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Since the natural history of syringomyelia is poorly understood, a conservative approach may be recommended. When surgery is not yet advised, patients should be carefully monitored by a neurologist or neurosurgeon. Periodic MRI's and physical evaluations should be scheduled at the recommendation of a qualified physician.
Since the natural history of syringomyelia is poorly understood, a conservative approach may be recommended. When surgery is not yet advised, patients should be carefully monitored by a neurologist or neurosurgeon. Periodic MRI's and physical evaluations should be scheduled at the recommendation of a qualified physician.
==Prevention==
==Prevention==
 
===Primary Prevention===
 
===Secondary Prevention===
*Physiotherapy
*Prompt Surgery


== Research ==
== Research ==

Revision as of 17:39, 24 September 2016

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Tarek Nafee, M.D. [2]

Overview

Syringomyelia is a generic term referring to a disorder in which a cyst or tubular cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. Since the spinal cord connects the brain to nerves in the extremities, this damage may result in pain, weakness, and stiffness in the back, shoulders, arms, or legs. Other symptoms may include headaches and a loss of the ability to feel extremes of hot or cold, especially in the hands. Each patient experiences a different combination of symptoms. These symptoms typically vary depending on the extent and, often more critically, to the location of the syrinx within the spinal cord.

Historical Perspective

Classification

Syringomyelia may be classified in various ways according to the anatomical features of the syrinx, or according to the underlying etiology of the disease.[1]

By Anatomy

Syringomyelia may be classified according to the anatomical description of the lesion (syrinx) as follows:[1]

  • Communicating vs. Non-communicating:
    • A communicating syringomyelia is one where the syrinx is continuous from the spinal cord, across the foramen magnum and the dilatation is continuous with the fourth ventricle.
    • Absence of this continuity is defined as a non-communicating syringomyelia.
  • Intracannalicular vs. Extracannalicular:
    • Intracannalicular synringomyelia originates within the central canal of the spinal cord.
    • Extracannalicular syringomyelia originates within the spinal cord parenchyma.

By Etiology

Syringomyelia may be classified according to the underlying etiology or associated condition as follows:[2][3][4]

  • Congenital Malformations
  • Post-infectious
  • Post-traumatic
  • Post-inflammatory
  • Neoplastic

Pathophysiology

Pathogenesis

The exact pathogenesis of syringomyelia remains unknown. Several theories have been postulated about the development of a syrinx in the spinal cord. The underlying mechanisms of the disease involves disruption of CNS flow, subsequent formation of a syrinx, and enlargement of the lesion to impinge on the surrounding nerve fibers resulting in a symptomatic presentation.

1. Disruption of CSF Flow
Disruption of CSF flow may occur secondary to any of the following conditions:
  • Congenital craniocervical abnormalities obstructing CSF flow from the ventricles to the central canal (e.g., arnold chiari malformation, XXXX, XXXXX)
  • Tumor or arachnoid cyst exhibiting a mass effect on the spinal cord
  • Sequelae of spinal cord trauma results in abnormal obstruction of the central canal
  • Sequelae of meningitis resulting in inflammation of the spinal cord meninges
  • Sequelae of inflammatory conditions such as sarcoidosis, multiple sclerosis, seronegative spondyloarthropathies)
2. Syrinx formation
The pathogenesis of a syrinx is largely unknown. There are four primary theories of intra and extra cannilicular
  • Gardner's hydrodynamic theory
  • William's theory
  • Oldfield's theory
  • Intramedullary pulse pressure theory
3. Development of symptoms
Once the syrinx enlarges enough to impinge on the surrounding spinal cord segments, symptoms related to the affected nerve fibers will develop due to the mass effect of the syrinx itself.

Genetics

Gross Pathology

Microscopic Pathology

Causes

The most common cause of syringomyelia is Chiari I malformation. Other causes of syringomyelia may include:

Common Causes

  • Other congenital abnormalities (e.g., XXXXX, XXXX, XXXX)
  • Traumatic spinal cord injury

Less Common Causes

  • Infections (e.g., XXXX, XXXX, XXXX)
  • Neoplasia (e.g., Ependymoma, hemangioblastoma)
  • Inflammatory conditions (e.g. multiple sclerosis, transverse myelitis, amylotrophic lateral sclerosis)

Differentiating Syringomyelia from other diseases

Risk Factors

Risk factors for the development of syringomyelia vary according to the underlying etiology:

  • Congenital Malformations
  • Post-infectious
  • Post-traumatic
  • Post-inflammatory
  • Neoplastic

Screening

Epidemiology and Demographics

Incidence

Syringomyelia has a prevalence estimated at 8.4 cases per 100,000 people,[5] or about 21,000 Americans, with symptoms usually beginning in young adulthood.

Prevalence

Age

Sex

Natural History, Complications, and Prognosis

Natural History

Complications

Prognosis

History and Symptoms

The primary symptom of post-traumatic syringomyelia (often referred to using the abbreviation of PTS) is pain, which may spread upward from the site of injury. Symptoms, such as pain, numbness, weakness, and disruption in temperature sensation, may be limited to one side of the body. Syringomyelia can also adversely affect sweating, sexual function, and, later, bladder and bowel control. A typical cause of PTS would be a car accident or similar trauma involving a whip-lash injury.

