Chiari Type 1 Deformity in Children: Pathogenetic, Clinical, Neuroimaging, and Management Aspects

Andrea Poretti; Ramy Ashmawy; Tomas Garzon-Muvdi; George I. Jallo; Thierry A. G. M. Huisman; Charles Raybaud

doi:10.1055/s-0036-1584563

Neuropediatrics, Inhaltsverzeichnis

Neuropediatrics 2016; 47(05): 293-307
DOI: 10.1055/s-0036-1584563

Review Article

Georg Thieme Verlag KG Stuttgart · New York

Chiari Type 1 Deformity in Children: Pathogenetic, Clinical, Neuroimaging, and Management Aspects

Andrea Poretti^*

¹Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

,

Ramy Ashmawy^*

²Department of Neuroradiology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada

,

Tomas Garzon-Muvdi

³Division of Pediatric Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

,

George I. Jallo

³Division of Pediatric Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

⁴Pediatric Neurosurgery and Institute for Brain Protection Sciences, Johns Hopkins All Children's Hospital, St. Petersburg, Florida, United States

,

Thierry A. G. M. Huisman^*

¹Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

,

Charles Raybaud^*

²Department of Neuroradiology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada

› Institutsangaben

Abstract

Our understanding of cerebellar tonsillar herniation evolved over time and nowadays various pathomechanisms have been proposed. Causes of tonsillar herniation share a discrepancy between content (fore- and hindbrain) and container (supratentorial cranial vault, posterior fossa), may be associated with abnormalities of the craniocervical junction, and may have a developmental or acquired nature. In tonsillar herniation, the hindbrain is not malformed but deformed. Accordingly, “Chiari type 1 deformity,” not “Chiari type 1 malformation” is the correct term to characterize primary tonsillar herniation. Chiari type 1 deformity is commonly seen in pediatric neurology, neuroradiology, and neurosurgery and may have various clinical presentations depending on patient age. In addition, Chiari type 1 deformity is increasingly found by neuroimaging studies as an incidental finding in asymptomatic children. An accurate and reliable selection of patients based on clinical and neuroimaging findings is paramount for the success of neurosurgical treatment. Future studies are needed to provide selection criteria with a higher sensitivity and specificity.

