Author(s): Kate Delaney, MD, Kendl Sankary, MD
Originally published: December 10, 2012 Last updated: June 19, 2024
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Disease/Disorder

Definition

Syringomyelia is the development of a longitudinal fluid-filled cyst, also referred to as a syrinx, within the grey matter of the spinal cord. The syrinx can expand rostrally or caudally and cause progressive weakness, stiffness, or chronic pain. Other symptoms include headaches, loss of temperature, sensation, and loss of bladder and bowel functions. Post-traumatic syringomyelia (PTS) occurs as a delayed complication in patients with traumatic spinal cord injury (SCI) but can also occur spontaneously or congenitally. Non-traumatic causes of syringomyelia will not be covered here.1

Etiology

After traumatic SCI, scar formation in the subarachnoid space can impair cerebrospinal fluid (CSF) flow, while enlarged perivascular spaces allow CSF to enter the gray matter and form a cyst-like cavity.2,3

PTS is more common after complete SCI but may occur following incomplete injuries and occurs following both tetraplegic and paraplegic injuries.4

Epidemiology including risk factors and primary prevention

The incidence of PTS is estimated at 25%-30% of new patients with traumatic SCI as seen on magnetic resonance imaging (MRI) studies, and the prevalence of asymptomatic PTS is estimated at approximately 28%.4 Post-mortem studies have reported an incidence of PTS of 22% in autopsies. PTS occurs more commonly in males since traumatic spinal cord injury occurs more commonly in males. It is also more commonly seen in complete injuries than in incomplete injuries, and in thoracic and cervical injuries as compared to lumbar SCI.5 Delayed PTS can cause significant morbidity in this patient population,2 and PTS is thought to cause neurologic decline in 3%-8% of patients with SCI.6 Progressive signs and symptoms may develop as early as three months after SCI but more typically within 5 years to decades after injury.1

Patho-anatomy/physiology

Although the precise pathogenesis of PTS is not known, it is thought to begin at the time of injury or shortly thereafter. Recent evidence supports the broadly accepted mechanism that spinal trauma causes subarachnoid fibrotic scarring, leading to obstruction of CSF flow.7 Reactive ependymal proliferation may cause segmental closures within the central canal, local distension, and passage of CSF into the grey matter of the spinal cord via enlarged perivascular spaces (i.e., Virchow-Robin spaces) in the perisyringeal region.2,3,7 The formation of arachnoid adhesions may further alter CSF flow dynamics such that CSF enters the spinal cord and causes progressive syringomyelia.8 Alternatively, ischemia within watershed regions of the spinal cord promotes release of destructive enzymes, free radical products, and other toxic agents causing cell apoptosis and extracellular fluid to coalesce into a syrinx.9

Most commonly, the syrinx extends superiorly from the level of SCI; however, it may extend inferiorly as well. The mechanism involved in the enlargement of previously stable post-traumatic syrinx cavities remains unclear but likely involves alterations in CSF flow dynamics and fluid turbulence within the syrinx cavity itself.1,10 It is also possible that worsening thoracic kyphosis and spinal stenosis contributes to alteration in fluid dynamics and syrinx formation.5

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

The mean interval from SCI to diagnosis is 9 to 15 years, but the reported range is as early as one month and as late as 45 years after injury.11 Often, a syrinx is an incidental finding on MRI. The most common symptoms of PTS include worsening sensory disturbance, new-onset neuropathic pain, autonomic dysfunction, spasticity, or motor weakness. PTS should be suspected in previously stable SCI patients who present with new neurological signs/symptoms above their level of injury, such as dissociated sensory loss, loss of reflexes, and new motor deficits. New-onset bladder or erectile dysfunction have been reported.12 Clinical symptoms may remain stable or may progress as the syrinx enlarges over time. Normally, disease progression is insidious, but there have been reports of rapid deterioration from hemorrhage into a syrinx or of rapid syrinx formation after operative intervention for acute SCI.13,14

Specific secondary or associated conditions and complications

Symptomatic PTS may lead to new physical impairments, functional decline, and other SCI-related complications. For example, a patient with C6 tetraplegia who relies on tenodesis for gripping objects could lose wrist extension and become more dependent on others for self-care.

Essentials of Assessment

History

Patients with PTS most commonly present with increased neuropathic pain at the level of the lesion or with a gradually ascending sensory impairment. They may also complain of increased spasticity or decreased strength. Some patients experience autonomic dysfunction, such as worsening orthostatic hypotension, autonomic dysreflexia or increased sweating.

