Transcutaneous neuromodulation versus oxybutynin for neurogenic detrusor overactivity in persons with spinal cord injury: A randomized, investigator blinded, parallel group, non-inferiority controlled trial.

Study Design: This study is a randomized, investigator-blinded, controlled trial with a non-inferiority design.

Objective: To investigate the effectiveness of neuromodulation by transcutaneous electrical stimulation of the somatic afferent nerves of the foot in neurogenic detrusor overactivity (NDO) in persons with spinal cord injury (SCI) and compare its effectiveness with oral oxybutynin.

Setting: The study was conducted in a rehabilitation in-patient ward of a tertiary care hospital.

Methods: Twenty-nine persons with SCI with NDO, either sex, aged 18 years and above were randomized into two groups, one group receiving oral oxybutynin (5 mg thrice a day for two weeks) and the other transcutaneous electrical stimulation (5 Hz, 200 µs pulse, biphasic, amplitude up to 60 mA, 30 min/day for two weeks). Bladder capacity was evaluated by clinical bladder evaluation (i.e. bladder capacity measured by adding leak volume, voiding volume if any, and post-void residue using a catheter) and cystometric bladder capacity by one-channel cystometry. Maximum cystometric pressure was evaluated by one-channel water cystometry. Data were analyzed with Fisher's Exact, t-test, and Wilcoxon rank sum tests.

Results: Bladder capacity improved significantly in the oxybutynin and neuromodulation groups as measured by one-channel water cystometry (136 ml vs. 120.57 ml) and clinical evaluation (138.93 ml vs. 112 ml). The increase in the neuromodulation group achieved the pre-decided non-inferiority margin of 30 ml over the oxybutynin group when measured by one-channel water cystometry but not by clinical evaluation. Maximum cystometric pressure did not significantly improve in either group when compared with the baseline.

Conclusion: Transcutaneous neuromodulation and oxybutynin effectively increased bladder capacity in persons with SCI with NDO. Neuromodulation by once-a-day transcutaneous electrical stimulation was non-inferior to thrice-a-day oxybutynin when evaluated by one-channel water cystometry. Clinical Trials Registry India identifier: CTRI/2018/05/013735.