Subcortical contributions to higher cognitive function in tumour patients undergoing awake craniotomy

Abstract

Primary brain tumours often occur near eloquent regions, affecting language, motor and memory capacity, with awake mapping and tailored resection designed to preserve higher cognitive functioning. The effects of such tumours on subcortical structures, including the thalamus and basal ganglia, have been largely unexplored, in spite of the known importance of such structures to higher cognitive functioning. We sought to explore the effects of volume changes of subcortical structures on cognition, in 62 consecutive patients diagnosed with primary brain tumour and cavernous malformations, referred to our neurosurgical practice. We found right caudate to be highly predictive of intelligence, left pallidum of total neuropsychological function and right hippocampus of mood. Our study is the largest of its kind in exploring subcortical substrates of higher cognition in consecutive patients with brain tumours. This research supports prior literature, showing subcortical structures to be related to higher cognitive functioning, particularly measures of memory and executive functioning implicated in fronto-subcortical circuits. Furthermore, involvement of right mesial temporal structures in mood, further strengthens the central role of Papez circuit in emotional quality of cognition. Attention to subcortical integrity is likely to be important in discussing postsurgical cognitive outcome with patients and their families.

Keywords: basal ganglia; fronto-subcortical; intelligence; neuropsychology; primary brain tumour.

Graphical Abstract

Figure 1

Relationship between right caudate volume and Total Z-score. (A) Scatterplot of Full Scale Intelligence Score – Right Caudate Volume Relationship. (B) Scatterplot of Total Z-score – Left Pallidum Volume Relationship; (C) Scatterplot of Total Z-score – Right Caudate Volume Relationship (Blue = Left Hemisphere; Red = Right Hemisphere).

Figure 2

Relationship between right putamen and Motor Z-score. (A) Scatterplot of Motor Z-score – Right Putamen Volume Relationship; (B) Scatterplot of Motor Z-score – Right Thalamus Relationship. (C) Scatterplot of Mood Z-score – Right Hippocampus Volume Relationship; (D) Scatterplot of Mood Z-score – Left Amygdala Volume Relationship. (Blue = Left Hemisphere; Red = Right Hemisphere).

Figure 3

Segmented volumes of subcortical regions and tumour in six patients with left hemispheric lesions (radiological convention) and lowest Total Z-scores.

Figure 4

Segmented volumes of subcortical regions and tumour in six patients with right hemispheric lesions (radiological convention) and lowest Mood Z-scores.