Elsevier

World Neurosurgery

Volume 108, December 2017, Pages 836-843
World Neurosurgery

Original Article
Syringo-Subarachnoid Shunt for the Treatment of Persistent Syringomyelia Following Decompression for Chiari Type I Malformation: Surgical Results

https://doi.org/10.1016/j.wneu.2017.08.002Get rights and content

Background

Approximately 30% of patients treated with foramen magnum decompression (FMD) for Chiari I–associated syringomyelia will show persistence, recurrence, or progression of the syrinx.

Objective

This study evaluates the clinical and radiologic outcomes of syringo-subarachnoid shunt (SSS) as the treatment for persistent syringomyelia after FMD.

Methods

Data were collected retrospectively. The primary outcome measurement was neurologic function (assessed with the Modified Japanese Orthopedic Association [mJOA] scale). Secondary outcome measurements were surgical complications, reoperation rate, and syrinx status on magnetic resonance imaging (MRI).

Results

Twenty-one patients (14 females [66.7%]) underwent SSS, either concurrent to the FMD or at a later stage. Two minor surgical complications were seen: a wound dehiscence and postoperative kyphosis, both requiring revision surgery. No major complication or mortality occurred. The median change in the mJOA score was an improvement of 3 out of a possible 17 points on the scale (mean follow-up, 24.9 months). Expressed as a percentage, overall improvement was 11.8% (95% confidence interval [CI], 5.9–17.6; P < 0.001). On postoperative MRI, shrinkage of the syrinx was seen in all but 1 patient in whom the syrinx remained unchanged. Expressed as percentage, the improvement of the syrinx surface was 76.3% (95% CI, 65.0–87.7; P < 0.001), and the improvement of syrinx span was 36.4% (95% CI, 21.8–50.9; P = 0.05).

Conclusion

SSS for persistent, recurrent, or increasing syrinx following FMD for Chiari I malformation is a safe and effective surgical treatment when performed selectively by an experienced neurosurgeon.

Introduction

Chiari I malformation, defined as a caudal displacement of the cerebellar tonsils, is associated with syringomyelia in 35%–75% of cases.1, 2, 3 The first-line surgical treatment for the Chiari–syrinx complex is foramen magnum decompression (FMD), although some authors advocate up-front shunting of the syrinx using a syringo-subarachnoid shunt (SSS).4, 5 The syrinx persists after FMD in up to 66% of patients.1 Patients with an increase in syrinx size and worsening of neurologic symptoms after FMD have also been described.2, 3, 6 The surgical treatment of persistent, recurrent, or increasing syringomyelia is still being debated. Some advocate re-decompression and duraplasty with or without cerebellar tonsils shrinking or resection, whereas others suggest an adhesiolysis of the arachnoidea at the region of the foramen magnum or a shunting procedure (syringopleural or syringo-subarachnoid shunt).1, 2, 3, 7, 8, 9 In an international survey regarding the management of Chiari I malformation and syringomyelia, the majority of respondents favored shunting of the syrinx to the subarachnoid space in cases of persistent or progressive syrinx after FMD.10 Despite what seems to be a common practice, to our knowledge, no series exists evaluating and focusing on the surgical outcome of SSS. In a small case series,11 syringopleural shunting was shown to be a valid option for refractory syringomyelia secondary to various pathologies (e.g., Chiari I malformation, posttraumatic, postinflammatory).

The aim of the current study is to report our experience treating patients with SSS for Chiari I malformation–related syrinx—either concurrently with FMD or after FMD—for persistent, recurrent, or increasing syrinx.

Section snippets

Methods

The study protocol was approved by the local ethics committee. Patient consent was not sought for this retrospective study, because it is not necessary according to local ethical guidelines. Of 71 consecutive patients undergoing FMD for Chiari I malformation at our department between 2003 and 2016, 21 patients (29.6%) underwent SSS, either concurrently with the FMD or at a later stage. Generally, SSS was the treatment of choice for syrinxes that were extreme at presentation or significantly

Results

We included 21 consecutive patients in the study; 16 patients underwent SSS for persistent, recurrent, or increasing syrinx after FMD, and 5 patients underwent concurrent SSS and FMD for an initially symptomatic and large syrinx. The patient group included 14 females (66.7%) and 7 males (33.3%) with an average age of 16.3 ± 15.4 years (median, 13 years; range, 3–61 years) at the time of SSS insertion. The patients' demographic and clinical data are presented in Table 2. Median clinical

Discussion

In this study, we reviewed 21 patients who underwent SSS for persistent, recurrent, or increasing syrinx after FMD for Chiari I malformation, or SSS combined with FMD for Chiari I malformation and an initially symptomatic and extensive syrinx. To our knowledge, this series is the first to evaluate the outcome of SSS in these patients. The significant improvement of the mJOA score by 11.8% and the significant radiologic improvement of the syrinx size by 76.3% indicates that this procedure is a

Conclusion

Considering on our results, SSS should be recommended as one of the major surgical options for persistent, recurrent, or increasing syrinx following FMD for Chiari I malformation. SSS seems to improve neurologic and radiologic outcomes for these patients. SSS for persistent, recurrent, or increasing syrinx following FMD for Chiari I malformation is a safe and effective surgical treatment when performed selectively by an experienced neurosurgeon.

Acknowledgment

The authors thank Adina Sherer for the medical editing of this manuscript.

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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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