Keywords

Chiari type 1 - children - cerebellum - neuroimaging - neurosurgery

Volltext

Referenzen

References
1 Chiari H. Über Veränderungen des Kleinhirns, des Pons und der Medulla oblongata infolge von congenitaler Hydrocephalie des Grosshirns. Denkschr der Kais Akad Wiss Wien mathnaturw 1896; 63: 71-116
2 Chiapparini L, Saletti V, Solero CL, Bruzzone MG, Valentini LG. Neuroradiological diagnosis of Chiari malformations. Neurol Sci 2011; 32 (Suppl. 03) S283-S286
3 Tubbs RS, Oakes WJ. The Chiari Malformations. New York, Heidelberg, Dordrecht, London: Springer; 2013
4 Barkovich AJ, Wippold FJ, Sherman JL, Citrin CM. Significance of cerebellar tonsillar position on MR. AJNR Am J Neuroradiol 1986; 7 (5) 795-799
5 Tubbs RS, Lyerly MJ, Loukas M, Shoja MM, Oakes WJ. The pediatric Chiari I malformation: a review. Childs Nerv Syst 2007; 23 (11) 1239-1250
6 Tubbs RS. Definitions and anatomic considerations in Chiari I malformation and associated syringomyelia. Neurosurg Clin N Am 2015; 26 (4) 487-493
7 Aitken LA, Lindan CE, Sidney S , et al. Chiari type I malformation in a pediatric population. Pediatr Neurol 2009; 40 (6) 449-454
8 Loukas M, Shayota BJ, Oelhafen K , et al. Associated disorders of Chiari type I malformations: a review. Neurosurg Focus 2011; 31 (3) E3
9 Hennekam RC, Biesecker LG, Allanson JE , et al; Elements of Morphology Consortium. Elements of morphology: general terms for congenital anomalies. Am J Med Genet A 2013; 161A (11) 2726-2733
10 Sarnat HB. Semantics do matter! Precision in scientific communication in pediatric neurology. J Child Neurol 2007; 22 (11) 1245-1251
11 Voelker R. Chiari conundrum: researchers tackle a brain puzzle for the 21st century. JAMA 2009; 301 (2) 147-149
12 Reneman L, de Win MM, Booij J , et al. Incidental head and neck findings on MRI in young healthy volunteers: prevalence and clinical implications. AJNR Am J Neuroradiol 2012; 33 (10) 1971-1974
13 Gur RE, Kaltman D, Melhem ER , et al. Incidental findings in youths volunteering for brain MRI research. AJNR Am J Neuroradiol 2013; 34 (10) 2021-2025
14 Yılmaz Ü, Çeleğen M, Yılmaz TS, Gürçınar M, Ünalp A. Childhood headaches and brain magnetic resonance imaging findings. Eur J Paediatr Neurol 2014; 18 (2) 163-170
15 Tubbs RS, McGirt MJ, Oakes WJ. Surgical experience in 130 pediatric patients with Chiari I malformations. J Neurosurg 2003; 99 (2) 291-296
16 Haughton VM, Korosec FR, Medow JE, Dolar MT, Iskandar BJ. Peak systolic and diastolic CSF velocity in the foramen magnum in adult patients with Chiari I malformations and in normal control participants. AJNR Am J Neuroradiol 2003; 24 (2) 169-176
17 Bogdanov EI, Heiss JD, Mendelevich EG, Mikhaylov IM, Haass A. Clinical and neuroimaging features of “idiopathic” syringomyelia. Neurology 2004; 62 (5) 791-794
18 Brickell KL, Anderson NE, Charleston AJ, Hope JK, Bok AP, Barber PA. Ethnic differences in syringomyelia in New Zealand. J Neurol Neurosurg Psychiatry 2006; 77 (8) 989-991
19 McBratney-Owen B, Iseki S, Bamforth SD, Olsen BR, Morriss-Kay GM. Development and tissue origins of the mammalian cranial base. Dev Biol 2008; 322 (1) 121-132
20 Menezes AH, Fenoy KA. Remnants of occipital vertebrae: proatlas segmentation abnormalities. Neurosurgery 2009; 64 (5) 945-953 , discussion 954
21 Lemire RJ. Embryology of the skull. In: Cohen MM, ed. Craniosynostosis Diagnosis, Evaluation, and Management. 2nd ed. Oxford: Oxford University Press; 2000: 25-34
22 Marin-Padilla M, Marin-Padilla TM. Morphogenesis of experimentally induced Arnold—Chiari malformation. J Neurol Sci 1981; 50 (1) 29-55
