Chiari malformation Type I and syrinx in children undergoing magnetic resonance imaging

Clinical article

Restricted access


Chiari malformation Type I (CM-I) with an associated spinal syrinx is a common pediatric diagnosis. A better understanding of the relative age-related prevalence and MR imaging characteristics of these associated conditions may lead to improved treatment decisions.


The authors performed a retrospective review of 14,116 consecutive individuals 18 years of age or younger who had undergone brain or cervical spine MR imaging at the University of Michigan between November 1997 and August 2008. In the patients with CM-I, demographic, clinical, and radiographic information was recorded.


Five hundred nine children (3.6%) with CM-I were identified. Among these patients, 23% also had a spinal cord syrinx, and 86% of the syringes were found in the cervical spine. The MR imaging prevalence of CM-I with a syrinx was 1.2% in girls and 0.5% in boys (p < 0.0001). The severity of impaired CSF flow at the foramen magnum was associated with the amount of tonsillar herniation (p < 0.0001) and conformation of the tonsils (p < 0.0001). Patients with CM-I were treated surgically in 35% of cases; these patients exhibited more severe tonsillar herniation (p < 0.0001) and impaired CSF flow (p < 0.0001) as compared with those who did not undergo surgery. On imaging, 32% of all the patients with CM-I were considered symptomatic by the treating physician. Patients were more likely to be considered symptomatic if they were female, had a syrinx, displayed abnormal tonsillar pulsations, or had a greater amount of tonsillar herniation.


In this study the authors describe the age-related prevalence and MR imaging characteristics of CM-I and its association with a syrinx and other abnormalities in a large group of children who underwent MR imaging for any indication. Syringes are more common in older children, in girls, and in patients with a greater degree of tonsillar descent and CSF flow impairment.

Abbreviations used in this paper: CM-I = Chiari malformation Type I; EMERSE = Electronic Medical Record Search Engine.

Article Information

Address correspondence to: Cormac O. Maher, M.D., Department of Neurosurgery, University of Michigan, 1500 East Medical Center Drive, Room 3552, Taubman Center, Ann Arbor, Michigan 48109-5338. email:

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Line graph reflecting the percentage of children, according to age (in years), in whom a diagnosis of CM-I was made at the time of MR imaging.

  • View in gallery

    Line graph depicting the percentage of children with CM-I, according to age (in years), in whom spinal syrinx was diagnosed on MR imaging.

  • View in gallery

    Bar graph illustrating the number of patients with CM-I alone (black bars) versus those with both CM-I and syrinx (gray bars), according to the measurement (in mm) of tonsillar descent below the foramen magnum. Those with greater amounts of tonsillar decent were more likely to have an associated syrinx.

  • View in gallery

    Bar graph showing the cranial extent of syrinx in patients at the time of the initial syrinx diagnosis, according to the adjacent vertebral level.

  • View in gallery

    Bar graph showing the patients treated with decompression (black bars) versus without surgery (gray bars), according to age (in years).


  • 1

    Aboulezz AOSartor KGeyer CAGado MH: Position of cerebellar tonsils in the normal population and in patients with Chiari malformation: a quantitative approach with MR imaging. J Comput Assist Tomogr 9:103310361985

  • 2

    Aitken LALindan CESidney SGupta NBarkovich AJSorel M: Chiari type I malformation in a pediatric population. Pediatr Neurol 40:4494542009

  • 3

    Al-Holou WNYew AYBoomsaad ZEGarton HJMuraszko KMMaher CO: Prevalence and natural history of arachnoid cysts in children. Clinical article. J Neurosurg Pediatr 5:5785852010

  • 4

    Armonda RACitrin CMFoley KTEllenbogen RG: Quantitative cine-mode magnetic resonance imaging of Chiari I malformations: an analysis of cerebrospinal fluid dynamics. Neurosurgery 35:2142241994

  • 5

    Barkovich AJWippold FJSherman JLCitrin CM: Significance of cerebellar tonsillar position on MR. AJNR Am J Neuroradiol 7:7957991986

  • 6

    Blagodatsky MDLarionov SNManohin PAShanturov VAGladyshev YuV: Surgical treatment of “hindbrain related” syringomyelia: new data for pathogenesis. Acta Neurochir (Wien) 124:82851993

