Bladder Neuromodulation
113Overactive bladder (OAB) is an incurable medical condition that affects approximately 15% of adults worldwide, particularly in individuals over the age of 65. Patients experience episodes of urgency (sudden urge to empty bladder) that can occur more than 8 times during wakefulness and more than 2 times during sleep. Not only does OAB significantly affect an individual’s quality of life, but long-term treatment is also a tremendous socio-economic burden. As an alternative to drugs and sacral nerve stimulation, the focus of our research involves the treatment of OAB by electrical stimulation of peripheral nerve targets. By convention, this is achieved by electrical activation of the posterior tibial nerve, such as provided clinically by Urgent® PC (Cogentix Medical Inc) and the NURO System (Medtronic Corp).
Recent work in our lab has uncovered a novel bladder-inhibitory reflex that is evoked by electrical stimulation of the saphenous nerve (SAFN). We have shown in pre-clinical animal studies that this reflex causes robust and long-lasting inhibition of bladder function. More importantly, this SAFN-mediated reflex is evoked at stimulation amplitudes that are significantly lower than those required by posterior tibial nerve stimulation. In collaboration with clinical urologists located in Canada and the U.S., we are working towards better understanding the underlying mechanism(s) of this reflex and its potential clinical use as a therapy for OAB. [Image: autonomic innervation of mammalian bladder]

 

Obstructive Sleep Apnea
HGN Stimulation smallObstructive sleep apnea (OSA) is characterized by repeated episodes of narrowing or complete collapse of the upper airway during sleep. Approximately 2% to 7% of the adult population is estimated have OSA. If left untreated, patients can exhibit signs of excessive daytime sleepiness, cognitive dysfunction, or impaired work performance. The treatment of OSA comes in many different forms, such as continuous positive airway pressure (CPAP) therapy, oral appliances, surgical procedures, and more recently the use of hypoglossal nerve stimulation (Inspire Medical Systems Inc). Each of these treatments are designed to compensate for anatomical or physiological factors that contribute to the development of apneic/hypopneic events. Such factors can include excessive body weight, age, sex, and craniofacial features. Interestingly, recent clinical studies suggest that shifts in body fluid may also play a significant role in OSA. Through collaboration with clinical researchers at the Toronto Rehabilitation Institute, we are developing novel animal models that will help us better understand potential physiological mechanisms that can promote the incidence of OSA.[Image: reference from www.nejm.org]

 

Peripheral Nerve Interfaces
etens smallWe are developing novel methods aimed at improving the electrical connection between electrodes and the peripheral nervous system. As one example, we have developed a minimally invasive nerve stimulation system called enhanced transcutaneous electrical nerve stimulation (eTENS). By electrically coupling a surface electrode to a highly conductive implant – such as a platinum nerve cuff – placed around a target nerve, we can significantly reduce the stimulation amplitude needed to elicit nerve action potentials. This approach could offer multiple advantages over conventional nerve stimulation methods, such as surface stimulation (TENS), percutaneous nerve stimulation, and implantable pulse generators. Another area of research involves the design of nerve cuff electrodes that can achieve reliable, low-noise recording of peripheral nerve activity. Computational modeling and in vivo experiments are being used to test pre-clinical prototypes. [Image: finite element model simulation of the eTENS system]