Role of microglia in blood pressure and respiratory responses to acute hypoxic exposure in rats

概要

(Aims)
Postprostatectomy incontinence (PPI) is a major complication of prostatectomy. Although pelvic floor muscle training (PFMT) can successfully treat PPI, evidence for how muscle movement affects continence recovery is lacking. Cine magnetic resonance imaging (MRI) provides dynamic information as consecutive images with high accuracy and high reproducibility. It would be suitable for monitoring the pelvic floor muscle motion. We evaluated dynamic factors of prostatectomy patients using cine MRI to identify risk factors for PPI and reveal the contribution of pelvic floor muscles to continence recovery.

(Methods)
A total of 128 prostate cancer patients who underwent robot-assisted laparoscopic surgery were enrolled. Cine MRI was performed preoperatively and 6 months after surgery. Continence was defined as pad-free or use of safety pads. During scanning, we measured some parameters at resting phase, voiding phase, and PFMT phase. We newly defined the bladder neck elevation distance during pelvic floor muscle training as the bladder elevation distance (BED). Other static or dynamic parameters were also measured. Patients with continence recovery within 1 month comprised the continence group (n=48); other patients comprised the incontinence group (n=80). We analyzed the parameters

between two groups using Mann-Whitney U test or chi-square test, and between pre-post operations using Wilcoxon signed-rank test. Preoperative parameters were also analyzed using multivariable analysis. Kaplan-Meier analysis with log-rank testing was also applied for preoperative BED.

(Results)
In the two groups, there was no significant difference in any parameters of patient characteristics, perioperative data, pathological results and with or without nerve-sparing technique. In the continence group, preoperative BED was significantly longer than in the incontinence group (10.4 vs 8.2 mm; P<0.001). Postoperative BED of the continence group also tended to be longer (9.9 vs 8.0 mm; P=0.057). Only in postoperative state, posterior urethrovesical angle (PUVA) of the continence group was significantly smaller than the incontinence group at both resting and voiding phase (130 vs 135 °; P=0.005, 138 vs 143 °; P=0.026). Postoperative membranous urethral length (MUL) of the continence group was significantly longer (14.5 vs 12.4 mm; P<0.001). Multivariate analysis showed that preoperative BED significantly contributed to getting recovery of continence (HR=0.96; P=0.016). Patients with longer preoperative BED (>8.5mm) got recovery of continence significantly faster than patients with shorter (<8.5mm) (log-rank test; P=0.038).

(Discussion)
Preoperative BED could be a great predictor for early recovery of continence after radical prostatectomy. This parameter is acquired from dynamic and highly accurate data of cine MRI. Moreover, cine MRI could detect not only anatomical features, but also actual function of pelvic floor muscle. We and the patient can consider his own risk of PPI using cine MRI. Moreover, long BED might indicate better PFMT, and PFMT biofeedback using cine MRI has a potential to achieve early recovery of continence. Some reports demonstrated that smaller PUVA made recovery of continence earlier, and the results of the present study supported the theory. Surgical effort to preserve MUL would also result in preventing PUVA opened.

(Conclusion)
A novel dynamic parameter of BED was strongly related to recovery of early continence after radical prostatectomy. This is the first study to show that cine MRI is useful for digitizing the level of PMFT skill and predicting the risk of PPI.