Purpose: Management of idiopathic detrusor instability is difficult in most patients mainly due to the lack of a complete understanding of the pathophysiology. Oxybutynin and transcutaneous electrical nerve stimulation have been used but to our knowledge no direct comparisons have been made.
Materials and methods: Patients with frequency, urgency, urge incontinence and proved detrusor instability were studied with urodynamics, quality of life instruments, and frequency and volume charts. Patients were randomized to transcutaneous electrical nerve stimulation or oxybutynin. After 6 weeks of treatment, they were reassessed and after a washout of 2 weeks, they were started on the second arm of treatment and reassessed 6 weeks later.
Results: A total of 13 male and 30 female patients were studied. Functional capacity had increased and number of voids daily had decreased significantly compared with before treatment in both arms (p <0.005). There were significant improvements in symptom specific quality of life measures but no changes were found on the global Short Form 36 (SF-36) quality of life questionnaire. The volume to first desire to void and first unstable contraction had increased significantly with oxybutynin but not with transcutaneous electrical nerve stimulation. Of 23 patients 7 were stabilized with treatment, including 2 with oxybutynin only, 2 with either nerve stimulation or oxybutynin and the remaining 3 with only nerve stimulation. Total bladder capacity did not change significantly with either treatment but patients noticed side effects more commonly with oxybutynin.
Conclusions: Both treatments clearly improved subjective parameters. However, only oxybutynin showed significant improvements in objective urodynamic parameters. Transcutaneous electrical nerve stimulation can be used in patients who cannot take oxybutynin. Further studies are needed to show the long-term efficacy and cost analyses of nerve stimulation.