Urinary incontinence and its functional anatomy in frontotemporal lobar degenerations

Purpose: The frontal lobes play a crucial role in micturition control. However, no reports exist on the functional role of distinct frontal brain regions in urinary incontinence (UIC) in patients with a neurodegenerative damage of the frontal lobe. The aim of the present study was therefore to explore if functional brain lesions were associated with UIC in patients suffering from frontotemporal lobar degenerations (FTLD). Methods: Forty-four patients, including eight incontinent subjects, underwent cranial positron emission tomography scanning with ¹⁸F-fluoro-2-deoxy-glucose ( ¹⁸F-FDG PET) to assess the relative metabolic rate of glucose (rCMRglc). Group comparisons of rCMRglc were conducted in SPM2 to identify brain regions where the group of incontinent patients (FTLD+UIC) had significant alterations compared with the group without UIC (FTLD-UIC). Results: At the stringent statistical threshold of p < 0.05, corrected for multiple comparisons according to the family-wise error rate, the statistical analysis revealed two significant right-hemispheric hypometabolic clusters located in the premotor/anterior cingulate cortex and the putamen/claustrum/insula. No hypermetabolic regions were found. Conclusions: The present study is the first to provide evidence for brain functional alterations involved in the occurrence of UIC in FTLD. These results provide an important piece of evidence to the understanding of a particularly distressing autonomic nervous system symptom of dementia.