Syringomyelia is an abnormal cystic collection of fluid, or syrinx that forms within the parenchyma of the spinal cord.
There are two major types of syringomyelia: congenital or acquired1. Most cases of congenital syringomyelia are associated with neurologic conditions, such as Chiari malformations; however, idiopathic and rare familial cases are described2. Acquired syringomyelia, also known as primary spinal syringomyelia, can be secondary to spinal cord injury, arachnoiditis, inflammatory or infectious conditions, or neoplasms.
Other terms used to describe syringomyelia include communicating or non-communicating syringomyelia. Communicating syringomyelia is caused by enlargement of the central canal in continuity with the 4th ventricle and is often associated with hydrocephalus 3. Noncommunicating syringomyelia refers to cavities without communication with the fourth ventricle and is often associated with trauma 4 . However, magnetic resonance imaging (MRI) studies have shown that most collections are not in continuity with the 4th ventricle, and therefore the terms communicating and noncommunicating are falling out of favor. Posttraumatic syringomyelia that occurs as a complication of spinal cord injury has been covered in a separate template, and therefore will not be covered here.
Epidemiology including risk factors and primary prevention
Children and young adults are most commonly affected by syringomyelia. Historical studies showed an overall prevalence of 9 per 100,000; however, the widespread use of MRI has increased detection. The majority of cases occur between the ages of 20 to 50, with mean age of onset at 30 years. Syringomyelia occurs more often in men than women 5. The most common cause of syringomyelia is Chiari I malformation 6 . Syringomyelia associated with Chiari malformations is most commonly cervical, whereas idiopathic cases may have a higher prevalence of thoracic lesions in children 7.Other, less common associations with syringomyelia include history of spinal cord trauma, spinal cord tumors, or post-inflammatory process such as transverse myelitis, arachnoiditis, and meningitis 8.
The pathophysiology of syringomyelia is not entirely understood. The majority of pathophysiological theories are described using Chiari I malformation as a cause of syringomyelia 8.It was historically believed that syrinx formation was the result of cerebrospinal fluid (CSF) being driven into the parenchyma of the spinal cord through persistent connections with the 4th ventricle or perivascular channels. Chiari I malformations affect the flow of CSF through the foramen magnum, resulting in altered fluid dynamics 9. Recent studies and theories, however, support the idea that the accumulations are at least partially because of impaired venous compliance leading to a build-up of extracellular fluid 10. Mass effect on neurons as well as chemical mediators, such as substance P, contribute to symptoms 11. Asymmetric syringomyelias result in differential growth in both the adjacent hemicord and vertebrae resulting in scoliosis.
There remains limited research on the pathophysiology of syringomyelia unrelated to Chiari I Malformation 8.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
Symptomatic syringomyelia presents with progressive neurologic deterioration over months to years, though rapid deterioration has been described. Initial symptoms from Chiari I malformations typically become clinically evident in young adulthood, and it can take several years from symptom onset until diagnosis 4.Symptoms of syringomyelia can vary between patients and some may be asymptomatic. The general symptoms of syringomyelia include pain, altered sensation, motor deficits, and autonomic dysfunction. Clinical examination findings often reveal extremity weakness, altered light touch and/or pain/temperature sensation in an irregular distribution, muscle wasting, scoliosis, ataxia, spasticity, and/or hyper- or hyporeflexia, depending on the level of syringomyelia 5. With earlier diagnosis made by MRI, the coexistent syringomyelia is often detected before the classical symptoms are evident. In cases of idiopathic syringomyelia detected on imaging, patients are often asymptomatic or do not have symptoms directly attributable to a syrinx 7.
Specific secondary or associated conditions and complications
In children with syringomyelia associated with Chiari I malformations, about 30% will have progressive scoliosis. Syringomyelia and Chiari I malformations are now more commonly being found in the workup of scoliosis. A left-sided curve, back pain, or other atypical symptoms should prompt the practitioner to have a higher level of suspicion for nonidiopathic causes for scoliosis. Hydrocephalus may also be associated with syringomyelia 12. Complications of syringomyelia include scoliosis, chronic pain, and symptoms associated with progressive myelopathy 13.
Essentials of Assessment
Syringomyelia is complex and initial presentation is often affected by etiology, location, and pathology., Patients may present with congenital anomalies or symptoms maybe clinically silent for long periods. Patients with concomitant Chiari I malformations often present with symptoms due to the malformation before manifestations of the syrinx itself. Chiari Malformations anomalies often manifest at two time points: (around 8-9 years of age or around 41-46 years of age) 14. These include headaches, clumsiness, inner ear dysfunction, altered facial sensations, ocular changes, dysarthria, and dysphagia. In children, one of the most prominent associations between Chiari malformation and Syringomyelia is early onset scoliosis 15. Symptoms from the syrinx itself include weakness, clumsiness, paresthesias, and dysesthesias. Symptoms do not necessarily follow an expected anatomical pattern based on location and may be unilateral. Unsteady gait, muscle atrophy, spasticity, urinary or fecal incontinence, or male impotence may also be described10,16.Neuropathic and Chronic Pain can be a sequel that presents during their thirties to forties 17.
