Accepted Manuscript

Arachnolysis or Cerebrospinal Fluid Diversion for Adult-Onset Syringomyelia? ASystematic Review of the Literature

George M. Ghobrial, MD Richard T. Dalyai, MD Mitchell G. Maltenfort, PhD SrinivasK. Prasad, MD James S. Harrop, MD Ashwini D. Sharan, MD

PII: S1878-8750(14)00590-7

DOI: 10.1016/j.wneu.2014.06.044

Reference: WNEU 2437

To appear in: World Neurosurgery

Received Date: 10 September 2013

Revised Date: 9 June 2014

Accepted Date: 24 June 2014

Please cite this article as: Ghobrial GM, Dalyai RT, Maltenfort MG, Prasad SK, Harrop JS, Sharan AD,Arachnolysis or Cerebrospinal Fluid Diversion for Adult-Onset Syringomyelia? A Systematic Review ofthe Literature, World Neurosurgery (2014), doi: 10.1016/j.wneu.2014.06.044.

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Arachnolysis or Cerebrospinal Fluid Diversion for Adult-Onset Syringomyelia? A Systematic

Review of the Literature

Running title: Arachnolysis or CSF Diversion for Syringomyelia ?

George M. Ghobrial MD,1 Richard T Dalyai MD,

1 Mitchell G. Maltenfort PhD,

2 Srinivas K. Prasad MD,

1

James S Harrop MD, 1

Ashwini D. Sharan MD1,3

1-Department of Neurological Surgery

Thomas Jefferson University Hospital

909 Walnut St., 3rd

floor

Philadelphia, PA 19107

2- Department of Orthopedic Surgery

Thomas Jefferson University Hospital

Philadelphia, PA 19107

3- Corresponding Author:

Ashwini D. Sharan MD

Associate Professor of Neurological Surgery

Thomas Jefferson University Hospital

Ashwini.Sharan@jefferson.edu

Cell 215-955-7003

Fax 215-503-7373

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Abstract

OBJECTIVES: To identify surgical practice patterns in the literature for non-pediatric

syringomyelia by systematic review and to determine: (1) What is the best clinical practice of

CSF diversion that will maximize clinical improvement and/or the lowest recurrence rate? (2)

Does arachnolysis, rather than CSF diversion, lead to prolonged times to clinical recurrence?

Methods: A PubMed (1966 to Aug 2012), Cochrane Register of Controlled Trials, CINAHL,

SCOPUS, and Cochrane Database of Systematic Reviews, database search was conducted for

pertinent articles by the authors with postinfectious, posttraumatic, or idiopathic syringomyelia.

RESULTS: An advanced PUBMED search in August 2012 yielded 1350 studies, finding

twelve studies meeting CEBM criteria for level 4 evidence as a case series, with a total of 410

patients (mean age 39 years). Data on 486 surgeries were collected. Mean follow-up data was

available for ten studies, with a mean follow-up time of 62 months. On regression analysis,

increased age had a significant correlation with a higher likelihood of having clinically

significant recurrence on mean follow-up (P<0.05). The use of arachnolysis in surgery was

associated with a longer duration until clinically symptomatic recurrence (P=0.02). Data on

mortality was unavailable. The mean number of surgeries per patient across all studies was 1.20

(range 0.95-2.00).

CONCLUSION: With post-infectious and post-traumatic etiologies, arachnolysis was the only

surgical treatment to have a statistically significant effect on lowering recurrence rates. More

prospective, randomized, controlled studies are required to reach a clear consensus.

Key Words: Syrinx, Syringopleural Shunt, syringomyelia, syringosubarachnoid, arachnolysis

Short title: Surgical Management of Syringomyelia: A Systematic Review

Introduction

Syringomyelia is described as a pathologic condition of the spinal cord where there is a cystic

dilatation and expansion of the spinal cord resulting from abnormal cerebrospinal flow

dynamics. Its incidence is difficult to determine and varies based on the underlying etiology and

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population studied. The most common etiologies are posttraumatic, postinfectious, hindbrain

hernation-related (Chiari), and occasionally due to craniovertebral junction lesions. One

estimate of the risk of syringomyelia after traumatic spinal cord injury is 28%.[41] Physiologic

studies point to abnormal CSF pulse pressure and velocity as well as flow into the spinal cord via

perivascular spaces as a mechanism for symptomatic growth of a syrinx.[24, 42] Additional

work points to arachnoidopathy, leading to aberrant CSF flow, ultimately resulting in

extramedullary arachnoid cysts that develop pressure with time.[11, 29, 54]

