This study aimed to explore effects of Finetech-Brindley stimulator acting on a new reflex pathway of atonic bladder after medullary cone injury and to stimulate bladder urination. Intradural microanastomosis was performed between the proximal L6 anterior root and distal S2 anterior root of Beagle dogs, and a new reflex pathway was established after a period of axon regeneration. 8 months after neurosuture was performed, neuro-electrophysiology and electromyogram were observed before and after destroying S2 spinal segments, respectively, in order to determine the long-term bladder function. Meanwhile, Finetech-Brindley sacral anterior root stimulator (SARS) was implanted proximally of the anastomosis, and stimulated urination was observed, then urodynamic test and cystography were performed. Eight months after operation, left neuro-anastomotic stomas of experiment dogs were stimulated with Finetech-Brindley sacral anterior root stimulator before and after paraplegia. Motion evoked potential (MEP) and electromyogram (EMG) of detrusor muscle were recorded in the distal anastomotic stomas, with similar waveforms and amplitudes. All experimental dogs urinated while being stimulated with Finetech-Brindley stimulator. Urodynamic test showed that the bladder pressure rose rapidly at the beginning of stimulation, while the intra-abdominal pressure rose more slightly. When the stimulation was terminated, the bladder pressure declined rapidly, confirming that the raised bladder pressure was mainly resulted from the contraction of detrusor muscle. Cystography showed that the residual urine volume reduced after stimulation. The urination function of atonic bladder after medullary cone injury could be reconstructed by Finetech-Brindley stimulator through spinal nerve-anastomosis, and the urination mode was stimulus urination accompanied with severe jitter of posterior limbs while being stimulated.
Key words: Finetech-Brindley sacral anterior root stimulator, spinal cord injury, bladder, reflex pathway, urination, cystography.
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