Noninvasive mapping of visuospatial attention by navigated repetitive transcranial magnetic stimulation in patients with parietal lobe tumors.

Abstract

Objective: Visuospatial neglect corresponds to a burdening cognitive deficit with reduced space attention and disturbed stimuli detection of the contralateral side. Unilateral strokes, tumor lesions, or intracerebral hemorrhage may cause it. Identifying specific areas responsible for the onset of visuospatial neglect has proven difficult. The authors hereby aimed to detect neglect-positive areas in patients with parietal gliomas undergoing tumor resection through navigated repetitive transcranial magnetic stimulation (nrTMS).

Methods: The authors performed a monocentric prospective study that included patients with suspected parietal lobe gliomas. After obtaining patient consent, time-locked nrTMS was performed for neglect testing using the Landmark Task and grayscale test on 52 predefined cortical spots before and after surgery. Errors were categorized as leftward/rightward errors or deviations and no response errors. Additionally, patients performed two paper-and-pencil tests to evaluate clinical neglect.

Results: Nineteen patients were enrolled in the study. Ten patients had a glioma, 8 had brain metastases, and 1 patient had a meningioma. Error rates and leftward deviations were significantly higher in the right hemisphere. The supramarginal and angular gyrus and the superior parietal and occipital areas seemed especially important. After surgery, errors increased substantially in the right hemisphere. The Landmark Task and grayscale test showed high sensitivity (100%) and a negative predictive value (100%).

Conclusions: Visuospatial neglect can be evoked reliably by nrTMS in patients with parietal tumors. The study showed promising results for the intraoperative use of nrTMS visuospatial neglect mapping.