NORD gratefully acknowledges R. Shane Tubbs, PhD, Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, for assistance in the preparation of this report.
Syringomyelia is a condition characterized by a fluid-filled cavity or cyst known as a syrinx that forms within the spinal cord. Syringomyelia is a chronic condition and a syrinx can expand over time compressing or destroying the surrounding nerve tissue. A wide variety of symptoms can potentially be associated with syringomyelia depending upon the size and exact location of the syrinx. Common signs/symptoms include pain in the neck and shoulders, muscle weakness, pain and stiffness in the legs, numbness or decreased sensation, especially to hot and cold, abnormal curvature of the spine (scoliosis), muscle contractions, and uncoordinated movements (ataxia). The majority of cases of syringomyelia are associated with a complex brain abnormality known as a Chiari malformation. Additional known causes of syringomyelia include tethered cord syndrome, meningitis (arachnoiditis), certain tumors of the spinal cord, and trauma. In some patients, no underlying cause can be identified (idiopathic).
The terminology used in the medical literature to describe syringomyelia can be confusing. Syringomyelia is often associated with an abnormality of the craniovertebral junction, usually a Chiari malformation (types I and II), and these cases may be referred to as congenital syringomyelia. Secondary syringomyelia refers to cases that have a known cause. The term primary syringomyelia has been used to refer to cases of unknown cause or to cases that occur because of specific known causes that damage the spinal cord. Posttraumatic syringomyelia refers to cases that result from trauma to the spinal cord (these cases are sometimes sub-classified as primary syringomyelia).
Some individuals have a condition related to syringomyelia known as hydro(syringo)myelia, which is characterized by abnormal widening of the central canal of the spinal cord (the normal small canal running through the center of the spinal cord). Some physicians use the terms syringomyelia or hydromyelia interchangeably. Hydromyelia may also be present in infants and young children with or without brain abnormalities, such as Chiari malformation type II that is seen in patients with spina bifida. The fluid-filled cavities in cases of syringomyelia often do not connect to any other fluid-filled areas or spaces and occur more often in adults than children.
The specific symptoms and severity of syringomyelia can vary greatly from one person to another. Some individuals may not have any noticeable symptoms (asymptomatic); others may have a variety of symptoms that can progress to cause significant disability. It is important to note the highly variable nature of syringomyelia and to realize that affected individuals can have different sets of symptoms and a different rate of progression (or no progression of the disease at all).
Syringomyelia is usually slowly progressive, but rapid onset can occur. Common symptoms include pain in the neck and shoulders. Pain may also affect the arms and hands and may be described as a burning, tingling or piercing sensation. Some affected individuals also experience numbness or decreased sensation, especially to hot and cold. Muscle weakness and wasting, especially of the hands, arms, and eventually the shoulders, may also develop. The upper (cervical and thoracic) portions of the spinal cord are often affected in syringomyelia. Affected individuals may first notice a loss of feeling for pain and temperature in their fingers, hands, arms, and upper chest. In the early stages, a sense of touch is still present. A loss of feeling may spread over the shoulders and back, described as a “cape-like” distribution.
Affected individuals may also develop pain and stiffness (spasticity) in the legs and uncoordinated movements (ataxia), eventually affecting the ability to walk. In severe cases, paralysis of the arms or legs can occur. Some affected individuals may develop muscle contractions such as small, involuntary muscle contractions or “twitches” (fasciculations).
Skeletal abnormalities can develop including the abnormal side-to-side curvature of the spine (scoliosis). In some children, scoliosis may be the only symptom. Some individuals may develop Charcot joints, in which chronic, progressive degeneration of the joint occurs because of damage to the nerves that supply the joint. Charcot joints are initially seen as swelling and redness of the affected areas. Without treatment, deformity of the affected joints can occur.
Some affected individuals develop symptoms associated with damage to the autonomic nervous system, which is the part of the nervous system that controls involuntary functions. Such symptoms include loss of bowel and bladder control, excessive sweating (hyperhidrosis), and fluctuating blood pressure levels. Horner’s syndrome, an uncommon condition that develops because of damage to one of the nerves that supplies the eyes and face, may also occur. Horner’s syndrome usually affects one side of the face and is characterized by a droopy eyelid, narrowing of the opening between the eyelids, decreased pupil size, and decreased sweating on the affected side of the face.
Individuals with syringomyelia associated with a Chiari malformation may also have a condition called hydrocephalus, in which there is an abnormal accumulation of cerebrospinal fluid in the brain. In infancy, hydrocephalus can cause a variety of symptoms including an abnormally enlarged head, vomiting, headache, sleepiness, irritability, seizures, and downward deviation of the eyes.
The exact, underlying reason for the formation of a syrinx is unknown. Most theories implicate the obstruction or disruption of the flow of cerebrospinal fluid (CSF) as the most common cause. CSF is a clear fluid that surrounds and is within the brain and surrounds the spinal cord. CSF has several functions including protecting and cushioning the brain and giving the brain buoyancy. CSF is also found in the central canal, a small canal that runs through the center of the spinal cord in infants. The central canal eventually collapses over time.
A variety of conditions that block or impair the normal flow cerebrospinal fluid have been associated with syringomyelia. The condition most commonly associated with syringomyelia is the Chiari malformations, a group of complex brain abnormalities that affect the area in the lower back of the skull where the brain and spinal cord connect (craniovertebral junction).
Syringomyelia can also develop following spinal cord injury (SCI). These cases are sometimes referred to as posttraumatic syringomyelia. The development of posttraumatic syringomyelia may occur many years after the initial traumatic injury.
