Study design, materials and methods
The study design was a randomised controlled trial of 8-weeks of PFMT or usual care, plus a single session of transcutaneous SCS (tSCS). Participants with a supra-sacral SCI, and proven NDO during urodynamics were recruited. Urodynamics and pelvic floor assessments were performed at baseline (wk0), post-intervention (wk8) and 6-weeks post-intervention (wk14).
Individuals were taught an intensive PFMT programme to complete at home. Additionally, participants completed a supervised session of PFMT at week 2, 4 and 6 of the intervention.
At wk8, tSCS was delivered through electrodes placed between the T11-12 vertebra and iliac crest. Stimulation (30Hz and 1000μs pulse widths, Digitimer DS7) was applied continuously during urodynamic cycles of bladder filling and emptying. A control fill was followed by cycles with tSCS, with and without voluntary pelvic floor exercises (PFE), and then a final control fill.
Primary outcome measures were maximum cystometric capacity (MCC), maximum detrusor contraction (MDP) and pelvic floor EMG net work average (NWA) (uV).
Results
Eight participants with SCI were recruited; 5 in the intervention group and 3 in the control. NWA increased from baseline to end of intervention in participants who underwent PFMT for 8 weeks, however, this returned to baseline in the following 6 weeks (Figure 1).
From baseline to post-intervention, MCC decreased by -12 ± 81ml and -5 ± 91ml, and MDP by -8 ± 17 cmH2O and -9 ± 5 cmH2O, for intervention and control groups, respectively.
During the tSCS session, response to each urodynamic condition differed between intervention participants. Mean MCC and MDP decreased across all conditions when compared to the control cycle. There was minimal change in mean MCC when tSCS was applied with and without PFE. Mean MDP reduced considerably during tSCS, which appeared to be further enhanced by tSCS with PFE, -13.0 ± 31.1 cmH2O and -19.8 ± 29.6 cmH2O, respectively (Figure 2).
For control participants, during the first cycle with tSCS there was a mean reduction in MCC of -18.3 ± 16.1ml. During the second tSCS cycle, all control participants demonstrated an increase in MCC, mean 33.3 ± 23.6ml, compared to control cycle (Figure 2). There was a mean increase in MCC by 16.7 ± 22.5ml during the final control cycle (without tSCS). There were minimal changes in MDP during tSCS cycles 1 and 2, by 1.3 ± 2.5, and -3.7 ± 3.1 cmH2O, respectively. The greatest change in MDP was demonstrated during the final control cycle, -4.8 ± 14.2 cmH2O.
Interpretation of results
There were improvements in pelvic floor motor function for participants who followed the 8-week PFMT intervention. There appeared to be a reduction in detrusor pressure with minimal change in bladder capacity across conditions applying tSCS, both with and without PFE, for intervention participants.
Response to tSCS during urodynamic cycles differed between intervention and control groups. MCC during tSCS varied widely within groups and between groups. There was a greater reduction in MDP for the intervention group compared to the control group during tSCS urodynamic cycles.