Treatment guidelines are varied, and large case series are limited. In the case of arachnoid

adhesions and recurrent cystic compression, the treatment is often arachnolysis, with or without

cerebrospinal fluid (CSF) diversion. Kaplain-Maier curve data from prior studies show clinically

sympstomatic recurrence rates after treatment of 34 and 40% at 5 and 10 years, respectively.[36]

Given the prevalence of patients with any variety of specific syringe- pleural,peritoneal, or

subarachnoid shunts is so low, there are no set guidelines for its use. Surgical decisions are thus

guided by institutional experience and previous training bias. One prior systematic review of the

literature explores the indications of surgery, recommending against early decompression with

the specific goal to prevent post-traumatic syringomyelia, as well as surgery for the goal of

treating pain and other sensory findings without motor deficits in the setting of an expanding

syrinx.[8] Pertinent clinical questions not previously answered in a systematic review include:

(1) What is the best clinical practice or implementation of cerebrospinal fluid (CSF) diversion

that will lead to the highest likelihood of clinical improvement and/or lowest recurrence rate? (2)

Does primary arachnolysis, rather than CSF diversion, lead to prolonged times to clinical

recurrence? In the case of Chiari Malformation, the cystic compression, and the underlying

etiology is more pathologic than arachnoiditis. This disease entity has established treatments that

differ greatly than posttraumatic and postinfectious arachnoiditis, resulting in syrinx formation.

Since treatment of the underlying Chiari is considered the definitive treatment for syringomyelia,

this systematic review does not aim to include Chiari or Chiari-related etiologies.

Methods

A PubMed (1966 to Aug 2012), Cochrane Register of Controlled Trials (1950 to August

2012), CINAHL (1981 to August 2012), SCOPUS (1960 to August 2012), Cochrane Database of

Systematic Reviews (2005 to August 2012) database search was conducted for articles pertaining

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to postinfectious, posttraumatic, or idiopathic adult syringomyelia. Keywords and MeSH terms

utilized were consistent through all search engines and included ‘Syrinx’, ‘Syringopleural shunt’,

‘syringoperitoneal shunt’, ‘syringosubarachnoid shunt’, ‘syringomyelia’, ‘hydromyelia’,

‘arachnolysis’, ‘cystopleural’, ‘cystoperitoneal’, and ‘shunting’. Papers were limited to English,

human subjects, and those published or published before print. Relevant papers were then

carefully selected by two authors (G.G., R.D.) and then applicable articles of interest were

reviewed from the respective bibliographies, where all articles were reviewed for inclusion by

the remaining authors.

Study Selection

Comparative case series, comparative cohort studies, clinical trials, meta-analyses, and

systematic reviews were eligible for inclusion. Those abstracts excluded were noncomparative

and descriptive studies, technical notes, and case reports. Articles included must have had to

analyze one or more variables described in the pertinent clinical questions, specifically, type of

intervention for symptomatic syringomyelia or arachnoid adhesion, method of surgical

intervention, arachnolysis, shunting, or both. Exclusion criteria included articles that were

unrelated to the interventions or outcomes of interest, as well as pediatric syringomyelia

including those related to pediatric hindbrain herniation/Chiari malformations. The primary

outcome of interest was time to recurrence of neurological complaint or deficit. Secondary

outcomes of interest were factors associated with decreased recurrence of symptomatic

syringomyelia as well as complication rate. Studies that met these criteria were included in the

final analysis (Table 3). Meta-analyses that met criteria were included for comparison to results.

This reference was reviewed in detail to confirm that no individual studies were duplicated in the

final analysis.

Data Extraction and Analysis

Grading of articles on quality of evidence was done via the Oxford Center for Evidence-

Based Medicine (CEBM) ranking criteria (table 1).[26] Data for the number of patients,

presenting complaint, type of neurosurgical intervention, post-operative functional outcome, rate

of recurrence of symptoms, overall complication rate, hospital length of stay (LOS), and average

interval of follow-up was recorded. Recurrence rate was defined by the percentage of patients in

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each study with recurrent symptoms . While the time to recurrence was defined by each

individual study was evaluated, most commonly this was documented as the time to recurrence

of initial presenting neurologic complaints. Data extracted was confirmed by two authors (G.G.

and R.D.) on an independent basis. A proprietary software package was utilized for statistical

analysis (‘R’ v. 2.15.1 by the R Foundation for Statistical Computing, Vienna Austria). A

generalized linear model with quasibinomial family to account for variation beyond that

expected in ordinary binomial (logistic) regression was utilized. The extra variation was

expected because of the dissimilarity between studies.

