{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,11]],"date-time":"2026-07-11T13:37:01Z","timestamp":1783777021704,"version":"3.55.0"},"reference-count":24,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2020,7]]},"abstract":"<jats:sec><jats:title>OBJECTIVE<\/jats:title><jats:p>Chiari I malformation (CM-I) has traditionally been defined by measuring the position of the cerebellar tonsils relative to the foramen magnum. The relationships of tonsillar position to clinical presentation, syringomyelia, scoliosis, and the use of posterior fossa decompression (PFD) surgery have been studied extensively and yielded inconsistent results. Obex position has been proposed as a useful adjunctive descriptor for CM-I and may be associated with clinical disease severity.<\/jats:p><\/jats:sec><jats:sec><jats:title>METHODS<\/jats:title><jats:p>A retrospective chart review was performed of 442 CM-I patients with MRI who presented for clinical evaluation between 2003 and 2018. Clinical and radiological variables were measured for all patients, including presence\/location of headaches, Chiari Severity Index (CSI) grade, tonsil position, obex position, clival canal angle, pB-C2 distance, occipitalization of the atlas, basilar invagination, syringomyelia, syrinx diameter, scoliosis, and use of PFD. Radiological measurements were then used to predict clinical characteristics using regression and survival analyses, with performing PFD, the presence of a syrinx, and scoliosis as outcome variables.<\/jats:p><\/jats:sec><jats:sec><jats:title>RESULTS<\/jats:title><jats:p>Among the radiological measurements, tonsil position, obex position, and syringomyelia were each independently associated with use of PFD. Together, obex position, tonsil position, and syringomyelia (area under the curve [AUC] 89%) or obex position and tonsil position (AUC 85.4%) were more strongly associated with use of PFD than tonsil position alone (AUC 76%) (P<jats:sub>diff<\/jats:sub> = 3.4 \u00d7 10<jats:sup>\u22126<\/jats:sup> and 6 \u00d7 10<jats:sup>\u22124<\/jats:sup>, respectively) but were only slightly more associated than obex position alone (AUC 82%) (P<jats:sub>diff<\/jats:sub> = 0.01 and 0.18, respectively). Additionally, obex position was significantly associated with occipital headaches, CSI grade, syringomyelia, and scoliosis, independent of tonsil position. Tonsil position was associated with each of these traits when analyzed alone but did not remain significantly associated with use of PFD when included in multivariate analyses with obex position.<\/jats:p><\/jats:sec><jats:sec><jats:title>CONCLUSIONS<\/jats:title><jats:p>Compared with tonsil position alone, obex position is more strongly associated with symptomatic CM-I, as measured by presence of a syrinx, scoliosis, or use of PFD surgery. These results support the role of obex position as a useful radiological measurement to inform the evaluation and potentially the management of CM-I.<\/jats:p><\/jats:sec>","DOI":"10.3171\/2020.2.peds19486","type":"journal-article","created":{"date-parts":[[2020,4,10]],"date-time":"2020-04-10T12:05:52Z","timestamp":1586520352000},"page":"45-52","source":"Crossref","is-referenced-by-count":15,"title":["Obex position is associated with syringomyelia and use of posterior fossa decompression among patients with Chiari I malformation"],"prefix":"10.3171","volume":"26","author":[{"given":"Gabe","family":"Haller","sequence":"first","affiliation":[{"name":"Departments of Neurological Surgery,"},{"name":"Neurology,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brooke","family":"Sadler","sequence":"additional","affiliation":[{"name":"Neurology,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Timothy","family":"Kuensting","sequence":"additional","affiliation":[{"name":"Neurology,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nivan","family":"Lakshman","sequence":"additional","affiliation":[{"name":"Departments of Neurological Surgery,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jacob K.","family":"Greenberg","sequence":"additional","affiliation":[{"name":"Departments of Neurological Surgery,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jennifer M.","family":"Strahle","sequence":"additional","affiliation":[{"name":"Departments of Neurological Surgery,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tae Sung","family":"Park","sequence":"additional","affiliation":[{"name":"Departments of Neurological Surgery,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthew