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PEER-REVIEW REPORTS

When Is Duraplasty Required in the Surgical Treatment of Chiari Malformation Type IBased on Tonsillar Descending Grading Scale?Adem Yilmaz1, Ayhan Kanat2, Ahmet Murat Musluman1, Ibrahim Çolak1, Yuksel Terzi3,

Selim Kayacı4, Yunus Aydin1

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INTRODUCTION

For surgical treatment of Chiari malforma-tion type I (CM-I), there is no consensusamong surgeons about which method ispreferred. More recently, many surgeonshave advocated posterior fossa decompres-sion (PFD) without duraplasty (7, 21, 30).Other surgeons prefer to perform bone de-compression of the posterior fossa and du-raplasty (12, 17, 26). PFD with duraplasty isassociated with a lower risk of reoperationthan PFD without duraplasty but a greaterrisk for cerebrospinal fluid (CSF)–relatedcomplications. We hypothesized that extra-dural PFD with or without duraplasty maybe better tolerated by patients than intra-dural procedures. Duraplasty itself with PFDsurgery may decrease postoperative syrinxsize, improve Japanese Orthopaedic Associa-tion (JOA) scores (4), and improve recovery

Key words� Cerebellar tonsillar descent grading� Chiari malformation type I� Posterior fossa decompression duraplasty

Abbreviations and AcronymsCCJ: Craniocervical junctionCM-I: Chiari malformation type ICSF: Cerebrospinal fluidCTD: Cerebellar tonsillar descentJOA: Japanese Orthopaedic AssociationMRI: Magnetic resonance imagingPFD: Posterior fossa decompression

From the 1Department of Neurosurgery, SisliResearch and Education Hospital, Istanbul;

2Department of Neurosurgery, Rize University Medical School,ize; 3Department of Statistics, University of Ondokuz Mayisaculty of Science and Arts, Samsun; and 4Department ofeurosurgery, Sar Hospital, Rize, Turkey

o whom correspondence should be addressed:dem Yilmaz, M.D. [E-mail:[email protected]]

itation: World Neurosurg. (2011) 75, 2:307-313.OI: 10.1016/j.wneu.2010.09.005

ournal homepage: www.WORLDNEUROSURGERY.org

vailable online: www.sciencedirect.com

878-8750/$ - see front matter © 2011 Elsevier Inc.ll rights reserved.

rate. To evaluate our hypothesis, we retro- b

WORLD NEUROSURGERY 75 [2]: 307-313

pectively studied 82 consecutive patients un-ergoing PFD with or without duraplasty andompared the outcomes of patients. To ournowledge, there has been no published re-ort on the effect of duraplasty based cerebel-

ar tonsillar descent (CTD) grading in the sur-ical treatment of CM-I. The main aim of thistudy was to assess the effectiveness of dura-lasty based on CTD grading scale in symp-

omatic CM-I.

ETHODS

atientsfter approval from the our clinic review

� OBJECTIVE: To evaluate the effect odescent (CTD) grade in the surgical(CM-I).

� METHODS: Medical records and m2 patients with surgical correction of998 –2009 were reviewed. The preopatients were divided two groups: durroup (group 2). The preoperative andavity, Japanese Orthopaedic Assocostoperative complications were det

RESULTS: There was 58 patientsforamen magnum decompression, C1duraplasty; the 24 patients in group 2(PFD) alone with no dural openingsignificant differences between preosyringomyelia cavity and JOA scores(group 2) groups in CTD grades 1 andcavity and clinical improvement werewith group 2 (P < 0.05). Complicationsincreased compared with group 2 (P <