Additional conditions that are associated with syringomyelia include certain spinal cord tumors, meningitis, inflammation of the arachnoid membrane (arachnoiditis), one of the membranes that surrounds and protects the spinal cord, and a tethered spinal cord, which is usually a stretch-induced functional disorder associated with the fixation (tethering) effect of inelastic tissue (filum terminale usually infiltrated with fat) found at the caudal end of the spinal cord, limiting its movement.
Spinal dysraphism (spina bifida occulta), which is characterized by malformations of the spinal canal and its contents, can also be associated with syringomyelia. Spinal dysraphism is often associated with a tethered spinal cord.
In some individuals, syringomyelia can develop without any known cause. These cases are referred to as idiopathic syringomyelia.
Syringomyelia most commonly presents in young adults between 20 and 40 years of age, but can also develop in young children or older adults. Some reports suggest that syringomyelia is slightly more common in males than females. One estimate places the incidence at 8.4 individuals per 100,000 in the general population in the United States.
A diagnosis of syringomyelia is based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests. In some cases, syringomyelia is discovered incidentally when a person is being evaluated for another reason.
Clinical Testing and Workup
A specialized imaging technique called magnetic resonance imaging (MRI) is used to diagnose syringomyelia. An MRI uses a magnetic field and radio waves to produce cross-sectional images of particular organs and bodily tissues such as the brain and spinal cord. An MRI can reveal a syrinx or another condition related to syringomyelia such as an intraspinal tumor or Chiari malformation. The location and extent of the syrinx is much more accurately determined and treatment can begin, when appropriate, earlier than in the past with older diagnostic techniques (e.g., myelogram).
The treatment of syringomyelia is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, neurologists, neurosurgeons, surgeons, eye specialists (ophthalmologists) and other healthcare professionals may need to systematically and comprehensively plan an affected child’s treatment.
Specific therapeutic procedures and interventions may vary, depending upon numerous factors, such as disease progression; the presence or absence of certain symptoms; the underlying cause; the impact of symptoms on quality of life; an individual’s age and general health; and/or other elements. Decisions concerning the use of particular drug regimens and/or other treatments should be made by physicians and other members of the health care team in careful consultation with the patient based upon the specifics of his or her case; a thorough discussion of the potential benefits and risks, including possible side effects and long-term effects; patient preference; and other appropriate factors.
Some individuals with syringomyelia who do not have any symptoms may not require treatment, but should be regularly monitored to see whether the disorder progresses.
General therapeutic options include pain medications (analgesics), physical therapy, and a reduction in activities, especially those that require straining such as heavy lifting. The goal of treatment for syringomyelia is to restore the proper flow of cerebrospinal fluid and to remove the pressure that a syrinx places on the spinal cord. Initial treatment is usually targeted at the underlying cause of syringomyelia.
There is no specific, agreed-upon therapy or treatment regimen for the most common cause of a syrinx, a Chiari malformation. Neurosurgeons and other physicians may disagree as to the best approach to treat a Chiari malformation. Different neurosurgeons may recommend different surgical techniques or treatment regimens.
Like syringomyelia, individuals with a Chiari malformation who do not have symptoms are generally not treated, but monitored to see whether the disorder progresses. If mild or nonspecific symptoms are present, such as neck pain or headaches, physicians may recommend conservative treatment. Symptomatic Chiari malformations are most often treated by surgery. There are no specific criteria or objective tests that can be used to determine when to undergo surgery or the best procedures to choose. The most common surgery is known as posterior fossa decompression. With this procedure, a surgeon creates room by removing small pieces of bone in the back of the skull, thereby enlarging the foramen magnum. This relieves pressure and reduces compression of the brainstem. The surgeon may also choose to open the covering (dura mater) of the brain in this region and explore the herniated tissue and then sew in a graft (duraplasty).
If hydrocephalus is associated with the Chiari malformation-related syrinx, then the surgeon will usually treat this first. The most common surgical treatment is to place a shunt that connects the dilated ventricles of the brain to another cavity of the body. The most common cavity chosen is the abdomen. Once the hydrocephalus is treated, then the Chiari malformation is addressed.
Surgery may be used to treat other conditions that cause syringomyelia including surgery to remove a tumor. Tethered spinal cord may require surgery to release the tension of the cord.
In some cases, a tiny tube called a shunt/stent may be placed into the syrinx. The shunt allows the fluid within the syrinx to drain to an area outside of the spinal column. Shunting can stop the progression of the disorder and relieve some symptoms such as pain and headaches. However, shunts can be associated with significant side effects including spinal cord injury or infection, bleeding (hemorrhaging), and blockage.
Posttraumatic syringomyelia may be difficult to treat. Surgery is recommended for individuals with neurological deterioration and/or intractable pain. Surgery is aimed at expanding the area around the spinal cord by the site of trauma or injury and to decrease fluid volume. The insertion of shunt may also be used to treat posttraumatic syringomyelia. Shunting in posttraumatic syringomyelia carries risks including further spinal cord injury and may need to be replaced if the shunt becomes clogged or defective. Many physicians consider shunts a last resort for individuals with posttraumatic syringomyelia.
Surgery for syringomyelia can often lead to an improvement of symptoms and stabilization of the disorder in many individuals. However, syringomyelia can recur after successful treatment, thereby necessitating more operations.
After surgery, the physician will evaluate the syrinx to make sure that it stabilizes or decreases in size. These evaluations will entail obtaining an MRI.
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