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Classification of Symptomatic Chiari I Malformation to Guide Surgical Strategy

Published online by Cambridge University Press:  02 December 2014

Mohammed F. Shamji
Division of Neurosurgery, The Ottawa Hospital
Enrique C. G. Ventureyra*
Division of Neurosurgery, The Ottawa Hospital Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Benedicto Baronia
Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Munyao Nzau
Division of Neurosurgery, The Ottawa Hospital Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Michael Vassilyadi
Division of Neurosurgery, The Ottawa Hospital Division of Neurosurgery, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Division of Neurosurgery, Children's Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, Ontario, K1H 8L1, Canada.
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Treatment options for Chiari I malformations include posterior fossa decompression (PFD) with additional techniques including laminectomy, intradural exploration, and duraplasty. Neuroimaging findings of cisterna magna volume, syringomyelia, and intraoperative ultrasonography may tailor surgical intervention.


We developed an algorithm classifying symptomatic Chiari I patients into three groups to define minimum operation. Without syringomyelia, the presence of cisterna magna defined Group A and the absence defined Group B. Patients with syrinx formed Group C. Mild structural pathology (Group A) or adequate space following PFD (Group B, normal intraoperative ultrasound (IOUS)) should be treated by PFD alone. Conversely, presence of syringomyelia (Group C) or inadequate space following PFD (Group B, abnormal IOUS) should additionally have duraplasty. We applied this algorithm to patients treated at a single institution over 16 years.


Twenty-four symptomatic Chiari I malformation patients were divided into three groups that did not differ by age, gender, or extent of tonsillar ectopia. All patients treated by this algorithm experienced clinical and radiographic improvement. This included eight Group B patients who underwent PFD only (n=6) or additional duraplasty (n=2) decided by IOUS.


Treatment of symptomatic Chiari I malformation may have inadequate outcome with conservative strategy or complications with aggressive strategy. This algorithm utilizes preoperative neuroimaging and intraoperative ultrasound to tailor intervention, with excellent clinical outcome and radiographic syrinx resolution on application to 24 patients. Further validation requires prospective multicenter evaluation with larger patient population.

