Cionic Neural Sleeve MultiStim System Demonstrates Reduction in Lower Extremity Spasticity in Combination with Triggered Functional Stimulation to Improve Gait and Quality of Life

Background

Spasticity is one of the most common symptoms in individuals with upper motor neuron (UMN) conditions such as stroke, multiple sclerosis (MS), spinal cord injury (SCI), and cerebral palsy (CP). It is commonly defined as a velocity-dependent involuntary resistance to stretch, which can be felt as a contraction or shortening of muscles. Depending on the severity of spasticity, it can result in tightness, reduced joint range of motion, pain, sleep issues, fatigue, or impaired mobility, and culminate in reduced quality of life. In the lower extremities, spasticity commonly affects the gastrocnemius, soleus, and knee extensor muscles, which can cause impaired gait and increase fall incidence.

The prevalence of spasticity varies across diseases. Spasticity presents in up to 97% of stroke survivors with moderate to severe motor deficits, contributes to disability in up to 84% of individuals with MS, and is present in 80% of individuals with CP and up to 93% of individuals with spinal cord injuries. Medical management of spasticity and its related symptoms often continues throughout the lifespan, and as one study of stroke survivors has demonstrated, there is a 4x increase in direct costs to the healthcare system for those with spasticity compared to those without. Therefore, managing spasticity is a critical component of improving functional independence in individuals with UMN conditions and reducing associated healthcare costs.

In a home use trial, seven individuals with upper motor neuron conditions used the Cionic Neural Sleeve MultiStim System with functional and afferent electrical stimulation-assisted walking. Participants reported improvements in daily activities, social avoidance/anxiety, need for intervention, overall spasticity impact, and need for assistance/repositioning.

Introduction

Pharmacological treatment is currently the gold standard for spasticity management. Common prescribed options include Baclofen and other muscle relaxants, botulinum toxin, and anxiolytics. While these medications can provide relief, these treatments are often associated with side effects such as drowsiness, dizziness, and muscle weakness. Such effects can interfere with a person’s activities of daily living, causing the patient to lower their dosage or discontinue treatment. As a result, spasticity remains inadequately controlled.

Advances in non-invasive electrical stimulation have shown promise as an alternative and adjunct to drug-based therapy for spasticity. Neuromuscular electrical stimulation of the antagonist muscle can cause reciprocal inhibition of the spastic muscle to reduce muscle tone, while sensory (afferent) electrical stimulation can directly promote muscle relaxation of the target muscle. Unlike pharmacological treatments, non-invasive electrical stimulation does not incite systemic side effects and may directly address spastic muscles. Although further research is needed to establish long-term outcomes, non-invasive electrical stimulation can be a practical solution to complement or reduce reliance on medication.

Traditional functional electrical stimulation devices for gait solely address muscle activation and commonly target the tibialis anterior muscle to improve dorsiflexion and reduce foot drop during ambulation. However, when spasticity occurs in the plantarflexors it can reduce the effectiveness of the stimulation to the dorsiflexors. Therefore, a device that is able to apply afferent and efferent stimulation to augment muscle activation and minimize spasticity may improve gait efficiency and quality.

The Cionic Neural Sleeve MultiStim System

The Cionic Neural Sleeve MultiStim system administers electrical stimulation to lower extremity muscles to address weakness, motor control issues, and spasticity during gait in individuals with UMN conditions. The Cionic Neural Sleeve MultiStim System interleaves multiple pulse trains into a single integrated stimulation pattern, or multimodal electrical stimulation (MMES), to provide continuous afferent stimulation to spastic muscles and trigger stimulation to weak and poorly controlled muscles timed to the gait cycle.

In order to achieve MMES, the Cionic Neural Sleeve utilizes a sophisticated stimulation scheduler that interleaves multiple pulse trains into a single integrated stimulation pattern. While the device has only one power amplifier stage, it leverages a software controlled hardware mux to direct the stimulation to any configuration of Anode and Cathode electrodes. The scheduler time slices the power amplifier stage to simultaneously stimulate different muscles with different stimulation patterns (frequency, pulse width, intensity), up to 12 independent pulse trains, in real-time.

The Cionic Neural Sleeve MultiStim System is capable of stimulating the quadriceps, hamstrings, gastrocnemius, tibialis anterior, and peroneus longus muscles. As a result, its users can achieve flexible, adaptable, and personalized stimulation for ambulation.

Home Spasticity Study

In a 2-week home use trial, CIONIC assessed lower extremity spasticity in seven participants with UMN conditions who reported symptoms of leg spasticity (Table 1). At the initial evaluation, all participants had been using the Cionic Neural Sleeve to improve muscle activation during gait and were instructed on configuring afferent stimulation on their Cionic Neural Sleeve MultiStim System. The participants were instructed to resume their previously established usage schedule using the Cionic Neural Sleeve MultiStim System for electrical stimulation assisted walking and spasticity reduction.

Table 1: Subject Characteristics

Lower extremity spasticity was assessed using the Patient Reported Impact of Spasticity Measure (PRISM) survey. PRISM is a 41-item survey that considers the impact of spasticity in seven subscales. There are six negative impact subscales: SAA - social avoidance/anxiety, PA - psychological agitation, SE - social embarrassment, DA - daily activities, NA - need for assistance/repositioning, and NI - need for intervention, and a single PI - positive impact subscale. Subscale scores were determined by summing across item scores, then calculating a subscale improvement by subtracting the scores at week 2 from the scores at baseline divided by the number of questions in the scale to normalize across subscales.

A percentage change was calculated by subtracting the scores at survey point 2 from the scores at baseline and dividing by baseline such that a positive difference between baseline and follow up scores indicated improvement. As a result of the 2-week trial, the cohort scored symptom improvement in SE (45.83%), PA (33.33%), SAA (28.87%), NI (26.32%), DA (25.40%), and NAP (19.70%) subscales of the PRISM survey. The average improvement across the negative subscales was 29.92% with 0% change to the positive impact subscale.

Conclusion

The Cionic Neural Sleeve MultiStim System is the first device to combine traditional functional stimulation with continuous afferent stimulation to increase muscle activation and promote muscle relaxation for improved gait. Afferent and efferent stimulation was applied to all major muscle groups in the upper and lower leg in a personalized fashion. Results of this two-week study suggest that afferent stimulation integrated with functional stimulation for gait can be used daily in the home and community environments to improve lower extremity spasticity. This study is limited by a small sample size, participants’ variable experience with the device prior to the start of the study, and the absence of a control group, which may reduce the generalizability and validity of the findings. Further research using a randomized controlled trial design is warranted to validate these preliminary findings.