Physical examination

A comprehensive neurological examination in accordance with the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) is important, both to evaluate new symptoms and to detect potentially insidious deficits. Initial findings consistent with PTS are ascending loss of deep tendon reflexes and pin prick sensation, which is often unilateral.6 Patients will often present with an increase in spasticity without an identifiable cause such as a urinary tract infection. Findings of a Charcot joint, dysautonomia, and late spinal deformity are common in PTS and should prompt further work-up.15

Functional assessment

PTS may cause further impairment in muscle strength, which can result in loss of independence with self-care and mobility. Ongoing functional assessments are important to assess for any decline and determine the level of assistance needed. Patients may require new physical therapy or occupational therapy assessment, or psychological evaluation for adjustment to changes in their disability.

Laboratory studies

A normal urinalysis in a patient presenting with a marked increase in spasticity, autonomic dysreflexia or orthostatic hypotension should prompt the clinician to consider the diagnosis of PTS instead of a urinary tract infection.

Imaging

MRI T1- and T2-weighted images are the primary imaging modality used to diagnose PTS. A well demarcated fluid-filled cyst within the spinal cord will have characteristics similar to CSF. If the syrinx fluid is hypointense on T2-weighted imaging compared to CSF, this indicates a flow void and increased pressure.13 Images taken in rapid succession can be used for “dynamic imaging” (i.e., “cine mode”) to observe CSF flowing around the spinal cord and within the syrinx. MRI with intravenous gadolinium may help to differentiate between a syrinx, intra- or extramedullary spinal cord tumors, arteriovenous malformations and multiple sclerosis. Computed tomography (CT) with contrast may complement the use of MRI in characterizing these lesions and evaluate progression and response to treatment.16 For patients who are unable to get an MRI, a plain CT spine may show radiolucency in the intradural space and CT myelogram with contrast may show enhancement of the syrinx. CT myelogram could be used to investigate CSF flow and for any extradural sites of obstruction.17

Supplemental assessment tools

Electrodiagnostic (EDX) testing may be useful in characterizing whether there may be a peripheral nerve contribution to the patient’s symptoms, such as a compressive mononeuropathy or plexopathy. However, MRI is the diagnostic modality of choice for PTS since commonly performed EDX techniques are not sensitive nor specific for PTS.18

Early predictions of outcomes

PTS follows a largely unpredictable disease progression. It is difficult to determine which patients will experience further neurological decline based solely on imaging findings. However, standardized tools to assess function, such as the Functional Independence Measures (FIM) instrument or Section GG that identifies functional abilities and goals as the new basis for Case Mix Groups [CMGs] can be used to objectively track a subject’s self-care, sphincteric control, mobility, and other functional measures.

Social role and social support system

Patients and their families must consider new functional impairments that result from PTS including the patient’s ability for self-care and mobility. These factors directly affect caregiver burden and patients may require more assistance in the home or need institutional care.

Rehabilitation Management and Treatments

Available or current treatment guidelines

Although there is no universally accepted clinical practice guideline for the management of PTS, the following guidelines have been proposed by a meta-analysis.4,15

  • Surgical decompression of PTS is not recommended for sensory loss or pain. (weak)
  • Surgical decompression is not recommended for asymptomatic, but expanding PTS. (weak)
  • Surgical decompression is recommended for patients developing motor weakness in the setting of PTS. (strong)
  • The preferred surgical technique for treatment of PTS is spinal cord untethering with expansile duraplasty. (weak)
  • There is no indication for direct surgical decompression at the time of initial injury for the purpose of preventing symptomatic syringomyelia, due to its low incidence.

Surgical decompression is aimed at restoring normal CSF flow. In rare cases, a shunting procedure may be necessary to drain the cystic cavity within the spinal cord. Shunts, however, frequently become clogged or dislodged, which may necessitate a repeat surgical procedure. The medical literature does not support one surgical technique as superior to another; however, a consensus panel gave a weak recommendation that spinal cord untethering with expansile duraplasty as the preferred first-line surgical technique.4

Syrinx formation recurs after surgical decompression in 50% of patients at 5 years. With the low incidence of symptomatic PTS and the high recurrence of syrinx formation after surgical decompression, there is no indication for prophylactic decompression at the time of initial injury.19 There is little evidence on surgical decompression for asymptomatic PTS that is expanding on MRI.4 Decompression surgery in PTS has been shown to be effective at preventing or improving motor strength deficits, but not sensory dysfunction or neuropathic pain. Interestingly, a retrospective study of 34 patients found that a change in syrinx volume post-operatively is not correlated with clinical outcomes.16 An observational study of 23 patients found that those with a moniliform syrinx as opposed to a distended syrinx had better surgical outcomes.20

