Brain responses to mechanical rectal stimulation in patients with faecal incontinence: an fMRI study

Regional homogeneity alterations in patients with functional constipation and their associations with gene expression profiles

Functional constipation, a highly prevalent functional gastrointestinal disorder, often accompanies by mental and psychological disorders. Previous neuroimaging studies have demonstrated brain functional and structural alterations in patients with functional constipation. However, little is known about whether and how regional homogeneity is altered in these patients. Moreover, the potential genetic mechanisms associated with these alterations remain largely unknown. The study included 73 patients with functional constipation and 68 healthy controls, and regional homogeneity comparison was conducted to identify the abnormal spontaneous brain activities in patients with functional constipation. Using Allen Human Brain Atlas, we further investigated gene expression profiles associated with regional homogeneity alterations in functional constipation patients with partial least squares regression analysis applied. Compared with healthy controls, functional constipation patients demonstrated significantly decreased regional homogeneity in both bilateral caudate nucleus, putamen, anterior insula, thalamus and right middle cingulate cortex, supplementary motor area, and increased regional homogeneity in the bilateral orbitofrontal cortex. Genes related to synaptic signaling, central nervous system development, fatty acid metabolism, and immunity were spatially correlated with abnormal regional homogeneity patterns. Our findings showed significant regional homogeneity alterations in functional constipation patients, and the changes may be caused by complex polygenetic and poly-pathway mechanisms, which provides a new perspective on functional constipation's pathophysiology.

Relationship between desire to void and bladder capacity and rectal sensory function in patients with multiple sclerosis and anorectal disorders

AIMS

The primary aim of this study was to assess the relationship between a strong desire to void (SDV) and rectal sensory function in patients with multiple sclerosis (PwMS) and anorectal disorders. The secondary aim was to identify clinical, urodynamic or manometric factors associated with greater rectal sensory function impairment in this population.

METHODS

Thirty PwMS (mean age 49.2 ± 10.9 years) with anorectal disorders (constipation and/or fecal incontinence) participated in this observational study. Rectal sensory parameters during anorectal manometry were recorded at a strong desire to void and after urination (PV, post-void). The primary outcome was the desire to defecate volume. Secondary outcomes were first perception and maximum tolerated threshold volumes, presence and modulation of recto-anal inhibitory reflex.

RESULTS

The mean desire to defecate volume was 125 ± 59 mL at SDV and 104 ± 64 mL at PV (P < .001). The mean maximum tolerated volume was 167 ± 61 mL at SDV vs 141 ± 64 mL after urination (P = .01). The other parameters were not different between SVD and PV conditions. No predictive factors for greater impairment of rectal sensory function were identified.

CONCLUSION

This study suggests a relationship between bladder sensation and thus bladder capacity, and rectal sensory function in PwMS and with anorectal disorders.

Brain MRI Lesions are Related to Bowel Incontinence in Multiple Sclerosis

BACKGROUND AND PURPOSE

Bowel incontinence in multiple sclerosis might be associated with specific lesion sites. This study intended to determine associations between bowel incontinence and cerebral multiple sclerosis lesions using a voxel-wise lesion symptom mapping analysis.

METHODS

We conducted a retrospective study of multiple sclerosis patients with self-reported bowel incontinence and matched controls. Lesions were manually outlined on T2-weighted MRI scans and transformed into stereotaxic space. We performed a voxel-wise subtraction analysis subtracting the lesion overlap of patients without from patients with bowel incontinence. Finally, we compared the absence or presence of bowel incontinence between patients with and without lesions in a given voxel using the Liebermeister test.

RESULTS

A total of 51 patients were included in the study. The analysis yielded associations between bowel incontinence and lesions in the supramarginal gyrus of the left secondary somatosensory cortex and another lesion cluster in the right parahippocampal gyrus and amygdala.

CONCLUSIONS

Our analysis indicates associations between bowel incontinence and lesions in the left supramarginal gyral area contributing to integrating anorectal-visceral sensation and in the right parahippocampal gyrus and amygdala contributing to generating visceral autonomic arousal states. Moreover, our results suggest left hemispheric dominance of sensory visceral integration, while limbic areas of the right hemisphere seem to contribute to the autonomic component of the defecation process. A limitation of our study is the retrospective evaluation of the bowel incontinence status based on medical records. Further research should evaluate the bowel incontinence status in multiple sclerosis patients prospectively to overcome the limitations of the current study.