According to the National Institutes of Health (NIH), more than 700,000 people in the U.S. suffer a stroke each year, and approximately two-thirds of these individuals survive and require rehabilitation to re-learn skills that are lost when part of the brain is damaged. For example, these skills can include coordinating leg movements in order to walk or carrying out the steps involved in any complex activity. Rehabilitation also teaches survivors new ways of performing tasks to circumvent or compensate for any residual disabilities. For some stroke survivors, rehabilitation is an ongoing process to maintain and refine skills.

The StepWatch Activity Monitor, worn on the ankle, monitors and records the number of steps a subject takes during a specific time period. The monitor’s sensitivity is optimized for a subject’s gait characteristics, such as shuffling. (Orthocare Innovations photo)
Physical therapists specialize in treating disabilities related to motor and sensory impairments. They are trained in all aspects of anatomy and physiology related to normal function, with an emphasis on movement. They assess the stroke survivor’s strength, endurance, range of motion, gait abnormalities, and sensory deficits to design individualized rehabilitation programs aimed at regaining control over motor functions. Strategies used by physical therapists to encourage the use of impaired limbs include selective sensory stimulation such as tapping or stroking, active and passive range-of-motion exercises, and temporary restraint of healthy limbs while practicing motor tasks. Some physical therapists may use a new technology, transcutaneous electrical nerve stimulation (TENS), which encourages brain reorganization and recovery of function. TENS involves using a small probe that generates an electrical current to stimulate nerve activity in stroke-impaired limbs.

In general, physical therapy emphasizes practicing isolated movements, repeatedly changing from one kind of movement to another, and rehearsing complex movements that require a great deal of coordination and balance, such as walking up or down stairs or moving safely between obstacles. People too weak to bear their own weight can still practice repetitive movements during hydrotherapy (in which water provides sensory stimulation as well as weight support) or while being partially supported by a harness. A recent trend in physical therapy emphasizes the effectiveness of engaging in goaldirected activities, such as playing games, to promote coordination. Physical therapists frequently employ selective sensory stimulation to encourage use of impaired limbs and to help survivors with neglect regain awareness of stimuli on the neglected side of the body.

People who’ve had injury to their nervous system after disorders like stroke want to regain more than just basic movements. They want to get back to moving the way they did before. Scientists are now testing the idea that damaged muscles may recover better and faster with help from technology. NIH-funded researchers at Arizona State University (ASU) have recently designed a lightweight robotic device called RUPERT (for Robotic Upper Extremity Repetitive Therapy) that helps stroke survivors regain some basic activity in their arms.

In the Alter-G G-Trainer, the patient’s lower body is sealed in an airtight enclosure, and the system adjusts to the person’s size and weight. Airpressure lifts the body, reducing strain, and minimizing impact on the legs. (Alter-G photo)
The device has an advanced control system that detects the wearer’s intent to move. It can help them do the things we often take for granted, like reaching for a cup, eating, or moving something from one place to another. RUPERT is being developed by Kinetic Muscles, Inc., which previously helped ASU produce a similar device for recovering hand function called the Hand Mentor. Power for these devices is supplied by “pneumatic muscles” — small instruments that use compressed air to mimic muscle movements. Research teams funded by NICHD and NIH’s National Institute of Biomedical Imaging and Bioengineering (NIBIB) began testing the Hand Mentor last year in stroke survivors.

The National Institute of Neurological Disorders and Stroke (NINDS), a component of the NIH, has primary responsibility for sponsoring research on disorders of the brain and nervous system, including the restoration of function after stroke. The NINDS also supports research on ways to enhance repair and regeneration of the central nervous system. Scientists funded by the NINDS are studying how the brain responds to experience or adapts to injury by reorganizing its functions (plasticity) by using noninvasive imaging technologies to map patterns of biological activity inside the brain. Other NINDS-sponsored scientists are looking at brain reorganization after stroke and determining whether specific rehabilitative techniques, such as constraintinduced movement therapy and transcranial magnetic stimulation, can stimulate brain plasticity, thereby improving motor function and decreasing disability.

Gait Analysis

Another development in rehabilitation research is a movement analysis lab at NIH’s Clinical Center. Specialized video cameras record the movements of reflective markers attached to the patient’s feet, legs, and hips. Sensors go on the patient’s skin to record leg muscle activity. Special plates built into the lab’s floor measure the forces exerted by the patient’s body on the floor. Once all the signals are collected by the computer, the rehab team uses that information to get a very detailed idea of how the person’s joints and muscles move. They can then design a tailored recovery plan for each patient’s unique situation.