� CONCLUSIONS: This study shows tCTD grade 3 Chiari malformation mayvolume of concomitant syringomyeliapatients, PFD without duraplasty may

oard, the senior author’s (Y.A.) database d

, FEBRUARY 2011 ww

f all 82 consecutive patients who had CM-Iith or without syringomyelia over a 10-

ear period (1998 –2009) was reviewed. Allatients were older than 18 years and under-ent the PFD procedure at our institution.M-I cases were diagnosed with the aid ofagnetic resonance imaging (MRI). The

efinition of CM-I in this study was that theerebellar tonsil descended more than 5m below the foramen magnum. The pre-

perative stage of CTD was determined onRI based on the following three classifica-

ions: grade 1, the tonsil descended morehan 5 mm below the foramen magnum butid not reach the C1 arch; grade 2, the tonsileached the C1 arch; and Grade 3, the tonsil

raplasty based on cerebellar tonsillartment of Chiari malformation type I

tic resonance imaging (MRI) scans ofI performed at the authors’ clinic fromve CTD grading scale was obtained.sty group (group 1) and nonduraplastystoperative size of the syringomyelian (JOA) scores, recovery rate, andned.

group 1, who underwent combinedC2 if necessary) laminectomy, and

rwent posterior fossa decompressionformed. There were no statisticallytive and postoperative size of theraplasty (group 1) and nonduraplastyCTD grade 3, the decrease in syrinx

tistically better in group 1 comparedroup 1 were statistically significantly5).

FD and duraplasty for the treatment ofd to a more reliable reduction in the

JOA scores. In CTD grade 1 and 2erformed.

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PEER-REVIEW REPORTS

ADEM YILMAZ ET AL. DURAPLASTY IN SURGICAL TREATMENT OF CHIARI MALFORMATION TYPE I

comparisons among these categories, JOAscores, recovery rate, decrease in syrinxsize, complications, and reoperation ratewere assessed for each grade (Table 1).

Surgical indications were usually headacheor tussive headache; drop attacks; neck, arm,or back pain; swallowing difficulties; or upperextremity numbness or tingling. The pres-ence of a syrinx was also an indication forsurgery when it occurred in the presence ofthe aforementioned symptoms.

Surgical ProcedureAll patients underwent osseous decompres-sion including PFD and C1 laminectomyand were grouped according to tonsillar de-scending grading scale. The degree of ton-sillar descent was graded in relation to thesuperior and inferior borders of the C1 lam-ina. The specific surgical procedure (non-duraplasty or duraplasty) was chosen basedon the surgeon’s experience and prefer-ence. After general anesthesia was adminis-tered, all surgeries were performed with thepatient in the prone position with rigid headfixation. A midline incision extending fromthe inion to the upper cervical spine wasused to perform a standard subperiostealdissection of muscle from the occipital andcervical region. Muscle attachments werepreserved at the superior nuchal line andusually at the C2 lamina. Osseous decom-pression was achieved with a high-speed airdrill, encompassing the inferior aspect ofthe occipital bone with modest superior ex-

Figure 1. (A) Grade 1 tonsillar descent. Tonsil dedescent. Tonsil descended to C1 arch level. (C)

C1 arch.

tension (approximately 1.5–2.0 cm) and lat- o

308 www.SCIENCEDIRECT.com

ral extension to the lateralmost aspect ofhe foramen magnum and cervical spinalanal, and C1 laminectomy (and C2 if nec-ssary) was performed. In the duraplastyroup, after the dura was opened, duralrafting was performed with cadavericura, bovine pericardium, fascia lata, or au-

ologous pericranium. No sealant was usedo reinforce the dural suture line, and noorced inspiratory pressure was routinelysed to test the integrity of the dural clo-ure. In the nonduraplasty group, only boneemoval was performed. Finally, the woundas meticulously closed with interrupted

utures, each layer at a time: muscles, fas-ia, subcutaneous tissue, and skin.

ollow-upostoperative clinical improvement was as-essed from clinic notes and generally re-ected subjective reports of improvement

n symptoms evaluated using the JOA scalend recovery rate. Recovery rate accordingo the JOA scale (15), which indicates theegree of normalization after surgery, wasalculated using the following formula:

