AA

Syringomyelia

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Alibrahim F, McIntyre A, Benton B, Faltynek P, Sequeira K, Teasell R (2018). Syringomyelia Following Spinal Cord Injury. In Eng JJ, Teasell RW, Miller WC, Wolfe DL, Townson AF, Hsieh JTC, Connolly SJ, Noonan VK, Loh E, Sproule S, McIntyre A, Querée M, editors. Spinal Cord Injury Rehabilitation Evidence. Version 7.0: p 1-20.


 

Key Points

  • Anti-inflammatory medications given early post-spinal cord injury reduces development of heterotopic ossification.
  • Warfarin may inhibit the development of heterotopic ossification post-spinal cord injury.
  • Alendronate does not prevent the development of heterotopic ossification and may cause contractures.
  • Etidronate may be effective for halting the progression of heterotopic ossification when administered early.
  • Pamidronate halts secondary progression of heterotopic ossification post-surgical excision.
  • Pulse low intensity electromagnetic field therapy is effective in preventing heterotopic ossification post spinal cord injury.
  • Radiotherapy can reduce the progression and recurrence of heterotopic ossification.
  • Surgical resection of heterotopic ossification can improve hip range of motion but it may recur in a large number of individuals.
  • Surgical resection and pamidronate treatment halts secondary heterotopic ossification progression.

Executive Summary

Post-traumatic syringomyelia refers to the formation of an intramedullary cyst filled with cerebrospinal fluid (CSF) within the spinal cord (Brodbelt & Stoodley, 2003). Though uncommon, its impact can be devastating following spinal cord injury (SCI). It can be seen as early as two months after injury, or many years later (Vernon, Silver, & Symon, 1983).

What is the epidemiology of syringomyelia after spinal cord injury?
Syringomyelia occurs in approximately 2% of individuals with SCI (Klekamp & Samii 2002). There is a 22% higher incidence of syringomyelia found at autopsy than those presenting clinically (Vannemreddy et al. 2002). No relationship has been reported between the level of SCI and the likelihood of developing syringomyelia, however, an increased risk of post-traumatic syringomyelia has been reported in complete SCI individuals (Vannemreddy et al. 2002; Kramer & Levine 1997).

What is the pathophysiology and clinical presentation of syringomyelia after spinal cord injury?
The pathophysiology of syringomyelia following SCI is not completely understood. The most supported theory is William’s “Cranial-Spinal Pressure Dissociation Theory” which involves formation of the cavity and its enlargement and extension (Williams et al. 1981). Most commonly, it is thought to be asymptomatic. When it expands or compresses surrounding nerve tracts, is can cause radicular pain, gait ataxia, sensory disturbance, dysesthesias and motor weakness (Brodbelt & Stoodley 2003; Klekamp & Samii 2002; Kramer & Levine 1997; Lyons et al. 1987). As syringomyelia progresses, reduction in sensation and increased spasticity may be seen (Carroll & Brackenridge 2005). Progression is usually slow in most patients, with the clinical presentation remaining static for many years (Mariani et al. 1991).

How is syringomyelia diagnosed?

  • Magnetic Resonance Imaging (MRI) is currently the diagnostic test of choice for syringomyelia.
  • Myelography Enhanced Computed Tomography (CT-myelography). A significant improvement over plain CT, as it is able to show swelling and fixation of the cord and localized CSF flow obstruction (Dworkin & Staas 1985; Klekamp & Samii 2002).
  • Virtual Endocopy (VE) by Computer Tomography allows non-invasive exploration of the spinal canal in all directions and can provide information regarding the extent of stenosis, which plain CT cannot provide. Ultrasonography is useful in localizing syrinxes, determining the safest place to open the dura, and facilitating optimal shunt placement during surgery (Brodbelt & Stoodley 2003).
  • Intraoperative Somatosensory Evoked Potentials have limited value in assessing for syringomyelia, however may be used during surgery to prevent neurological damage.

What are the management options for syringomyelia?

Medications Used to manage presenting symptoms, but they do not treat the syringomyelia itself.
Surgery Only recommended for patients with neurological deterioration or intractable pain (El Masry & Biyani 1996; Klekamp & Samii 2002). Commonly reported in the treatment of syringomyelia in SCI patients.
Shunting Can be performed using syringoperitoneal, syringopleural, syringosubarachnoid, or ventriculoperitoneal shunts. Shunting improves pain, motor function and sensory loss in some SCI patients with syringomyelia (Karam et al. 2014; Ushewokenze et al. 2010; Schaan & Jaksche 2001; Falci et al. 1999; Lee et al. 2000; Lee et al. 2001; Hess & Foo 2001; Hida et al. 1994). High rate of shunt failure has been observed.
Untethering Used to prevent or revise neurological or orthopedic sequelae. Untethering improves motor and sensory loss (Falci et al. 2009; Falci et al. 1999; Lee et al. 2000; Lee et al. 2001), and improves spasticity in more patients with syringomyelia than shunting (Lee et al. 2000; Lee et al. 2001).
Subarachnoid–Subarachnoid Bypass (S-S Bypass) A new type of surgical technique for posttraumatic syringomyelia that may improve motor and bladder functioning (Hayashi et al. 2013).
Cordectomy Used to manage spasticity, pain and improve neurological dysfunction; An invasive and irreversible procedure, it is only considered when other options have been exhausted (Gautschi et al. 2011).
Neural Tissue Transplantation A novel treatment for syringomyelia that involves transplantation of neural tissue alone or in conjunction with surgical unthethering or cyst shunting. Embryonic tissue transplantation along with drainage, untethering and shunting may obliterate syringomyelia cysts and improve sensory loss (Falci et al. 1997; Wirth III et al. 2001). However, further investigation is required.

Gaps in Literature:

Causes of Syringomyelia: The exact incidence and etiology (tumor, infection, trauma, chiari malformation, etc.) is uncertain.

Signs and Symptoms
Symptoms of syringomyelia are variable and may include any of the following:
• Radicular pain, gait ataxia, sensory disturbance, dysesthesias and motor weakness, reduction in sensation, and increased spasticity. These differ from the classic symptoms seen in syringomyelia patients.
• Those that are not well studied include syringobulbia and death.

Management
Indications for each treatment modality are limited. Therefore, determining when to consider untethering, bypass, etc., can become a challenge. Furthermore, complications of treatment modalities are sparce in the literature.

Prognosis
To our knowledge, there is no published literature that specifically outlines the prognosis of syringomyelia following SCI, nor is there evidence suggesting recurrence risk after each treatment.