Syringomyelia is a rare disease of the spinal cord characterized by the presence of a fluid-filled cavity (cyst) in the spinal canal. This cavity constricts the surrounding nervous tissue, which results compression of spinal nerves.
Syringomyelia may be innate. Congenital syringomyelia is usually due to a defect in the region where the brain and spinal cord are linked as a result of an early disorder of organ development. Syringomyelia can also appear throughout life after an injury, a spinal tumor, or an inflammation of the spinal cord (acquired or secondary syringomyelia is characterized by the fact that the cavity contains a fluid rich in proteins similar to cerebrospinal fluid). All syringomyelia, regardless of whether they are congenital or acquired, originate in the same way: a cyst is generated with cerebrospinal fluid inside, inside the spinal cord, it accumulates and seeks another escape route.
Common symptoms of syringomyelia are disorders of sensitivity, pain, muscle weakness or parasitic. In some cases, the cavity which is generated inside the spinal cord can reach the brain and oppress the nervous tissue. If they affect the lower cerebral segments, it is spoken of syringobulbia. A common symptom of this condition is a disorder of the eye movements, which is manifested by tremors of the eyeball (nystagmus).
Since the onset of the first discomfort it is common for a gradual worsening of syringomyelia to occur over the years or decades until it becomes paraplegia. To prevent the progression of the disorder, it is necessary to decrease the pressure on the tissue. This is achieved by an operation intended to widen the space for the spinal cord or to derive the cerebrospinal fluid from the cavity to another area of the body. When treating syringomyelia, in addition to the surgical measures, individually adapted analgesic therapy and physiotherapy are useful. However, this disease is incurable.
The term syringomyelia is derived from the word syrinx (Greek: syrinx) and designates a disease of the spinal cord characterized by the presence of a cavity that extends longitudinally along the spinal cord, generating compressions at that level . Sometimes these cavities extend to the brain and press the nerve tissue. If the cavities reach the lower segments of the brain, the disease is also called syringobulbia.
Syringomyelia may be congenital or acquired. In the congenital form the cavity is filled with cerebrospinal fluid, whereas in the acquired syringomyelia it contains a fluid rich in proteins that resembles the CSF.
The terms syringomyelia and hydromelia are often used interchangeably. However, in megalelia, a congenital subtype of syringomyelia, there is a dilatation of the canal through which the cerebrospinal fluid (the medullary central canal) circulates.
Incidence of syringomyelia
Syringomyelia is very uncommon. Each year affects between one and two people per million. The incidence of syringomyelia varies regionally. Congenital syringomyelia appears with a higher than average frequency in some families. In men, the prevalence of this disorder is approximately double than women.
What Causes Syringomyelia
All forms of syringomyelia have the same causes: formation of a cyst at the level of the spinal cord because the cerebrospinal fluid can not flow freely, accumulates and seeks a new escape route.
Cerebrospinal fluid is produced by specialized cells of the cerebral ventricles and travels through the ventricle system, bathes the brain and spinal cord, and is ultimately absorbed by another group of cells. If the CSF flow is interrupted or obstructed at any point in this system, accumulation occurs. Syringomyelia develops when the stagnant fluid looks for another path and forms cavities full of CSF (syringes). Because the brain and spinal cord are in a narrow, narrow bone space, the cysts can generate pressure on the nerves, which causes the first symptoms of the disease. The severity of syringomyelia does not depend on the size of a cavity, but the location of the syringomyelia inside the spinal cord or lower regions of the brain determines the type of discomfort.
All syringomyelia may be due to several causes:
Congenital syringomyelia is caused in most cases by an anatomical alteration in the junction of the brain and spinal cord. The cerebellum or medulla oblongata are displaced downwards towards the spinal canal, as a result of a very early disorder of the formation of the organs that usually occurs in the fifth or sixth week of development of the embryo. The displacement of these cerebral regions compromises the circulation of cerebrospinal fluid. It can take many years until the formation of a cavity, which usually appears in the cervical and dorsal medulla.
Acquired or secondary syringomyelia is occasionally the result of an accident involving a spinal cord injury. Another possible cause of the acquired form of the disease is an arachnoid inflammation of the spinal cord, which can develop due to inflammation in other membranes of the brain or marrow. The inflamed arachnoid attaches to the surrounding tissue which prevents the normal circulation of CSF. Likewise, tumors of the spinal cord can form cavities. Combinations of various causes are also feasible.
