CLINICAL ARTICLE J Neurosurg 126:1912–1923, 2017 I n today’s society, with easy access to travel and numer- ous opportunities for communication between people from different cultural backgrounds and languages, it has become customary to learn more than one language throughout life. The term bilingualism is used when some- one speaks 2 languages with high profciency, while multi- lingualism refers to people who speak 3 or more languages fuently. 13 Even in individuals who are highly bilingual, one language usually dominates over the other. Second- language learners seldom achieve the same level of prof- ABBREVIATIONS AoA = age of acquisition; ESM = electrical stimulation mapping; fMRI = functional MRI; L1 = native language; L2 = acquired language. SUBMITTED November 29, 2015. ACCEPTED May 26, 2016. INCLUDE WHEN CITING Published online August 19, 2016; DOI: 10.3171/2016.5.JNS152791. Age of language acquisition and cortical language organization in multilingual patients undergoing awake brain mapping Alejandro Fernández-Coello, MD, 1–3 Viktória Havas, PhD, 4,5 Montserrat Juncadella, PhD, 6 Joanna Sierpowska, MSc, 4,8 Antoni Rodríguez-Fornells, PhD, 4,7,8 and Andreu Gabarrós, MD, PhD 1 Sections of 1 Neurosurgery and 6 Neurology, Hospital Universitari de Bellvitge, Campus Bellvitge, University of Barcelona– IDIBELL; 2 Department of Pathology and Experimental Therapeutics, Anatomy and Human Embryology Unit, and 8 Department of Basic Psychology, Campus Bellvitge, University of Barcelona; 4 Cognition and Brain Plasticity Group, IDIBELL, L’Hospitalet de Llobregat; 3 CIBER de Bioingeniería, Biomateriales y Nanomedicina; 7 Catalan Institution for Research and Advanced Studies, Barcelona, Spain; and 5 Department of Language and Literature, Norwegian University of Science and Technology, Trondheim, Norway OBJECTIVE Most knowledge regarding the anatomical organization of multilingualism is based on aphasiology and functional imaging studies. However, the results have still to be validated by the gold standard approach, namely electri- cal stimulation mapping (ESM) during awake neurosurgical procedures. In this ESM study the authors describe language representation in a highly specifc group of 13 multilingual individuals, focusing on how age of acquisition may infuence the cortical organization of language. METHODS Thirteen patients who had a high degree of profciency in multiple languages and were harboring lesions within the dominant, left hemisphere underwent ESM while being operated on under awake conditions. Demographic and language data were recorded in relation to age of language acquisition (for native languages and early- and late- acquired languages), neuropsychological pre- and postoperative language testing, the number and location of language sites, and overlapping distribution in terms of language acquisition time. Lesion growth patterns and histopathological characteristics, location, and size were also recorded. The distribution of language sites was analyzed with respect to age of acquisition and overlap. RESULTS The functional language-related sites were distributed in the frontal (55%), temporal (29%), and parietal lobes (16%). The total number of native language sites was 47. Early-acquired languages (including native languages) were represented in 97 sites (55 overlapped) and late-acquired languages in 70 sites (45 overlapped). The overlapping dis- tribution was 20% for early-early, 71% for early-late, and 9% for late-late. The average lesion size (maximum diameter) was 3.3 cm. There were 5 fast-growing and 7 slow-growing lesions. CONCLUSIONS Cortical language distribution in multilingual patients is not homogeneous, and it is infuenced by age of acquisition. Early-acquired languages have a greater cortical representation than languages acquired later. The preva- lent native and early-acquired languages are largely represented within the perisylvian left hemisphere frontoparietotem- poral areas, and the less prevalent late-acquired languages are mostly overlapped with them. https://thejns.org/doi/abs/10.3171/2016.5.JNS152791 KEY WORDS electrical stimulation mapping; multilingual brain; language mapping; diagnostic and operative techniques ©AANS, 2017 J Neurosurg Volume 126 • June 2017 1912 Unauthenticated | Downloaded 05/18/22 04:54 PM UTC