B.","family":"Dobbs","sequence":"additional","affiliation":[{"name":"Orthopaedic Surgery, and"},{"name":"Shriners Hospital for Children, St. Louis, Missouri"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christina A.","family":"Gurnett","sequence":"additional","affiliation":[{"name":"Neurology,"},{"name":"Orthopaedic Surgery, and"},{"name":"Pediatrics, Washington University School of Medicine; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David D.","family":"Limbrick","sequence":"additional","affiliation":[{"name":"Departments of Neurological Surgery,"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1754","reference":[{"key":"b1","series-title":"The Chiari Malformations","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4614-6369-6","year":"2013","unstructured":"Tubbs RS, Oakes WJ, eds. The Chiari Malformations. Springer Science+Business Media; 201310.1007\/978-1-4614-6369-6"},{"issue":"6","key":"b2","series-title":"J Comput Assist Tomogr","doi-asserted-by":"publisher","first-page":"1033","DOI":"10.1097\/00004728-198511000-00005","article-title":"Position of cerebellar tonsils in the normal population and in patients with Chiari malformation: a quantitative approach with MR imaging","volume":"9","author":"Aboulezz AO","year":"1985","unstructured":"Aboulezz AO, Sartor K, Geyer CA, Gado 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. 1985;9(6):1033\u20131036.10.1097\/00004728-198511000-000054056132"},{"issue":"5","key":"b3","series-title":"AJNR Am J Neuroradiol","first-page":"795","article-title":"Significance of cerebellar tonsillar position on MR","volume":"7","author":"Barkovich AJ","year":"1986","unstructured":"Barkovich AJ, Wippold FJ, Sherman JL, Citrin CM. Significance of cerebellar tonsillar position on MR. AJNR Am J Neuroradiol. 1986;7(5):795\u2013799.3096099"},{"issue":"4","key":"b4","series-title":"Neurosurg Clin N Am","doi-asserted-by":"publisher","first-page":"555","DOI":"10.1016\/j.nec.2015.06.002","article-title":"Complex Chiari malformations in children: diagnosis and management","volume":"26","author":"Brockmeyer DL","year":"2015","unstructured":"Brockmeyer DL, Spader HS. Complex Chiari malformations in children: diagnosis and management. Neurosurg Clin N Am. 2015;26(4):555\u2013560.10.1016\/j.nec.2015.06.00226408065"},{"issue":"2","key":"b5","series-title":"Eur Spine J","doi-asserted-by":"publisher","first-page":"619","DOI":"10.1007\/s00586-015-4011-1","article-title":"Comparison of spinal deformity in children with Chiari I malformation with and without syringomyelia: matched cohort study","volume":"25","author":"Godzik J","year":"2016","unstructured":"Godzik J, Dardas A, Kelly MP,  Comparison of spinal deformity in children with Chiari I malformation with and without syringomyelia: matched cohort study. Eur Spine J. 2016;25(2):619\u2013626.2598120610.1007\/s00586-015-4011-1"},{"issue":"4","key":"b6","series-title":"J Neurosurg Pediatr","doi-asserted-by":"publisher","first-page":"368","DOI":"10.3171\/2014.1.PEDS13105","article-title":"Relationship of syrinx size and tonsillar descent to spinal deformity in Chiari malformation Type I with associated syringomyelia","volume":"13","author":"Godzik J","year":"2014","unstructured":"Godzik J, Kelly MP, Radmanesh A,  Relationship of syrinx size and tonsillar descent to spinal deformity in Chiari malformation Type I with associated syringomyelia. J Neurosurg Pediatr. 2014;13(4):368\u2013374.2452785910.3171\/2014.1.PEDS13105"},{"issue":"3","key":"b7","series-title":"Neurosurgery","doi-asserted-by":"publisher","first-page":"279","DOI":"10.1227\/NEU.0000000000000608","article-title":"The Chiari Severity Index: a preoperative grading system for Chiari malformation type 1","volume":"76","author":"Greenberg JK","year":"2015","unstructured":"Greenberg JK, Yarbrough CK, Radmanesh A,  The Chiari Severity Index: a preoperative grading system for Chiari malformation type 1. Neurosurgery. 2015;76(3):279\u2013285.2558495610.1227\/NEU.0000000000000608"},{"issue":"7","key":"b8","series-title":"Neurol Res","doi-asserted-by":"publisher","first-page":"694","DOI":"10.1179\/1743132812Y.0000000066","article-title":"Positive and negative predictors for good outcome after decompressive surgery for Chiari malformation type 1 as scored on the Chicago Chiari Outcome Scale","volume":"34","author":"Hekman KE","year":"2012","unstructured":"Hekman KE, Aliaga L, Straus D,  Positive and negative predictors for good outcome after decompressive surgery for Chiari malformation type 1 as scored on the Chicago Chiari Outcome Scale. Neurol Res. 2012;34(7):694\u2013700.10.1179\/1743132812Y.000000006622781921"},{"issue":"1","key":"b9","series-title":"J Neurosurg Pediatr","doi-asserted-by":"publisher","first-page":"65","DOI":"10.3171\/2017.8.PEDS17345","article-title":"Morphometric and volumetric comparison of 102 children with symptomatic and asymptomatic Chiari malformation Type I","volume":"21","author":"Khalsa SSS","year":"2018","unstructured":"Khalsa SSS, Geh N, Martin BA,  Morphometric and volumetric comparison of 102 children with symptomatic and asymptomatic Chiari malformation Type I. J Neurosurg Pediatr. 