Association between postoperative DTI metrics and neurological deficits after posterior fossa tumor resection in children

Objective: Resection of posterior fossa tumors in children may be associated with persistent neurological deficits. It is unclear if these neurological deficits are associated with persistent structural damage to the cerebellar pathways. The purpose of this research was to define longitudinal changes in diffusion tensor imaging (DTI) metrics in white matter cerebellar tracts and the clinical correlates of these metrics in children undergoing resection of posterior fossa tumors.

Methods: Longitudinal brain DTI was performed in a cohort of pediatric patients who underwent resection of posterior fossa tumors. Fractional anisotropy (FA) of the superior cerebellar peduncles (SCPs) and middle cerebellar peduncles (MCPs) was measured on preoperative, postoperative, and follow-up DTI. Early postoperative (< 48 hours) and longer-term follow-up neurological deficits (mutism, ataxia, and extraocular movement dysfunction) were documented. Statistical analysis was performed to determine differences in FA values based on presence or absence of neurological deficits. Statistical significance was set at p < 0.05.

Results: Twenty children (mean age 6.1 ± 4.1 years [SD], 12 males and 8 females) were included in this study. Follow-up DTI was performed at a median duration of 14.3 months after surgery, and the median duration of follow-up was 19.7 months. FA of the left SCP was significantly reduced on postoperative DTI in comparison with preoperative DTI (0.44 ± 0.07 vs 0.53 ± 0.1, p = 0.003). Presence of ataxia at follow-up was associated with a persistent reduction in the left SCP FA on follow-up DTI (0.43 ± 0.1 vs 0.55 ± 0.1, p = 0.016). Patients with early postoperative mutism who did not recover at follow-up had significantly decreased FA of the left SCP on early postoperative DTI in comparison with those who recovered (0.38 ± 0.05 vs 0.48 ± 0.06, p = 0.04).

Conclusions: DTI after resection of posterior fossa tumors in children shows that persistent reduction of SCP FA is associated with ataxia at follow-up.