Postoperative score � Preoperative score

Recovery rate �%� � __________ � 100

18 � Preoperative score

All patients underwent MRI 3–5 days afterurgery and at least one subsequent MRI ses-ion at the follow-up consultation, usually–12 months later. The presence or absence

ed to above C1 arch. (B) Grade 2 tonsillar3 tonsillar descent. Tonsil descended below

f syringomyelia and its location and extent in s

WORLD NEUROSURGE

he cervical or the thoracic cord (or both) weressessed preoperatively and at least 6 monthsostoperatively and as needed thereafter. Syr-

nx improvement was defined as any demon-trable decrease in maximal syrinx diameter,s seen on MRI at least 6 months postopera-ively. In practical terms, syrinxes that weremaller postoperatively showed minimal re-idual, indistinguishable from mild dilationf the central canal. In patients with postoper-tive MRI (Figure 2), the change in the size ofhe syrinx cavity was classified as improveddecreased maximal diameter), unchanged,r increased.

utcome Measureshe long-term (average 9 months postopera-

ively) surgery-related result was consideredxcellent if symptoms resolved. The resultas considered good if the patient experi-

nced significant improvement but also resid-al symptoms. A poor result indicated nohange in symptoms or deterioration. Specif-cally noted symptoms were assessed at theime of follow-up examination.

tatistical Evaluationtatisticalanalysiswasperformedwiththeassis-ance of computer statistics programs (SPSS0.0.7;SPSS,Inc.,Chicago,Illinois,USA)byoneftheauthors(Y.T.).Statisticalanalysiswasper-ormed using Student t test, analysis of varianceest, and univariate and multivariate regressionnalysis. A probability value �0.05 was consid-red statistically significant.

ESULTS

ean age of patients in each group was sim-lar at the time of surgery (duraplasty group8.9 years and nonduraplasty group 31ears). There were 58 patients in group 1,ho underwent combined PFD, C1 (and C2

f necessary) laminectomy, and duraplasty;he 24 patients in group 2 underwent PFDithout duraplasty. There were 36 men and6 women.

roup 1 (Duraplasty Group)f the 58 patients in group 1, 25 (43.1%)ere in CTD grade 1, 21 (36.2%) were inTD grade 2, and 12 (20.7%) were in CTDrade 3. The means of the JOA scores before

scendGrade

urgery and at the final follow-up evaluation

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PEER-REVIEW REPORTS


were 14.2 points (range 10 –17 points) and16.01 points (range 8 –18 points), and themean recovery rate was 56.3%. An improve-ment in symptoms occurred in 52 (89.6%)of these patients. Based on CTD gradingscale in group 1, all 25 patients in grade 1,18 (85.7%) of 21 patients in grade 2, and9 (75%) of 12 patients in grade 3 showedclinical improvement. Of these patients, 45(77.5%) had syringomyelia. Of the patientswho underwent follow-up MRI, 41 (91.1%)

Table 1. Japanese Orthopaedic AssociatAssessment Scale

Score

Motor Dysfunction Scoreof Upper Extremities

0 Inability to move

1 Inability to eat w

2 Inability to butto

3 Able to button s

4 Able to button s

5 No dysfunction

Motor Dysfunction Scoreof Lower Extremities

0 Complete loss o

1 Sensory preserva

2 Able to move le

3 Able to walk on

4 Able to walk up

5 Moderate to sigstairs without ha

6 Mild lack of stab

7 No dysfunction

Sensory Dysfunction Scoreof Upper Extremities

0 Complete loss o

1 Severe sensory l

2 Mild sensory los

3 No sensory loss

Sphincter Dysfunction Score

0 Inability to mictu

1 Marked difficulty

2 Mild to moderat

3 Normal micturat

Modified from Benzel EC, Lancon J, Kesterson L, Hadden Tspondylotic myelopathy. J Spinal Disord 4:286-95, 199

had a decrease in the size of syringomyelia, w


nd 37 (90.2%) had clinical improvement.n addition, 10 (83.3%) of 13 patients with-ut syringomyelia experienced clinical re-overy. The size of the syringomyelia cavityas decreased in 17 (89.4%) patients inrade 1, 16 (94.12 %) patients in grade 2,nd 8 (88.8%) patients in grade 3.

