Closed-loop neuromodulation holds promising potential to improve mobility in people with progressive multiple sclerosis (MS) by directly modulating neural circuits involved in movement control. Progressive MS often leads to worsening motor symptoms such as muscle weakness, spasticity, and impaired coordination, which severely limit mobility. Closed-loop neuromodulation refers to a system where neural activity is continuously monitored and stimulation is adjusted in real time to optimize therapeutic effects, unlike open-loop systems that deliver fixed stimulation regardless of ongoing neural states.
In progressive MS, damage to the central nervous system disrupts communication between the brain and spinal cord, leading to impaired motor control. Neuromodulation techniques, such as transcutaneous spinal cord stimulation (tSCS) or functional electrical stimulation (FES), can activate spinal interneurons and motor pathways below the lesion or damaged areas. This activation can enhance spinal cord excitability and promote neuroplasticity—the nervous system’s ability to reorganize and form new connections—which may partially restore motor function.
Closed-loop neuromodulation improves on traditional stimulation by using feedback signals, such as muscle activity or movement sensors, to tailor stimulation parameters dynamically. This adaptability can enhance the precision and effectiveness of stimulation, potentially leading to better improvements in gait, balance, and overall mobility. For example, FES applied to the common peroneal nerve timed with the gait cycle can correct foot drop, a common mobility problem in MS, improving walking speed and reducing falls. Closed-loop systems can optimize this timing and intensity based on real-time feedback, maximizing functional gains.
Moreover, closed-loop spinal cord stimulation may induce multi-system benefits beyond motor improvements. By modulating spinal circuits, it can influence autonomic functions and reduce symptoms like spasticity and bladder dysfunction, which indirectly support mobility by improving overall physical condition and comfort. Long-term stimulation can lead to neuroplastic changes in spinal cord circuits, potentially stabilizing or reversing some of the neural damage caused by MS.
The therapeutic effects of closed-loop neuromodulation may extend beyond immediate improvements during stimulation. Some studies suggest that repeated stimulation sessions can produce carryover or training effects, where motor function improves even without active stimulation. These effects may result from enhanced neural excitability, motor relearning, and muscle strengthening, contributing to sustained mobility gains.
Despite these promising mechanisms, the application of closed-loop neuromodulation in progressive MS is still emerging. Challenges include identifying optimal biomarkers for feedback control, individualizing stimulation protocols, and integrating devices into daily life. However, advances in wearable sensors, machine learning algorithms, and non-invasive stimulation technologies are rapidly addressing these issues.
In summary, closed-loop neuromodulation offers a sophisticated approach to improving mobility in progressive MS by dynamically enhancing neural circuit function, promoting neuroplasticity, and enabling personalized therapy. Its ability to adapt stimulation in real time based on physiological feedback distinguishes it from traditional methods and holds promise for more effective and sustained motor improvements in this challenging condition.