What are the symtomps of syringomyelia?
Syringomyelia can manifest itself through very different symptoms. Its magnitude depends on the location of the cavities (syringes) in the spinal cord. These oppress the adjacent nervous tissue and thus trigger different neurological signs or symptoms.
Shoulder pain, arm pain, neck pain or headache are common symptoms of syringomyelia. In addition, this disease damages the ways of conducting temperature and pain, so that those affected are not able to feel a wound or a burn. Paralysis or spasticity may also occur in the arms or legs, and decreased or complete disappearance of sweating. Rarely, there is an increase in sweating.
Bone alterations accompany syringomyelia often cause damage to the spine and joints. This also causes appearance of other symptoms as painful limitations of mobility. In some cases circulatory disorders arise; skin appears bluish and cold and later soft and swollen. Disorders of sensitivity and circulation cause wounds to heal with greater difficulty and can lead to complications.
If the cavity of the spinal cord reaches the lower parts of the brain, the disorder is called syringobulbia, which is manifested by signs of degeneration in the nerves of the brain. A particularly frequent symptom of syringobulbia is an alteration of the ocular movement known as nystagmus: the eyes move rapidly first in one direction and then slowly in the opposite direction. Another symptom of the presence of cavities in this brain region is the decrease in muscle mass in the tongue. Sometimes the face is also affected by disorders of sensation or pain in the region innervated by the trigeminal nerve. These discomforts usually appear unilaterally and progress at high speed.
How is syringomyelia diagnosed?
The diagnosis of syringomyelia is established using a nuclear magnetic resonance. MRI images of the spinal canal and adjacent brain regions clearly show the characteristic cavity of syringomyelia and its extent. If the disease is due to a tumor, there is a high probability that it can be detected with a contrast medium in the MRI. A more specific MRI test also allows visualization of the cerebrospinal fluid circulation: it even recognizes small changes in flow due to minimal adhesions.
In order to rule out inflammation or infection during the diagnosis of syringomyelia, it is advisable to take a sample of cerebrospinal fluid from the lower lumbar spine (lumbar puncture) for further analysis.
It is also feasible to perform a myelography before a possible intervention. In this procedure, the doctor inserts a hollow needle into the subarachnoid space and injects a contrast medium so that the extent of the space through which the cerebrospinal fluid circulates can be visualized in an X-ray image. The special radiological study of the vertebral column that is carried out later allows to determine with precision if the cavity is connected directly with the central spinal canal or not.
How is syringomyelia treated?
The treatment of syringomyelia is oriented to the mitigation of the symptoms, for which it is essential to establish an adapted analgesic therapy. In addition, it is advisable that people with this disease begin early with physiotherapy and receive a comprehensive training. On the other hand, the treatment seeks to stop or slow the progress of the disease. For this purpose surgery is adequate to reduce the pressure exerted by the CSF cyst within the spinal cord on the nervous tissue.
Another surgical procedure for the treatment of syringomyelia is the decompression of foramen magnum: the surgeon widens the upper hole of the skull through which the spinal cord (foramen magnum) passes through the first two vertebral arches. If syringomyelia is not congenital but acquired (for example, caused by an accident), it is usually practiced only the resection of the vertebral arches at the corresponding height. In case the cavity is caused by a tumor, it is usually enough to cut the tissue as a window to considerably improve the discomfort. When the arachnoid is adhered after an inflammation of the syringomyelia, it is helpful to surgically separate the adhesion from the membrane.
Syringomyelia usually adopts a slow progressive course. However, syringomyelia varies greatly depending on the patient. In up to half of the cases, the disease slowly evolves or stops completely. Approximately one quarter of patients experience worsening of symptoms and surgery is scarcely able to slow the progression of the disease.
If syringomyelia is acquired as a result of an accident and a spinal cord injury, it tends to be constantly aggravated. If the cavities (syringes) are formed by tumors of the spinal cord, the prognosis depends to a large extent on the underlying disease. A surgery performed in a timely manner can significantly increase the quality of life of those affected. In the advanced stage of syringomyelia usually carries additional damage to the marrow because of poor irrigation of the marrow. Excessive growth of the connective tissue of the brain can form partitions within the cavity, or it may be completely replete.