A physical exam should include a thorough neurologic and musculoskeletal exam including evaluation of reflexes, tone, sensory, and motor function (Proctor). A Cobb Angle should be used to assess scoliotic curve 15). The classical description of a cape-like loss of pain and temperature sensation but preservation of light touch is rare. Nonmyotomal or nondermatomal motor and sensory defects are often asymmetric, as are altered reflexes 4.When associated with Chiari malformations, headache or neck pain can by exacerbated by maneuvers that increase CSF pressures, such as a Valsalva 13. Atrophy of intrinsic hand muscles or fasciculations may also be an early finding when anterior horn cells are affected. Signs of myelopathy in the lower extremities, such as spasticity, can become evident as the disease progresses. Neuropathic pain described as burning, or shock like can be elicited 17
Patients with motor and sensory deficits should be assessed for strength, balance, bed mobility, transfer status, ambulatory or wheelchair mobility status, as well as their ability to bathe, dress, and groom. Because pain medications can affect cognition, assessment of school or work skills, driving skills, memory, safety awareness, attention, medication management, and finance management should be undertaken. Coughing, hypoxia, or wet dysphonia are frank indicators for swallowing evaluation, but patients should be evaluated for silent aspiration.
The diagnosis of syringomyelia is confirmed with MRI imaging, but laboratory testing can be used to rule in or out the cause of a syrinx of unknown etiology. Syringomyelia has been found as sequelae of spinal infections as well as in the setting of tuberculosis, and if clinical suspicion is high, testing for these causes is warranted. Testing for systemic inflammatory conditions may also be useful in certain cases with unclear etiology.
MRI is the gold standard for diagnosis of syringomyelia. Specifically, T1-,T2-, FLAIR-,T2*, enhanced T1 sequences are used to evaluate the syrinx. Dynamic MRI with study of CSF flow is used to confirm the diagnosis. Cine phase contrast MRI yields detailed information on both anatomy and CSF flow. Impairment of cerebrospinal fluid flow across the foramen magnum can be used to select patients for surgical decompression of the foramen and can be predictive of symptom recurrence after surgery. To identify the site of cerebral spinal fluid obstruction, a 3D constructive interference sequence in steady state or phase contrast MR can be used 17
. CT myelography can be used when MRI is unavailable or unsafe.
Supplemental assessment tools
Electromyographic (EMG) studies may be used early in the work-up of extremity pain, weakness, or sensory changes to determine their etiology. SSEP/MEP differences can sometimes be detected before clinical changes17They may also be used to measure disease progression over time for patients being treated conservatively or postoperatively. More detailed imaging of the spinal column with plain radiographs or CT may help evaluate coexisting scoliosis 4.
Early predictions of outcomes
Increased age and duration of symptoms at the time of surgical decompression have been shown to predict worse clinical outcomes for patients with a syrinx and Chiari malformation 18. Early decompression of Chiari I malformations may halt the progression or improve associated spinal deformities. While symptoms may stabilize for some patients, progressive symptoms should be treated aggressively, because they can lead to increased morbidity and even death 4. . Surgical outcomes including syrinx size and complication rate did not differ with decompression between an extra arachnoid technique and arachnoid dissection 19.
Syringomyelia is most often associated with Chiari I malformations and posttraumatic causes. Less common etiologies include postinfectious and postinflammatory causes. Case reports of familial causes exist, but there are no clear environmental links to syringomyelia at this time.
Social role and social support system
Patients may require assistance with redefining their social roles as impairments worsen and more adaptive equipment is needed. Assistance should be provided for developing a support network of family, friends, clergy, social work, peer support, vocational rehabilitation, coordination with school and work staff, and respite programs.
Parents (or legal guardians) should be intimately involved in the decision-making process for pediatric patients. Delay in treatment once neurologic symptoms develop could result in poor outcomes 20, 21.
Rehabilitation Management and Treatments
Available or current treatment guidelines
There are no formal published treatment guidelines for nontraumatic syringomyelia. In general, current management is individualized to the patient’s symptoms.
At different disease stages
The natural history of Chiari malformations and associated syringomyelia is unpredictable
Nonoperative management may be considered for patients with small 2 level syrinxes and who are asymptomatic or have relatively mild symptoms; however, they must be monitored regularly with MRI.8,11,13-15, 16, 20, 22-25
Patients with new neurologic symptoms, mass lesions, worsening pain, expanding syrinxes, or increasing scoliosis should be referred for neurosurgical evaluation. Neurosurgical evaluation should occur before scoliosis surgery because of the increased risk of neurologic deterioration 20.Hydrocephalus should be shunted before considering surgery for syringomyelia 4.