  • 7

    Bogdanov EIMendelevich EG: Syrinx size and duration of symptoms predict the pace of progressive myelopathy: retrospective analysis of 103 unoperated cases with craniocervical junction malformations and syringomyelia. Clin Neurol Neurosurg 104:90972002

  • 8

    Cahan LDBentson JR: Considerations in the diagnosis and treatment of syringomyelia and the Chiari malformation. J Neurosurg 57:24311982

  • 9

    Elster ADChen MY: Chiari I malformations: clinical and radiologic reappraisal. Radiology 183:3473531992

  • 10

    Eule JMErickson MAO'Brien MFHandler M: Chiari I malformation associated with syringomyelia and scoliosis: a twenty-year review of surgical and nonsurgical treatment in a pediatric population. Spine (Phila Pa 1976) 27:145114552002

  • 11

    Genitori LPeretta PNurisso CMacinante LMussa F: Chiari type I anomalies in children and adolescents: minimally invasive management in a series of 53 cases. Childs Nerv Syst 16:7077182000

  • 12

    Grabb PAMapstone TBOakes WJ: Ventral brain stem compression in pediatric and young adult patients with Chiari I malformations. Neurosurgery 44:5205281999

  • 13

    Greitz D: Unraveling the riddle of syringomyelia. Neurosurg Rev 29:2512642006

  • 14

    Guo FWang MLong JWang HSun HYang B: Surgical management of Chiari malformation: analysis of 128 cases. Pediatr Neurosurg 43:3753812007

  • 15

    Haines SJBerger M: Current treatment of Chiari malformations types I and II: a survey of the Pediatric Section of the American Association of Neurological Surgeons. Neurosurgery 28:3533571991

  • 16

    Hanauer DA: EMERSE: The Electronic Medical Record Search Engine. AMIA Annu Symp Proc 2006:9412006

  • 17

    Haroun RIGuarnieri MMeadow JJKraut MCarson BS: Current opinions for the treatment of syringomyelia and chiari malformations: survey of the Pediatric Section of the American Association of Neurological Surgeons. Pediatr Neurosurg 33:3113172000

  • 18

    Hida KIwasaki YKoyanagi IAbe H: Pediatric syringomyelia with chiari malformation: its clinical characteristics and surgical outcomes. Surg Neurol 51:3833911999

  • 19

    Holly LTBatzdorf U: Syringomyelia associated with intradural arachnoid cysts. J Neurosurg Spine 5:1111162006

  • 20

    Kane WJMoe JH: A scoliosis-prevalence survey in Minnesota. Clin Orthop Relat Res 69:2162181970

  • 21

    Katzman GLDagher APPatronas NJ: Incidental findings on brain magnetic resonance imaging from 1000 asymptomatic volunteers. JAMA 282:36391999

  • 22

    Kim LJRekate HLKlopfenstein JDSonntag VK: Treatment of basilar invagination associated with Chiari I malformations in the pediatric population: cervical reduction and posterior occipitocervical fusion. J Neurosurg 101:2 Suppl1891952004

  • 23

    Krieger MDMcComb JGLevy ML: Toward a simpler surgical management of Chiari I malformation in a pediatric population. Pediatr Neurosurg 30:1131211999

  • 24

    Lipson ACEllenbogen RGAvellino AM: Radiographic formation and progression of cervical syringomyelia in a child with untreated Chiari I malformation. Pediatr Neurosurg 44:2212232008

  • 25

    Meadows JKraut MGuarnieri MHaroun RICarson BS: Asymptomatic Chiari Type I malformations identified on magnetic resonance imaging. J Neurosurg 92:9209262000

  • 26

    Menezes AH: Chiari I malformations and hydromyelia—complications. Pediatr Neurosurg 17:1461541992

  • 27

    Milhorat THChou MWTrinidad EMKula RWMandell MWolpert C: Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 44:100510171999

  • 28

    Morris ZWhiteley WNLongstreth WT JrWeber FLee YCTsushima Y: Incidental findings on brain magnetic resonance imaging: systematic review and meta-analysis. BMJ 339:b30162009

  • 29

    Muhonen MGMenezes AHSawin PDWeinstein SL: Scoliosis in pediatric Chiari malformations without myelodysplasia. J Neurosurg 77:69771992

