The Effects of Cervical Nerve Stimulation (CNS) on Fall Risk

Every year, 3 million older people are treated for fall injuries, and nearly 800,000 are hospitalized, many of which due to head injuries or hip fractures. In 2015 alone, Medicare and Medicaid paid nearly 75% of the $50 Billion in medical costs generated by falls. As the US population continues to age, more adults are beginning to deal with movement related disorders, and the need to be able to detect and mitigate these risks is becoming more necessary. Classical metrics of fall risk can capture static stability, but recent advancements have yielded new metrics to analyze balance and stability during movement, such as the Maximum Lyapunov Exponent (MLE). Much work has been devoted to characterizing gait, but little has explored novel way to reduce fall risk with interventional therapy. Targeting certain cranial nerves using electrical stimulation has shown potential for treatment of movement disorders such as Parkinson’s Disease (PD) in certain animal models. For human models, based on ease of access, connection to afferents leading to the lower lumber region and key brain regions, as well as general parasympathetic response, targeting the cervical nerves may have a more significant effect on balance and posture. This project explored the effects of transcutaneous Cervical Nerve Stimulation (CNS) on posture stability and gait with the practical application of ultimately applying this treatment to fall risk populations. Data was collected on each of the 31 healthy adults (22.3 ± 6.3 yrs) both pre and post stimulation for metrics representative of fall risk such as postural stability both eyes open and closed, Timed-Up-and-Go (TUG) time, gait velocity, and MLE. Significant differences manifested in the postural stability sub-metric of sway area with subject eyes open in the active stimulation group. The additional 8 metrics and sub-metrics did not show statistically significant differences among the active or sham groups. It is reasonable to conclude that transcutaneous CNS does not significantly affect fall risk metrics in healthy adults. This can potentially be attributed to either the stimulation method chosen, internal brain control mechanisms of posture and balance, analysis methods, and the Yerkes-Dodson law of optimal arousal. However, no adverse events were reported in the active group and thus is a safe therapy option for future experimentation.