Longitudinal signal changes in the dentato-rubro-olivary pathway of patients with posterior fossa syndrome

Abstract Background Posterior fossa syndrome (PFS) is a complication of posterior fossa surgery that is associated with damage to the dentato-rubro-olivary pathway. The mechanism of injury to this pathway and its evolution is not well understood. Methods We conducted a retrospective review of brain magnetic resonance images (MRIs) in patients with medulloblastoma treated at a pediatric oncology center over an 8-year period. The MRI signal abnormalities in the superior cerebellar peduncles (SCPs), the dentate nuclei, and the inferior olivary nuclei (ION) were graded by a neuroradiologist blinded to the diagnosis of PFS immediately postoperative and at 6 and 12 months after surgery. A multivariable logistic regression model was used to estimate signal abnormalities in the SCPs and dentate nuclei at the immediately postoperative time point. A logistic generalized estimating equation model was used for longitudinal analysis of signal abnormalities in the SCPs, dentate nuclei, and ION. Results On immediately postoperative imaging, patients with PFS were more likely to exhibit T2 hyperintensity in the SCPs, as compared to patients without PFS (odds ratio [OR] = 8.71, 95% confidence interval [CI] = 3.93-19.27), which was more frequently due to surgical injury than transient edema (82% vs 18%). On longitudinal analysis, T1 hyperintensity in bilateral dentate nuclei was more likely to develop in the PFS group (OR = 2.16, 95% CI = 1.54-3.02). Conclusions Patients with PFS had a higher incidence of SCP injury on immediately postoperative MRIs and were more likely to experience dystrophic mineralization in bilateral dentate nuclei during follow-up, suggestive of trans-synaptic degeneration.