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SYRINGOMYELIA Syringomyelia (sear-IN-go-my-EEL-ya) is a chronic disorder involving the Spinal Cord in which a fluid filled cavity (or cyst) forms within the Spinal Cord. This cyst (called a Syrinx) expands and elongates over time, destroying the center of the Spinal Cord. As the nerve fibers inside the Spinal Cord are damaged, a wide variety of symptoms can occur, depending upon the size and location of the Syrinx. (There are other terms applied to this condition that are used interchangeably by physicians. These terms, Syringomyelia, Hydromyelia or Syrinx, all refer to an internal expansion of a normally very narrow Central Canal which occupies a center position the Spinal Cord and which is not normally dilated.)There are two major types of Syringomyelia. In most cases it is related to a congenital malformation involving the Cerebellum and Brain Stem called the Arnold-Chiari Malformation. This "malformation" occurs during fetal development and is characterized by downward displacement of the lower part of the Cerebellum (Cerebellar Tonsils) through the Foramen Magnum, into the upper (superior) portion of the Cervical Spinal Canal. This displacement blocks the normal flow of Cerebrospinal Fluid (CSF). If Cerebrospinal Fluid, as a result of the interference with its normal flow within the Fourth Ventricle of the Brain, is abnormally directed (under pressure developed in the cyclical beating of the Brain which is synchronous with beating of the Heart) into this Central Canal of the Spinal Cord, it may dilate the Central Canal. This "hydrocephalus" of the Spinal Cord is the "Syrinx". The Syrinx may compress the surrounding Spinal Cord resulting in damage by internal compression which then may interfere with the normal functioning of the Spinal Cord. Syringomyelia can also be associated with an abnormal "Curvature of the Spine" (a condition known as "Scoliosis".) It is important to recognize that when scoliosis is initially identified, neuroimaging tests should be considered since the underlying cause of the scoliosis may be the presence of the Arnold-Chiari Type I Malformation. Not all patients with Arnold-Chiari Malformations will develop a Syrinx, however. it can also occur as a complication of Spinal Cord trauma, Meningitis, Spinal Cord Tumor (17% of patients with a Syrinx will also have a Spinal Cord Tumor), Arachnoiditis or a Tethered Spinal Cord. In these cases the Syrinx forms in the section of the Spinal Cord damaged by these conditions.
As more people are surviving Spinal Cord injuries, more cases of post-traumatic Syringomyelia are being diagnosed. Symptoms may appear months or even years after the initial injury and are related to the site and anatomical level of the Spinal Cord that was subjected to the trauma. Some cases of Syringomyelia are Familial (Genetically determined) although this is rare. SYMPTOMS Symptoms usually begin between the ages of 25 and 40 and may worsen with straining or any activity that causes Cerebrospinal Fluid pressure to fluctuate. Some patients, however, may have long periods of stability. The majority of patients suffer, at some point in the progression of this disorder. Each patient experiences a different combination of symptoms depending on the anatomical level of the Spinal Cord that is involved in the Syringomyelia process and the extent of the Syrinx.The symptoms of Syringomyelia, which tend to develop slowly, are numerous and may manifest in various combinations of different symptoms. Symptoms may, rarely, develop suddenly as a result of a severe cough or strain. Common symptoms include:
DIAGNOSIS Neuroimaging MRI scanning is the most effective diagnostic tool for evaluating Syringomyelia. The standard comprehensive MRI study of this condition includes images obtained with and without Gadolinium (the paramagnetic "enhancing substance") that will help to diagnose the presence of a Spinal Cord Tumor.
TREATMENT Non-surgical Since the natural history of Syringomyelia in any individual patient is not immediately apparent, particularly if they are not symptomatic, surgical management may not be required or appropriate. These patients should be carefully monitored by a neurologist or neurosurgeon with experience in this disorder. Serial MRI scans together with periodic neurological evaluations are important since the failure to identify early neurological deterioration could result in irreversible deficits. Follow up may be required for many years.It is apparent that not all patients will advance to the stage where surgery is required; it is also true that evaluation of the condition is often difficult because Syringomyelia patients can remain stationary for long periods of time, while others progress rapidly. Surgery As with many Brain and Spinal Cord disorders, it is important to find a Neurosurgeon with considerable experience in the treatment of Syringomyelia. Often times, that Neurosurgical Consultant is also highly experienced in the management of Arnold-Chiari Malformation patients.Surgery is the only available treatment for Syringomyelia since there are no medications, manipulations or interventions available for this disorder. Posterior Fossa Craniotomy/Craniectomy Once the patient with this disorder becomes symptomatic or develops progression of neurological deficits, definitive treatment is required. The objective of any treatment is to stop the progression of symptoms and hopefully to relieve the symptoms. While it is acknowledged that there are a variety of approaches that can be used, our considerable experience has convinced us that treatment is best accomplished by an operation that results in the "decompression" of the Brain Stem, Cerebellum and Spinal Cord, along with the re-establishment of more normal Cerebrospinal Fluid circulation.The operation, which is similar to the one advocated for Arnold-Chiari Malformation (called a Sub-occipital or Posterior Fossa Craniectomy) involves the removal of the bone from the