009 Language decline following white matter tract damage during anterior temporal lobe resection in language dominant hemisphere

Anterior temporal lobe resection (ATLR) for temporal lobe epilepsy (TLE) has remission rates up to 80%, however is underutilised, in part because of the risk of language decline following surgery. Language decline occurs in up to 50% of ATLR in the language dominant side. This can occur despite careful planning with functional MRI (fMRI) language mapping. Several white matter bundles are close to the resection area which could contribute to language decline. Diffusion MRI-based fibre tracking to map the arcuate, uncinate, inferior fronto-occipital, inferior, and middle longitudinal fasciculus was performed on 43 patients. We extracted the left-sided bundles in those temporal lobe epilepsy patients who had left-dominant language based on verbal fluency functional MRI (fMRI) and a left-sided resection. Resection masks were manually drawn and used as exclusion regions. Changes from pre- to post-operative tractography and language ability were measured as percentages. Linear regression revealed that the McKenna Graded Naming test decline was predicted by the arcuate and middle longitudinal fasciculus resection (F(2,41)=5.562, p=0.007) with an adjusted R2 of 0.175. These findings demonstrate that damage to anterior arcuate extensions and the middle longitudinal fasciculus affects picture naming ability.lawrence.binding.19@ucl.ac.uk