roup 2 (Nonduraplasty Group)roup 2 comprised 24 patients who under-

ervical Spine Myelopathy Functional

Definition

s

spoon but able to move hands

t but able to eat with a spoon

ith great difficulty

ith slight difficulty

r and sensory function

ithout ability to move legs

unable to walk

oor with a walking aid (ie, cane or crutch)

own stairs with handrail

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ut able to walk with smooth reciprocation unaided

sensation

pain

oluntarily

micturation

ulty with micturation

cal laminectomy and dentate ligament section for cervical

ent PFD and C1 laminectomy without du-

, FEBRUARY 2011 ww

aplasty. There were 11 (45.8%) patients inTD grade 1, 8 (33.3%) patients in CTDrade 2, and 5 (20.9%) patients in CTDrade 3. The means of the JOA scores beforeurgery and at final follow-up evaluationere 14.8 points (range 9 –18 points) and

6.5 points (range 12–18 points), and theean recovery rate was 51.9%. An improve-ent in symptoms occurred in 19 (79.1%)

f these patients. Based on CTD gradingcale, 10 (90.9%) of 11 patients in grade 1, 675%) of 8 patients in grade 2, and 3 (60%)f 5 patients in grade 3 experienced an im-rovement of symptoms. Of these patients,9 (79.1%) had syringomyelia. Of the pa-ients who underwent follow-up MRI, 1684.2%) had a decrease in the size of syrin-omyelia, and 16 (84.2%) had clinical im-rovement. Three (60%) of five patientsithout syringomyelia experienced clinical

ecovery.

rocedure-Related Complicationsomplications occurred in seven patients in

he duraplasty group (group 1): CSF leak inhree cases, additional focal neurologic def-cit in two cases, superficial infection in onease, and meningitis in one case. Two pa-ients (3.6%) in group 1 underwent reopera-ion because of open CSF fistulas. In theonduraplasty group (group 2), surgicalomplications included a superficial woundnfection and temporary neurologic deficitn one patient. Two patients (9.5%) inroup 2 underwent reoperation because of

nadequate decompression (Table 2).The cavity size of syringomyelia preoper-

tively and postoperatively, JOA scores, re-overy rate, and complication rate were de-ermined. Two samples Student t test wereerformed. There were no statistically sig-ificant differences between preoperativend postoperative cavity sizes of syringomy-lia and JOA scores in duraplasty and non-uraplasty groups in CTD grades 1 and 2; inTD grade 3, the decrease in syrinx cavitynd clinical improvement were statisticallyetter in group 1 compared with group 2 (P

0.05). Complications in group 1 were sta-istically significantly increased comparedith group 2 (P � 0.05).

DISCUSSION

Surgery for CM-I with or without syringo-

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PEER-REVIEW REPORTS


circulation at the foramen magnum, (2) re-duction of the syrinx if there is one, and (3)relief of the compression exerted by the cer-ebellar tonsils on the brainstem (Figure 3).The correct way to treat Chiari malforma-tions is one of the most disputed issues inneurosurgery (1, 12, 23, 26).

Surgical ProcedureConsiderable debate exists about whichsurgical options are best for the manage-ment of CM-I. Patients with herniationshould be deemed candidates for decom-pression with or without duraplasty. Theaim of this study was to compare the surgi-cal outcomes of patients with CM-I afterPFD with or without duraplasty based onCTD grading scale. The outcome of decom-pression surgery usually is evaluated bycomparing symptoms before and after sur-gery. In an effort to define the current sur-gical strategies, members of the AmericanAssociation of Neurological Surgeons weresurveyed as to the surgical approach theyused in pediatric patients with CM-I (10).Only 9% recommended performing decom-pressive surgery in asymptomatic patients.

Figure 2. Syrinx regression after decompressivePostoperative craniocervical MRI.

For the treatment of symptomatic patients,


various approaches were used: Approxi-mately 20% recommended osseous decom-pression only; 30% recommended osseousdecompression with dural grafting; 25% rec-ommended osseous decompression withdural grafting and intradural dissection ofadhesions; and 30% recommended osse-ous decompression with dural grafting, in-tradural dissection, and tonsillar manipula-tion and resection (10). Authors of recentreports in the literature have suggested thatgood clinical outcomes can be attainedwithout more complex and invasive neuro-surgical procedures (9, 16).

