Surgical Management of Chiari Malformations: Preliminary Results of Surgery According to the Mechanisms of Ptosis of the Brain Stem and Cerebellum

Abstract

Introduction We classified Chiari malformation type I (CM-I) according to the mechanism of ptosis of the brain stem and cerebellum, based on a morphometric study of the posterior cranial fossa (PCF) and craniovertebral junction (CVJ). Surgery was performed to manage the mechanism of the hindbrain ptosis.

Materials and Methods We calculated the volume of the PCF (VPCF) and the area surrounding the foramen magnum (VSFM) and measured the axial length of the enchondral parts of the occipital bone (occipital bone size) and the hindbrain. According to these measures, we classified CM-I into type A (normal VPCF, normal VSFM, and normal occipital bone size), type B (normal VPCF, small VSFM, and small occipital bone size), and type C (small VPCF, small VSFM, and small occipital bone size). Foramen magnum decompression (FMD) (280 cases) was performed on CM-I types A and B. Expansive suboccipital cranioplasty (ESCP) was performed on CM-I type C. Posterior craniocervical fixation (CCF) was performed in cases with CVJ instability. Lysis of the adhesion and/or sectioning of the filum terminale were performed on cases with tethered cord syndrome.

Results Both ESCP and FMD had a high rate of improvement of neurological symptoms (87%) and recovery rate. There was only small number of complications. CCF had a high rate of improvement of neurological symptoms (88%) and joint stabilization.

Conclusion In the management of Chiari malformation, appropriate surgical methods that address ptosis of the hindbrain should be chosen. Each surgical approach resulted in a good improvement of neurological symptoms.

Keywords

Chiari malformation - morphometric study - posterior cranial fossa - craniovertebral junction - surgical management - outcome

Note

This study has been approved by Institutional Review Boards of Koudoukai Health System, Osaka City University Graduate School of Medicine, Osaka, Japan, and North Shore University Hospital–Long Island Jewish Health System, New York, United States.