What can make PTS difficult to diagnose is the fact that symptoms can often first appear long after the actual cause of the syrinx occurred, e.g. a car accident occurring and then the patient first experiencing PTS symptoms such as pain, loss of sensation, reduced ability on the skin to feel varying degrees of hot and cold, a number of months after car accident. Syringomyelia causes a wide variety of neuropathic symptoms due to damage of the spinal cord. Patients may experience chronic pain, abnormal sensations and loss of sensation particularly in the hands. Some patients experience paralysis or paresis temporarily or permanently. A syrinx may also cause disruptions in the parasympathetic and sympathetic nervous systems, leading to abnormal body temperature or sweating, bowel control issues, or other problems. If the syrinx is higher up in the spinal cord or affecting the brainstem as in syringobulbia, vocal cord paralysis, ipsilateral tongue wasting, trigeminal nerve sensory loss, and other signs may occur.[6] Rarely, bladder stones can occur in the onset of weakness in the lower extremities.[7]

Physical Examination

Signs of the disorder tend to develop slowly, although sudden onset may occur with coughing, straining, or myelopathy. If not treated surgically, syringomyelia often leads to progressive weakness in the arms and legs, loss of hand sensation, and chronic, severe pain.

Imaging Findings

Other, more common disorders share the early symptoms of syringomyelia. In the past, this has made diagnosis difficult. The advent of one diagnostic test, however, called magnetic resonance imaging or MRI, has significantly increased the number of syringomyelia cases diagnosed in the beginning stages of the disorder.

Physicians now use magnetic resonance imaging (MRI) to diagnose syringomyelia. The MR imager takes pictures of body structures, such as the brain and spinal cord, in vivid detail. This test will show the syrinx in the spine or any other conditions, such as the presence of a tumor. MRI is safe, painless, and informative and has greatly improved the diagnosis of syringomyelia. In addition, computed axial tomography (CT) scans of a patient's head may reveal the presence of tumors and other abnormalities such as hydrocephalus.

Like MRI and CT scans, another test, called a myelogram, takes x-ray-like pictures and requires a contrast medium or dye to do so. Since the introduction of MRI this test is rarely necessary to diagnose syringomyelia.

Other Diagnostic Studies

The physician may order additional tests to help confirm the diagnosis. One of these is called electromyography (EMG), which measures muscle weakness. The doctor may also wish to test cerebrospinal fluid pressure levels and to analyze the cerebrospinal fluid by performing a lumbar puncture.

Medical Therapy

Drugs have no curative value as a treatment for syringomyelia. The role of medical therapy in management of syringomyelia is for treatment of underlying conditions or management of associated symptoms.

Treatment of underlying Conditions

Radiation and chemotherapy may be utilized for management of an underlying spinal cord tumor. Antibiotics may be used to treat an underlying infection (meningitis or encephalitis)

Management of Symptoms

Analgesics may be used to control pain. Gaba inhibitors neurontin pregebalin may be used to control peripheral neuropathy. Drugs may be used for urinary or fecal incontinence or neurogenic bladder.

In the absence of symptoms, syringomyelia is usually not treated. In addition, a physician may recommend not treating the condition in patients of advanced age or in cases where there is no progression of symptoms. Whether treated or not, many patients will be told to avoid activities that involve straining.

Surgery

The first step after diagnosis is finding a neurosurgeon who is experienced in the treatment of syringomyelia. Surgery is the only viable treatment for syringomyelia, and a neurosurgeon is the only specialist qualified to provide a fully informed recommendation. Not all patients will advance to the stage where surgery is needed. Evaluation of the condition is often difficult because syringomyelia can remain stationary for long periods of time, and in some cases progress rapidly.

Surgery is not always recommended for syringomyelia patients. For many patients, the main treatment is analgesia. A typical treatment of syringomyelia involving severe chronic pain would involve two or more medications. One medication for "classical" back pain such as a weak or strong opioid (e.g. tramadol and Oxycontin respectively) combined with a medication to combat any neuropathic pain symptoms such as shooting and stabbing pains (e.g. Neurontin or Lyrica). In addition, paracetamol can be used to combat headaches. Such long term treatment of chronic pain should be monitored with blood tests to assess any adverse effects of the medication on the liver, with the dosages being then changed accordingly, depending on the outcome of such blood tests.

Surgery of the spinal cord has certain, characteristic risks associated with it and the benefits of a surgical procedure on the spine have to be weighed up against the possible complications associated with any procedure. Surgical treatment is aimed at correcting the condition that allowed the syrinx to form. It is vital to bear in mind that the drainage of a syrinx does not necessarily mean the elimination of the syrinx-related symptoms, but rather is aimed at stopping progression. In simple terms this means that a syrinx with the main symptom of pain, may not actually lead to any reduction (or only a part reduction) in the pain symptoms after the syrinx has been drained! In cases involving an Arnold-Chiari malformation, the main goal of surgery is to provide more space for the cerebellum at the base of the skull and upper cervical spine without entering the brain or spinal cord. This often results in flattening or disappearance of the primary syrinx or cavity, over time, as the normal flow of cerebrospinal fluid is restored. If a tumor is causing syringomyelia, removal of the tumor is the treatment of choice and almost always eliminates the syrinx.

