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 pain1. Other symptoms include headaches, loss of temperature sensation, and loss of bladder and bowel functions2. Post-traumatic syringomyelia (PTS) occurs as a delayed complication in patients with traumatic spinal cord injury (SCI). Congenital causes of syringomyelia will not be covered here.
PTS is more common after complete SCI but may occur following incomplete injuries, and occurs following both tetraplegic and paraplegic injuries3.
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) studies3. Post-mortem studies have reported an incidence of 22% in autopsies. Delayed PTS can cause significant morbidity in this patient population4. PTS is thought to cause neurologic decline in only 3%-8% of patients with SCI5. Progressive signs and symptoms may develop as early as three months after SCI but generally within 5 years or as late as 32 years after injury1,6-7. Symptomatic PTS has a reported prevalence rate of 4%, but the prevalence of asymptomatic PTS among patients with SCI is estimated at approximately 28%8.
Although the precise pathogenesis of PTS is not known, it is thought to begin at the time of injury or shortly thereafter. The most widely accepted mechanism holds that spinal trauma causes subarachnoid scarring, leading to obstruction of cerebrospinal fluid (CSF) flow. Reactive ependymal proliferation may cause segmental closures within the central canal, local distension, and passage of cerebrospinal fluid (CSF) into the grey matter of the spinal cord via enlarged perivascular spaces (i.e., Virchow-Robin spaces)4,6,9. The formation of arachnoid adhesions may further alter CSF flow dynamics such that CSF enters the spinal cord causing progressive syringomyelia10. 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 syrinx11.
Most commonly, the syrinx extends superiorly from the level of SCI; however, it may extend inferiorly12. 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 itself13-14.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
The mean interval from SCI to diagnosis of PTS is 2.8 years with a range of 3 months to 34 years. Often, a syrinx is found as 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, reflex abolition, and motor deficit. New-onset bladder or erectile dysfunction have been reported15. Deficits 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 syrinx16.
Specific secondary or associated conditions and complications
Symptomatic PTS may worsen an incomplete SCI leading to new physical impairments, functional decline, and other SCI-related complications. For example, a patient with a C6 tetraplegia who relies on tenodesis for gripping objects could lose wrist extension and become more dependent on others for self-care.
2. ESSENTIALS OF ASSESSMENT
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 orthostatic hypotension, autonomic dysreflexia or increased sweating.
A comprehensive neurological examination in accordance with the International Standards for Neurological Classification of Spinal Cord Injury 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.5 Patients will often present with increases in spasticity without an evident 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-up17.
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 supportive psychological counseling for adjustment to changes in their disability.
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.
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 pressure16. Images taken in rapid succession can be used for “dynamic imaging” (ie “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, ateriovenous malformations and multiple sclerosis. Computed tomography (CT) with contrast may complement the use of MRI in characterizing these lesions.
Supplemental assessment tools
Electrodiagnostic (EDX) testing is useful in characterizing an individual patient’s neurologic status. In PTS, clinical findings are consistent with a mixed upper and lower motor neuron lesion. Initially, prolonged F-waves and decreased conduction velocity on motor-evoked potential testing may be seen. Later findings suggest motor neuron loss with axonal sprouting such as enlarged motor unit action potential amplitudes and reduced recruitment1. Reduced compound muscle action potential amplitudes may be seen, but sensory nerve action potentials should be preserved. EDX is useful in differentiating neurological decline due to PTS from that caused by a co-existing plexopathy or peripheral nerve injury.
Early predictions of outcomes
PTS follows a largely unpredictable course. It is difficult to determine which patients will experience further neurological decline based solely on imaging findings. However, activity participation and environmentally based outcomes can be measured using the Functional Independence Measures (FIM) instrument.
Social role and social support system
Loss of function may take away a patient’s independence and negatively affect their social integration. Newly developed impairments in self-care and mobility increase care-giver burden. Patients may require more assistance in the home or need institutional care.
3. 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 recent meta-analysis3,17.
- 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 procedure18. 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 technique3.
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. There is little evidence on surgical decompression for asymptomatic PTS that is expanding on MRI3. Decompression surgery in PTS has been shown to be effective at arresting or improving motor strength deficits, but not sensory dysfunction or neuropathic pain.
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. Exercises that create Valsalva-like effects should be avoided. Occupational therapy to design functional splints and other assistive devices to facilitate self-care tasks may be needed. A decline in motor strength necessitates neurosurgical consultation.