Publication History

Received: 01 June 2019

Accepted: 11 August 2019

Article published online:
30 September 2019

• References

• 1 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 (01) 40-47
• 2 Milhorat TH, Chou MW, Trinidad EM. et al. Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 1999; 44 (05) 1005-1017
• 3 Alperin N, Loftus JR, Oliu CJ. et al. Magnetic resonance imaging measures of posterior cranial fossa morphology and cerebrospinal fluid physiology in Chiari malformation type I. Neurosurgery 2014; 75 (05) 515-522 , discussion 522
• 4 Badie B, Mendoza D, Batzdorf U. Posterior fossa volume and response to suboccipital decompression in patients with Chiari I malformation. Neurosurgery 1995; 37 (02) 214-218
• 5 Cinalli G, Spennato P, Sainte-Rose C. et al. Chiari malformation in craniosynostosis. Childs Nerv Syst 2005; 21 (10) 889-901
• 6 Karagöz F, Izgi N, Kapíjcíjoğlu Sencer S. Morphometric measurements of the cranium in patients with Chiari type I malformation and comparison with the normal population. Acta Neurochir (Wien) 2002; 144 (02) 165-171 , discussion 171
• 7 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 (02) 113-118
• 8 Milhorat TH, Bolognese PA, Nishikawa M, McDonnell NB, Francomano CA. Syndrome of occipitoatlantoaxial hypermobility, cranial settling, and Chiari malformation type I in patients with hereditary disorders of connective tissue. J Neurosurg Spine 2007; 7 (06) 601-609
• 9 Milhorat TH, Bolognese PA, Nishikawa M. et al. Association of Chiari malformation type I and tethered cord syndrome: preliminary results of sectioning filum terminale. Surg Neurol 2009; 72 (01) 20-35
• 10 Goel A, Jain S, Shah A. Radiological evaluation of 510 cases of basilar invagination with evidence of atlantoaxial instability (group a basilar invagination). World Neurosurg 2018; 110: 533-543
• 11 Goel A, Gore S, Shah A, Dharurkar P, Vutha R, Patil A. Atlantoaxial fixation for Chiari 1 formation in pediatric age group patients: report of treatment in 33 patients. World Neurosurg 2018; 111: e668-e677
• 12 Goel A, Kaswa A, Shah A. Atlantoaxial fixation for treatment of Chiari formation and syringomyelia with no craniovertebral bone anomaly: report an experience with 57 cases. Acta Neurochir Suppl (Wien) 2018; 125: 101-110
• 13 Milhorat TH, Nishikawa M, Kula RW, Dlugacz YD. Mechanisms of cerebellar tonsil herniation in patients with Chiari malformations as guide to clinical management. Acta Neurochir (Wien) 2010; 152 (07) 1117-1127
• 14 Nishikawa M, Bolognese PA, Kula RW. et al. Pathogenesis and classification of Chiari malformation type I based on the mechanism of ptosis of the brain stem and cerebellum: a morphometric study of the posterior cranial fossa and craniovertebral junction. J Neurol Surg B Skull Base, in press
• 15 Fukui M, Chiba K, Kawakami M. et al; Subcommittee on Low Back Pain and Cervical Myelopathy Evaluation of the Clinical Outcome Committee of the Japanese Orthopaedic Association. An outcome measure for patients with cervical myelopathy: Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ): Part 1. J Orthop Sci 2007; 12 (03) 227-240
• 16 Oaks J. Chiari malformation and syringomyelia. In: Reagachary SS, Williams RH. eds. Principles of Neurosurgery. London: Mosby-Wolf; 1994: 11-18
• 17 Sakamoto H, Nishikawa M, Hakuba A. et al. Expansive suboccipital cranioplasty for the treatment of syringomyelia associated with Chiari malformation. Acta Neurochir (Wien) 1999; 141 (09) 949-960 , discussion 960–961
• 18 Nishikawa M, Ohata K. Surgical treatment of Chiari malformation. In: Ohata K. ed. Spinalcord Surgery Neurosurgery Now. Tokyo: Medical View; 2011: 138-153
• 19 Milhorat TH, Bolognese PA. Tailored operative technique for Chiari type I malformation using intraoperative color Doppler ultrasonography. Neurosurgery 2003; 53 (04) 899-905 , discussion 905–906
• 20 Cui LG, Jiang L, Zhang HB. et al. Monitoring of cerebrospinal fluid flow by intraoperative ultrasound in patients with Chiari I malformation. Clin Neurol Neurosurg 2011; 113 (03) 173-176
• 21 Bond AE, Jane Sr JA, Liu KC, Oldfield EH. Changes in cerebrospinal fluid flow assessed using intraoperative MRI during posterior fossa decompression for Chiari malformation. J Neurosurg 2015; 122 (05) 1068-1075
• 22 Winegar CD, Lawrence JP, Friel BC. et al. A systematic review of occipital cervical fusion: techniques and outcomes. J Neurosurg Spine 2010; 13 (01) 5-16
• 23 Batzdorf U, McArthur DL, Bentson JR. Surgical treatment of Chiari malformation with and without syringomyelia: experience with 177 adult patients. J Neurosurg 2013; 118 (02) 232-242
• 24 Klekamp J, Batzdorf U, Samii M, Bothe HW. The surgical treatment of Chiari I malformation. Acta Neurochir (Wien) 1996; 138 (07) 788-801
• 25 Tubbs RS, Beckman J, Naftel RP. et al. Institutional experience with 500 cases of surgically treated pediatric patients with Chiari malformations. J Neurosurg Pediatr 2011; 7: 248-256
• 26 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 (02) 161-177
• 27 Nishikawa M, Ohata K, Baba M, Terakawa Y, Hara M. Chiari I malformation associated with ventral compression and instability: one-stage posterior decompression and fusion with a new instrumentation technique. Neurosurgery 2004; 54 (06) 1430-1434 , discussion 1434–1435