Surgery results in stabilization or modest improvement in symptoms for most patients. Delay in treatment may result in irreversible spinal cord injury. Recurrence of syringomyelia after surgery may make additional operations necessary; these may not be completely successful over the long term.

In some patients it may also be necessary to drain the syrinx, which can be accomplished using a catheter, drainage tubes, and valves. This system is also known as a shunt. Shunts are used in both the communicating and noncommunicating forms of the disorder. First, the surgeon must locate the syrinx. Then, the shunt is placed into it with the other end draining cerebrospinal fluid (CSF) into a cavity, usually the abdomen. This type of shunt is called a ventriculoperitoneal shunt and is particularly useful in cases involving hydrocephalus. By draining syrinx fluid, a shunt can arrest the progression of symptoms and relieve pain, headache, and tightness. Without correction, symptoms generally continue.

The decision to use a shunt requires extensive discussion between doctor and patient, as this procedure carries with it greater risk of injury to the spinal cord, infection, blockage, or hemorrhage and may not necessarily work for all patients. Draining the syrinx more quickly does not produce better outcomes, but a shunt may be required if the fluid in the syrinx is otherwise unable to drain.

In the case of trauma-related syringomyelia, the surgeon operates at the level of the initial injury. The syrinx collapses at surgery but a tube or shunt is usually necessary to prevent re-expansion.

Since the natural history of syringomyelia is poorly understood, a conservative approach may be recommended. When surgery is not yet advised, patients should be carefully monitored by a neurologist or neurosurgeon. Periodic MRI's and physical evaluations should be scheduled at the recommendation of a qualified physician.

Prevention

Primary Prevention

Secondary Prevention

  • Physiotherapy
  • Prompt Surgery

Research

The precise causes of syringomyelia are still unknown. Scientists at the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland, and at grantee institutions across the country continue to explore the mechanisms that lead to the formation of syrinxes in the spinal cord. For instance, Institute investigators have found that as the heart beats, the syrinx fluid is abruptly forced downward. They have also demonstrated the presence of a block to the free flow of cerebrospinal fluid that normally occurs in and out of the head during each heartbeat. Duke University is conducting research to see if syringomyelia might be genetic.[8]

Surgical techniques are also being refined by the neurosurgical research community. In one treatment approach currently being evaluated, neurosurgeons perform a decompressive procedure where the dura mater, a tough membrane covering the cerebellum and spinal cord, is enlarged with a graft. Like altering a suit of clothing, this procedure expands the area around the cerebellum and spinal cord, thus improving the flow of cerebrospinal fluid and eliminating the syrinx.

It is also important to understand the role of birth defects in the development of hindbrain malformations that can lead to syringomyelia. Learning when these defects occur during the development of the fetus can help us understand this and similar disorders, and may lead to preventive treatment that can stop the formation of many birth abnormalities. Dietary supplements of folic acid during pregnancy have already been found to reduce the number of cases of certain birth defects.

Diagnostic technology is another area for continued research. Already, MRI has enabled scientists to see conditions in the spine, including syringomyelia, even before symptoms appear. A new technology, known as dynamic MRI, allows investigators to view spinal fluid pulsating within the syrinx. CT scans allow physicians to see abnormalities in the brain, and other diagnostic tests have also improved greatly with the availability of new, non-toxic, contrast dyes. Patients can expect even better techniques to become available in the future from the research efforts of scientists today.

See also

References

  1. 1.0 1.1 Milhorat TH (2000). "Classification of syringomyelia". Neurosurg Focus. 8 (3): E1. doi:10.3171/foc.2000.8.3.1. PMID 16676921.
  2. Larner AJ, Muqit MM, Glickman S (2002). "Concurrent syrinx and inflammatory central nervous system disease detected by magnetic resonance imaging: an illustrative case and review of the literature". Medicine (Baltimore). 81 (1): 41–50. PMID 11807404.
  3. Laxton AW, Perrin RG (2006). "Cordectomy for the treatment of posttraumatic syringomyelia. Report of four cases and review of the literature". J Neurosurg Spine. 4 (2): 174–8. doi:10.3171/spi.2006.4.2.174. PMID 16506486.
  4. Batzdorf U (2000). "Primary spinal syringomyelia: a personal perspective". Neurosurg Focus. 8 (3): E7. PMID 16676930.
  5. Brewis M, Poskanzer DC, Rolland C, et al, "Neurological disease in an English city". Acta Neurologica Scand Suppl 24:1--89, 1966.
  6. Greenberg, David A, et al: Clinical Neurology. 5th ed. Feb 9, 2002.
  7. Nishida, Takayasu, et al. "A large bladder stone caused by syringomyelia". Japanese Journal of Clinical Urology, Vol.60, No. 6, pp 413-415, 2006. ISSN:0385-2393.
  8. "Information about a Genetic Research Study for Chiari Type I Malformation (CMI) with or without Syringomyelia."

External links

Organizations


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