Feasibility of Long-term Tibial Nerve Stimulation Using a Multi-contact and Wirelessly Powered Neurostimulation System Implanted in Rats.

OBJECTIVE:Implant-driven tibial nerve stimulation therapy is an effective technique for treating overactive bladder. However, the monopolar lead design in the currently available implantable devices pose long-term therapeutic challenges in terms of efficiently and selectively delivering electrical pulses to the target. Hence, the purpose of this study was to (1) characterize the tibial nerve (TN) activation properties using a multi-contact implantable system and (2) evaluate the long-term stability of using such a neural interface in a preclinical model. MATERIALS AND METHODS:Ten adult Sprague-Dawley rats were used in this study. An implantable pulse generator was surgically inserted in the lower back region. The lead wire with 4 active electrodes was placed in parallel with the TN. The threshold for activating the TN was confirmed via movement of the hallux or toes as well as the foot EMG. The TN activation threshold was assessed biweekly, over a period of 12 weeks. RESULTS:Channel 1 exhibited the lowest motor threshold at T0 (mean = 0.58 ± 0.10 mA). A notable increase in motor twitch intensity was observed during the first test session (2 weeks) following surgical implantation (75.8 ± 30.5%, channel 1). Among the 10 rats tested, 8 rats successfully completed the 3-month study. CONCLUSION:Results from this study demonstrate the long-term feasibility of achieving tibial nerve stimulation with a multi-contact implantable device in a preclinical model. Future studies are warranted to assess the effects of using such a wirelessly powered system for treating lower urinary tract symptoms in patients.