Computerized assessment of detrusor instability in patients treated with sacral neuromodulation

PURPOSE: We previously described an automatic procedure for diagnosing and grading detrusor instability using a cystometric study. In our current study we applied a modified version of the program in patients with urge incontinence treated with sacral neuromodulation to test its capacity to detect changes after therapeutic intervention and understand the mode of action of neuromodulation. MATERIALS AND METHODS: We analyzed cystometric studies before and after neuromodulation in 26 consecutive patients, including 22 women and 4 men, and evaluated parameter changes. We also assessed the relationship of instability parameters at baseline with symptomatic results, which were derived from voiding-incontinence diaries, in female patients to identify urodynamic prognosticators of success. RESULTS: The automatic procedure correctly diagnosed stability and instability in our patients in 51 of the 52 measurements considered. Neuromodulation had an average suppressive effect on the amplitude of unstable contractions. At baseline the amplitude of the maximum unstable contraction and mean active pressure during unstable episodes were significantly less in the 7 women who achieved stability than in the 15 who did not. However, no urodynamic parameters were identified that predicted the symptomatic outcome of treatment. CONCLUSIONS: Our algorithm accurately diagnoses and grades detrusor instability, and provides parameters with predictive value in regard to the probability that a bladder may or may not become stable with neuromodulation. However, the symptomatic result of this treatment option seems to depend on noncystometric factors.