How Muscle Haptics Enhance Stroke Recovery

Stroke remains one of the leading causes of disability, often resulting in a range of impairments such as reduced motion, muscle weakness, and motor deficits due to impaired force generation [1]. One of the most common challenges for stroke survivors is reduced hand function, which significantly impacts their ability to perform daily activities [2][3].

Illustration of the motor pathway from the brain to the muscle.
Reference: occupationaltherapy.com

Traditional neurorehabilitation aims to reduce these motor impairments but often struggles with patient compliance due to the monotony of conventional physiotherapy techniques [4][5]. To address these challenges, technology-aided interventions like virtual reality (VR) are gaining momentum. VR-based stroke rehabilitation technologies make therapy more engaging and effective. However, while VR is extensively studied for its benefits in functional recovery, the role of haptic feedback remains underexplored.

The Role of Haptics in XR Rehabilitation

The term "haptic" originates from the Greek verb "to touch" and is now associated with the study of touch in human-computer interaction [6]. 

Haptic technology bridges the gap between touch and virtual environments, making human interactions more immersive and engaging. By enabling real-time muscle stimulation, it allows stroke survivors to engage in repetitive and precise exercises that promote neuroplasticity—the brain’s ability to re-educate and re-organise neural connections and pathways [7][8][9]. These exercises, designed to stimulate recovery, can recreate real-world movements within a virtual setting, using motion-tracking to mirror the patient’s limb movements [10][11]. Through stimulation, haptic devices enhance the overall experience, providing multi-sensory input that has been shown to improve strength, motor coordination, and dexterity when paired with repetitive motor tasks [7][12][13][14].

Overview of a muscle contraction using electrical stimulation.
Reference: occupationaltherapy.com

How Muscle Haptics Enhances Stroke Recovery

1. Strength and Motor Control: Repeated stimulation strengthens muscles and improves motor coordination.

2. Dexterity: Haptic feedback enhances fine motor skills by replicating real-world movements in virtual settings [11].

3. Neuroplasticity: Repeated motor tasks combined with real-time feedback encourage the brain to re-educate itself, aiding functional recovery [7][14].

Combining muscle haptics with extended reality supports neuromuscular recovery by stimulating muscles in virtual environments. This combination aids in muscle strengthening and improving motor function.

Evidence Supporting Haptic-Enhanced XR Rehabilitation

Multiple studies highlight the effectiveness of haptic feedback in stroke recovery:

1. Hand Function: Levin et al. (2006) demonstrated that using haptic systems like Cyberglove™ and Cybergrasp™ significantly improved hand function in patients with chronic hemiparesis after a 45-minute session [8].
   

2. Upper Limb in Chronic Stroke: Maris et al. (2018) found that 36 sessions of haptic-assisted training improved muscle strength and active shoulder range of motion (ROM) in stroke survivors [13]. Fourteen chronic stroke patients performed 36 sessions of 30 min duration each using the I-TRAVLE™ system. The outcomes assessed were active shoulder ROM, handgrip strength, strength and WMFT* activities.
   

3. Home-Based Upper Extremity Stroke Therapy: Thielbar et al. (2019) showed that home-based multi-user VR therapy improved upper limb function in 20 stroke patients over four weeks [14].

*The Wolf Motor Function Test (WMFT) is a test that measures upper extremity function.

Future of Muscle Haptics in Stroke Recovery

Integrating muscle haptics in XR-based rehabilitation offers a promising avenue for effective and functional recovery. These technologies are revolutionising how we approach neurorehabilitation by providing engaging and personalised. As research continues to validate its benefits, muscle haptics could become a standard part of rehabilitation programs, helping stroke survivors regain mobility and reclaim their independence.

References:

1. Lingo VanGilder J, Hooyman A, Peterson DS, Schaefer SY. Post-stroke cognitive impairments and responsiveness to motor rehabilitation: a review. Current Physical Medicine and Rehabilitation Reports. 2020 Dec;8(4):461-8.

2. Pérez‐Cruzado D, Merchán‐Baeza JA, González‐Sánchez M, Cuesta‐Vargas AI. Systematic review of mirror therapy compared with conventional rehabilitation in upper extremity function in stroke survivors. Australian occupational therapy journal. 2017 Apr;64(2):91-112.

3. Hayward KS, Kramer SF, Thijs V, Ratcliffe J, Ward NS, Churilov L, Jolliffe L, Corbett D, Cloud G, Kaffenberger T, Brodtmann A. A systematic review protocol of timing, efficacy and cost effectiveness of upper limb therapy for motor recovery post-stroke. Systematic reviews. 2019 Dec;8(1):1-8.

4. Maier M, Ballester BR, Verschure PF. Principles of neurorehabilitation after stroke based on motor learning and brain plasticity mechanisms. Frontiers in systems neuroscience. 2019 Dec 17;13:74.

5. Domínguez-Téllez, P., Moral-Muñoz, J.A., Salazar, A., Casado-Fernández, E. and Lucena-Antón, D., 2020. Game-based virtual reality interventions to improve upper limb motor function and quality of life after stroke: systematic review and meta-analysis. Games for Health Journal, 9(1), pp.1-10.

6.  Mousavi Hondori H, Khademi M, Dodakian L, McKenzie A, Lopes CV, Cramer SC. Choice of human–computer interaction mode in stroke rehabilitation. Neurorehabilitation and neural repair. 2016 Mar;30(3):258-65.

7.  Yeh SC, Lee SH, Chan RC, Wu Y, Zheng LR, Flynn S. The efficacy of a haptic-enhanced virtual reality system for precision grasp acquisition in stroke rehabilitation. Journal of healthcare engineering. 2017 Nov 5;2017.

8.  Lee J, Kim D, Sul H, Ko SH. Thermo‐Haptic Materials and Devices for Wearable Virtual and Augmented Reality. Advanced Functional Materials. 2021 Sep;31(39):2007376.

9. Lehmann I, Baer G, Schuster-Amft C. Experience of an upper limb training program with a non-immersive virtual reality system in patients after stroke: a qualitative study. Physiotherapy. 2020 Jun 1;107:317-26.

10. Iosa M. Virtual reality in stroke rehabilitation: virtual results or real values?. Arquivos de Neuro-Psiquiatria. 2019 Oct 24;77:679-80.

11. Merians AS, Fluet GG, Qiu Q, Lafond I, Adamovich SV. Learning in a virtual environment using haptic systems for movement re-education: can this medium be used for remodeling other behaviors and actions?. Journal of Diabetes Science and Technology. 2011 Mar;5(2):301-8.

12. Lehmann I, Baer G, Schuster-Amft C. Experience of an upper limb training program with a non-immersive virtual reality system in patients after stroke: a qualitative study. Physiotherapy. 2020 Jun 1;107:317-26.

13. Maris A, Coninx K, Seelen H, Truyens V, De Weyer T, Geers R, Lemmens M, Coolen J, Stupar S, Lamers I, Feys P. The impact of robot-mediated adaptive I-TRAVLE training on impaired upper limb function in chronic stroke and multiple sclerosis. Disability and Rehabilitation: Assistive Technology. 2018 Jan 2;13(1):1-9.

14. Thielbar KO, Triandafilou KM, Barry AJ, Yuan N, Nishimoto A, Johnson J, Stoykov ME, Tsoupikova D, Kamper DG. Home-based upper extremity stroke therapy using a multiuser virtual reality environment: a randomized trial. Archives of physical medicine and rehabilitation. 2020 Feb 1;101(2):196-203.