Next Generation Robots for Stroke Patients

Stoke victims – Statistics

As the evolution of robotic systems unfolds in the world around us, we are starting to see machines taking over manual tasks that would normally be performed by humans. This is already becoming apparent with the introduction of next generation robots as a trial method for assisting with the rehabilitation of stroke patients.

The pathophysiology behind a stroke begins with the interruption of a blood supply to the brain, which is due to a blood clot in the vessels channelling oxygenated blood to the brain, which results in a state of ischemia and damage to the brain tissue. Classic signs of a stroke can be sudden weakness or numbness of the face, arm or leg and typically manifests at one side of the body.  In addition to impairment of limb function, the sufferer can also experience dizziness, headaches, and confusion, and in severe cases the occurrence of a stroke can be fatal.

In the UK, there are estimated to be over 1,000,000 patients who have suffered from a stroke, with over 50% of these patients being left with a disability that affects their day-to-day activities. It is known that approximately a third of sufferers are over the age of 65 years. This cerebral accident costs the UK healthcare system over £8.2 billion on an annual scale. According to an updated report on Heart Disease and Stroke Statistics—2012 by the American Heart Association, In the United States for 2008, the cost of cardiovascular disease and stroke was estimated to be $297.7 billion, which included costs for physicians, medicine and carers.

The statistics on the prevalence of stroke is shocking and despite traditional methods to rehabilitate the victims (treatment including speech therapy, physiotherapy to name a few), the patient still needs a full-time carer in extreme cases and this can crush hopes for the patient of regaining independence.

So why not let a robot help. For most people, it is easy to think about an action such as moving a limb to perform a task, but this is the most challenging process for a stroke patient due to cerebral injury. Researchers at Rice University, University of Houston, and TIRR Memorial Hermann are currently in the process of developing a brain–machine interface system connected to a robot with an aim to help with the rehabilitation of a stroke patient’s upper limbs.

It is quite fascinating to think that an interface system could interpret a patient’s thoughts into action using an exoskeleton. The exoskeleton is designed to wrap around the patient’s arms and covers the patient from the fingers to the elbow. Take a look at the following video which demonstrates how one patient uses Myomo, a personal robotic device to regain mobility in his arm.

Damage to the nervous system requires repetitive task performance to help retrain the neuronal signalling pathway in regaining function and being able to transmit a signal that will control a movement. It is important to remember that the patient has to be motivated to initiate a movement to work hand-in-hand with the robotic interface system. This is probably going to be one of the major challenges seeing satisfactory results from the application of this new rehabilitation project.

This interface system involves use of Electroencephalography (EEG) devices that will translate brain wave activity from the stroke patient into signals to help operate the MAHI-EXO II robot. The robot is designed to have five degrees-of-freedom providing elbow and wrist flexion-extension (a position made possible when the joint angle to a limb decreases), pronation-supination (rotation of the forearm), and radial-ulnar deviation (physiological movement of the wrist).

The device also has an increased torque output for the forearms and elbow joints in addition to a passive degree-of-freedom to give flexibility in shoulder abduction therapy, which gives the patient a greater freedom of movement of the upper body. This design is currently set to be tested in clinical trials with patients whom have suffered from a stroke or spinal cord injury.

During the clinical trial phase for this interface system, it is hoped that the exoskeleton will help encourage repetitive movement of limbs to retrain the brain in regaining control and strengthening the sensory pathway for upper limb movement.

Compared to traditional rehabilitation programs that would involve a carer assisting the patient’s movements, the idea of a neural interface system with an exoskeleton is promising because it can interact with the patient’s brain waves and anticipate movement of the patient’s limbs – technology that could fully engage the patient during therapy.

What Feedback will the EEG Technology Provide about the Patient’s Brain Activity and Recovery?

The purpose of using the EEG interface system will allow for a real-time measurement to reflect the state of the patient’s brain (i.e., the plasticity in neural networks as a consequence of repetitive motion techniques due to intervention by the exoskeleton robot). This research opportunity really is one of few demonstrations of how combining robot technology with additional treatments could one day be a common practice in the rehabilitation of stroke patients.

Projects Already on the Pathway...

One of the most familiar projects that related to brain–machine interface systems for the purpose of rehabilitating patients with spinal cord injury is the BrainGate systems that involves placing a sensor in the area of the patient’s brain responsible for controlling limb movement. The project, which was researched by Prof John Donoghue at Brown University, has been mentioned recently in the media for its use on a patient suffering from Locked-in Syndrome and how she was able to use the neural interface system to control a robotic arm that helped bring a flask of coffee to her mouth.

The research on neural interface systems integrated with robots is fascinating and offers a promising approach to delivering care for stroke patients; however, such systems need to be fine-tuned to ensure the most efficacious and safe application of exoskeletons.

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