RESULTS

A PUBMED search in August 2012 yielded 1350 studies, finding twelve studies

meeting CEBM criteria for level 4 evidence as a case series, with a total of 410 patients (mean

age 39 years) (Figure 1). There were no previously published randomized controlled trials

pertaining to surgical management of syringomyelia. Data on 486 surgeries were collected.

Mean follow-up data was available for ten studies, with a mean follow-up time of 62 months

(Table 2). Data on etiology was tabulated for 395(96%) patients (table 2). The most common

etiology reported was was posttraumatic (n= 211, 51%), followed by hindbrain herniation (Chiari

malformation, n = 112, 27%). Seven studies tracked the mean duration of symptoms prior to the

initial surgical intervention across all etiologies, which was 67 months. Eight studies tabulated

data on post-operative syrinx size on MRI, finding 76% in reduction of the syrinx after surgery

(Table 3). Preoperative and post-operative functional outcomes were not available, for most

studies.

On regression analysis, increased age had a significant correlation with a higher

likelihood of clinically significant recurrence on mean follow-up (P < 0.05). The presence of

arachnolysis in surgery was associated with a longer duration until clinically symptomatic

recurrence (P=0.02). Younger patients (P = 0.04) and earlier follow-up appointment (P = 0.05)

were more likely seen with clinically stable disease (Table 4). Duration of symptoms prior to

surgery, and CSF diversion methods did not significantly impact clinical recurrence or functional

outcome. Data on complication rate was largely unavailable and without a standard definition.

The mean number of surgeries per patient across all studies was 1.20 (range 0.95-2.00). The

mean number of surgeries per patient per two years ranged from 0.2 to 1.37 (Table 3).

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DISCUSSION

Syringomyelia is a rare entity with a limited patient population reported in the literature. The

etiology of syringomyelia and arachnoid cyst formation is multifactorial, as evidenced by the

volume of literature regarding pathophysiology of intramedullary CSF cyst formation.[4, 5, 12,

17, 16, 18, 21-23] Spinal cord trauma resulting in an ischemic insult to the cord has been

thought to result in cystic degeneration of the spinal cord. This cystic formation then results in a

space for abnormal CSF flow, and finally pathologically high pressure causing dilation of the

cyst, resulting in spinal cord damage and neurologic symptoms.[6, 9, 20, 34, 32, 46, 47] Further

expansion of the cyst and dissection of a CSF cavity into the spinal cord parenchyma has been

proposed by Bernard Williams, one of the earliest investigators into the underlying mechanisms

of this disease.[55, 56] Often, arachnopathies, or abnormal adherences in the arachnoid tissue

results in abnormal CSF flow dynamics. This abnormal flow seen in the nontraumatic

syringomyelia patient results in CSF pulsations, either dissecting into the spinal cord itself, or

forming cystic, extramedullary cavities that fill and build pressure in a ‘one-way valve’ type

mechanism.[36] Further work regarding the anatomy of the leptomeninges has found a higher

incidence of septations in the posterior subarachnoid space, particularly in the upper thoracic

spinal cord. These septations are not found in the anterior subarachnoid space and can contribute

the formation of adhesions and arachnoid cysts.[36]

The vast majority of literature is presented as retrospective case series detailing the operative

experience at large, tertiary care centers. Obstacles to interpreting previous data has been the

great variation seen in individual surgical management prior to retrospective review. Indeed, no

two patients are alike in regards to surgical history for management of syringomyelia. This

complex clinical course makes interpretation of individual therapies difficult. Intuitively,

studies with a longer mean follow-up had a higher incidence of clinical recurrence of symptoms

and should be taken under consideration when comparing the individual surgical treatments

(Table 2). The mean number of surgeries per patient per two years was calculated to account for

this, but was not statistically significant.

