Spina Bifida Family Support
"Families Helping Families"
Author: Hassan A Al-Shatoury, MD, MSc, Research Fellow, Department of Neurosurgery, University of Illinois at Chicago - Coauthor(s): Franklin C Wagner, Jr, MD, Chief, Division of Spine and Spinal Cord Surgery, Professor, Department of Neurosurgery, University of Illinois at Chicago College of Medicine
Background: Syringomyelia is the development of a fluid-filled cavity or syrinx within the spinal cord. Hydromyelia is a dilatation of the central canal by cerebrospinal fluid (CSF) and may be included within the definition of syringomyelia. Types of syringomyelia include the following:
Syringomyelia with fourth ventricle communication
About 10% of syringomyelia cases are of this type. This communication can be observed on MRI. In some cases, a blockage of CSF circulation occurs. A shunt operation may be the best therapeutic option for these patients.
Syringomyelia due to blockage of CSF circulation (without fourth ventricular communication)
Representing at least 50% of all cases, this is the most common type of syringomyelia. Obstruction of CSF circulation from the basal posterior fossa to the caudal space may cause syringomyelia of this type. The most common example is Arnold-Chiari malformation, which also is associated with communicating syringomyelia. Other causes include the following:
Basal arachnoiditis (postinfectious, inflammatory, postirradiation, blood in subarachnoid space)
Basilar impression or invagination
Pathological masses (arachnoid cysts, rheumatoid arthritis pannus, occipital encephalocele, tumors)
Syringomyelia due to spinal cord injury
Fewer than 10% of syringomyelia cases are of this type. Mechanisms of injury include (1) spinal trauma, (2) radiation necrosis, (3) hemorrhage from aneurysm rupture or arteriovenous malformation or in a tumor bed, (4) infection (spinal abscess, human immunodeficiency virus, transverse myelitis), and (5) cavitation following ischemic injury or degenerative disease.
Syringomyelia and spinal dysraphism
Spinal dysraphism may cause syringomyelia through a variety of mechanisms, including those mentioned under the previous 3 categories. Identification and treatment of associated dysraphism has the greatest impact on arresting progression of syringomyelia.
Syringomyelia due to intramedullary tumors
Fluid accumulation usually is caused by secretion from neoplastic cells or hemorrhage. The tumors most often associated with syringomyelia are ependymoma and hemangioblastoma. Extramedullary intradural and extradural tumors are considered separately under the second category because the mechanism of syrinx formation is blockage of the CSF pathway.
Idiopathic syringomyelia has an unknown cause and cannot be classified under any of the previous categories.
Pathophysiology: Although many mechanisms for syrinx formation have been postulated, the exact pathogenesis is still unknown. Frequently cited theories are those of Gardner, William, and Oldfield.
Gardner's hydrodynamic theory
This theory proposes that syringomyelia results from a “water hammer”-like transmission of pulsatile CSF pressure via a communication between the fourth ventricle and the central canal of the spinal cord through the obex. A blockage of the foramen of Magendie initiates this process.
This theory proposes that syrinx development, particularly in patients with Chiari malformation, follows a differential between intracranial pressure and spinal pressure caused by a valvelike action at the foramen magnum. The increase in subarachnoid fluid pressure from increased venous pressure during coughing or Valsalva maneuvers is localized to the intracranial compartment.
The hindbrain malformation prevents the increased CSF pressure from dissipating caudally. During Valsalva, a progressive increase in cisterna magna pressure occurs simultaneously with a decrease in spinal subarachnoid pressure. This craniospinal pressure gradient draws CSF caudally into the syrinx.
Downward movement of the cerebellar tonsils during systole can be visualized with dynamic MRI. This oscillation creates a piston effect in the spinal subarachnoid space that acts on the surface of the spinal cord and forces CSF through the perivascular and interstitial spaces into the syrinx raising intramedullary pressure. Signs and symptoms of neurological dysfunction that appear with distension of the syrinx are due to compression of long tracts, neurons, and microcirculation. Symptoms referable to raised intramedullary pressure are potentially reversible by syrinx decompression.
History: Syringomyelia usually progresses slowly; the course may extend over many years. The condition may have a more acute course, especially when the brain stem is affected (ie, syringobulbia). Syringomyelia usually involves the cervical area. Symptomatic presentation depends primarily on the location of the lesion within the neuraxis. Clinical manifestations include the following:
Dissociated sensory loss: Syrinx interrupts the decussating spinothalamic fibers that mediate pain and temperature sensibility, resulting in loss of these sensations, while light touch, vibration, and position senses are preserved.
When the cavity enlarges to involve the posterior columns, position and vibration senses in the feet are lost; astereognosis may be noted in the hands.
Pain and temperature sensation may be impaired in either or both arms, or in a shawllike distribution across the shoulders and upper torso anteriorly and posteriorly.
Dysesthetic pain, a common complaint in syringomyelia, usually involves the neck and shoulders, but may follow a radicular distribution in the arms or trunk. The discomfort, which is sometimes experienced early in the course of the disease, generally is deep and aching and can be severe.
Syrinx extension into the anterior horns of the spinal cord damages motor neurons and causes diffuse muscle atrophy that begins in the hands and progresses proximally to include the forearms and shoulder girdles. Clawhand may develop.
Respiratory insufficiency, which usually is related to changes in position, may occur.
Arm reflexes are diminished early in the clinical course.
Lower limb spasticity, which may be asymmetrical, appears with other long-tract signs such as paraparesis, hyperreflexia, and extensor plantar responses.
Rectal examination includes an evaluation of volitional sphincter control and sensory assessment of sacral dermatomes.
Dissociated sensory impairment may be noted.
The syrinx may extend into the brain stem, affecting cranial nerves or cerebellar function.
Brainstem signs are common in syringomyelia associated with Chiari malformations.
Causes: Etiology of syringomyelia often is associated with craniovertebral junction abnormalities.
Other Problems to be Considered:
Craniovertebral junction anomalies
Increased intracranial pressure
Intrinsic tumors of the spinal cord
Cervical disk syndromes
Surgical Care: A variety of surgical treatments have been proposed for syringomyelia.
Diet: No specific diet is recommended for syringomyelia;
however, normalizing weight is encouraged, especially in patients with
Further Inpatient Care:
Worsening of neurological deficit
Shunt infection or obstruction
Further Outpatient Care:
Paraplegia or quadriplegia
Bowel and urinary dysfunction
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