Despite early diagnosis of PTS with MRI, there is not currently a widely agreed upon gold standard of treatment.5

At different disease stages

Patients with SCI who have MRI evidence of syrinx formation without new motor deficit should be managed conservatively with frequent imaging follow-up. Physical therapy intervention may help preserve or improve patients’ range of motion, muscle strength, endurance, and balance. Patients should avoid exercises that create Valsalva-like effects due to concern for increasing intrathoracic pressure and possible expansion of the syrinx due to a propulsion of CSF from epidural venous expansion.21 Occupational therapy evaluation may focus on reconfiguring splinting or other assistive devices to facilitate self-care tasks. Patients who have a decline in motor strength should have a neurosurgical consultation to discuss the risks and benefits of pursuing surgical intervention.

Coordination of care

Coordination of care among rehabilitation physicians, pain specialists, neurosurgeons, physical and occupational therapists and nursing staff is critical to optimizing the patient’s treatment. Timely identification of plateaus in neurological improvement, neurologic decline or newfound impairments in motor function drives treatment decisions. An updated neurologic exam and documented functional assessment should be readily available so that new deficits can be easily identified and shared amongst team members. Of equal importance is setting patient and caregiver expectations for changing functional needs and consideration for additional assistance at home or placement in a more supportive environment.

Patient & family education

The patient and family should be educated to identify and report any neurological changes or decrement in function to their SCI physician. Syrinx should be described as a complication from SCI that is treatable, to emphasize the importance of timely notification and examination from their physician. Information should be provided to patient and families about support groups and available resources within their respective communities.

Emerging/unique interventions

There are a few studies of using neuro-epithelial stem cells to treat PTS in rodent models,22,23 which demonstrate reduction in syrinx size as well as evidence tissue repair. There is one case report as well as publication of phase 2 clinical trial data demonstrating improvement in syrinx size on MRI as well as improvement in clinical symptoms for all patients.24,25 More invasive surgical techniques such as spinal cordectomy or spinal cord detethering and myelotomy may show benefit, but have not yet widely been adopted for PTS as more investigation is needed to determine if the benefit outweighs the increased risk.26,27

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

Serial neurologic examinations after traumatic SCI are necessary to detect change in baseline neurological status. Physicians should always consider the possibility of PTS to explain neurologic decline in a previously stable patient with history of traumatic SCI. Surgical decompression has been shown to clinically improve motor weakness secondary to syrinx formation, but generally does not change sensory loss or neuropathic pain.

Cutting Edge/Emerging and Unique Concepts and Practice

In 2018, a study performed on rats with SCI was conducted to evaluate the advantages of Diffusion Tensor Imaging (DTI) to estimate PTS formation after SCI. DTI and Diffuse Tensor Tractography (DTT) were used to analyze neuro-fiber changes after SCI. The conclusion of the study showed that the combination of DTI and DTT has characteristics of high-sensitivity and quantitation for PTS prognosis and can be predictive in the prognosis of PTS formation after SCI.28 A study of rats with PTS demonstrated that utilizing current techniques for assessing motor function in rats (Gait Analysis Instrumentation and Technology Optimized for Rodents (GAITOR) and Automated Gait Analysis Through Hues and Areas (AGATHA)) can demonstrate small changes due to PTS.29 These findings may help advance the study of PTS treatments in rodent models and translational research.

Gaps in the Evidence-Based Knowledge

It remains controversial if patients with symptomatic PTS without motor deficit benefit from surgical decompression by reduction in pain or return of sensation. While there are multiple options for PTS shunting procedures, there are not clear criteria for which patients may benefit best from which technique. There is also a gap in the medical literature regarding proper diagnostic approach and treatment for asymptomatic SCI patients with radiological evidence of an enlarging syrinx.

