Real-Time Neuropsychological Testing Protocol for Left Temporal Brain Tumor Surgery: A Technical Note and Case Report

Abstract

Background: The risk of surgery in eloquent areas is related to neuropsychological dysfunctions. Maximizing the extent of resection increases the overall survival. The onco-functional balance is mandatory when surgery involves cognitive areas, and maximal information on the cognitive status of patients during awake surgery is needed. This can be achieved using direct cortical stimulation mapping and, in addition to this, a neuropsychological monitoring technique called real-time neuropsychological testing (RTNT). The RTNT includes testing protocols based on the area where the surgery is performed. We reported on tests used for left temporal lobe surgery and our RTNT decision tree. Case Report: We reported our RTNT experience with a 25-year-old right-handed man with 13 years of schooling. He reported daily partial seizures. MRI revealed the presence of a low-grade glioma involving the temporo-insular cortex. The neuropsychological status presurgery which was within the normal range was combined with functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) information. Awake surgery plus RTNT was performed. Direct electrical stimulation during object naming elicited a motor speech arrest. Resection was continuously accompanied by the RTNT. The RTNT provided enriched information to the surgeon. Performance never dropped. A slight decrement in accuracy emerged for pseudoword repetition, short-term memory and working memory, phonological processing, and verbal comprehension. Total resection was performed, and the histological examination confirmed the nature of the lesion. Immediate postsurgery performance was within the normal range as it was the fMRI and DTI assessment. Conclusion: The RTNT provides essential information that can be used online, during surgery, for clinical aims to provide the surgeon with useful feedback on the cognitive status of patients.

Keywords: awake surgery; brain mapping; glioma; neuropsychology; plasticity.

FIGURE 1

Decision tree for awake surgery plus RTNT procedure. In the case presented here, we found that the patient—male, young (25 year old), right-handed—had a low-grade glioma involving the temporo-insular cortex. The fMRI and DTI examination indicate that the brain tumor is infiltrating the functional tissue. The neuropsychological assessment showed that the cognitive performance of the patient is within the normal range on the majority of the tests administered, and provided the patient is not feeling particularly anxious/depressed, awake surgery plus RTNT were selected.

FIGURE 2

Alternation of DES mapping and RTNT together with the RTNT protocol for left temporal resections. The first run of tasks is reported as an example. Each task includes 10 items.

FIGURE 3

Pre- (left panel) and post (right panel)-surgery fMRI maps for tongue movements (A), object naming (B), verb naming (C), and word/pseudoword reading (D) tasks. Activations are superimposed on the T2-weighted MRI axial slices of the patient.

FIGURE 4

Pre- (left panel) and post (right panel)-surgery DTI reconstructions of the inferior fronto-occipital fasciculus (A), superior longitudinal fasciculus (B), and corticospinal tract (C). Plots (D) represent mean fractional anisotropy (FA) and the number of streamlines for the patient and healthy controls.