Elsevier

World Neurosurgery

Volume 110, February 2018, Pages e53-e59
World Neurosurgery

Original Article
Syrinx to Subarachnoid Shunting for Syringomyelia

https://doi.org/10.1016/j.wneu.2017.09.205Get rights and content

Objective

Surgery for syringomyelia generally aims to treat the underlying cause, if it is known. Optimal management is unclear for idiopathic syringomyelia, or when treatment of the putative cause has failed or is high risk. Syrinx to subarachnoid shunting is an option for these cases; a series is reported to assess the outcomes of this approach.

Methods

We retrospectively analyzed the clinical and radiologic features of a consecutive series of patients with syringomyelia treated with syrinx to subarachnoid shunting.

Results

Forty-one patients (19 male, 4–79 years old) were treated from 2000 to 2016, including 15 patients with idiopathic syringomyelia, 13 with spinal trauma, 5 with Chiari malformation, 4 with arachnoiditis, 3 with tethered cord, and 1 with arachnoid bands. The patients were treated with a syrinx to subarachnoid shunt, and a subset also underwent expansile duraplasty. At follow-up (3–108 months, mean 36 months) syrinx size was reduced in 37 patients, and there was improvement or stabilization of symptoms in all but 1 patient. Three patients had temporary lower limb sensory symptoms after surgery. Other complications were 2 transient cerebrospinal fluid leaks, a pseudomeningocoele, and 1 postoperative myocardial infarction. Two cases of shunt dislodgement required reoperation, and a third case required early reoperation for an enlarging syrinx. There were no cases of shunt blockage or infection.

Conclusions

Syrinx to subarachnoid shunting is a safe and effective treatment for idiopathic syringomyelia and for patients who are not suitable for, or have not responded to, other treatment.

Introduction

Whereas most cases of syringomyelia occur in association with Chiari type I malformation,1 syrinx cavities also occur in the context of spinal trauma, infection, cord tethering, or arachnoiditis. A further proportion are due to unknown or idiopathic causes. Disturbance of cerebrospinal fluid (CSF) flow across the foramen magnum or in the spinal subarachnoid space appears to be common to most causes, but a unifying pathophysiologic explanation of syringomyelia remains elusive.2, 3

The clinical features of syringomyelia are characterized by motor and sensory deficits related to the level of the syrinx and the extent of associated spinal cord injury. Treatment is generally aimed at addressing the presumed underlying cause. Posterior fossa decompression is performed for Chiari-related syringomyelia,4, 5 with 80% to 90% efficacy reported for syrinx collapse.6, 7 However, there is no consensus method of treatment in cases where decompression for Chiari malformation has been unsuccessful, for those patients in which extensive detethering or decompression is considered too risky, or in cases where the underlying cause is unclear.

Treatment with syrinx shunts has been proposed for these patients,8, 9 with shunt destinations including the pleural space,10 the peritoneal cavity,11 and the spinal subarachnoid space.12 Greater and more rapid improvement in preoperative symptoms,11, 13, 14 and fewer postoperative symptoms,14 have been reported after syrinx fluid shunting procedures compared with decompression. By contrast, concerns persist regarding shunt surgery failing to collapse the cavity,15 the possibility of syrinx recurrence resulting from shunt malfunction,16, 17 or infection or cord injury.9, 18 Some of these risks may be minimized through the use of shunting to the spinal subarachnoid space, rather than to the pleural or peritoneal cavity.17, 19 Preserving the integrity of the arachnoid membrane and the subarachnoid space may improve the success rates for syrinx to subarachnoid shunts20 and may minimize the risk of overdrainage of CSF,11, 21 extradural fluid collection,22, 23 and spinal cord tethering.24

No large modern series of outcomes have been reported for syrinx to subarachnoid shunting, and small samples of patients, and differences in surgical techniques and indications for operation in past studies, may be a source of some of the conflicting results of syrinx shunting previously reported. The authors therefore present their experience in the management of syringomyelia using syrinx to subarachnoid shunts.

Section snippets

Materials and Methods

From January 2000 to December 2016, 159 patients were surgically treated for syringomyelia by the senior author. We retrospectively analyzed the clinical course, radiologic studies, and the surgical results only in patients from this cohort treated with syrinx to subarachnoid shunts. This study was approved by the Macquarie University Human Research Ethics Committee.

Results

Forty-one patients with syringomyelia were treated with syrinx to subarachnoid shunting, comprising 19 male and 22 female patients (mean age, 42 years; range, 4–79 years). Presenting symptoms and signs included pain, motor dysfunction, and sensory dysfunction (Table 1). Presurgical MRI demonstrated all syrinx cavities were larger than 2 mm in maximum diameter. The syrinx was in the thoracic spine in 18 cases (44%), 11 (27%) were in the cervical spine, 5 (12%) spanned the cervical-thoracic

Discussion

With a diverse pathophysiology and variability of clinical presentation, there is no clear consensus regarding the optimal surgical management of syringomyelia. Ideally, the goal of treatment would be to address the underlying mechanism of syrinx formation, although this is not well understood. Syrinx shunting cannot improve the CSF pathways around the foramen magnum, and fluid diversion has therefore been criticized for not addressing the putative pathophysiology underlying many presentations.9

Conclusions

Ideally, identification of the pathophysiology of each syringomyelia case should inform the selection of treatment.37 However, management of the presumed pathophysiologic condition may fail to reduce the syrinx cavity, or the major pathogenic factors responsible for syrinx initiation and propagation may not be readily identifiable. This case series demonstrates that in patients experiencing deteriorating neurologic function, a syrinx to subarachnoid shunt is a safe and effective treatment for

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    Conflict of interest statement: This study was supported by a grant from the Column of Hope.

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