A microchannel neuroprosthesis for bladder control after spinal cord injury in rats
Date
2014-07-11Author
Abstract
A severe complication of spinal cord injury is loss of bladder function
(neurogenic bladder), which is characterized by loss of bladder sensation and
voluntary control of micturition (urination), and spontaneous hyperreflexive
voiding against a closed sphincter (detrusor-sphincter dyssynergia). A sacral
anterior root stimulator at low frequency can drive volitional bladder voiding,
but surgical rhizotomy of the lumbosacral dorsal roots is needed to prevent
spontaneous voiding and dyssynergia. However, rhizotomy is irreversible and
eliminates sexual function, and the stimulator gives no information on bladder
fullness. We designed a closed-loop neuroprosthetic interface that measures
bladder fullness and prevents spontaneous voiding episodes without the need for
dorsal rhizotomy in a rat model. To obtain bladder sensory information, we
implanted teased dorsal roots (rootlets) within the rat vertebral column into
microchannel electrodes, which provided signal amplification and noise
suppression. As long as they were attached to the spinal cord, these rootlets
survived for up to 3 months and contained axons and blood vessels.
Electrophysiological recordings showed that half of the rootlets propagated
action potentials, with firing frequency correlated to bladder fullness. When the
bladder became full enough to initiate spontaneous voiding,
high-frequency/amplitude sensory activity was detected. Voiding was abolished
using a high-frequency depolarizing block to the ventral roots. A ventral root
stimulator initiated bladder emptying at low frequency and prevented unwanted
contraction at high frequency. These data suggest that sensory information from
the dorsal root together with a ventral root stimulator could form the basis for
a closed-loop bladder neuroprosthetic.
Description
Citation : Chew, D.J., Zhu, L., Delivopoulos, E. et al. (2013) A microchannel neuroprosthesis for bladder control after spinal cord injury in rat. Science translational medicine, 5 (210), pp. 210ra155
ISSN : 1946-6242
Research Institute : Leicester Institute for Pharmaceutical Innovation - From Molecules to Practice (LIPI)
Peer Reviewed : Yes