2018;21(1):65\u201371.10.3171\/2017.8.PEDS1734529125445"},{"issue":"2","key":"b10","series-title":"J Neurosurg Pediatr","doi-asserted-by":"publisher","first-page":"138","DOI":"10.3171\/2015.1.PEDS14475","article-title":"Posterior odontoid process angulation in pediatric Chiari I malformation: an MRI morphometric external validation study","volume":"16","author":"Ladner TR","year":"2015","unstructured":"Ladner TR, Dewan MC, Day MA,  Posterior odontoid process angulation in pediatric Chiari I malformation: an MRI morphometric external validation study. J Neurosurg Pediatr. 2015;16(2):138\u2013145.10.3171\/2015.1.PEDS1447526053869"},{"issue":"3","key":"b11","series-title":"J Neurosurg","doi-asserted-by":"publisher","first-page":"812","DOI":"10.3171\/2013.5.JNS121825","article-title":"Distribution of cerebellar tonsil position: implications for understanding Chiari malformation","volume":"119","author":"Smith BW","year":"2013","unstructured":"Smith BW, Strahle J, Bapuraj JR,  Distribution of cerebellar tonsil position: implications for understanding Chiari malformation. J Neurosurg. 2013;119(3):812\u2013819.10.3171\/2013.5.JNS12182523767890"},{"issue":"5","key":"b12","series-title":"Neurosurgery","doi-asserted-by":"publisher","first-page":"913","DOI":"10.1227\/00006123-199211000-00013","article-title":"Syringomyelia in Chiari malformation: relation to extent of cerebellar tissue herniation","volume":"31","author":"Stovner LJ","year":"1992","unstructured":"Stovner LJ, Rinck P. Syringomyelia in Chiari malformation: relation to extent of cerebellar tissue herniation. Neurosurgery. 1992;31(5):913\u2013917.10.1227\/00006123-199211000-000131436416"},{"issue":"2","key":"b13","series-title":"J Neurosurg Pediatr","doi-asserted-by":"publisher","first-page":"205","DOI":"10.3171\/2011.5.PEDS1121","article-title":"Chiari malformation Type I and syrinx in children undergoing magnetic resonance imaging","volume":"8","author":"Strahle J","year":"2011","unstructured":"Strahle J, Muraszko KM, Kapurch J,  Chiari malformation Type I and syrinx in children undergoing magnetic resonance imaging. J Neurosurg Pediatr. 2011;8(2):205\u2013213.10.3171\/2011.5.PEDS112121806364"},{"issue":"6","key":"b14","series-title":"J Neurosurg Pediatr","doi-asserted-by":"publisher","first-page":"607","DOI":"10.3171\/2014.11.PEDS14135","article-title":"The association between Chiari malformation Type I, spinal syrinx, and scoliosis","volume":"15","author":"Strahle J","year":"2015","unstructured":"Strahle J, Smith BW, Martinez M,  The association between Chiari malformation Type I, spinal syrinx, and scoliosis. J Neurosurg Pediatr. 2015;15(6):607\u2013611.10.3171\/2014.11.PEDS1413526030330"},{"issue":"1","key":"b15","series-title":"J Neurosurg Spine","doi-asserted-by":"publisher","first-page":"23","DOI":"10.3171\/2017.5.SPINE17264","article-title":"A points-based algorithm for prognosticating clinical outcome of Chiari malformation Type I with syringomyelia: results from a predictive model analysis of 82 surgically managed adult patients","volume":"28","author":"Thakar S","year":"2018","unstructured":"Thakar S, Sivaraju L, Jacob KS,  A points-based algorithm for prognosticating clinical outcome of Chiari malformation Type I with syringomyelia: results from a predictive model analysis of 82 surgically managed adult patients. J Neurosurg Spine. 2018;28(1):23\u201332.10.3171\/2017.5.SPINE1726429125433"},{"issue":"2","key":"b16","series-title":"J Neurosurg","first-page":"179","article-title":"A critical analysis of the Chiari 1.5 malformation","volume":"101","author":"Tubbs RS","year":"2004","unstructured":"Tubbs RS, Iskandar BJ, Bartolucci AA, Oakes WJ. A critical analysis of the Chiari 1.5 malformation. J Neurosurg. 