Monitoring cognition during awake brain surgery in adults: A systematic review.

INTRODUCTION: Historically, most studies about awake brain surgery have focused on language or motor functions. More recently, other cognitive functions have also been assessed. However, a clear overview of the neuropsychological tests or test paradigms that are used during such procedures is missing. The primary research question of this review is: What neuropsychological tests or paradigms are used during awake brain surgery? This review aims to give an extensive overview about the assessment of cognition during awake brain surgery.

METHOD: A systematic search was performed in PubMed and Embase. Studies about awake surgery that mentioned a specific test or test paradigm for assessing cognition were included in this review.

RESULTS: The search yielded 4,052 articles. A manual selection for cognition in title and abstract resulted in 360 studies. Those were evaluated in full text; 212 articles described a cognitive task or paradigm. Further reference-list search yielded 20 more studies. In 207 of 232 studies, a test for assessment of language is reported. Tests for the visuospatial domain and motor and sensory functions are described in, respectively, only 23 and 20 studies. Tests for memory, calculation, emotions, or other cognitive functions are reported only in a minority of the included studies.

CONCLUSIONS: Tests for assessment of language functions during awake brain surgery are widely reported. Other cognitive functions are underexposed. There is a need for development of tests or paradigms for assessment of other cognitive functions so that the broad spectrum of cognition can be monitored during awake brain surgery.