The goal of surgical treatment is to restore CSF flow. Neurosurgical approaches may include suboccipital decompression, duroplasty, laminectomy, tonsillar resection, removal of subarachnoid adhesions, shunting, cord untethering, syrinx fenestration, removal of tumor, infection, or arteriovenous malformation 20,22-24.Medical postoperative complications include aseptic or bacterial meningitis, deep venous thrombosis, urinary tract infection, and pneumonia.9 Therefore, standards of care should include infection prevention, venous thromboembolism prophylaxis, early removal of indwelling catheters, and bladder assessment and adequate pulmonary hygiene. Other surgical complications can include peri-operative hematomas, cerebrospinal fluid leakage, shunt obstruction and scar formation 26.
Stable postoperative patients should receive physical therapy, occupational therapy, and speech therapy. Goals are to relieve pain, preserve range of motion, normalize tone, and improve balance, strength, swallow, phonation, respiration, fine and gross motor coordination, activities of daily living, and sitting balance. Psychosocial counseling may help with coping. Pain may be treated with nonsteroidal anti-inflammatory drugs, muscle relaxants, anticonvulsants, antidepressants, topical agents, or narcotics 22.No drugs have been evaluated specifically for neuropathic pain in syringomyelia in humans. Tricyclic antidepressants such as amitriptyline have been shown useful in other conditions, but anticholinergic side effects must be considered Gabapentin and pregabalin have been shown to be effective in neuropathic pain in spinal cord injury with no difference in efficacy between the two . Lamotrigine and Carbemazapine have been moved to second line due to their side effect profiles Strong opioids are the last line of treatment 17. Sympathetic blockades may be helpful 11.There is no evidence that spinal infusions or modalities (electric stimulation, heat, massage) are helpful 22. Although there are reports that chiropractic treatment may improve pain and posture in syringomyelia, this has not been validated and is not a current standard of practice27. A case report suggests spinal cord stimulation may be effective for patients with syringomyelia related neuropathic pain 30.
Long-term complications can include shunt failure, catheter tip migration, and syrinx recurrence. If neurologic decline occurs, the patient should be referred back to neurosurgery 24.
Coordination of care
Care should be coordinated between the primary care physician or pediatrician, physiatrist, rehabilitation nurses, neurosurgeon, orthopedic surgeon, pain specialist, psychiatrist, social worker, physical therapist, occupational therapist, speech-language pathologist, dietician, and third-party payers. Community resources may include, but are not limited to, vocational rehabilitation, driver rehabilitation, support groups, sports programs, school programs, and legal and financial aid groups.
Patient & family education
Information for patients and families can be obtained from the Chiari & Syringomyelia Foundation or the American Syringomyelia & Chiari Alliance Project. Chiari Malformation and Syringomyelia–A Handbook for Patients and Their Families is available 28.
There are no outcome measures specific to syringomyelia. Neurosurgical and orthopedic studies have looked at syrinx size, neurologic symptoms, pain symptoms, rate of scoliosis curve progression, and American Spinal Injury Association motor scores as outcome indicators 11,29.EMG and somatosensory evoked potentials may be used for monitoring postsurgical outcomes. Rehabilitation-based functional measures have not been studied.
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
The presence of syringomyelia requires life-long management. Delay in treatment once neurologic symptoms appear may result in poorer outcomes 20, 21.
Cutting Edge/ Emerging and Unique Concepts and Practice:
Dynamic contrast-enhanced MRI technology enables viewing of spinal fluid pulsating within the syrinx, even before symptoms appear in syringomyelia.29
Exploration of the factors and their role in the development and progression of syringomyelia is researched in the following areas31:
- Role of genetic factors related to a Chiari I malformation.
- Learning the role of birth defects in the development of hindbrain malformations.
- Abnormal CSF flow that may contribute to the progression.
- Developing preventive treatment to stop the formation of birth defects.
- Role for the cardiovascular system, as evidenced by forceful downward movement of the CSF with heartbeat.
- Improvement in surgical techniques.
Gaps in the Evidence- Based Knowledge:
There are no evidence-based guidelines.
Rehabilitation is focused on ameliorating symptoms and not on a scientific evidence base. The exact mechanism of syrinx development remains unknown and no prevention or cure exists. Surgery for the treatment of syringomyelia may not be successful over the long term in relieving symptoms. The role of shunting procedures is questioned, and more recently their placement is regarded as a last resort 31.Although the diagnosis is easily done today with the relatively common availability of MRI scanning, it is difficult to decide what the optimal treatment strategy is for the individual patient. Considerable controversy still surrounds the management of hindbrain hernia and syringomyelia, and this debate is largely because of the uncharted natural history of the condition. Inevitably, any discussion of the management of syringomyelia involves intimately the management of Chiari I malformation 16 .The unanswered questions are when do hindbrain hernia/Chiari I malformation and syringomyelia or recurrent syringomyelia or associated hydrocephalus need treatment and what are the best surgical procedures? 16
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Original Version of the Topic
Jean L. Nickels, MD, K. Rao Poduri, MD. Syringomyelia. 9/20/2013
Previous Revision(s) of the Topic
Jean L. Nickels, MD, K. Rao Poduri, MD. Syringomyelia. 5/5/2016
Andriana Tompory, DO
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Jean L Nickels, MD
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Susan Belcher, MD
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K. Rao Poduri, MD
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