References

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  2. Curati WL, Kingsley DPE, Kendall BE, Moseley IF. MRI in chronic spinal cord trauma. Neuroradiology. 1992;35(1):30-35. doi:10.1007/BF00588274
  3. Johnson L, Bartlett-Tomasetig F, Fok S, et al. A novel method to quantify perivascular space enlargement near the syrinx in a rodent model of post-traumatic syringomyelia. Sci Rep. 2023;13(1):15043. doi:10.1038/s41598-023-42275-y
  4. Bonfield CM, Levi AD, Arnold PM, Okonkwo DO. Surgical Management of Post-Traumatic Syringomyelia. Spine (Phila Pa 1976). 2010;35(Supplement):S245-S258. doi:10.1097/BRS.0b013e3181f32e9c
  5. Kleindienst A, Laut FM, Roeckelein V, Buchfelder M, Dodoo-Schittko F. Treatment of posttraumatic syringomyelia: evidence from a systematic review. Acta Neurochir (Wien). 2020;162(10):2541-2556. doi:10.1007/s00701-020-04529-w
  6. Scelza WM, Dyson-Hudson TA. Neuromusculoskeletal complications of spinal cord injury. In: Kirshblum S, Campagnolo D, eds. Spinal Cord Medicine. 2nd ed. Lippincott Williams and Wilkins; 2011:282-308.
  7. Macdonald RL, Findlay JM, Tator CH. Microcystic spinal cord degeneration causing posttraumatic myelopathy. J Neurosurg. 1988;68(3):466-471. doi:10.3171/jns.1988.68.3.0466
  8. Kerslake RW, Jaspan T, Worthington BS. Magnetic resonance imaging of spinal trauma. Br J Radiol. 1991;64(761):386-402. doi:10.1259/0007-1285-64-761-386
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  11. Goetz LL, De Jesus O, McAvoy SM. Posttraumatic Syringomyelia. StatPearls.
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  14. Biswas A, Pandey SK, Gupta AK, Pandey J, Ghosh S. Very rare incidence of ascending paralysis in a patient of traumatic spinal cord injury: a case report. Spinal Cord Ser Cases. 2022;8(1):69. doi:10.1038/s41394-022-00536-4
  15. Klekamp J. Treatment of posttraumatic syringomyelia. J Neurosurg Spine. 2012;17(3):199-211. doi:10.3171/2012.5.SPINE11904
  16. Li YD, Therasse C, Kesavabhotla K, Lamano JB, Ganju A. Radiographic assessment of surgical treatment of post-traumatic syringomyelia. J Spinal Cord Med. 2021;44(6):861-869. doi:10.1080/10790268.2020.1743086
  17. Holly LT, Batzdorf U. Chiari malformation and syringomyelia. J Neurosurg Spine. 2019;31(5):619-628. doi:10.3171/2019.7.SPINE181139
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  19. Fadhil M, Wilson PJ, Reddy R. Does Direct Surgical Decompression After Traumatic Spinal Cord Injury Influence Post-Traumatic Syringomyelia Rates? An 18-Year Single-Center Experience. World Neurosurg. 2022;161:e664-e673. doi:10.1016/j.wneu.2022.02.074
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  23. Xu N, Xu T, Mirasol R, et al. Transplantation of Human Neural Precursor Cells Reverses Syrinx Growth in a Rat Model of Post-Traumatic Syringomyelia. Neurotherapeutics. 2021;18(2):1257-1272. doi:10.1007/s13311-020-00987-3
  24. Vaquero J, Hassan R, Fernández C, Rodríguez-Boto G, Zurita M. Cell Therapy as a New Approach to the Treatment of Posttraumatic Syringomyelia. World Neurosurg. 2017;107:1047.e5-1047.e8. doi:10.1016/j.wneu.2017.08.019
  25. Vaquero J, Zurita M, Rico MA, et al. Cell therapy with autologous mesenchymal stromal cells in post-traumatic syringomyelia. Cytotherapy. 2018;20(6):796-805. doi:10.1016/j.jcyt.2018.04.006
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  27. Azad TD, Materi J, Hwang BY, et al. Spinal cord untethering and midline myelotomy for delayed, symptomatic post-traumatic syringomyelia due to retained ballistic fragments: case report. Spinal Cord Ser Cases. 2022;8(1):66. doi:10.1038/s41394-022-00533-7
  28. Zhang C, Chen K, Han X, et al. Diffusion Tensor Imaging in Diagnosis of Post-Traumatic Syringomyelia in Spinal Cord Injury in Rats. Med Sci Monit. 2018;24:177-182. doi:10.12659/msm.907955
  29. Pukale DD, Farrag M, Leipzig ND. Detection of locomotion deficit in a post-traumatic syringomyelia rat model using automated gait analysis technique. PLoS One. 2021;16(11):e0252559. doi:10.1371/journal.pone.0252559

Original Version of the Topic

Robert E Moore, MD, Scott Campea, MD. Post-traumatic syringomyelia. 12/10/2012.

Previous Revision(s) of the Topic

Rajashree Srinivasan, MD, Angela Vrooman, DO. Post-traumatic syringomyelia. 8/18/2016.

Kirill Alekseyev, MD, MBA, Joshua Chen, MD. Post-Traumatic Syringomyelia. 5/12/2021

Author Disclosures

Kate Delaney, MD
Nothing to Disclose

Kendl Sankary, MD
Nothing to Disclose