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  1. 1. Preoperative functional magnetic resonance imaging assessment of higher-order cognitive function in patients undergoing surgery for brain tumors C. Amiez, P Kostopoulos, A-S Champod, D Louis Collins, J Doyon, R Del Maestro, M Petrides Montreal Neurological Institute, Dept Neurology & Neurosurgery, McGill University, Canada J. Neurosurg. Feb 2008 Sajedha Mahmood
  2. 2. Background  75000 cases of primary brain tumours /year in developed countries  Survival rate dependent on extent of resection and histological characteristics  PET and fMRI used to map sensory and motor functions and define areas of language processing with aim to preserve these functions  Higher motor functions (retrieving memory, response based on conditional rules) depends on integrity of frontal cortex  This study looks at fMRI in 4 patients preoperatively with tumours close to rostral part of dorsal premotor cortex (PMdr)  Task developed to assess selection between competing motor responses  Basic motor function not affected by PMdr
  3. 3. Methods  Neuroimaging using fMR while performing a visuomotor conditional task and 2 control tasks (motor and visual)  Tasks developed in healthy controls  Pre-task training 1 d prior to scanning session until performance >95% correct on 2 consecutive sets of 40 trials
  4. 4. Methods  4 patients with Grade II oligodendrogliomas  Preoperative determination of visuomotor region with fMRI  Postoperative fMRI at 2 months to ensure the functional region had not been resected  Neuropsychological testing to establish postoperative cognitive status  fMRI data transferred to neuronavigation system preoperatively with identification of anatomical landmarks using a 3D pointer
  5. 5. Methods  1 patient: intraoperative assessment of PMdr function during tumour resection  Assessment 30 min prior to surgery, in operating room post anaesthesia but prior to surgical intervention and during the surgery  1 patient had 6 functional runs, others 5 runs  Each run had 3 blocks of trials repeated twice in same order  Each run lasted 7 min  First trial onset synchronised with scanner acquisition
  6. 6. Imaging  Each patient scanned using 1.5 T Sonata MRI system  Comparison of pre and postoperative anatomical data  After high-resolution T1-weighted anatomical scan, images sensitive to BOLD signals were acquired  BOLD signals obtained in visuomotor task compared with signals in motor control to identify region with greater response to visuomotor task  Comparison of signals from motor control task with visual control task to identify hand region in primary motor cortex  Images realigned and analysed using specific software  Pre- and postoperative imaging data edited to account for any change in brain shape postoperatively using ANIMAL software  Part of the tumour located closest to the PMdr region resected last
  7. 7. Results  Locations of activity peaks assessed based on stereotactic coordinates and sulcal and gyral patterns  Functional region involved localised in PMdr in anterior part of precentral gyrus continuing on dorsal branch of superior precentral sulcus in all patients  Relationship of functional peak to tumour different in each patient  Primary hand motor region localised in a region clearly different from regions involved in visuomotor tasks  Post-OP IQ rates: 1- 125, 2-113, 3-103, 4-100  Success rates for subjects 1 - 4 (pre/postoperatively):  Visuomotor: 95.3, 100, 96.9, 99.4 % / 98.8, 98.8, 98.1, 99.4%  Motor: 96,100,100, 99.4%  Visual: 100, 100, 100, 100%
  8. 8. Results  3 patients had gross-total tumour resection as assessed by post-OP images  1 patient had sub-total (80%) resection due to intraoperative sensorimotor weakness  No change in tumour volume in 2 years follow-up
  9. 9. Conclusions  Sensorimotor conditional ability essential for everyday tasks e.g. correct response at traffic lights etc  Animal and human studies have shown lesions in PMdr result in deficits in sensorimotor performance  Functional neuroimaging useful in minimising cognitive deficits by accurate localisation of involved regions  Intraoperative behavioural assessment can be helpful during surgical procedure in modifying the approach

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