Acute monitoring of genitourinary function using intrafascicular electrodes: selective pudendal nerve activity corresponding to bladder filling, bladder fullness, and genital stimulation.

OBJECTIVE: To investigate the use of a microelectrode array with a high spatial density of penetrating intrafascicular electrodes for selective recording of pudendal nerve activity evoked by a variety of genitourinary stimuli. MATERIALS AND METHODS: Felines were anesthetized with alpha-chloralose and high-density Utah slanted electrode arrays (48 microelectrodes; 200-µm spacing) were implanted into the pudendal nerve for acute experimentation. Neural activity was recorded during bladder filling, spontaneous reflexive distention-evoked bladder contractions, and tactile somatosensory stimulation. RESULTS: The intrafascicularly implanted pudendal nerve electrodes were able to selectively record neural activity that corresponded to various genitourinary stimuli. Across all seven experimental animals, a total of 10 microelectrodes recorded neural units that were selectively driven by bladder filling or distention-evoked bladder contractions. Twenty-two electrodes were selectively driven by tactile stimulation. CONCLUSION: Microelectrode arrays implanted intrafascicularly into the pudendal nerve can be used to selectively record the neural responses that reflect bladder status and urogenital tactile stimulation. This work sets the stage for developing future implantable closed-loop neuroprosthetic devices for restoration of bladder function.

Assessment of rat sciatic nerve function following acute implantation of high density Utah slanted electrode array (25 electrodes/mm(2) ) based on neural recordings and evoked muscle activity.

INTRODUCTION: High density Utah slanted electrode arrays (HD-USEAs) have been developed recently for intrafascicular access to submillimeter neural structures. Insertion of such high electrode density devices may cause nerve crush injury, counteracting the intended improved selective nerve fiber access. METHODS: HD-USEAs were implanted into sciatic nerves of anesthetized rats. Nerve function was assessed before and after HD-USEA implantation by measuring changes in evoked muscle and nerve compound action potentials and single unit neuronal recordings. RESULTS: Neural activity was recorded with over half of all implanted electrodes. Average decreases of 38%, 36%, and 13% in nerve, medial gastrocnemius, and tibialis anterior compound action potential amplitudes, respectively, were observed following array implantation. Only 1 of 8 implantations resulted in loss of all signals. CONCLUSIONS: These studies demonstrate that HD-USEAs provide a useful neural interface without causing a nerve crush injury that would otherwise negate their use in acute preparations (<12 h).