Experimental: Pelvic floor exercises and Transcutaneous tibial nerve stimulation

Patients in this group will receive pelvic floor exercise program as described before and transcutaneous tibial nerve stimulation (TTNS).~The intervention will comprise 12 session of transcutaneous tibial nerve stimulation (Twice a week, for 6 continuous weeks). Each session will last 30 minutes. Two self adhesive surface electrodes will be positioned according to the protocol used by Booth et al and Sonmez et al, with the negative electrode 2 cm behind the medial malleolus, and positive electrode 10 cm proximal to it. Correct positioning will be determined by noting a hallux reaction (plantar flexion of great toe). Stimulation will be delivered at fixed frequency of 20 Hz and pulse width of 200 ms. The intensity level of the stimulation current (range 0-50 mA) will be determined once hallux reaction is observed, according to patient's tolerance.

Sham_comparator: Pelvic floor exercises and Sham Stimulation

Patients in this group will receive pelvic floor exercise program as described before and Sham stimulation.~The intervention will comprise 12 session of sham stimulation. (Twice a week, for 6 continuous weeks) Each session will last 30 minutes. Two self adhesive surface electrodes will be positioned According to the protocol used by Booth et al, with the negative electrode 2 cm behind the lateral malleolus, and positive electrode 10 cm proximal to it, therefore avoiding the posterior tibial nerve. The stimulation current will be reduced to 2 mA once the tingling sensation is obtained and patients will be informed that they may not feel electrical sensation during the session. Stimulation will be delivered at fixed frequency of 20 Hz and pulse width of 200 ms.~If willing, patients in this group will receive TTNS treatment after the study is completed.