QOS-49: IMPAIRED LINGUISTIC ABILITIES AND CORTICAL RE-MAPPING OF THE LANGUAGE PROCESSING IN LONG-TERM POSTERIOR FOSSA TUMOUR SURVIVORS

Posterior fossa tumour (PFT) survivors frequently display long-term cognitive deficits. Previous literature reports contradictory findings in relation to the linguistic abilities, and no studies to date investigated neural correlates of language processing in this group of patients, using functional imaging techniques. 21 patients aged 16-21 (seven medulloblastoma, eleven astrocytoma, two ependymoma and one high grade glioma), at least 12 months post-treatment, and 22 matched healthy controls had their language proficiency, non-verbal intelligence and manual dexterity assessed using Clinical Evaluation of Language Fundamentals (CELF-5) battery, Raven's Progressive Matrices (RPM+) and Purdue pegboard. Oromotor function was also investigated in patients using Frenchay Dysarthria Assessment (FDA-2). Of these, 16 patients and 20 healthy volunteers took part in a functional magnetic resonance imaging (fMRI) experiment, assessing patterns of cortical activation during semantic processing and speech articulation tasks. Behaviourally, patients performed significantly worse on all sub-tests of CELF-5, RPM+ and Purdue Pegboard. Significant associations have been observed between the linguistic abilities, non-verbal intelligence, manual dexterity and dysarthria score in patients, suggesting common developmental trajectories and susceptibility to impairment through neurological injury. Age at diagnosis, recovery time, tumour type or volume did not predict linguistic performance. More widespread cortical activation was evident during the language processing in patients compared to healthy controls. In addition, signal intensity change during the fMRI tasks negatively correlated with the performance scores on the associated CELF-5 tests. In combination with the deficient behavioural performance, these findings suggest increased compensatory neural activity, yet less efficient language processing in long-term PFT survivours.