Duraplasty versus NonduraplastySome authors have advocated that craniec-tomy alone for CM-I may be sufficient (7,21, 30), whereas others have argued that thedura must be opened (11, 17, 22). In a reviewof patients who underwent PFD with andwithout duraplasty, Matsumoto and Symon(17) noted no difference in the reduction ofhydromyelia; however, regarding the im-provement in symptoms, patients who didnot undergo duraplasty had a significantlyworse outcome compared with patients

y. (A) Preoperative craniocervical MRI. (B)

who underwent duraplasty. Some data sug-

WORLD NEUROSURGE

gest a more reliable outcome in size reduc-tion and even disappearance of an existingsyrinx are achieved when duraplasty is per-formed (12, 21, 26). Munshi et al. (21) de-scribed 33 patients who presented withChiari malformations during a 10-year pe-riod. Eleven patients underwent PFD with-out duraplasty (73% had improvement),and 23 underwent PFD with duraplasty(87% had improvement). The rate of minorcomplications was higher in the lattergroup. There seems to be a subset of pa-tients, however, whose symptoms resolveand whose hydromyelic cavity decreaseswith the removal of bone only (21). In an-other study performed in pediatric patients,it was found that PFD with duraplasty isassociated with a lower risk of reoperationthan PFD but a greater risk of CSF-relatedcomplications. There was no significantdifference between the two operative tech-niques with respect to clinical improvementor decrease in syringomyelia (7).

McGirt et al. (18) reviewed the records of256 children who underwent first-time PFDfor CM-I. All patients underwent suboccipitalcraniectomy and laminectomy of the atlas.The hindbrain was examined intraoperativelyon transdural ultrasonography. If the sub-arachnoid spaces dorsal to the cerebellar ton-sils and ventral to the medulla were effaced,and if the tonsils exhibited the characteristicrostrocaudal, pistonlike pulsation, duraplastywas performed. Otherwise, the dura materwas left undisturbed, and the procedure wasconcluded. In children with displacement ofthe tonsils below the inferior border of thearch of the atlas, ultrasonography-indicatedosseous decompression alone was associatedwith twice the risk of symptom recurrence asdecompression with duraplasty. In childrenwith lesser degrees of tonsillar displacement,duraplasty indicated by ultrasonography find-ings yielded the same results as achieved withosseous decompression alone. McGirt et al.(18) concluded that intraoperative ultra-sonography can be used to identify cases thatdo not require duraplasty among patientswith lesser degrees of tonsillar displacement,but it cannot be used for this purpose in pa-tients with more severe involvement.

Durham and Fjeld-Olenec (7) searchedMedline-Ovid, The Cochrane Library, andthe conference proceedings of the Ameri-can Association of Neurological Surgeonsand the Congress of Neurological Surgeons

surger

(2000 –2007) for surgical techniques of

RY, DOI:10.1016/j.wneu.2010.09.005

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PEER-REVIEW REPORTS


PFD and PFD with duraplasty in CM-I. Intheir meta-analysis, these authors evaluatedfive retrospective and two prospective co-hort studies involving 582 patients. Of the582 patients, 316 were treated with PFDwith duraplasty, and 266 were treated with

Figure 3. Artist’s drawing of preoperative and po

Table 2. Summary of Clinical Outcomes A

No.Patient

Posterior Fossa DecompressionC1 Laminectomy, Duraplasty(Group 1)

58 (70.8%

Tonsillar descent

Grade 1 25 (43.1%

Grade 2 21 (36.2%

Grade 3 12 (20.7%

Posterior Fossa Decompression,C1 Laminectomy (Group 2)

24 (29.2%

Tonsillar descent

Grade 1 11 (45.8%

Grade 2 8 (33.3%

Grade 3 5 (20.9%

CSF, cerebrospinal fluid.