23 Noudel R, Jovenin N, Eap C, Scherpereel B, Pierot L, Rousseaux P. Incidence of basioccipital hypoplasia in Chiari malformation type I: comparative morphometric study of the posterior cranial fossa. Clinical article. J Neurosurg 2009; 111 (5) 1046-1052
24 Smoker WR. Craniovertebral junction: normal anatomy, craniometry, and congenital anomalies. Radiographics 1994; 14 (2) 255-277
25 Chern JJ, Gordon AJ, Mortazavi MM, Tubbs RS, Oakes WJ. Pediatric Chiari malformation type 0: a 12-year institutional experience. J Neurosurg Pediatr 2011; 8 (1) 1-5
26 Vega A, Quintana F, Berciano J. Basichondrocranium anomalies in adult Chiari type I malformation: a morphometric study. J Neurol Sci 1990; 99 (2–3) 137-145
27 Menezes AH. Primary craniovertebral anomalies and the hindbrain herniation syndrome (Chiari I): data base analysis. Pediatr Neurosurg 1995; 23 (5) 260-269
28 Milhorat TH, Chou MW, Trinidad EM , et al. Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 1999; 44 (5) 1005-1017
29 Urbizu A, Poca MA, Vidal X, Rovira A, Sahuquillo J, Macaya A. MRI-based morphometric analysis of posterior cranial fossa in the diagnosis of chiari malformation type I. J Neuroimaging 2014; 24 (3) 250-256
30 Cesmebasi A, Loukas M, Hogan E, Kralovic S, Tubbs RS, Cohen-Gadol AA. The Chiari malformations: a review with emphasis on anatomical traits. Clin Anat 2015; 28 (2) 184-194
31 Tubbs RS, Beckman J, Naftel RP , et al. Institutional experience with 500 cases of surgically treated pediatric Chiari malformation type I. J Neurosurg Pediatr 2011; 7 (3) 248-256
32 Tubbs RS, Lancaster JR, Mortazavi MM , et al. Morphometry of the outlet of the foramen magnum in crania with atlantooccipital fusion. J Neurosurg Spine 2011; 15 (1) 55-59
33 Gholve PA, Hosalkar HS, Ricchetti ET, Pollock AN, Dormans JP, Drummond DS. Occipitalization of the atlas in children. Morphologic classification, associations, and clinical relevance. J Bone Joint Surg Am 2007; 89 (3) 571-578
34 Pang D, Thompson DN. Embryology and bony malformations of the craniovertebral junction. Childs Nerv Syst 2011; 27 (4) 523-564
35 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) 329-336
36 Stovner LJ, Bergan U, Nilsen G, Sjaastad O. Posterior cranial fossa dimensions in the Chiari I malformation: relation to pathogenesis and clinical presentation. Neuroradiology 1993; 35 (2) 113-118
37 Dufton JA, Habeeb SY, Heran MK, Mikulis DJ, Islam O. Posterior fossa measurements in patients with and without Chiari I malformation. Can J Neurol Sci 2011; 38 (3) 452-455
38 Buell TJ, Heiss JD, Oldfield EH. Pathogenesis and cerebrospinal fluid hydrodynamics of the Chiari I malformation. Neurosurg Clin N Am 2015; 26 (4) 495-499
39 Cinalli G, Spennato P, Sainte-Rose C , et al. Chiari malformation in craniosynostosis. Childs Nerv Syst 2005; 21 (10) 889-901
40 Tamburrini G, Caldarelli M, Massimi L, Gasparini G, Pelo S, Di Rocco C. Complex craniosynostoses: a review of the prominent clinical features and the related management strategies. Childs Nerv Syst 2012; 28 (9) 1511-1523
41 Rijken BF, Lequin MH, van der Lijn F , et al. The role of the posterior fossa in developing Chiari I malformation in children with craniosynostosis syndromes. J Craniomaxillofac Surg 2015; 43 (6) 813-819
42 Rijken BF, Lequin MH, Van Veelen ML, de Rooi J, Mathijssen IM. The formation of the foramen magnum and its role in developing ventriculomegaly and Chiari I malformation in children with craniosynostosis syndromes. J Craniomaxillofac Surg 2015; 43 (7) 1042-1048
