Poster C13, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall
Language outcome after anterior temporal lobectomy: insights from tractography
Ekaterina Stupina1, Anna Artemova1, Oleg Bronov2, Elisaveta Gordeyeva1, Dmitry Kopachev3, Elena Kremneva3, Marina Krotenkova3, Nikita Pedyash2, Andrey Zuev2, Andrey Zyryanov1, Olga Dragoy1,4;1National Research University Higher School of Economics, 2National Medical and Surgical Center named after N.I. Pirogov, 3Research Center of Neurology, 4Federal Center for Cerebrovascular Pathology and Stroke
A growing literature shows a critical role of white matter tracts (Catani, Jones, & ffytche, 2005) in neural mechanisms of language processing. This study investigates a relation between tracts damage and language outcome after anterior temporal lobe resection (ATLR). This surgery involves removal of the anterior part of the temporal lobe and mesial structures – the amygdala and the hippocampus (Clusmann et al., 2004), and is associated with language deterioration after the surgery in the language-dominant hemisphere (Sherman et al., 2011). The structural consequences of ATLR on the adjacent white-matter tracts and their relation to postoperative language deficits are not fully understood. In this study, we use a comprehensive language battery to analyze pre- and postoperative language status in patients undergoing ATLR. We also investigate if changes in the adjacent associative white-matter tracts and the resection volume predict postoperative language outcome. 18 patients (age range 20-47, M=34.8 y.o.) who underwent left ATLR due to intractable left temporal lobe epilepsy participated in the study. Before and 2-8 days after (M=4.7) the surgery, all patients were tested with the Russian Aphasia Test (RAT; Ivanova et al. 2016), which assesses both comprehension and production at all levels of linguistic processing. Before and 1-11 days after (M=4.7) the surgery, diffusion-tensor imaging (DTI) sequences were acquired for all patients using a 3T scanner (64 directions, 2 mm isovoxel, b=1500 s/mm2). After preprocessing, three ventral tracts in the left and right hemispheres were manually reconstructed based on the deterministic tensor-based model: inferior longitudinal (ILF), inferior fronto-occipital (IFOF), and uncinate (UF) fasciculi. Moreover, resection volumes were calculated based on normalized postoperative structural MRI images. Presurgically, all patients performed relatively well on language tests and showed close-to-normal language abilities. Some patients had problems with naming and verbal memory as reflected by object naming and sentence repetition tasks. Postsurgically, production but not comprehension was significantly affected (t=6.4, df=17, p<0.001): half of the patients decreased their overall production score by 13% or more. Object naming and sentence repetition tasks were affected the most. In 5 patients a different surgical approach was implemented, resulting in smaller resection of the anterior temporal lobe and better preservation of the ventral tracts: only in these patients UF and ILF could be reconstructed after the surgery using the same regions of interest as before the surgery. Taken as a binary predictor (all tracts preserved or not), ventral tracts preservation was associated with significantly less worsening in language production scores (by 9.6%, p=0.008). At the same time, resection volume and changes in volumes of each tract separately did not correlate with the extent of language worsening. Overall, our results suggest that preservation of ventral tracts is an important factor in language outcome in patients undergoing ATLR. However, larger samples are needed to separate the contribution of each ventral associative tract to postoperative language worsening. The study was supported by RFFI (grant no. 18-012-00829).
Themes: Disorders: Acquired, Methods
Method: White Matter Imaging (dMRI, DSI, DKI)