Long-term urodynamic follow-up after external sphincterotomy in patients with spinal cord injury

Aims: External sphincterotomy (ES) is a therapeutic option for male spinal cord injury patients with detrusor sphincter dyssynergia. However, some patients need to change their voiding management after ES. One of the potential causes of failure is reportedly detrusor dysfunction, but long-term urodynamic follow-up data after ES is limited. In the present study, we reviewed the urodynamic data before and after ES and analyzed it for possible causes of ES failure. Methods: A total of 37 patients who were followed up at our center for at least 5 years after ES were included. Mean follow-up period was 16.5 years. Urodynamic assessment was routinely performed every 2 or 3 years after ES, and the data were reviewed and analyzed. Results: Of the 37 patients, 27 are still managed with reflex voiding to a condom catheter (success group), while 10 needed to change their bladder management. Mean maximum bladder pressure (MBP) was preserved at a low level after ES. However, after ES, there was a gradual increase over time in both the mean bladder volume at first neurogenic detrusor overactivity (NDO) and the percentage of patients without NDO. The mean preoperative MBP in the success group was significantly higher than that in the failure group. Conclusions: MBP is maintained at a low level over 20 years after ES. However, NDO gradually decreases over time, which might be one of the reasons for failure after ES. In addition, low preoperative MBP would be a poor prognostic factor for ES.