decompression with duraplasty led to decreased syrin


FD alone. Patients undergoing PFD withuraplasty had a significantly lower reop-ration rate and a higher rate of CSF-relatedomplications. There were no significantifferences in clinical improvement or sy-ingomyelia decrease between PFD with

ative grade 3 Chiari type I. Posterior fossa

Chiari Surgery According to Cerebellar To

No.Syrinx

No. Patients withSymptom Improvement

Yes No

45 (77.5%) 52 (89.6%) 6 (10.4%)

19 (42.2%) 25 (100%) 0

17 (37.7%) 18 (85.7%) 3 (14.3%)

9 (20.1%) 9 (75%) 3 (25%)

19 (79.1%) 19 (79.1%) 5 (20.9%)

8 (42.1%) 10 (90.9%) 1 (9.1%)

7 (36.8%) 6 (85.7%) 1 (14.3%)

4 (21.1%) 3 (60%) 2 (40%)

dx cavity.

, FEBRUARY 2011 ww

nd without duraplasty (7). Existing evi-ence supports the rationale of enlarging

he craniocervical CSF spaces, however (2,0, 22). In the present study, as Durhamnd Fjeld-Olenec (7) reported, there wereo statistically significant differences be-

ween preoperative and postoperative cavityize of syringomyelia and JOA scores of du-aplasty and nonduraplasty groups in CTDrade 1 and 2 (P � 0.05), whereas in CTDrade 3, decrease in syrinx cavity and clini-al improvement were statistically signifi-antly better in the duraplasty group com-ared with nonduraplasty group (P � 0.05).

n this study, manipulation of the subarach-oid space and tonsil resection were noterformed because of complications. Theomplication rate was significantly highern the duraplasty group than nonduraplastyroup, however. We recommend using pre-perative CTD grading from MRI findings,nd duraplasty should be performed in allTD grade 3 patients.

s Duraplasty Associated with Frequenterebrospinal Fluid–Related Morbidity?

n light of the effort to move toward a lessnvasive and purportedly less morbid proce-

r Descent

. Patients withomyelia Decrease

No. Patients withComplicationss No

.1%) 4 (8.9%) 7 (12.0%)

.4%) 2 (10.6%) 1 (neurologic deficit),1 (superficial infection)

.1%) 1 (5.9%) 2 (CSF leak),1 (neurologic deficit),1 (meningitis)

.9%) 1 (11.1%) 1 (CSF leak)

.5%) 3 (12.5%) 2 (8.3%)

.5%) 1 (12.5%) 1 (superficial infection)

0%) 0

%) 2 (50%) 1 (neurologic deficit)

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) 17 (89

) 16 (94

) 8 (88

) 16 (87

) 7 (87

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PEER-REVIEW REPORTS


of dural-sparing surgery based on the as-sumption that dural opening is associatedwith frequent CSF-related morbidity (5, 6,17). The common opinion for osseous de-compression without duraplasty is sup-ported by the purportedly lower morbidityof this approach. In this study, according toour practice protocol, we performed in pa-tients with CM-I with or without syringo-myelia a standard PFD, including a smallsuboccipital and foramen magnum craniec-tomy, removal of the C-1 arch, and dura-plasty, or without duraplasty, and water-tight closure. In both groups, 2 patientsunderwent reoperation. The cause was CSFfistula in group 1 and insufficient decom-pression in group 2.

Occurrence of SyringomyeliaSyringomyelia occurs in 50%–76% of pa-tients. Altered CSF circulation at the fora-men magnum prevents instantaneous pres-sure equilibration between the intracranialand spinal subarachnoid space. Presum-ably, an intermittent vector of force devel-ops with each Valsalva maneuver, whichcan lead to the progressive downwardmovement of developing tissue through theforamen magnum. If the impediment toCSF equilibration occurs after the tonsilshave formed, the pressure gradient favorstonsillar herniation and may be responsiblefor the initiation of syringomyelia forma-tion (26, 28, 29). In the present study, 45(77.5%) of 58 patients in the duraplastygroup and 19 (79.1%) of 24 patients in thenonduraplasty group had syringomyelia.The size of the syringomyelia cavity wasdecreased in 41 (91.1%) patients in the dura-plasty group and 16 (87.5%) patients innonduraplasty group.

