Videourodynamic factors predictive of successful onabotulinumtoxinA urethral sphincter injection for neurogenic or non-neurogenic detrusor underactivity.

OBJECTIVE

The aim of the present study was to analyze treatment outcomes and identify videourodynamic factors predictive of successful urethral onabotulinumtoxinA treatment of neurogenic and non-neurogenic detrusor underactivity (DU).

METHODS

Patients with DU refractory to medical treatment were treated with injections totaling 100 U onabotulinumtoxinA into the urethral sphincter. Treatment outcomes were assessed 1 month after treatment using the Global Response Assessment. The videourodynamic parameters evaluated included bladder neck status during voiding, bladder sensation, detrusor pressure, maximum flow rate, and post-void residual volume. Treatment outcome was analyzed by patient and baseline videourodynamic characteristics.

RESULTS

In all, 60 patients (27 with non-neurogenic and 33 with neurogenic DU) were included in the study and received urethral sphincter injections of 100 U onabotulinumtoxinA in total. Good outcomes were reported in 36 (60%) patients (20 [74.1%] with non-neurogenic and 16 [48.5%] with neurogenic DU). Treatment outcome was significantly better in patients with non-neurogenic than neurogenic DU (P = .039). However, good treatment outcome was not related to age, gender, or any videourodynamic variables, except for an open bladder neck during voiding vs non-opening bladder neck (94.3% vs. 12.0%; P < .0001). The duration of the therapeutic effect was similar between patients with non-neurogenic and neurogenic DU (mean [± SD] 7.37 ± 3.69 vs. 7.69 ± 3.18 months, respectively; P = .788). In all, 12 patients reported de novo urinary incontinence after urethral onabotulinumtoxinA injection, 4 of whom developed stress urinary incontinence and 8 who had exacerbated urgency urinary incontinence.

CONCLUSION

Urethral sphincter injection of onabotulinumtoxinA is effective in 60% of patients with DU. Careful videourodynamic interpretation of bladder neck opening enables urologists to select appropriate candidates for onabotulinumtoxinA treatment.