Spinal Magnetic Resonance Diffusion Tensor Imaging (DTI) in OAB and UAB Caused by Tethered Cord Syndrome (TCS): Can the Yield Be Improved?

OBJECTIVE: This study aims to investigate spinal cord abnormalities in patients with Tethered Cord Syndrome (TCS) and lower urinary tract dysfunction using diffusion tensor imaging (DTI). Specifically, it seeks to explore the differences in the extent and severity of spinal cord injury between patients with overactive bladder (OAB) and underactive bladder (UAB) associated with TCS. METHODS: A total of 60 subjects were included in this study: 20 healthy volunteers and 40 patients with TCS, of which 20 had OAB and 20 had UAB. All patients underwent video-urodynamic testing and pelvic floor electrophysiological examination. Additionally, both patients and healthy controls underwent MRI and DTI scanning of the T10-L5 spinal segment. The fractional anisotropy (FA) were calculated from specific regions of interest. Measurements were taken three segments above the conus medullaris for all participants. The position of the conus medullaris was determined by comparing MRI T1-weighted imaging segments, and the FA values were extracted. Comparisons of FA values at the T11, T12, and L1 levels were conducted among the control, UAB, and OAB groups. Then, FA of T11, T12, and L1 were compared among three groups separately. RESULTS: All fractional anisotropy (FA) values were successfully measured from diffusion tensor imaging (DTI) scans in both healthy volunteers and patients. The patient cohort was categorized into two groups based on video-urodynamic examination: the underactive bladder (UAB) group (n = 20) and the overactive bladder (OAB) group (n = 20). The control group exhibited average FA values of 0.386. In contrast, the OAB group demonstrated average FA values of 0.347, while the UAB group had values of 0.369. Both the OAB and UAB groups had lower mean FA values than the healthy control group, with statistical significance only in the OAB group. Further analysis revealed that at the T11-T12-L1 spinal segments, FA values were reduced in both patient groups compared to controls, but the difference reached statistical significance only for the OAB group. CONCLUSION: DTI proved effective in identifying the extent of spinal cord damage in patients with TCS. In patients with OAB, spinal cord damage was extensive, with the most severe lesions localized to the T12 segments. These findings suggest that, for patients with OAB due to TCS, spinal cord injury above the L1 vertebral level may represent an underlying pathological condition. FA values are valuable diagnostic indicators for assessing spinal cord integrity.