Posterior fossa syndrome and increased mean diffusivity in the olivary bodies

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Posterior fossa syndrome (PFS) is a common postoperative complication following resection of posterior fossa tumors in children. It typically presents 1 to 2 days after surgery with mutism, ataxia, emotional lability, and other behavioral symptoms. Recent structural MRI studies have found an association between PFS and hypertrophic olivary degeneration, which is detectable as T2 hyperintensity in the inferior olivary nuclei (IONs) months after surgery. In this study, the authors investigated whether immediate postoperative diffusion tensor imaging (DTI) of the ION can serve as an early imaging marker of PFS.


The authors retrospectively reviewed pediatric brain tumor patients treated at their institution, Lucile Packard Children’s Hospital at Stanford, from 2004 to 2016. They compared the immediate postoperative DTI studies obtained in 6 medulloblastoma patients who developed PFS to those of 6 age-matched controls.


Patients with PFS had statistically significant increased mean diffusivity (MD) in the left ION (1085.17 ± 215.51 vs 860.17 ± 102.64, p = 0.044) and variably increased MD in the right ION (923.17 ± 119.2 vs 873.67 ± 60.16, p = 0.385) compared with age-matched controls. Patients with PFS had downward trending fractional anisotropy (FA) in both the left (0.28 ± 0.06 vs 0.23 ± 0.03, p = 0.085) and right (0.29 ± 0.06 vs 0.25 ± 0.02, p = 0.164) IONs compared with age-matched controls, although neither of these values reached statistical significance.


Increased MD in the ION is associated with development of PFS. ION MD changes may represent an early imaging marker of PFS.

ABBREVIATIONS DTC = dentatothalamocortical; DTI = diffusion tensor imaging; FA = fractional anisotropy; GMT = Guillain-Mollaret triangle; HOD = hypertrophic olivary degeneration; ION = inferior olivary nucleus; MD = mean diffusivity; PFS = posterior fossa syndrome; ROI = region of interest; SCP = superior cerebellar peduncle.

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Contributor Notes

Correspondence Kristen W. Yeom: Lucile Packard Children’s Hospital, Stanford University, Palo Alto, CA. WHEN CITING Published online July 26, 2019; DOI: 10.3171/2019.5.PEDS1964.

D.Y. and R.J. contributed equally to this work.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.


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