43 Wu YW, Chin CT, Chan KM, Barkovich AJ, Ferriero DM. Pediatric Chiari I malformations: do clinical and radiologic features correlate?. Neurology 1999; 53 (6) 1271-1276
44 Caldarelli M, Novegno F, Di Rocco C. A late complication of CSF shunting: acquired Chiari I malformation. Childs Nerv Syst 2009; 25 (4) 443-452
45 Atkinson JL, Weinshenker BG, Miller GM, Piepgras DG, Mokri B. Acquired Chiari I malformation secondary to spontaneous spinal cerebrospinal fluid leakage and chronic intracranial hypotension syndrome in seven cases. J Neurosurg 1998; 88 (2) 237-242
46 Tachibana S, Harada K, Abe T, Yamada H, Yokota A. Syringomyelia secondary to tonsillar herniation caused by posterior fossa tumors. Surg Neurol 1995; 43 (5) 470-475 , discussion 475–477
47 Poretti A, Mall V, Smitka M , et al. Macrocerebellum: significance and pathogenic considerations. Cerebellum 2012; 11 (4) 1026-1036
48 Gripp KW, Hopkins E, Doyle D, Dobyns WB. High incidence of progressive postnatal cerebellar enlargement in Costello syndrome: brain overgrowth associated with HRAS mutations as the likely cause of structural brain and spinal cord abnormalities. Am J Med Genet A 2010; 152A (5) 1161-1168
49 Calandrelli R, D'Apolito G, Marco P, Zampino G, Tartaglione T, Colosimo C. Costello syndrome: analysis of the posterior cranial fossa in children with posterior fossa crowding. Neuroradiol J 2015; 28 (3) 254-258
50 Galarza M, Martínez-Lage JF, Ham S, Sood S. Cerebral anomalies and Chiari type 1 malformation. Pediatr Neurosurg 2010; 46 (6) 442-449
51 Di Rocco C, Frassanito P, Massimi L, Peraio S. Hydrocephalus and Chiari type I malformation. Childs Nerv Syst 2011; 27 (10) 1653-1664
52 Wen L, Ma C, Wang H, Hu Z. The role of hydrocephalus in the development of Chiari I malformation and syringomyelia. J Neurol Sci 2014; 344 (1–2) 240-242
53 Tubbs RS, Rutledge SL, Kosentka A, Bartolucci AA, Oakes WJ. Chiari I malformation and neurofibromatosis type 1. Pediatr Neurol 2004; 30 (4) 278-280
54 Conway RL, Pressman BD, Dobyns WB , et al. Neuroimaging findings in macrocephaly-capillary malformation: a longitudinal study of 17 patients. Am J Med Genet A 2007; 143A (24) 2981-3008
55 Keppler-Noreuil KM, Rios JJ, Parker VE , et al. PIK3CA-related overgrowth spectrum (PROS): diagnostic and testing eligibility criteria, differential diagnosis, and evaluation. Am J Med Genet A 2015; 167A (2) 287-295
56 Banik R, Lin D, Miller NR. Prevalence of Chiari I malformation and cerebellar ectopia in patients with pseudotumor cerebri. J Neurol Sci 2006; 247 (1) 71-75
57 Lam S, Auffinger B, Tormenti M, Bonfield C, Greene S. The relationship between obesity and symptomatic Chiari I malformation in the pediatric population. J Pediatr Neurosci 2015; 10 (4) 321-325
58 Sinclair N, Assaad N, Johnston I. Pseudotumour cerebri occurring in association with the Chiari malformation. J Clin Neurosci 2002; 9 (1) 99-101
59 Arnautovic A, Splavski B, Boop FA, Arnautovic KI. Pediatric and adult Chiari malformation type I surgical series 1965-2013: a review of demographics, operative treatment, and outcomes. J Neurosurg Pediatr 2015; 15 (2) 161-177
60 Albert GW, Menezes AH, Hansen DR, Greenlee JD, Weinstein SL. Chiari malformation type I in children younger than age 6 years: presentation and surgical outcome. J Neurosurg Pediatr 2010; 5 (6) 554-561
61 Pindrik J, Johnston Jr JM. Clinical presentation of chiari I malformation and syringomyelia in children. Neurosurg Clin N Am 2015; 26 (4) 509-514
62 Toldo I, Tangari M, Mardari R , et al. Headache in children with Chiari I malformation. Headache 2014; 54 (5) 899-908
