Annu Int Conf IEEE Eng Med Biol Soc. 2022 Jul;2022:744-747. doi: 10.1109/EMBC48229.2022.9871292.
Bladder dysfunction is a major health risk for people with spinal cord injury. Recently, we have demonstrated that epidural sacral spinal cord stimulation (SCS) can be used to activate lower urinary tract nerves and provide both major components of bladder control: voiding and continence. To effectively control these functions, it is necessary to selectively recruit the afferents of the pudendal nerve that evoke these distinct bladder reflexes. Translation of this innovation to clinical practice requires an understanding of optimal electrode placements and stimulation parameters to guide surgical practice and therapy design. Computational modeling is an important tool to address many of these experimentally intractable stimulation optimization questions. Here, we built a realistic MRI-based finite element computational model of the feline sacral spinal cord which included realistic axon trajectories in the dorsal and ventral roots. We coupled the model with biophysical simulations of membrane dynamics of afferent and efferent axons that project to the lower urinary tract through the pelvic and pudendal nerves. We simulated the electromagnetic fields arising from stimulation through SCS electrodes and calculated the expected recruitment of pelvic and pudendal fibers. We found that SCS can selectively recruit pudendal afferents, in agreement with our experimental data in cats. Our results suggest that SCS is a promising technology to improve bladder function after spinal cord injury, and computational modeling unlocks the potential for highly optimized, selective stimulation. Clinical Relevance - This model provides a method to non-invasively establish electrode placement and stimulation parameters for improving bladder function with epidural spinal cord stimulation.
膀胱功能障碍是脊髓损伤患者的主要健康风险。最近，我们已经证明，硬膜外骶脊髓刺激（SCS）可用于激活下尿路神经，并提供膀胱控制的两个主要组成部分：排尿和控尿。为了有效地控制这些功能，有必要选择性地募集引起这些不同膀胱反射的阴部神经传入纤维。将这一创新转化为临床实践需要了解最佳电极放置和刺激参数，以指导手术实践和治疗设计。计算模型是解决许多实验上难以解决的刺激优化问题的重要工具。在这里，我们构建了一个基于 MRI 的真实猫科动物骶脊髓有限元计算模型，其中包括背根和腹根中的真实轴突轨迹。我们将模型与通过骨盆神经和阴部神经投射到下尿路的传入和传出轴突的膜动力学的生物物理模拟耦合。我们模拟了通过 SCS 电极产生的电磁场，并计算了预期对骨盆和阴部纤维的募集。我们发现 SCS 可以选择性地募集阴部传入纤维，这与我们在猫身上的实验数据一致。我们的结果表明，SCS 是改善脊髓损伤后膀胱功能的有前途的技术，而计算模型则为高度优化、选择性刺激开辟了潜力。临床相关性 - 该模型提供了一种方法，可以通过硬膜外脊髓刺激非侵入性地建立电极放置和刺激参数，以改善膀胱功能。
