‘Intelligent suit’ supported by AI and electrical stimulation could enhance spinal cord injury recovery

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Experts in Germany are working on an ‘intelligent suit’ with which they hope to significantly improve rehabilitation after a serious spinal cord injury. This artificial intelligence (AI)-supported solution will be developed over the next three years by researchers from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU; Erlangen, Germany) working in collaboration with Heidelberg University and Heidelberg University Hospital (both Heidelberg, Germany).

“Although great progress has been made in recent years, the therapies which are currently available do not correspond to the principles of motor learning,” said Claudio Castellini (FAU, Erlangen, Germany), discussing the limitations of existing spinal cord injury treatments intended to help restore arm and hand function. “Firstly, especially weak muscles are not targeted sufficiently, and, secondly, patients are not actively encouraged to execute useful motor exercises. Our experience has shown that this leads to patient engagement waning over time.”

Castellini and colleagues intend to overcome these drawbacks with their AI-based technology, which combines the electrical stimulation of muscles with support for mobility using artificial tendons, and reacts to patients’ intended movements. The German Research Foundation has provided a total of approximately €1 million in funding for the project, dubbed ‘HIT-Reha’ and launched on 1 June 2023.

Injuries to the spinal cord often lead to the impediment of many daily activities. However, injuries like this are not necessarily irreversible. For example, if the long nerve fibres are not separated entirely from the brain, some remnants of motor control remain.

“In such cases, there is a good chance of regaining at least some mobility,” said Castellini. “The potential for regeneration is particularly high in the first 12 months after the injury, when new neurons can be generated and new networks created.”

The rehabilitation of arm and hand function is mainly based on the repeated execution of mobility exercises. Patients are supported by qualified therapists or, at times, also by robots. The methods used include functional electrical simulation (FES), in which electrodes trigger targeted muscle contractions, as well as exoskeletons or suits; orthoses that support and assist movement using pulley mechanisms, or inflatable air chambers.

However, these current rehabilitation measures are not sufficiently tailored to patients’ individual requirements and abilities, meaning the full potential for treatment fails to be realised.

Over the next three years, Castellini and colleagues aim to develop a suit that they hope will significantly improve the success of therapy after spinal cord injuries. Their ‘exo-suit’ consists of a compression jacket, arm cuffs and gloves, and combines the support systems available to date, such as FES and pulley mechanics, but with one special addition: AI-supported recognition of patients’ intended movements.

“Integrated sensors measure muscle activity,” explained Marek Sierotowicz (FAU, Erlangen, Germany). “Self-learning algorithms take this input and use it to calculate the patient’s intended movement, and adjust the assistance systems accordingly.”

Specifically, this means that the AI tells the FES system and the exo-suit where muscle contractions should be triggered or pulleys tautened in order to support the intended movement.

FAU is predominantly responsible for developing methods to perceive the patient’s intended movements. For this to work, researchers first have to construct a complete virtual model of the anatomical structure of the muscles and skeleton, and train it accordingly.

“We will carry out our initial tests with people who are not disabled and gather as much data as possible,” added Sierotowicz. “The better we train AI, the more reliably we will be able to recognise movement patterns and the more accurately the assistance systems will be able to work in the future.”

In addition to providing precise movement support, the intelligent interplay between EFS and robotic pulley systems may also ensure a more gentle treatment is delivered, as experience has shown that using FES alone requires a high intensity of stimulation and patients often find it unpleasant. The researchers are convinced that their invention will lead to a significant improvement in the success of rehabilitation after a spinal cord injury, as outlined in an FAU press release.


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