Coordination of care
Coordination of care among rehabilitation physicians, neurosurgeons, physical and occupational therapists and nursing staff may help identify sudden plateaus in neurological recovery, neurologic decline or any new impairments in function. An updated neurologic exam and documented functional assessment (ie, functional independence measure [FIM]) score should be readily available so that new deficits can be easily identified and shared amongst team members. Coordination of assistance at home or placement in a subacute nursing facility may be needed.
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. Small changes can be easily overlooked, but can be a sign of insidious neurological decline from a potentially reversible process.
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 SCI patient. Surgical decompression has been shown to clinically improve motor weakness secondary to syrinx formation, but generally not sensory loss or neuropathic pain.
4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
5. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
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. There is also a gap in the medical literature regarding proper treatment for asymptomatic SCI patients with radiological evidence of an enlarging syrinx.
- Svircev JN, Little JW. Syringomyelia. In: Lin VW, Bono CM, Cardenas DD, et al. Spinal Cord Medicine Principles and Practice. 2nd ed. New York, NY: Demos Medical Publishing; 2010:569-574.
- Syringomyelia Fact Sheet 2015. NINDS. http://www.ninds.nih.gov/disorders/syringomyelia/syringomyelia_brochure.pdf. Accessed Nov 3, 2015.
- Bonfield CM, Levi AD, Arnold PM, et. al. Surgical management of post-traumatic syringomyelia. Spine. Oct.2010;35(21S):S245-258.
- Curati WL, Kingsley DP, Kendall BE, Moseley IF. MRI in chronic spinal cord trauma. Neuroradiology. 1992;35:30–5.
- Scelza WM, Dyson-Hudson TA. Neuromusculoskeletal complications of spinal cord injury. In: Kirshblum S, Campagnolo DI, Nash MS, et al. Spinal Cord Medicine. 2nd ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2011:284-287.
- Reddy KK, Del Bigio MR, Sutherland GR. Ultrastructure of the human post-traumatic syrinx. J Neurosurg. 1989;71:239–43.
- Barnett HJ, Butterell EH, Jousse AT, Wynne-Jones M. Progressive myelopathy as a sequel to traumatic paraplegia. Med Serv J Can. 1966;22:631–50.
- Perrouin-Verbe B, Lenne-Aurier K, Robert R, Auffray-Calvier E, Richard I, Mauduyt de la Grève I, et al. Post-traumatic syringomyelia and post-traumatic spinal canal stenosis: a direct relationship: review of 75 patients with a spinal cord injury. Spinal Cord 1998;36:137–143.
- MacDonald RL, Findlay JM, Tator CH. Microcystic spinal cord degeneration causing post-traumatic myelopathy. J Neurosurg. 1988;68:466–71.
- Kerslake RW, Jaspan T, Worthington BS. Magnetic resonance imaging of spinal trauma. Br J Radiol. 1991;64:386–402.
- Brodbelt AR, Stoodley MA. Posttraumatic syringomyelia: a review. Clinical Neuroscience. 2003:401-408.
- Quencer RM, Green BA, Eismont FJ. Post-traumatic spinal cord cysts: Clinical features and characterization with metrizamide computed tomography. Radiology. 1983;146:415–23.
- Jinkins JR, Reddy S, Leite CC, Bazan C, 3rd, Xiong L. MR of parenchymal spinal cord signal change as a sign of active advancement in clinically progressive post-traumatic syringomyelia. AJNR Am J Neuroradiol. 1998;19:177–82.
- Olly LT, Johnson JP, Masciopinto JE, Batzdorf U. Treatment of post-traumatic syringomyelia with extradural decompressive surgery. Neurosurg Focus. 2000;8:E8.
- Post-traumatic syringomyelia: What should know the urologist? Prog Urol. 2013 Jan;23(1)8-14. Epub 2012 Oct. 15.
- Potter K, Saifuddin A. MRI of chronic SCI. Radiology (Brit). May 2003:347-352.
- Klekamp J. Treatment of posttraumatic syringomyelia. Spine. July 13, 2012: 1-13.
- Little J. Conditions: Post-Traumatic Syringomyelia. Spinal Cord Injury Update 1998. Available at: http://asap.org/index.php/disorders/post-traumatic-syringomyelia/.
Original Version of the Topic:
Robert E Moore, MD, Scott Campea, MD. Post-traumatic syringomyelia. Publication Date: 2012/12/10.
Todd Lefkowitz, DO
Imedecs: Monetary – Consultant
Kirill Alekseyev, MD, MBA
Nothing to Disclose