back of the Posterior Fossa, (called the "Sub-occipital bone".) The outer covering of the Brain, (a tough leather-like substance called the Dura Mater) must also be opened and ultimately "expanded" by suturing in place a "dural graft". This combined procedure results in the establishment of much more room for the Brain, Brain Stem and the Spinal Cord. A critical portion of this operation involves microsurgically dividing the tense arachnoid bands that hold the Cerebellar Tonsils to the inside of the Dura Mater and to the Medulla. (This is described in greater detail below and illustrated in Figures 4A & 4B.) In most cases, depending on the unique anatomy of a particular patient, the back portion of the upper one or two Cervical Vertebrae must also be removed. (This is particularly done in only in those patients where it is imperative to successfully relieve any compression of the Spinal Cord from the downward migration of the Cerebellar Tonsils as occurs in the Arnold-Chiari Malformation.) The removal of the back portion of the vertebra is called a "Cervical Laminectomy". All portions of the procedures described above (Posterior or Sub-occipital Craniectomy, Superior Cervical Laminectomy and insertion of a Dural Decompression Graft) are accomplished at the same time, through the same surgical incision in the back of the head and upper neck. Our experience with over 200 patients with Arnold-Chiari Malformation (with over thirty years of follow up in some cases) has given us some unique insight into the methods to re-establish of Cerebrospinal Fluid circulation and to diminish the "water hammer" effect that appears to result in the formation of a Syrinx. We routinely microsurgically divide the tense arachnoid bands that hold the Cerebellar Tonsils to the inside of the Dura Mater and to the Medulla. Once this is accomplished, we routinely microsurgically separate the Cerebellar Tonsils, in the midline, free up these arachnoidal band-like attachments and then enter the lower to mid-portion of the Fourth Ventricle. Once this is done, CSF can escape the previously abnormal and confining environment, thus allowing for a re-establishment of a reabsorbtion pathway and the redirection of the CSF pulse wave away from the Central Canal of the Spinal Cord. This latter maneuver is extremely important, in our opinion and experience, in the successful treatment of most Syrinx related problems. While this may not entirely reverse the Syrinx and/or the symptoms, it usually aborts the inevitable progression of the Syrinx and frequently results in a flattening or disappearance of the Syrinx as the normal flow of Cerebrospinal Fluid is restored.
"Shunt Procedure" An alternative treatment involves the insertion of a tiny (1 millimeter diameter) Silastic tube (a shunt) into the Syringomyelia cavity. The operation consists of Laminectomy (removal of the Lamina - the roof of the Spinal Column) at the particular Spinal level overlying the Syrinx. After opening the Dura Mater, a tiny opening is made in the back of the Spinal Cord in order to insert the tube into the Syringomyelia cavity. The tube is fixed in place with a very fine non-absorbable (permanent) suture and serves to reroute the Cerebrospinal Fluid from within the Spinal Cord. A successful surgery will, hopefully, stabilize the condition and perhaps gain a modest improvement in symptoms. Unfortunately this operation requires opening the Spinal Cord over a miniscule segment which nevertheless, destroys that tiny portion of the Spinal Cord where the opening is made. In our experience, this invariably results in some sensory impairment and/or dysaesthesia (disagreeable altered sensation) since the area of the back of the Spinal Cord is a "sensory tract". Historically, over time, this surgery is not always successful and multiple surgeries may be necessary.Terminal Ventriculostomy The "Terminal Ventricle" is a peculiar anatomical structure that becomes apparent in some patients with Syringomyelia. The Central Canal of the Spinal Cord may be dilated at the end of the Spinal Cord. In these patients, it is possible to open into that "Ventricle" to place a tiny Silastic tube (similar to the one described above). This results in a "venting" or indirect decompression of the Syrinx which is connected to the Terminal Ventricle through the Spinal Cord's Central Canal. This operation can be accomplished using Minimally Invasive technique through a Thoraco-lumbar junction Laminectomy. It, as well, requires opening through "normal" Spinal Cord which means risking some neurological function. In this case the very end of the Spinal Cord may not place the patient at much risk. The actual risk depends on the precise location of this Terminal Ventricle.PROGNOSIS It is imperative to realize that early and definitive treatment is fundamental to the successful management of patients who are symptomatic from a Syrinx. The chances for successful resolution of the myriad of neurological problems that can accompany this syndrome are lessened the longer that a symptomatic patient delays definitive treatment. The symptoms due to Syringomyelia are more difficult to completely resolve compared to those associated with other spine disorders. The success here is inversely proportional to the extent of the Syrinx, the amount of Spinal Cord substance that has been destroyed, the extent of functional neurological impairment as well as the length of time of the neurological disturbance. It is for these reasons that early treatment is very important.For additional information contact the organizations below: National Institute of Neurological Disorders and Stroke(request Publication #94-3780 on Syringomyelia) National Institutes of Health Bethesda, MD 20892 USA
Office of Scientific and Health Reports
American Syringomyelia Alliance Project, Inc.
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All content ©2024 by Neurosurgical Consultants, P.A. Author, Martin L. Lazar, MD, FACS All Rights Reserved. See Usage Notices. |