63 Nohria V, Oakes WJ. Chiari I malformation: a review of 43 patients. Pediatr Neurosurg 1990– 1991; 16 (4–5) 222-227
64 Steinbok P. Clinical features of Chiari I malformations. Childs Nerv Syst 2004; 20 (5) 329-331
65 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) 40-47
66 Sperling NM, Franco Jr RA, Milhorat TH. Otologic manifestations of Chiari I malformation. Otol Neurotol 2001; 22 (5) 678-681
67 Nathadwarawala KM, Richards CA, Lawrie B, Thomas GO, Wiles CM. Recurrent aspiration due to Arnold-Chiari type I malformation. BMJ 1992; 304 (6826) 565-566
68 Greenlee JD, Donovan KA, Hasan DM, Menezes AH. Chiari I malformation in the very young child: the spectrum of presentations and experience in 31 children under age 6 years. Pediatrics 2002; 110 (6) 1212-1219
69 Paul KS, Lye RH, Strang FA, Dutton J. Arnold-Chiari malformation. Review of 71 cases. J Neurosurg 1983; 58 (2) 183-187
70 Isu T, Chono Y, Iwasaki Y , et al. Scoliosis associated with syringomyelia presenting in children. Childs Nerv Syst 1992; 8 (2) 97-100
71 Zadeh HG, Sakka SA, Powell MP, Mehta MH. Absent superficial abdominal reflexes in children with scoliosis. An early indicator of syringomyelia. J Bone Joint Surg Br 1995; 77 (5) 762-767
72 Wu L, Qiu Y, Wang B, Zhu ZZ, Ma WW. The left thoracic curve pattern: a strong predictor for neural axis abnormalities in patients with “idiopathic” scoliosis. Spine 2010; 35 (2) 182-185
73 deSouza RM, Zador Z, Frim DM. Chiari malformation type I: related conditions. Neurol Res 2011; 33 (3) 278-284
74 McGirt MJ, Attenello FJ, Atiba A , et al. Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases. Childs Nerv Syst 2008; 24 (11) 1333-1339
75 Hingwala D, Chatterjee S, Kesavadas C, Thomas B, Kapilamoorthy TR. Applications of 3D CISS sequence for problem solving in neuroimaging. Indian J Radiol Imaging 2011; 21 (2) 90-97
76 Haughton V, Mardal KA. Spinal fluid biomechanics and imaging: an update for neuroradiologists. AJNR Am J Neuroradiol 2014; 35 (10) 1864-1869
77 Fakhri A, Shah MN, Goyal MS. Advanced imaging of Chiari 1 malformations. Neurosurg Clin N Am 2015; 26 (4) 519-526
78 Enzmann DR, Pelc NJ. Cerebrospinal fluid flow measured by phase-contrast cine MR. AJNR Am J Neuroradiol 1993; 14 (6) 1301-1307 , discussion 1309–1310
79 Alperin N, Kulkarni K, Loth F , et al. Analysis of magnetic resonance imaging-based blood and cerebrospinal fluid flow measurements in patients with Chiari I malformation: a system approach. Neurosurg Focus 2001; 11 (1) E6
80 Ventureyra EC, Aziz HA, Vassilyadi M. The role of cine flow MRI in children with Chiari I malformation. Childs Nerv Syst 2003; 19 (2) 109-113
81 Quigley MF, Iskandar B, Quigley ME, Nicosia M, Haughton V. Cerebrospinal fluid flow in foramen magnum: temporal and spatial patterns at MR imaging in volunteers and in patients with Chiari I malformation. Radiology 2004; 232 (1) 229-236
82 Shah S, Haughton V, del Río AM. CSF flow through the upper cervical spinal canal in Chiari I malformation. AJNR Am J Neuroradiol 2011; 32 (6) 1149-1153
83 Hofmann E, Warmuth-Metz M, Bendszus M, Solymosi L. Phase-contrast MR imaging of the cervical CSF and spinal cord: volumetric motion analysis in patients with Chiari I malformation. AJNR Am J Neuroradiol 2000; 21 (1) 151-158
84 Mauer UM, Gottschalk A, Mueller C, Weselek L, Kunz U, Schulz C. Standard and cardiac-gated phase-contrast magnetic resonance imaging in the clinical course of patients with Chiari malformation type I. Neurosurg Focus 2011; 31 (3) E5