Syringopleural Shunting

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The first syringopleural shunt was performed in 1892, with postoperative neurologic

improvement.[1] This procedure has become a popular procedure due to the anatomic proximity

of the pleural space to the cervicothoracic syrinx of interest, as well as the negative pressure of

the pleural space. Williams and colleagues[58] advocated the initial use of syringopleural

shunting over syringoperitoneal shunting due to the convenient anatomical location, with no

need for repositioning introperatively. More recent use of the syringopleural shunt by Isik et al.

has found good results in the short term.[28] Cacciola et al[10] found on 1 year follow-up with

sixteen patients that had underwent syringopleural Shunts for syringomyelia an improvement in

their modified Japanese Orthopedic Association Score. Long term outcomes are mixed, citing a

higher failure rate with recurrent symptoms.[44, 45, 60] Isik et al[28] in a retrospective review

halted neurologic progression with syringopleural shunting in nine patients, with three patients

requiring craniovertebral decompression (CVD) as a second procedure. More pronounced

improvement was noted with larger syrinxes with an average time for decompression from six to

ten months. Bindal[7] and Vernet reported good long term results with limited morbidity for

pediatric populations with Chiari as an underlying etiology of syringomyelia.[52] Still, other

data reports a high likelihood of repeat surgery within one year.[35, 44]

Many of these patients had CVD as a primary or secondary procedure, and should be taken

into consideration when evaluating the efficacy. For this reason, we have excluded hindbrain

hernation and patients with craniovertebral decompression from the systematic review, given the

extensive differences between pediatric populations compared to adults with post-traumatic and

post-infectious etiologies. Also, there is already plenty of retrospective data that shows greater

clinical improvement when CVD precedes CSF shunting.[27, 30, 43] The addition of this major

surgery makes a comparison of other treatments of CSF diversion not feasible.

Syringosubarachnoid Shunting

Syringosubarachnoid shunting carries a low morbidity[2, 15, 27, 30, 39, 49, 48, 50, 52, 61]

and is the least invasive of the CSF shunting procedures. Vaquero et al[51] in a retrospective

review of 9 patients halted progression of neurologic deficits utilizing syringosubarachnoid

shunts for syringomyelia. Tator et al[49] demonstrated favorable results on follow-up with

syringosubarachnoid shunting in 72.5% of patients. Literature regarding syringosubarachnoid

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shunting is limited to retrospective case series, and no comparative studies are available to

demonstrate its relative efficacity.

One concern raised with creating a channel from the syrinx to the subarachnoid space, is flow

reversal into the syrinx, particularly in the case of a tight posterior fossa, where valsalva

maneuvers encourage CSF flow gradients into the syrinx.[57] Ultimately, this procedure

remains available to the clinician, when shunting to the pleural or peritoneal space is not feasible

(given a prior history of thoracic or abdominal surgery, pleurodesis, or intraabdominal surgeries

raising concerns about scarring). Also, as seen in our analysis, the outcomes of previous series

did not differ greatly for syringosubarachnoid shunting (table 3). The patients most definitely

would be experience less post-operative pain, because there is no need for a second incision with

this procedure.

Lumboperitoneal Shunting

Limited experience in the literature is reported for the use of lumboperitoneal shunts for

syringomyelia. It’s benefit is the drainage of CSF from the lumbar cisterns without the risk of

neurologic deterioration from myelotomy. This is weighted against the lack of direct

decompression and lysis of adhesions at the level of pathology. Oluigabo[38] treated nineteen

patients, with a mean follow-up of 25 months, finding neurologic improvement in five patients,

and halting disease progression in the majority.

Arachnolysis

Many advocate for the initial use arachnolysis without CSF shunting, citing excellent

results.[3, 33, 40, 53] Aghakhani et al[3] in a retrospective comparison of arachnolysis versus

syringopleural shunting as the primary treatment for symptomatic syringomyelia, found superior

results in the arachnolysis group, with regard to rates of reoperation, time to deterioration, and

clinical recurrence.

Largely, patients that had underwent arachnolysis during their clinical course, regardless of

the etiology of the syringomyelia, had a significantly longer symptom-free duration before

clinical recurrence. Klekamp et al[35] reviewed 131 patients with a history of post-traumatic

syringomyelia, where 61 patients underwent surgical intervention. Interestingly, the onset of

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symptoms due to syringomyelia, after SCI ranged from one month to 46 years.[35] The most

common symptom encountered was worsening motor function. Excellent results were obtained

with arachnolysis, untethering, and duraplasty alone, whereas CSF shunting was reserved as a

secondary measure. This surgical measure addresses the underlying etiology of disrupted CSF

flow dynamics, dilation of the arachnoid and cord compression.[33] For the subgroup of patients

in the posttraumatic syringomyelia analysis by Klekamp et al[35], those with clinically stable

neurological function had the same progression-free survival at 10 years regardless of surgery or

not. Those with neurologic worsening had a better functional outcome with surgery (79%

progression-free survival at 5 yrs). Also, for those patients not responding to arachnolysis and

shunting, patients with complete injuries were offered cordectomy to halt progression once and

for all, which this did work for four patients in their series, as well as previous published.[14, 15,

19, 31, 37, 59]

One further consideration is the surgical extent of arachnolysis and decompression. This

variation in surgical technique may be crucial to successful outcome. Surgical technique in this

nonstandard procedure varies greatly. Klekamp and Edgar[13, 35] advocate the use of

duraplasty to increase the size of the arachnoid space to limit tethering, as well as meticulously

limit bleeding into the arachnoid space. Further work might include in the future post-operative

MR imaging to show the extent of decompression of the subarachnoid space after untethering.