Value of the Present StudyThis consecutive series of 82 patientstreated for CM-I constitutes one of thelarger series reported (3, 8, 11, 13, 14, 19, 24,25, 27). In this study, in CTD grade 3 pa-tients, PFD and duraplasty seem to be theessential surgical treatment of this condi-tion. Overall, the significant and sustainedpostoperative improvement shown in these82 patients suggests a favorable therapeuticresult in itself and when compared withother results obtained in previously re-
ported studies. Although the data of the

resent study reflect our current practiceegimen, there have been no prospectivetudies in which one treatment form is di-ectly compared with another. In addition,n light of the many theories of pathophys-ology, broad clinical presentations, and

ultitude of surgical interventions withariable outcomes, it is not surprising that aingle surgical approach does not exist, andhe results of treatment are difficult to as-ess given the absence of uniform outcomeeasures and a randomized controlled trial

n which the different treatments are com-ared. In most articles in which outcome isiscussed, the authors have reported an0%–90% rate of good outcome, with ei-her resolution of the symptoms or cessa-ion of progression.

ONCLUSIONS

FD with duraplasty in CM-I is associatedith a greater risk for CSF-related compli-

ations. As a result, in this study, complica-ions from surgical intervention were mini-

al and results were good, although moreomplications were observed in the dura-lasty group (Table 2). In our experience,FD with or without duraplasty in symp-

omatic adult patients with CM-I is success-ul in most cases with minimal complica-ions. We believe that the risk of CSF leakas to be accepted as a downside of thessential procedure, which is opening theura and widening the cisternal space withgraft.We recommend tailoring the surgical ap-

roach to treat the dominant clinical prob-em. There is little controversy today that theommon denominator of all treatment strate-ies is posterior craniovertebral decompres-ion with or without duraplasty. Properatient selection is crucial to prevent unneces-ary procedures and to maximize outcome,nd we recommend using CTD grading scaleefore planning duraplasty, which should beeserved for patients who are CTD grade 3.urther studies are needed to characterize bet-er the effect of patients’ tonsillar descendingrade on clinical outcome.

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WORLD NEUROSURGE

2. Armonda RA, Citrin CM, Foley KT, Ellenbogen RG:Quantitative cinemode magnetic resonance imag-ing of Chiari I malformations: an analysis of cere-brospinal fluid dynamics. Neurosurgery 35:214-24,1994.

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4. Benzel EC, Lancon J, Kesterson L, Hadden T: Cervi-cal laminectomy and dentate ligament section forcervical spondylotic myelopathy. J Spinal Disord4:286-95, 1991.

5. Bertrand SL, Drvaric DM, Roberts JM: Scoliosis insyringomyelia. Orthopedics 12:335-7, 1989.

6. Bondurant CP, Oro JJ: Spinal cord injury withoutradiographic abnormality and Chiari malformation.J Neurosurg 79:833-8, 1993.

7. Durham SR, Fjeld-Olenec K: Comparison of poste-rior fossa decompression with and without dura-plasty for the surgical treatment of Chiari malfor-mation type I in pediatric patients: a meta-analysis. JNeurosurg Pediatr 2:42-9, 2008.

8. Gardner WJ: Hydrodynamic mechanism of syringo-myelia: its relationship to myelocele. J Neurol Neu-rosurg Psychiatry 28:247-59, 1965.

9. Genitori L, Peretta P, Nurisso C, Macinante L,Mussa F: Chiari type I anomalies in children andadolescents: minimally invasive management in aseries of 53 cases. Childs Nerv System 16:707-18,2000.

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onflict of interest statement: The authors declare that therticle content was composed in the absence of anyommercial or financial relationships that could beonstrued as a potential conflict of interest.

eceived 17 June 2010; accepted 10 September 2010

itation: World Neurosurg. (2011) 75, 2:307-313.OI: 10.1016/j.wneu.2010.09.005

ournal homepage: www.WORLDNEUROSURGERY.org

vailable online: www.sciencedirect.com

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1878-8750/$ - see front matter © 2011 Elsevier Inc.All rights reserved.


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