, is there any way to prevent re-tethering?
Simply put, there are two ways: one is to reduce adhesions; the other is to prevent the child from growing. Obviously the second point is not realistic. So let’s put more effort into reducing adhesions.
In the case of a lipoma-type spinal cord tethering, for example, first, the surgery should be as sharp as possible to separate the tissues, which causes the least damage; second, as much of the lipoma as possible should be removed to ensure neurological function, so that the spinal cord will be smaller and less likely to come into contact with the dura mater. With neurophysiological monitoring, the lipoma can be removed as much as possible while preserving neurological function. Of course it is important to keep a hand in the cut, and one of the tips of the surgery is to preserve the two lateral portions of the lipoma envelope. This way, when the two sides are sewn together, the integrity of the spinal cord morphology can be reestablished and a smooth surface can be formed so that adhesions with the dura are less likely to occur.
Again, the spinal canal should be enlarged for narrow repairs. Remember that the dura should not be sutured to a large size. When suturing the musculofascial, the excess dura is crumpled together and causes narrowing of the dural sac, making adhesions more likely to occur. In this case, the dura is suspended by prolene sutures in height, depth, and width over the bony or fascial membrane or ligaments to achieve a true expanded repair.
If the dural sac is still narrow at this point, then removing some of the back bone (spinous processes and laminae) can leave more space for the spinal cord.
It is also important to keep the cerebrospinal fluid clear intraoperatively. Low-power bipolar electrocoagulation and warm saline work best to stop the bleeding quickly and reduce re-adhesion. The use of any glue, anti-adhesive material, or hemostatic material is not recommended. Artificial dura is not used if possible.
5. Is spinal cord re-tethering caused by recurrence of lipoma compressing the spinal cord?
As mentioned earlier, 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 area, striving for complete release of the adhesions.
In fact, we have found that the main cause of spinal cord reattachment in our clinical practice is the failure of the first surgery to completely release the adhesions, followed by the reattachment.
The main locations where the first surgery failed to completely release are the spinal cord and nerve roots on the caudal side and the severe side of the horseshoe group.
The most severe re-adhesions tend to occur dorsally. The factors that predispose to dorsal adhesions can be found in the latter articles.
6. What are the clinical manifestations of spinal cord reattachment?
The original symptoms reappear after the first surgical release or new symptoms appear gradually, such as
a. Sensory disorders of the lower limbs: manifested as abnormal sensation and pain in the lower limbs, perineum and low back.
b. Motor disorders of lower extremities: manifesting as abnormal walking, weakness, deformation and pain of lower extremities, mostly starting from the side with severe tethering adhesions. The spine is tilted forward, the buttocks are tilted back, and walking is like duck walk. Scoliosis can also be combined with scoliosis.
c. 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.
d. Lower limb deformities: severe lateral leg thinning, neurogenic clubfoot.
The baby in the picture below had been operated on in an outside hospital when he was a few months old, and for some reason the embolus was not completely released and only a partial removal of the lipoma was done. After the surgery, the child’s lower limb movement and bowel movements were normal. However, at the age of two, he had problems walking, and five months ago, he slowly became unaware of urination and defecation. Such a child should undergo reoperation under neurophysiological monitoring as early as possible to completely loosen the embolus.
7.What tests are usually needed for a baby suspected of having a spinal cord re-embolization?
MRI is the most effective and primary test, and should be repeatedly compared with several previous MRI studies. Significant central canal dilatation or progressive worsening of dilatation and lipoma adhesions suggest the possibility of reembolization; ultrasound can examine residual urine and assess vesicoureteral reflux, and urodynamics can provide a more accurate picture of bladder function.
8.What kind of patients can have spinal cord re-embolization surgery?