This can be then shown to correlate with the success of arachnoidopathy. Additionally, interest

in the role of arachnolysis as a primary treatment has been promising. Hayashi et al[25]

achieved a mean reduction of the syringomyelia from 9 to 5 vertebral levels when detethering of

the adhesions and placement of up to two silicone tubes to divert CSF rostral and caudal to the

site of arachnolysis was performed.

Comparison of Surgical Procedures

Multivariate regression analysis demonstrated that decreased age, arachnolysis, and

decreased time to follow-up were the only significant factors that lowered recurrence rates (table

4). CSF diversion did not have a significant impact on outcome. Complication rates are

obscured by the lack in uniformity of surgical procedures, even among individual series

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themselves. Many patients had multiple surgeries, and follow-up times varied greatly. Likely,

the lack of uniformity in follow-up time is what has contributed most to the variations in success

rates.[34] Unfortunately, regardless of surgical intervention, patients with symptomatic

syringomyelia will undergo multiple procedures in their lifetime. In our statistical analysis,

arachnolysis was the only procedure to have a statistically significant impact on decreasing

symptomatic recurrence. After the failure of this therapy, an argument can be made for CSF

flow diversion via any of the aforementioned shunting methods. More evidence has been

published recently in support for arachnolysis, duroplasty, and/or subarachnoid-subarachnoid

shunting, without fenestration of the syrinx at this time. Good outcomes were reported in the

majority of these patients.[16, 25, 35, 36] Bonfield and colleagues[8] in the only prior systematic

review are able to draw few conclusions from the literature based on the lack of randomized

controlled evidence. They make weak recommendations in favor of duroplasty with

arachnodolysis as the primary treatment over shunting of the syrinx, in the setting of acute motor

weakness, but not in the case of acute sensory or pain syndromes.[8] Despite the lack of level I

evidence to support the use of any primary therapy over another, equivalent outcomes have been

demonstrated in methods of CSF flow restoration without syringotomy.

The limitations of making treatment decisions based off of retrospective data alone are

significant. This systematic review highlights the need for a syringomyelia registry, where a

prospective database for this relatively uncommon disease can be used to follow outcomes.

Lastly, it must be emphasized that there is an inherent difficulty encountered with making

management recommendations for syringomyelia, as well as other uncommon surgical conditions. The

chief limitation is that many tertiary care spine centers are treating diseases based off of their own

recommendations, a difficulty which a can be fixed with multi-center, randomized, controlled trials.

Conclusion

Syringomyelia is a debilitating disease where there exists no clearly superior method of

surgical management. Among retrospective reviews of adults with symptomatic syringomyelia

with predominantly post-infectious and post-traumatic etiologies, arachnolysis, rather than CSF

diversion, was the only initial surgical treatment to have a statistically significant affect on

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lowering recurrence rates. However, recommendations are limited by both the lack of

prospective studies, and long-term surveillance, both of which are vital to detecting the

frequency of rescarring and need for further surgery. Prospective and randomized, controlled

studies however, are lacking with uniformity in treatment and follow-up to make a clear

consensus as to what is the surgical management of choice for syringomyelia.

Acknowledgements: None

Conflicts of Interest and Source Funding:

There were no conflicts of interest in the manuscript, including financial, consultant, institutional

and other relationships that might lead to bias or a conflict of interest. There were no sources of

funding available for this manuscript.

Abbreviations

CSF – cerebrospinal fluid, CEBM- Centers for evidence Based medicine, LOS- length of stay,

CVD- craniovertebral decompression.

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Figure Legend

Figure 1: Flow diagram demonstrating relevant articles reviewed and exclusion algorithm.

