Functional MRI of sensory motor cortex: comparison between finger-to-thumb and hand squeeze tasks.

BACKGROUND: An important imaging technique that has advanced decision-making for noninvasive preoperative evaluation is functional magnetic resonance imaging (fMRI). Preoperative fMRI imaging based on blood oxygenation level dependent (BOLD) fMRI is routinely used to map a variety of eloquent cortex brain functions such as language, visual, and sensory-motor regions. PURPOSE: The purpose of this study was to evaluate the regional volumes of sensory and motor cortex (SMC) activation by two widely used fMRI motor tasks: a simple hand squeeze (HS) versus a more complex finger-to-thumb (FTT) opposition. METHODS: Ten right-handed (five males; five females) subjects were studied using a block design BOLD fMRI technique at 1.5T. A region of interest analysis was performed in the right and left SMC following a HS and FTT task with the dominant right hand. RESULTS: Results show the total volume of motor and sensory activation for ipsilateral and contralateral areas for the FTT task was statistically larger than the HS task (P= .02). CONCLUSION: Due to the greater degree of activation of the SMC with the FTT task, we suggest use of this task over the HS task if a patient can adequately perform the more complex FTT task. The greater SMC activation using FTT task compared to the HS task was primarily due to an increase in activation in the post-central sensory cortex. There was less lateralization, and therefore a greater degree of bilateral SMC activation, in the FTT task compared to the HS task. These results show the importance of optimization and fMRI task selection for presurgical SMC mapping.

Central nervous system findings on functional magnetic resonance imaging in patients before and after treatment with anticholinergic medication.

PURPOSE: Anticholinergic medications are commonly used to treat urinary urgency and frequency. Muscarinic receptors are located in areas beyond the detrusor muscle. In this study we measured changes in central nervous system activity in patients with lower urinary tract symptoms treated with tolterodine or a placebo. MATERIALS AND METHODS: A total of 20 female patients with urinary frequency were randomized to 4 weeks of treatment with tolterodine or a placebo. Functional magnetic resonance imaging based on blood oxygenation level dependant imaging of the brain during bladder filling was performed before and after treatment. For each patient the bladder was filled by a urethral catheter and emptied 5 times. RESULTS: Multiple brain areas showed significant activation with bladder filling compared to the empty state and many areas also showed deactivation. Overall brain activation with bladder filling was decreased after treatment in both groups. After treatment 2 areas of the parietal cortex (precuneus and postcentral gyrus) showed significantly greater activity in patients treated with tolterodine vs placebo. Two areas of the cerebellum (anterior lobe and culmen) showed significantly greater activity in the placebo group, and these were also areas of significant deactivation in the tolterodine group. CONCLUSIONS: Brain activity changes as well as the areas of activation after treatment of lower urinary tract symptoms in patients with an anticholinergic medication or placebo are different in the 2 groups. Whether this finding represents action at the central nervous system or the bladder level is not known.