2004;101(2)(suppl):179\u2013183.15835105"},{"key":"b17","series-title":"The Chiari Malformations","doi-asserted-by":"publisher","first-page":"241","DOI":"10.1007\/978-1-4614-6369-6_19","article-title":"Newer subsets: Chiari 0 and Chiari 1.5 malformations","author":"Mariwalla NR","year":"2013","unstructured":"Mariwalla NR, Boydston WR, Chern JJ. Newer subsets: Chiari 0 and Chiari 1.5 malformations. In: Tubbs RS, Oakes WJ, eds. The Chiari Malformations. Springer Science+Business Media; 2013:241\u2013246.10.1007\/978-1-4614-6369-6_19"},{"issue":"10","key":"b18","series-title":"Childs Nerv Syst","doi-asserted-by":"publisher","first-page":"1123","DOI":"10.1007\/s00381-008-0601-0","article-title":"Imaging the craniocervical junction","volume":"24","author":"Smoker WR","year":"2008","unstructured":"Smoker WR, Khanna G. Imaging the craniocervical junction. Childs Nerv Syst. 2008;24(10):1123\u20131145.1846133610.1007\/s00381-008-0601-0"},{"issue":"2","key":"b19","series-title":"J Neurosurg Pediatr","doi-asserted-by":"publisher","first-page":"134","DOI":"10.3171\/2012.3.PEDS11340","article-title":"Complex Chiari malformations in children: an analysis of preoperative risk factors for occipitocervical fusion","volume":"10","author":"Bollo RJ","year":"2012","unstructured":"Bollo RJ, Riva-Cambrin J, Brockmeyer MM, Brockmeyer DL. Complex Chiari malformations in children: an analysis of preoperative risk factors for occipitocervical fusion. J Neurosurg Pediatr. 2012;10(2):134\u2013141.10.3171\/2012.3.PEDS1134022725652"},{"issue":"2","key":"b20","series-title":"J Neurosurg","doi-asserted-by":"publisher","first-page":"291","DOI":"10.3171\/jns.2003.99.2.0291","article-title":"Surgical experience in 130 pediatric patients with Chiari I malformations","volume":"99","author":"Tubbs RS","year":"2003","unstructured":"Tubbs RS, McGirt MJ, Oakes WJ. Surgical experience in 130 pediatric patients with Chiari I malformations. J Neurosurg. 2003;99(2):291\u2013296.10.3171\/jns.2003.99.2.0291"},{"issue":"suppl 3","key":"b21","series-title":"Neurol Sci","doi-asserted-by":"publisher","first-page":"S283","DOI":"10.1007\/s10072-011-0695-0","article-title":"Neuroradiological diagnosis of Chiari malformations","volume":"32","author":"Chiapparini L","year":"2011","unstructured":"Chiapparini L, Saletti V, Solero CL,  Neuroradiological diagnosis of Chiari malformations. Neurol Sci. 2011;32(suppl 3):S283\u2013S286.10.1007\/s10072-011-0695-021800079"},{"key":"b22","series-title":"The Chiari Malformations","doi-asserted-by":"publisher","first-page":"83","DOI":"10.1007\/978-1-4614-6369-6_6","article-title":"Epidemiology of the Chiari I malformation","author":"Heiss JD","year":"2013","unstructured":"Heiss JD. Epidemiology of the Chiari I malformation. In: Tubbs RS, Oakes WJ, eds. The Chiari Malformations. Springer Science+Business Media; 2013:83\u201392.10.1007\/978-1-4614-6369-6_6"},{"issue":"1","key":"b23","series-title":"J Neurosurg","first-page":"43","article-title":"Inclination of the odontoid process in the pediatric Chiari I malformation","volume":"98","author":"Tubbs RS","year":"2003","unstructured":"Tubbs RS, Wellons JC III, Blount JP,  Inclination of the odontoid process in the pediatric Chiari I malformation. J Neurosurg. 2003;98(1)(suppl):43\u201349.12546387"},{"key":"b24","series-title":"The Chiari Malformations","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1007\/978-1-4614-6369-6_1","article-title":"Introduction and classification of the Chiari malformations","author":"Tubbs RS","year":"2013","unstructured":"Tubbs RS, Oakes WJ. Introduction and classification of the Chiari malformations. In: Tubbs RS, and Oakes WJ, eds. The Chiari Malformations. Springer Science+Business Media; 2013:1\u20133.10.1007\/978-1-4614-6369-6_1"}],"container-title":["Journal of Neurosurgery: Pediatrics"],"original-title":[],"link":[{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg-pediatr\/26\/1\/article-p45.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg-pediatr\/26\/1\/article-p45.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/thejns.org\/downloadpdf\/journals\/j-neurosurg-pediatr\/26\/1\/article-p45.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,4,15]],"date-time":"2023-04-15T17:11:43Z","timestamp":1681578703000},"score":1,"resource":{"primary":{"URL":"https:\/\/thejns.org\/view\/journals\/j-neurosurg-pediatr\/26\/1\/article-p45.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,7]]},"references-count":24,"journal-issue":{"issue":"1"},"URL":"https:\/\/doi.org\/10.3171\/2020.2.peds19486","relation":{},"ISSN":["1933-0707","1933-0715"],"issn-type":[{"value":"1933-0707","type":"print"},{"value":"1933-0715","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,7]]}}}