We know that spinal cord embolization is a prophylactic procedure, and so is re-tethering surgery. The spinal cord embolism is already organically altered by the time symptoms appear, and we cannot restore it to full normal. This means that early identification of spinal cord re-tethering and timely and proper treatment can stop the deterioration of the disease. On the basis of this, rehabilitation can be carried out to achieve a more satisfactory result together. There are probably the following cases whether to operate or not.
A. If the first surgery did not cause spinal cord nerve damage, but the embolus is not completely released, spinal cord embolus re-tethering surgery should be performed as soon as possible when the spinal cord tethering syndrome appears.
B. If the first surgery caused serious injury to the spinal cord and nerves, incontinence and almost complete loss of walking possibility, even if the tethering is not completely released, reoperation is generally not recommended.
C. If the spinal cord nerve injury caused by the first operation is completely released and the tethering is aggravated by the re-tethering nerve disorder after the operation, reoperation for release can be considered. However, the spinal cord nerve injury caused by the first surgery cannot be recovered.
D. The first surgery did not cause spinal cord nerve injury, and the tethering was completely released, and re-tethering appeared after surgery, which should be promptly surgically released.
E. The embolus of the first surgery is completely released, but it causes spinal cord and nerve root injury, and the symptoms that appear immediately after surgery cannot be improved by reoperation.
9. Why must neurophysiological monitoring be used in spinal cord re-tethering?
We know that microscopic observation still only distinguishes nerve and non-neural tissue morphologically, and the doctor’s judgment is still a subjective speculation. However, the morphological structure in 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. Neurophysiological monitoring can minimize the damage to the nerve during surgery. No matter how complex the structure, electrophysiological monitoring can accurately determine the difference between nerve and other tissues. During surgery, the nerves that innervate both lower extremities and urination and defecation are identified and preserved by first monitoring the tissue to be isolated with a stimulator and then isolating it repeatedly.
The application of neurophysiological monitoring is a landmark advancement. It is the equivalent of adding a pair of penetrating eyes to the physician. This is even more important than experience, just as a new car is destined to run faster than an old horse.
When tethering again, the surgeon opens the surgical incision to face the scarred tissue, at this time, the doctor’s state is described as confused and anxious, but with the electrophysiological stimulator to explore the road, the benefits speak for themselves.
10. Is it necessary to remove the bone behind the spinal canal during spinal cord tethering surgery?
Our practice is generally like this: for spinal cord tethering caused by lipomas in the third lumbar vertebra and below, the laminae and spinous processes of the corresponding segment are removed as much as possible during surgery for the simple reason that removing the bones makes room for the dural sac so that the spinal cord and dura are not prone to untouching adhesions. Removal of the lamina below the third lumbar vertebra has little effect on the stability of the spine. The second lumbar vertebra and above try to reset the vertebral plates and spinous processes. There are two reasons for this: one is that these vertebrae are the main weight-bearing vertebrae (such as the 12th thoracic vertebra and the 1st lumbar vertebra), and the second is that even if the laminae are reset here, the spinal cord and dural adhesions are not likely to cause spinal cord embolism (if you cannot read this article, please review the previous nine articles several times).
11.The last question is: When is re-tethering surgery appropriate?
We know that spinal cord embolism is a preventive surgery. Once there are symptoms, surgery is needed immediately, no matter what age, even for newborns; babies with abnormalities behind the waist found after birth, but no symptoms can be operated on 3-6 months after birth; children with spinal cord tethering who are not noticed after birth, but are still growing, should be operated on as soon as possible; children with scoliosis and spinal cord tethering syndrome should have spinal cord tethering six months before surgery to correct scoliosis After puberty, patients who are not growing do not need surgery if they have no symptoms.
The timing of surgery for spinal cord re-embolization varies.
1, the image shows that there is still embolism, but there is no symptom aggravation or new symptoms, you can continue to observe. Even if surgery is performed, the later the better.
2.Imaging shows the presence of embolism, and there is an aggravation of the original symptoms or the appearance of new symptoms, and once it is determined, surgery is performed immediately.