Page 154 - Bladder Dysfunction in the Context of the Bladder-Brain Connection - Ilse Groenendijk.pdf

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Chapter 8
A previous study used ALE analysis in 181 patients to demonstrate which brain areas are involved during bladder filling, which is the main sensory task of the LUT.10 Bladder filling has often been studied, whereas the somatosensory representation of the genitals has rarely been investigated.11-14 Data seem not yet sufficient to perform a meta-analysis on the somatosensory representation of the external genitalia. The 7T fMRI study presented in chapter 3 showed which brain areas are involved in pelvic floor muscle contractions in healthy individuals. The 7T fMRI study presented in chapter 4 demonstrated which brain areas are involved in the individual processing of sensory information of male genitals in healthy individuals. The findings of chapters 2, 3 & 4, increased the knowledge on the involved brain areas in the central motor and sensory control of the LUT. This basic knowledge about the central control of the LUT is essential for the use of fMRI in individual patients in clinical practice.
2. Are the activity patterns divergent between patients and healthy subjects?
The further applicability of dynamic brain imaging to study the control of the LUT depends on clinical validation of the differences observed in outcomes between differ- ent populations, i.e. healthy persons versus patients and between patients before and after therapy. Research has demonstrated on group level that the results of dynamic brain imaging are different between patients and healthy subjects, and before and after therapy. Several brain areas, such as the supplementary motor area, the cingulate gyrus and the prefrontal cortex, have been described to be of interest when studying these differences.15-20 At present, it is still unclear whether the differences between patients and healthy individuals and before and after therapy are detectable on individual level.
3. Is this ‘tool’ eligible for studying the LUT in individuals?
Single subject results obtained with the use of ultra-high field imaging regarding more basic tasks (e.g. digit somatotopy) have been found complementary to group results.21, 22 Results on individual level for the LUT are scarce, however, which is at least partly related to the suspected inter-individual differences caused by the affective involvement in these tasks.23 In the studies presented in chapters 3 & 4, activity patterns of individuals were analyzed using 7T fMRI to investigate whether in relation to the motor and sensory innervation of the LUT these patterns are comparable to group results. Both studies demonstrated that 7T fMRI is a feasible technique to study LUT whole-brain activity pat- terns at single-subject level.
4. Do we need ultra-high field imaging?
In previous studies using 1.5T and 3T fMRI, demonstrating individual results was uncom- mon as these results would not have a spatial acuity that allows for interpretation of individual results.23 At 7T, signal-to-noise ratios and blood-oxygenation-level-dependent