Objective quantitative measures of physical function have become increasingly important throughout many areas of rehabilitation research and practice. The StepWatch™ activity monitor records, documents, and assesses a subject’s gait. It is a reliable, unobtrusive instrument that allows users to easily record the number of steps a person takes every minute in normal daily life for up to six continuous weeks per session.

StepWatch was originally developed in a small research laboratory with assistance from a Small Business Innovation Research (SBIR) grant awarded by the National Center for Medical Rehab ilitation Research, part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development at NIH. StepWatch was developed as a research instrument for looking at the real-world activity of lowerlimb ampu tees. It was discovered that typical step counting devices, i.e. pedometers, were not especially accurate even for nonamputee subjects and were not useful for people with atypical gait.

Orthocare Innovations (www.orthocareinnovations.com), the maker of StepWatch, is now addressing issues related to user-friendliness and manufacturing, thus greatly improving the public’s access to the device as well as the commercial viability of the technology. SBIR-supported efforts are also underway to increase the usefulness of the system through the development of a central database, collection of normative data, and implementation of a Webbased, single-test ordering system for clinical applications. StepWatch has received U.S. Food and Drug Administration marketing clearance as a Class II device.

StepWatch monitors and records continuously the number of steps per time interval over extended monitoring periods. While subjects are typically monitored for 1-2 week time periods, StepWatch can store step data for up to two months at one-minute intervals before requiring data to be downloaded. The time-sequenced data, along with StepWatch software, allows patterns of activity and rest to be visualized in great detail.

The StepWatch Activity Monitor (SAM) is worn on the ankle. Consisting of a sensor, electronics, and battery inside a polycarbonate case, StepWatch is completely sealed and durable. It weighs about 1.3 ounces, and is contoured to fit comfortably against the leg. An elastic attachment strap ensures that the monitor remains securely attached to the ankle without irritating the skin. Alternatively, the straps can be removed and the monitor worn in a soft cloth sleeve at the ankle.

The monitor’s sensitivity is optimized for a subject’s gait characteristics by the standard programming mode or explicitly using the advanced programming option. The standard mode permits users to confidently program the StepWatch™ by entering the subject’s height and answering simple questions that describe the subject’s gait.

“Space-Age” Rehab

In space, lack of gravity can cause problems for astronauts’ bodies. NASA Ames Research Center scientist Robert Whalen proposed using differential air pressure in space to mimic the Earth’s gravity to prevent bone loss and muscle deterioration.

In his research, Whalen developed the hypothesis that musculoskeletal maintenance in space requires Earth-equivalent functional loading (or weighting), which is loading bones and muscles with activities and force levels in space similar to daily activity on Earth. Astronauts use treadmills with a loading harness to hold them in place on the treadmill. However, the treadmill loading harness can be uncomfortable and prevents astronauts from exercising normally and with the same intensity as on Earth. Whalen suggested using air pressure as an effective way of applying a high force, equal to body weight, to astronauts during treadmill exercise to replace the harness system.

After patenting his gravity differential technology in 1992, Whalen licensed his patent in 2005 to a private company to help rehabilitate patients needing support as they learned (or re-learned) to stand, walk, and run. Based in Menlo Park, CA, Alter-G Inc. (www.alter-g.com) adapted the technology for athletic and medical uses here on Earth in the form of a specialized treadmill called the GTrainer. This rehabilitation device applies air pressure to a patient’s lower body in order to unload weight, which reduces the stress placed on the lower body during rehabilitation.

The Adaptability Training System being developed by the NSBRI and NASA induces balance disturbances through support surface movement and changes in visual information. The treadmill can be moved in different directions, providing a variety of balance challenges as the user walks. (NASA photo)
The G-Trainer has been a successful option in military hospitals for orthopedic and neurological uses, including helping patients rehabilitate after traumatic brain injury to transition from ambulatory assistive devices to independent movement. Someone who is recovering from a brain injury can re-learn proper balance and gait while getting as much physical support from the G-Trainer as needed.

Patients don specially designed shorts, which attach to an enclosure. After the patient’s lower body is sealed in the airtight enclosure, the system performs a calibration, adjusting to the person’s size and weight. If a patient desires more weightlessness, a button is pressed on a touchscreen, and the air pressure increases, lifting the body, reducing strain, and further minimizing impact on the legs.

Another rehabilitation system originally developed for astronauts is the Adaptability Training System, developed by the National Space Biomedical Research Institute (NSBRI) and NASA. The system consists of a treadmill mounted on a base that can be actively moved in different directions, paired with a virtual scene projected in front of the subject providing a variety of balance challenges as the user walks. This concept will also have benefits for people with balance disorders.

The treadmill has a projection screen in front of it that shows an image of a room or hallway that moves as the user walks. Disturbances are simulated by tilting the treadmill in one direction as the image is tilted in another.