Vibrotactile Stimuli For Functional Rehabilitation In Neurological Individuals

Background: Neurological disorders such as Spinal Cord Injury (SCI), Cerebral Palsy (CP), and stroke pose significant challenges to sensorimotor function in affected individuals, with traditional therapies often yielding incomplete recovery. This thesis investigates Focal Muscle Vibration (FMV) as a non-invasive intervention to enhance motor and sensory rehabilitation in neurological diseases, addressing gaps in mechanistic understanding, functional performance and clinical efficacy. Objective: The overarching aim of this thesis is to investigate FMV's role in sensorimotor rehabilitation by understanding its neurophysiological impacts following its use as an exercise intervention in people suffering from neurological diseases. Three specific research objectives were pursued: Objective 1 (OB1) — Device Engineering: To engineer a wearable FMV device capable of delivering precise and reproducible vibrations suitable for neuromuscular and sensory rehabilitation. Objective 2 (OB2) — Neurophysiological Effects: To investigate the specific effects of prolonged FMV exposure on motor function, spasticity, and brain activity in individuals with SCI and CP, and how these effects vary with different vibration frequencies. Objective 3 (OB3) — Device Feasibility: To evaluate the feasibility, usability, and short-term clinical effects of a co-designed wearable FMV device on spasticity and upper limb function in stroke survivors. Methods: An FMV device was developed using ERM vibration motor and characterized for frequency output using accelerometers. An electronic circuitry using was designed to operate the device at the desired frequencies (60-120 Hz) after the frequency characterization. This device was then used for the experimental studies. Experimental evaluations included three cohort studies investigating the neurophysiological impacts and usability of the FMV device in CP, SCI and stroke cohorts as detailed below: CP: Effects of 8 weeks of FMV applied to quadriceps at 80 Hz and 100 Hz was assessed via EEG and EMG in a cohort of 65 CP children. Resting-state functional connectivity (FC) and movement related cortical potentials (MRCPs) were used to see the cortical impacts of FMV through the EEG assessments. Muscle activations, fatigue and co-contraction metrics were assessed through EMG assessments. SCI: Three weeks of FMV to the Achilles tendon was delivered to 10 SCI patients, and their EEG FC was investigated. Stroke: An FMV device usability study in stroke (n= 12) was also conducted using a specifically modified commercial FMV device, with a view to establish for its potential for translation from laboratory to home-based use. Patient feedback was collected to update the original device design. After the updated device design, a single 30-minute dose of FMV was delivered to the arms, and clinical assessments of Fugl-Meyer Upper Extremity (FMUE) and modified Ashworth scores (MAS) were conducted. Results: OB1 — Fully Met: A wearable FMV device was designed and developed, delivering vibration frequencies at four levels (60, 80, 100 and 120 Hz) with a mean accuracy of 96.83%. The device was wearable, lightweight (65 g), and low-cost (under £100), meeting all pre-specified engineering requirements. OB2 — Fully Met (CP); Partially Met (SCI): In CP, FMV demonstrated frequency-dependent enhancements in beta-band functional connectivity, reduced movement-related cortical potentials, improved muscle activation, and delayed fatigue, with 100 Hz yielding superior motor outcomes. In SCI, significant alpha- and beta-band EEG connectivity changes in central-parietal regions were observed, suggesting neuroplasticity; however, clinical spasticity reductions were modest and the sample size (n = 10) precluded definitive conclusions, making this objective partially met for the SCI cohort. OB3 — Partially Met: The co-designed device was found to be comfortable and easy to use by stroke patients and clinicians. A single session of FMV produced improvements in FMUE scores but no significant changes in spasticity (MAS). Given the feasibility-study design with a small cohort (n = 12) and a single-session protocol, the clinical effectiveness component of OB3 is considered partially met, warranting further investigation in powered randomised trials. Conclusion: Findings support FMV's role in modulating cortical and neuromuscular pathways, with implications for personalised, accessible rehabilitation. OB1 was fully met through the development of a characterised, wearable, low-cost FMV device. OB2 was fully met for the CP cohort, demonstrating cortical and neuromuscular benefits, while SCI findings remain promising but preliminary, partially meeting OB2 for that population. OB3 was partially met, confirming device usability and short-term upper limb gains in stroke, with further powered trials needed to confirm clinical efficacy. Limitations include small samples and short follow-up periods, warranting larger trials. This work advances wearable FMV therapy toward evidence-based practice, bridging engineering innovation and clinical application for improved neurological outcomes.