85 Kumar M, Rathore RK, Srivastava A, Yadav SK, Behari S, Gupta RK. Correlation of diffusion tensor imaging metrics with neurocognitive function in Chiari I malformation. World Neurosurg 2011; 76 (1–2) 189-194
86 Abeshaus S, Friedman S, Poliachik S , et al. Diffusion tensor imaging changes with decompression of Chiari I malformation. Neurosurgery 2012; 71: E578
87 Eshetu T, Meoded A, Jallo GI, Carson BS, Huisman TA, Poretti A. Diffusion tensor imaging in pediatric Chiari type I malformation. Dev Med Child Neurol 2014; 56 (8) 742-748
88 Yan H, Zhu Z, Liu Z , et al. Diffusion tensor imaging in cervical syringomyelia secondary to Chiari I malformation: preliminary results. Spine 2015; 40 (7) E381-E387
89 Vandertop WP. Syringomyelia. Neuropediatrics 2014; 45 (1) 3-9
90 Tubbs RS, Iskandar BJ, Bartolucci AA, Oakes WJ. A critical analysis of the Chiari 1.5 malformation. J Neurosurg 2004; 101 (2, Suppl): 179-183
91 Novegno F, Caldarelli M, Massa A , et al. The natural history of the Chiari type I anomaly. J Neurosurg Pediatr 2008; 2 (3) 179-187
92 Whitson WJ, Lane JR, Bauer DF, Durham SR. A prospective natural history study of nonoperatively managed Chiari I malformation: does follow-up MRI surveillance alter surgical decision making?. J Neurosurg Pediatr 2015; 16 (2) 159-166
93 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) 86-91
94 Oldfield EH, Muraszko K, Shawker TH, Patronas NJ. Pathophysiology of syringomyelia associated with Chiari I malformation of the cerebellar tonsils. Implications for diagnosis and treatment. J Neurosurg 1994; 80 (1) 3-15
95 McGirt MJ, Attenello FJ, Datoo G , et al. Intraoperative ultrasonography as a guide to patient selection for duraplasty after suboccipital decompression in children with Chiari malformation type I. J Neurosurg Pediatr 2008; 2 (1) 52-57
96 Attenello FJ, McGirt MJ, Gathinji M , et al. Outcome of Chiari-associated syringomyelia after hindbrain decompression in children: analysis of 49 consecutive cases. Neurosurgery 2008; 62 (6) 1307-1313 , discussion 1313
97 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
98 Krishna V, McLawhorn M, Kosnik-Infinger L, Patel S. High long-term symptomatic recurrence rates after Chiari-1 decompression without dural opening: a single center experience. Clin Neurol Neurosurg 2014; 118: 53-58
99 Attenello FJ, McGirt MJ, Garcés-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) 183-190
100 Wester K, Pedersen PH, Kråkenes J. Spinal cord damage caused by rotation of a T-drain in a patient with syringoperitoneal shunt. Surg Neurol 1989; 31 (3) 224-227
101 Batzdorf U, Klekamp J, Johnson JP. A critical appraisal of syrinx cavity shunting procedures. J Neurosurg 1998; 89 (3) 382-388
102 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 Pediatr 2008; 2 (1) 42-49
103 Hankinson T, Tubbs RS, Wellons JC. Duraplasty or not? An evidence-based review of the pediatric Chiari I malformation. Childs Nerv Syst 2011; 27 (1) 35-40
104 Pillay PK, Awad IA, Little JR, Hahn JF. Symptomatic Chiari malformation in adults: a new classification based on magnetic resonance imaging with clinical and prognostic significance. Neurosurgery 1991; 28 (5) 639-645
105 Tubbs RS, Webb DB, Oakes WJ. Persistent syringomyelia following pediatric Chiari I decompression: radiological and surgical findings. J Neurosurg 2004; 100 (5, Suppl Pediatrics): 460-464
106 Dyste GN, Menezes AH, VanGilder JC. Symptomatic Chiari malformations. An analysis of presentation, management, and long-term outcome. J Neurosurg 1989; 71 (2) 159-168