Page 63 - Bladder Dysfunction in the Context of the Bladder-Brain Connection - Ilse Groenendijk.pdf
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                 Whole brain 7T-fMRI during pelvic floor muscle contraction in male subjects 61
INTRODUCTION
Pelvic floor disorders (PFDs), such as urinary and fecal incontinence as well as pelvic organ prolapse, are highly prevalent in both men and women.1 Given the increase of PFD symptoms with increasing age and the steady increase in life expectancy, PFD currently forms a major healthcare problem with significant economic and social burden.1,2
The pelvic floor musculature and pelvic organs are innervated by the pudendal and pelvic nerves, the activity of which is controlled by various parts of the central nervous system. Indeed, over the past decades different studies using a variety of imaging tech- niques have revealed that many different brain areas are involved in voluntary pelvic floor muscle contraction (PFMC).3-8 In healthy volunteers, group analyses showed that the primary motor cortex, supplementary motor area (SMA), insula, thalamus and cer- ebellum can all be activated during PFMC.3,4,8,9 Voluntary control of the pelvic floor must be distinguished from involuntary control of the pelvic floor during continence, which is controlled by separate central pathways.3
Interestingly, patients suffering from PFD may show different activations of the central nervous system during PFMC compared to healthy volunteers.10,11
FMRI studies using 1.5-or 3-Tesla (T) magnets typically study BOLD (Blood-oxygen-level dependent) responses in groups of subjects, which requires additional smoothing to compensate for the variability of anatomical structures. Obtaining reliable single-subject responses requires higher SNR (Signal-to-Noise Ratio) and BOLD sensitivity. Therefore, the use of dynamic brain imaging as a diagnostic tool in individual PFD patients had so far only limited value in daily clinical practice.
Recently, high resolution (voxel size ~1mm3) fMRI at increased field strengths (7T) has led to significant improvement in the achievable spatial resolution.12 The increases in both SNR and BOLD signal at high-fields12 make single subject imaging possible.13 Fur- thermore, 7T-fMRI has been used successfully to map digit representations in individu- als.14 With state-of-the-art 7T-fMRI one can obtain a higher resolution BOLD signals from cortical to cerebellar regions simultaneously.15
The primary aim of this study is to demonstrate that 7T-fMRI can visualize the neural representations of the male pelvic floor in the whole brain of a single subject. Secondary aims are to define the involved brain areas in male pelvic floor control and to compare the individual results with our group results in the context of the available literature. Furthermore, we aimed to study the differences of functional connectivity of the in- volved brain areas between both tasks. Movements of tongue muscles, were chosen as a control task, because this midline motor task is mainly involved in different, well automated voluntary behaviours such as eating and speaking.
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