SYRINGOMYELIA

What is syringomyelia? The spinal cord is the nervous organ that flows within the vertebral column and goes from the hole in the skull that connects it with the vertebral column until the vertebra L1. All along its way are the motor and sensory nerves from the base of the head until the end of the vertebral column at the coccyx. The spinal cord is composed very much like the brain: the central part has a butterfly shape and is made out of grey matter mainly made of nerve cells and it is covered by a white substance mainly made of nerve fibres. When a cavity in way of a cyst appears in the spinal cord affecting mainly the grey matter, it is called syringomyelia, because the central hole makes the spinal cord look like a flute or “syrinx”, in Greek. In most cases, the cause of the cyst forming is unknown . What are the symptoms? EThe pacient has the sense of touch altered in some part of the body, especially arms, in such a way that they can feel objects when they touch them, but cannot tell the temperature, therefore, they burn themselves easily without pain. There is a loss of muscle mass resulting in loss of strength. Gait abnormalities. Possibility of paralysis . Fig 1.- 26-year-old male who reported lack of temperature sensitivity, especially obvious when having a shower, on left half of head and body for the past year. Immediately after the operation where the filum terminale was cut, he recovered the sense of touch and temperature and five years later he has barely felt the symptoms again.

What causes syringomyelia?
Some forms of syringomyelia occur as a complication of trauma, a tumor, an infection, fusion of the spine cord in the lumbar region of the vertebral column due to congenital developmental problems like spina bifida, meningocele and myelomeningocele. However, in most cases, the cause is unknown, since none of the mentioned causes appears.

What is brought into syringomyelia as a novelty by Institut Neurològic de Barcelona?
Idiopathic syringomyelia, where the cause is unknown, may be due, according to a few authors, to an alteration in the circulation of the cerebrospinal fluid or to a small posterior fossa. The alterations of fluid flow are present, but are of such little magnitude that cannot explain the important injuries presented by patients. As for the size of the portion of the skull qhere the cerebellum is lodged, some research studies show that there is no significant difference between syringomyelia patients and other people.
Some clear arguments point out that syringomyelia is the result of the necrosis of cells inside the spinal cord because of insufficient blood flow when there is tethering of the spinal cord. Traction is transmitted by the filum terminale and its insertion in the coccyx ligament, both with no function in adult humans.
Research and tests with animals have proven that a mild tethering of the spinal cord makes neurons stop functioning due to insufficient blood flow.
In humans, intense tethering decreases blood flow inside the spinal cord, because there are important arteries there for the spinal cord and because spinal cord arteries are centripetal, they go from the outside to the inside, especially at the cervical region, since there is the limit to the downward movement. The lack of blood flow causes the necrosis or death of part of the spinal cord tissue, and then it attracts interstitial fluid from within the spine and forms a cyst in the centre of the spinal cord called syringomyelic cavity, syrinx or Syringomyelia, a disease described 500 years ago, of unknown cause up to present.

Is this explanation of syringomyelia of any use to the patients?
Of course, with the simple section of this ligament the strain to which the spinal cord is subject stops, and then the blood flow within the spinal cord improves so the progression of the disease stops.

Does the section of the filum terminale help the patient recover from the symptoms?
Most of the symptoms are due to irreversible injury of the nerve tissue, which cannot be replaced. But alternative circuits may be used and some of the cells that stopped functioning but had not died may be recovered when the blood flow is established again, which will improve some symptoms. The sooner the spinal cord ceases to suffer, the better will be the prognosis.

What exactly is the surgical section of the filum terminale?
The surgical section of the filum terminale is carried out by making a small incision on the sacrum, at the end of the backbone, so there is no alteration of the spine mechanics, visualizing the filum terminale and cutting it by means of microsurgery techniques, all of which is done in hardly half an hour and the patient is in hospital less than a day.

What are the consecuences of cutting this ligament?
The filum terminale is the result of the empty cover of the spine cord at the lower back or lumbosacral region. In the human embryo, the vertebral column and the spinal cord inside it have the same length and they are separated by some membranes, namely, dura mater, arachnoid mater and pia mater. With the normal growth of the person, the vertebral column grows about twenty centimeters more than the spinal cord. The layers that separate the spinal cord from the vertebral column in the lower back region do not contain spine cord anymore and fold as a fibrous cord which forms the filum terminale; this portion of the spinal cord can be compared to a sock we are wearing and we pull taking it half way off our foot: the half that does not contain our foot could be cut with no risk to our foot. In much the same way, the filum terminale can be cut at any point with no harm (1, 2).

Does the tethering of the spinal cord have any other effects?
The strain of the filum terminale, besides causing syringomyelia, has a flexion-producing effect on the vertebral column which causes scoliosis. In order to prevent the strain of the spinal cord, it also pulls downward the lower part of the brain, the socalled cerebellar tonsils, into the foramen occipitalis which connects the skull to the spine, causing the Arnold Chiari malformation, a disease described 100 years ago and was of unknown cause up to present.

What happens with the cyst?
In the case of syringomyelia, the section of the filum terminale stops the disease. The cyst resulting from the necrosis remains the same, but it may disappear when the space surrounding the spinal cord opens spontaneously or does so towards its centre where there is the ependymal canal, which connects the centre of the spinal cord to the brain cavities. The symptoms of the disease are caused by the cell death and the tumor-like effect of the cyst. The section of the filum has two beneficial effects: it stops the death of cells caused by spine cord strain and it diminishes the tumor-like effect of the cyst because it relaxes the spinal cord.

Has this treatment been applied to patients?
Patients of the three diseases, that is, scoliosis, Arnold Chiari malformation and syringomyelia, have been operated; some had all three conditions, and in some cases, the improvement has been dramatic.

Can you give an example?
Case 14, a forty-eight year old woman had a very pronounced scoliosis; she had had back pains since the age of fourteen, whatever position she was in, even lying in bed, when getting up, when rolling constantly, she did not have a pause for thirty-four years. She was operated seven months ago and has not had the slightest vertebral pain since.
Case 2, a case of syringomyelia: a young man of twenty-five, he had no sense for temperature on the left side of his body and had a big cyst in the centre of the spinal cord (case 2 of publication 3). Six hours after the operation, the specialist verified the total recovery of the patient’s sense of touch, the improvement lasting to present, five years later. This patient now works in a warehouse in Galicia, while other specialists, at the sight of his serious injuries predicted total disability in two years after diagnosing syringomyelia.
Or case 36, a patient who had all three diseases and suffered from jerking of hands and arms (fasciculations) which prevented him from writing, besides other symptoms. The symptoms improved greatly immediately after the operation and they disappeared almost completely within one month .

Bibliography
1. Siringomielia, escoliosis y malformación de Arnold-Chiari idiopáticas, etiología común (PDF).
2. Platibasia, impresión basilar, retroceso odontoideo y kinking del tronco cerebral, etiología común con la siringomielia, escoliosis y malformación de Arnold-Chiari idiopáticas (PDF).
3. Nuevo tratamiento quirúrgico para la siringomielia, la escoliosis, la malformación de Arnold-Chiari, el kinking del tronco cerebral, el retroceso odontoideo, la impresión basilar y la platibasia idiopáticas (PDF).
4. "Results of the section of the filum terminale in 20 patients with syringomyelia, scoliosis and Chiari malformation". Acta Neurochir (Wien). 2005 Feb 24 (PDF).
5. "Aportación a la etiología de la siringomielia". PhD thesis (PDF).