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J Neurosurg Pediatr. 2017 May;19(5):511-517. doi: 10.3171/2016.11.PEDS16263. Epub 2017 Feb 17.

Comparison of posterior fossa volumes and clinical outcomes after decompression of Chiari malformation Type I.

Author information

1
Department of Neurosurgery, University of Michigan Health System, Ann Arbor, Michigan.
2
Department of Neurosurgery, George Washington University.
3
Division of Neurosurgery, Children's National Health System, Washington, DC.
4
George Washington University School of Medicine and Health Sciences; and.

Abstract

OBJECTIVE Previous studies have indicated an association of Chiari malformation Type I (CM-I) and a small posterior fossa. Most of these studies have been limited by 2D quantitative methods, and more recent studies utilizing 3D methodologies are time-intensive with manual segmentation. The authors sought to develop a more automated tool to calculate the 3D posterior fossa volume, and correlate its changes after decompression with surgical outcomes. METHODS A semiautomated segmentation program was developed, and used to compare the pre- and postoperative volumes of the posterior cranial fossa (PCF) and the CSF spaces (cisterna magna, prepontine cistern, and fourth ventricle) in a cohort of pediatric patients with CM-I. Volume changes were correlated with postoperative symptomatic improvements in headache, syrinx, tonsillar descent, cervicomedullary kinking, and overall surgical success. RESULTS Forty-two pediatric patients were included in this study. The mean percentage increase in PCF volume was significantly greater in patients who showed clinical improvement versus no improvement in headache (5.89% vs 1.54%, p < 0.05) and tonsillar descent (6.52% vs 2.57%, p < 0.05). Overall clinical success was associated with a larger postoperative PCF volume increase (p < 0.05). These clinical improvements were also significantly associated with a larger increase in the volume of the cisterna magna (p < 0.05). The increase in the caudal portion of the posterior fossa volume was also larger in patients who showed improvement in syrinx (6.63% vs 2.58%, p < 0.05) and cervicomedullary kinking (9.24% vs 3.79%, p < 0.05). CONCLUSIONS A greater increase in the postoperative PCF volume, and specifically an increase in the cisterna magna volume, was associated with a greater likelihood of clinical improvements in headache and tonsillar descent in patients with CM-I. Larger increases in the caudal portion of the posterior fossa volume were also associated with a greater likelihood of improvement in syrinx and cervicomedullary kinking.

KEYWORDS:

CM-I = Chiari malformation Type I; Chiari malformation Type I; PCF = posterior cranial fossa; outcomes; posterior fossa volume; volumetric analysis

PMID:
28291422
DOI:
10.3171/2016.11.PEDS16263
[Indexed for MEDLINE]

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