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Table 1- Centers for Evidence Based Medicine Criteria

Level of Evidence Study Methodology

Ia Systematic Review of

Randomized Controlled

Trials

Ib Randomized Controlled Trial

II Systematic Review of Cohort

Studies

III Case-Control Study

IV Case Series

V Expert Opinion

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Citation Indications for

treatment

primary treatment N Surgeries,

n

mean

follow-

up (m)

Reoperation

tracked?

duration

of

symptoms

prior to

surgery

(m)

decreased

syrinx by

MRI? ( % )

clinical

recurrence

at mean

f/u, %

Aghakani et

al.45

neurological

deficit

arachnoidolysis vs.

CSF diversion

34 42 86 yes 133 86 73

Cacciola et

al.26

neurological

deficit

Syringopleural

shunting

20 20 37.5 yes n/a 89.4 0

Isik et al.25

neurological

deficit

Syringopleural

shunting

44 48 109 yes 24 98 20

Klekamp et

al.32

neurological

deficit

Arachnoidolysis,

duraplasty

61 71 51 yes 56 61 58

Oluigobo et

al.43

neurological

deficit

lumboperitoneal

shunting

19 19 25 no n/a 10.5 33

Padovani et

al.41

neurological

deficit

syringosubarachnoid

shunting

29 32 60 no 72 100 10

Sgouros et

al.28

neurological

deficit

syringopleural and

syringosubarachnoid

shunting

73 73 120 yes n/a n/a 50

Tator et al.

(1982)40

neurological

deficit

syringosubarachnoid

shunting

20 40 60 no 6 n/a 25

Tator et al.

(1988)39

neurological

deficit

syringosubarachnoid

shunt for

syringomyelia

40 38 55.2 yes 82 n/a 10

Ushewokunze

et al.42

neurological

deficit

Arachnoidolysis 40 67 64 yes 72 64 24.9

Vaquero et

al.43

neurological

deficit

syringosubarachnoid

shunting

9 9 17.5 yes 91 100 0

Williams et

al.24

neurological

deficit

syringopleural

shunting

21 27 n/a no n/a n/a 19

Table 2. Clinical course and outcomes of syringomyelia series

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Variables Prolonging Clinical Recurrence

OR 95%

L

95%

H

p-

value

Arachnoidolysis 7.66

5

2.95

6

19.87

9

0.024

7

decreased age 1.14

8

1.06

1

1.242 0.041

Duration of symptoms prior to surgery 0.99

7

0.98

8

1.011 0.967

Decreased duration prior to follow-up 1.03

6

1.01

3

1.06 0.050

2

Table 3. Factors prolonging Clinical Recurrence

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Etiology

Citation Methodol

ogy

N Mean

treatment

age

Surgical

interven

tion

hindbrain

herniation

posttrau

matic

infectious craniovert

ebral

junction

lesion

idiopathic

Aghakani

et al.51

(2010)

Retrospec

tive

34 40 arachnoi

dolysis

vs. CSF

diversio

n

0 19 0 0 0

Cacciola

et

al.26

(2009)

Retrospec

tive

20 51.3 Syringop

leural

shunting

6 8 2 4 0

Isik et

al.6(2012)

Retrospec

tive

44 33.5 Syringop

leural

shunting

32 12 0 0 0

Klekamp

et

al.22

(2002)

Prospectiv

e

61 45 Arachnoi

dolysis,

duraplas

ty

0 61 0 0 0

Oluigobo

et

al.50

(2010)

Retrospec

tive

19 48 lumbope

ritoneal

shunting

5 1 5 2 6

Padovani

et

al.46

(1989)

Retrospec

tive

29 33 syringos

ubarach

noid

shunting

22 4 3 0 0

Sgouros et

al34

(1995)

Retrospec

tive

73 38 syringop

leural

and

syringos

ubarach

noid

shunting

27 34 1 11 0

Tator et

al.

(1982)45

Retrospec

tive

20 44 syringos

ubarach

noid

shunting

0 4 1 0 15

Tator et

al.

(1988)44

Retrospec

tive

40 44 syringos

ubarach

noid

shunt

for

syringo

myelia

12 11 5 0 12

Ushewoku

nze et

al.47

(2010)

Retrospec

tive

40 32 Arachnoi

dolysis

0 40 0 0 0

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Vaquero

et

al.48

(1987)

Retrospec

tive

9 28 syringos

ubarach

noid

shunting

0 9 0 0 0

Williams

et

al.29

(1987)

Retrospec

tive

21 33 syringop

leural

shunting

8 8 2 2 1

Table 1. Syringomyelia: characteristics of the literature

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CSF – cerebrospinal fluid

CEBM – Centers for evidence based medicine

LOS- length of stay,

CVD- craniovertebral decompression.