Original Article
Copyright © The Canadian Journal of Neurological 2010


1. Chiari, H. Uber Veranderungen des Kleinhirins infolge von Hydrocephalie des Grosshirns. Dtsch Med Wochenshr. 1891;17:11725.Google Scholar
2. Nishikawa, M, Sakamoto, H, Hakuba, A, Nakanishi, N, Inoue, Y. Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. J Neurosurg. 1997;86(1):407.Google Scholar
3. Prassopoulos, P, Cavouras, D, Golfinopoulos, S. Developmental changes in the posterior cranial fossa of children studied by CT. Neuroradiology. 1996;38(1):803.CrossRefGoogle ScholarPubMed
4. Sekula, RF Jr., Jannetta, PJ, Casey, KF, Marchan, EM, Sekula, LK, McCrady, CS. Dimensions of the posterior fossa in patients symptomatic for Chiari I malformation but without cerebellar tonsillar descent. Cerebrospinal Fluid Res. 2005;2:11.CrossRefGoogle ScholarPubMed
5. Sgouros, S, Kountouri, M, Natarajan, K. Posterior fossa volume in children with Chiari malformation Type I. J Neurosurg. 2006;105 Suppl 2:1016.Google Scholar
6. Trigylidas, T, Baronia, B, Vassilyadi, M, Ventureyra, EC. Posterior fossa dimension and volume estimates in pediatric patients with Chiari I malformations. Childs Nerv Syst. 2008;24(3):32936.Google Scholar
7. Caldarelli, M, Novegno, F, Vassimi, L, Romani, R, Tamburrini, G, Di Rocco, C. The role of limited posterior fossa craniectomy in the surgical treatment of Chiari malformation Type I: experience with a pediatric series. J Neurosurg. 2007;106 Suppl 3:18795.Google ScholarPubMed
8. Genitori, L, Peretta, P, Nurisso, C, Macinante, L, Mussa, F. Chiari type I anomalies in children and adolescents: minimally invasive management in a series of 53 cases. Childs Nerv Syst. 2000;16 (10-11):70718.Google Scholar
9. Limonadi, FM, Selden, NR. Dura-splitting decompression of the craniocervical junction: reduced operative time, hospital stay, and cost with equivalent early outcome. J Neurosurg. 2004;101 Suppl 2:1848.Google ScholarPubMed
10. Navarro, R, Olavarria, G, Seshadri, R, Gonzales-Portillo, G, McLone, DG, Tomita, T. Surgical results of posterior fossa decompression for patients with Chiari I malformation. Childs Nerv Syst. 2004; 20(5):34956.CrossRefGoogle ScholarPubMed
11. Yeh, DD, Koch, B, Crone, KR. Intraoperative ultrasonography used to determine the extent of surgery necessary during posterior fossa decompression in children with Chiari malformation type I. J Neurosurg. 2006;105 Suppl 1:2632.Google Scholar
12. Attenello, FJ, McGirt, MJ, Garces-Ambrossi, GL, Chaichana, KL, Carson, B, Jallo, GI. Suboccipital decompression for Chiari I malformation: outcome comparison of duraplasty with expanded polytetrafluoroethylene dural substitute versus pericranial autograft. Childs Nerv Syst. 2009;25(2):18390.Google Scholar
13. Durham, SR, Fjeld-Olenec, K. Comparison of posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation Type I in pediatric patients: a meta-analysis. J Neurosurg Pediatrics. 2008;2(1):429.Google Scholar
14. Munshi, I, Frim, D, Stine-Reyes, R, Weir, BK, Hekmatpanah, J, Brown, F. Effects of posterior fossa decompression with and without duraplasty on Chiari malformation-associated hydromyelia. Neurosurgery. 2000;46(6):13849; discussion 89-90.Google Scholar
15. Klekamp, J, Batzdorf, U, Samii, M, Bothe, HW. The surgical treatment of Chiari I malformation. Acta Neurochir (Wien). 1996;138(7):788801.Google Scholar
16. Hida, K, Iwasaki, Y. Syringosubarachnoid shunt for syringomyelia associated with Chiari I malformation. Neurosurg Focus. 2001;11(1):E7.CrossRefGoogle ScholarPubMed
17. Iwasaki, Y, Hida, K, Koyanagi, I, Abe, H. Reevaluation of syringosubarachnoid shunt for syringomyelia with Chiari malformation. Neurosurgery. 2000;46(2):40712; discussion 12-13.Google Scholar
18. Bindal, AK, Dunsker, SB, Tew, JM Jr. Chiari I malformation: classification and management. Neurosurgery. 1995;37(6):106974.Google Scholar
19. Sahuquillo, J, Rubio, E, Poca, MA, Rovira, A, Rodriguez-Baeza, A, Cervera, C. Posterior fossa reconstruction: a surgical technique for the treatment of Chiari I malformation and Chiari I/syringomyelia complex-preliminary results and magnetic resonance imaging quantitative assessment of hindbrain migration. Neurosurgery. 1994;35(5):87484; discussion 84-5.Google Scholar
20. Sakamoto, H, Nishikawa, M, Hakuba, A, Yasui, T, Kitano, S, Nakanishi, N, et al. Expansive suboccipital cranioplasty for the treatment of syringomyelia associated with Chiari malformation. Acta Neurochir (Wien). 1999;141(9):94960; discussion 60-1.Google Scholar
21. Schijman, E, Steinbok, P. International survey on the management of Chiari I malformation and syringomyelia. Childs Nerv Syst. 2004;20(5):3418.Google Scholar
22. Haroun, RI, Guarnieri, M, Meadow, JJ, Kraut, M, Carson, 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. 2000;33(6):3117.CrossRefGoogle ScholarPubMed
23. Krieger, MD, McComb, JG, Levy, ML. Toward a simpler surgical management of Chiari I malformation in a pediatric population. Pediatr Neurosurg. 1999;30(3):11321.Google Scholar
24. Dyste, GN, Menezes, AH, VanGilder, JC. Symptomatic Chiari malformations. An analysis of presentation, management, and long-term outcome. J Neurosurg. 1989;71(2):15968.CrossRefGoogle ScholarPubMed
25. Levine, DN. The pathogenesis of syringomyelia associated with lesions at the foramen magnum: a critical review of existing theories and proposal of a new hypothesis. J Neurol Sci. 2004;220(1-2):321.CrossRefGoogle ScholarPubMed
26. Ventureyra, EC, Aziz, HA, Vassilyadi, M. The role of cine flow MRI in children with Chiari I malformation. Childs Nerv Syst. 2003;19(2):10913.Google Scholar
27. Attenello, FJ, McGirt, MJ, Gathinji, M, Datoo, G, Atiba, A, Weingart, J, et al. Outcome of Chiari-associated syringomyelia after hindbrain decompression in children: analysis of 49 consecutive cases. Neurosurgery. 2008;62(6):130713; discussion 13.Google Scholar
28. Feldstein, NA, Choudhri, TF. Management of Chiari I malformations with holocord syringohydromyelia. Pediatr Neurosurg. 1999;31(3):1439.Google Scholar
29. Park, JK, Gleason, PL, Madsen, JR, Goumnerova, LC, Scott, RM. Presentation and management of Chiari I malformation in children. Pediatr Neurosurg. 1997;26(4):1906.Google Scholar
30. McGirt, MJ, Attenello, FJ, Datoo, G, Gathinji, M, Atiba, A, Weingart, JD, et al. Intraoperative ultrasonography as a guide to patient selection for duraplasty after suboccipital decompression in children with Chiari malformation Type I. J Neurosurg Pediatrics. 2008;2(1):527.Google Scholar
31. Milhorat, TH, Bolognese, PA. Tailored operative technique for Chiari type I malformation using intraoperative color Doppler ultrasonography. Neurosurgery. 2003;53(4):899905; discussion 905-6.CrossRefGoogle ScholarPubMed
32. Alzate, JC, Kothbauer, KF, Jallo, GI, Epstein, FJ. Treatment of Chiari I malformation in patients with and without syringomyelia: a consecutive series of 66 cases. Neurosurg Focus. 2001;11(1):E3.Google Scholar
33. Galarza, M, Sood, S, Ham, S. Relevance of surgical strategies for the management of pediatric Chiari type I malformation. Childs Nerv Syst. 2007;23(6):6916.CrossRefGoogle ScholarPubMed
34. Hoffman, CE, Souweidane, MM. Cerebrospinal fluid-related complications with autologous duraplasty and arachnoid sparing in type I Chiari malformation. Neurosurgery. 2008;62(3 Suppl 1):15660; discussion 60-1.Google Scholar
35. Hayhurst, C, Richards, O, Zaki, H, Findlay, G, Pigott, TJ. Hindbrain decompression for Chiari-syringomyelia complex: an outcome analysis comparing surgical techniques. Br J Neurosurg. 2008;22(1):8691.Google Scholar
36. Lipson, AC, Ellenbogen, RG, Avellino, AM. Radiographic formation and progression of cervical syringomyelia in a child with untreated Chiari I malformation. Pediatr Neurosurg. 2008;44(3):2213.CrossRefGoogle Scholar
37. Goh, S, Bottrell, CL, Aiken, AH, Dillon, WP, Wu, YW. Presyrinx in children with Chiari malformations. Neurology. 2008;71(5): 3516.CrossRefGoogle ScholarPubMed