Mapping of long-term cognitive and motor deficits in pediatric cerebellar brain tumor survivors into a cerebellar white matter atlas

Abstract

Purpose: Diaschisis of cerebrocerebellar loops contributes to cognitive and motor deficits in pediatric cerebellar brain tumor survivors. We used a cerebellar white matter atlas and hypothesized that lesion symptom mapping may reveal the critical lesions of cerebellar tracts.

Methods: We examined 31 long-term survivors of pediatric posterior fossa tumors (13 pilocytic astrocytoma, 18 medulloblastoma). Patients underwent neuronal imaging, examination for ataxia, fine motor and cognitive function, planning abilities, and executive function. Individual consolidated cerebellar lesions were drawn manually onto patients' individual MRI and normalized into Montreal Neurologic Institute (MNI) space for further analysis with voxel-based lesion symptom mapping.

Results: Lesion symptom mapping linked deficits of motor function to the superior cerebellar peduncle (SCP), deep cerebellar nuclei (interposed nucleus (IN), fastigial nucleus (FN), ventromedial dentate nucleus (DN)), and inferior vermis (VIIIa, VIIIb, IX, X). Statistical maps of deficits of intelligence and executive function mapped with minor variations to the same cerebellar structures.

Conclusion: We identified lesions to the SCP next to deep cerebellar nuclei as critical for limiting both motor and cognitive function in pediatric cerebellar tumor survivors. Future strategies safeguarding motor and cognitive function will have to identify patients preoperatively at risk for damage to these critical structures and adapt multimodal therapeutic options accordingly.

Keywords: Adolescence; Brain tumor; Childhood; Cognitive function; Executive function; Lesion symptom mapping; VLSM.

Fig. 1

Lesion overlay in pediatric cerebellar tumor survivors. Legend to Fig. 1: PA pilocytic astrocytoma, MB medulloblastoma. Color code indicates numbers of overlapping lesions. Arabic numbers indicate y-coordinates in MNI space. Right-sided lesions being flipped to the left on cerebellar template with deep cerebellar nuclei in green and white matter tracts in yellow/orange

Fig. 2

Lesion symptom maps of motor and cognitive function in pediatric cerebellar tumor survivors. Legend to Fig. 2: zICARS z-score of total ICARS score, Manu-F frequency of fine motor hand movement, Manu-A automation of fine motor hand movement, FSIQ full scale intelligent quotient, VIQ verbal IQ, PIQ performance IQ, TOL age corrected percentile rank score of Tower of London, BS baseline speed (ANT), FI-T reaction time at feature identification among similar patterns (ANT), SV-T reaction time of shifting attention at attention flexibility (ANT). Deep cerebellar nuclei are shown in green, white matter tracts in yellow/orange. Color code indicates z-score in lesion symptom map. Arabic numbers indicate y-coordinates in MNI space

Fig. 3

Involvement of proximal SCP in lesion symptom maps of motor and cognitive function in pediatric cerebellar tumor survivors. Legend to Fig. 3: zICARS z-score of total ICARS score, Manu-F frequency of fine motor hand movement, Manu-A automation of fine motor hand movement, FSIQ full scale intelligent quotient, VIQ verbal IQ, PIQ performance IQ, TOL age corrected percentile rank score of Tower of London, BS baseline speed (ANT), FI-T reaction time at feature identification among similar patterns (ANT), SV-T reaction time of shifting attention at attention flexibility (ANT). Deep cerebellar nuclei are shown in green, white matter tracts in yellow/orange. Color code indicates z-score in lesion symptom map. Slices show lesion symptom maps at coordinate z =  − 32 in MNI space