  • 30

    Navarro ROlavarria GSeshadri RGonzales-Portillo GMcLone DGTomita T: Surgical results of posterior fossa decompression for patients with Chiari I malformation. Childs Nerv Syst 20:3493562004

  • 31

    Nishikawa MSakamoto HHakuba ANakanishi NInoue Y: Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. J Neurosurg 86:40471997

  • 32

    Nishizawa SYokoyama TYokota NTokuyama TOhta S: Incidentally identified syringomyelia associated with Chiari I malformations: is early interventional surgery necessary?. Neurosurgery 49:6376412001

  • 33

    Noudel RJovenin NEap CScherpereel BPierot LRousseaux P: Incidence of basioccipital hypoplasia in Chiari malformation type I: comparative morphometric study of the posterior cranial fossa. Clinical article. J Neurosurg 111:104610522009

  • 34

    Novegno FCaldarelli MMassa AChieffo DMassimi LPettorini B: The natural history of the Chiari Type I anomaly. J Neurosurg Pediatr 2:1791872008

  • 35

    Oldfield EHMuraszko KShawker THPatronas NJ: Pathophysiology of syringomyelia associated with Chiari I malformation of the cerebellar tonsils. Implications for diagnosis and treatment. J Neurosurg 80:3151994

  • 36

    Ono ASuetsuna FUeyama KYokoyama TAburakawa SNumasawa T: Surgical outcomes in adult patients with syringomyelia associated with Chiari malformation type I: the relationship between scoliosis and neurological findings. J Neurosurg Spine 6:2162212007

  • 37

    Pillay PKAwad IALittle JRHahn JF: Symptomatic Chiari malformation in adults: a new classification based on magnetic resonance imaging with clinical and prognostic significance. Neurosurgery 28:6396451991

  • 38

    Pujol JRoig CCapdevila APou AMartí-Vilalta JLKulisevsky J: Motion of the cerebellar tonsils in Chiari type I malformation studied by cine phase-contrast MRI. Neurology 45:174617531995

  • 39

    Rekate HL: Editorial. Natural history of the Chiari Type I anomaly. J Neurosurg Pediatr 2:1771782008

  • 40

    Saez RJOnofrio BMYanagihara T: Experience with Arnold-Chiari malformation, 1960 to 1970. J Neurosurg 45:4164221976

  • 41

    Schijman ESteinbok P: International survey on the management of Chiari I malformation and syringomyelia. Childs Nerv Syst 20:3413482004

  • 42

    Stovner LJRinck P: Syringomyelia in Chiari malformation: relation to extent of cerebellar tissue herniation. Neurosurgery 31:9139171992

  • 43

    Tubbs RSWebb DBOakes WJ: Persistent syringomyelia following pediatric Chiari I decompression: radiological and surgical findings. J Neurosurg 100:5 Suppl Pediatrics4604642004

  • 44

    Tubbs RSWellons JC IIIBlount JPGrabb PAOakes WJ: Inclination of the odontoid process in the pediatric Chiari I malformation. J Neurosurg 98:1 Suppl43492003

  • 45

    Vernooij MWIkram MATanghe HLVincent AJHofman AKrestin GP: Incidental findings on brain MRI in the general population. N Engl J Med 357:182118282007

  • 46

    Weber FKnopf H: Cranial MRI as a screening tool: findings in 1,772 military pilot applicants. Aviat Space Environ Med 75:1581612004

  • 47

    Wetjen NMHeiss JDOldfield EH: Time course of syringomyelia resolution following decompression of Chiari malformation Type I. J Neurosurg Pediatr 1:1181232008

  • 48

    Wu YWChin CTChan KMBarkovich AJFerriero DM: Pediatric Chiari I malformations: do clinical and radiologic features correlate?. Neurology 53:127112761999

  • 49

    Yue NCLongstreth WT JrElster ADJungreis CAO'Leary DHPoirier VC: Clinically serious abnormalities found incidentally at MR imaging of the brain: data from the Cardiovascular Health Study. Radiology 202:41461997

  • 50

    Zhang ZQChen YQChen YAWu XWang YBLi XG: Chiari I malformation associated with syringomyelia: a retrospective study of 316 surgically treated patients. Spinal Cord 46:3583632008




All Time Past Year Past 30 Days
Abstract Views 152 152 19
Full Text Views 131 131 15
PDF Downloads 81 81 8
EPUB Downloads 0 0 0


Google Scholar