Efficacy and mechanism of sub-sensory sacral (optimised) neuromodulation in adults with faecal incontinence: study protocol for a randomised controlled trial oleh Eleanor McAlees, Paul F. Vollebregt, Natasha Stevens, Tom C. Dudding, Anton V. Emmanuel, Paul L. Furlong, Shaheen Hamdy, Richard L. Hooper, James F. X. Jones, Christine Norton, P. Ronan O’Connell, S. Mark Scott, Charles H. Knowles