Promising neurotech for spinal cord injury: available and emerging applications

You or someone you care about has sustained a spinal cord injury (SCI). You have heard that there are many advances and research occurring in the treatment and management of spinal cord injury but it is hard to decipher the facts from the hype. Neurotech Network is dedicated to providing unbiased information about neurotechnology, a field that offers technical devices and therapies for persons living with neurological conditions like SCI. This will provide some of the broad categories and what they include along with the latest research and links to the device directory. This is not intended to replace advise from a treating physician but to educate you to have an informative conversation with your physician or therapist.

Neurotechnology, the use of medical electronics to interact with the human nervous system, has made rapid advancements in recent history: components have shrunk, electronics improved, and we, as a society, have become more accepting of interacting with technology. Devices are available commercially for SCI treatment in such areas as pain management, spasticity control, breathing assistance, mobility and new rehabilitation techniques. There are also many new technologies being investigated in research centers. These devices cannot reverse the damage to the spinal cord. Instead, they are tools that can be used, for instance, to combat secondary conditions, provide further independence and/or aid in the rehabilitation process. Let’s look at this in a little more detail.

What is Neurotechnology?

Neurotechnology is a broad term used to refer to medical electronics that interact with the human nervous system. The basis of neurotechnology is the electrical signals the body uses to send messages. Even though a muscle is paralyzed, it does not mean that the muscle or the relative peripheral nerve can not be stimulated.

In the 1950’s, the first attempt was made to apply electrical stimulation to the phrenic nerve to allow a person to breathe without a ventilator. This gradually developed into a field of science called FES (Functional Electrical Stimulation). FES encompasses a variety of therapeutic techniques and treatments used to activate muscles that may not be functioning properly due to injury, disease or a physical abnormality. Over the decades, stimulation is now applied to nerves plus sensing technology can be used to drive treatments, prosthetics or to improve diagnosis.

Areas of Consideration

Below are some important considerations to review prior to participating in a therapy, treatment or device use.

• It must be recognized that all neurotechnology programs may not be appropriate for all people with SCI. Researchers and clinicians currently working in this area, understand the existing criteria and are developing new guidelines to determine for whom neurotechnology devices and therapies will be most beneficial and successful. Some levels of injury are more adaptable to some treatments than others.
• Systems are implanted, external or are a combination (hybrid) of both. Implanted systems tend to be more “invasive” and therefore require a surgical or other procedure to install the system into the body of a potential user. External systems are applied outside the body or on the surface of the skin. Hybrid systems have components that are both implanted and external.
• The cost to use various systems is a very important consideration. Insurance may not reimburse for devices and therapies, especially if they are considered research or experimental. Review your insurance policy very carefully. Do Not Agree to participate in a protocol, therapy or research project until you have thoroughly explored the reimbursement options, out of pocket expenses and know the cost to you!
• Be aware that some treatments, therapies or devices are potentially dangerous if not used correctly.
• Not all people with SCI are appropriate for particular neurotechnologies. Your specific case should be reviewed by a medical professional, with SCI expertise, during consideration and prior to starting to use any program.

Categories of Applications

Here is a brief introduction to a few advances that are currently available, as well as some resources that will help you stay updated on what is coming in the near future. This section describes neurotechnology applications for different functional needs for a person living with spinal cord injury. A link to our directory of devices is available at the end of this section. Again, not all devices and therapies are appropriate for all injury levels. Consult a physician prior to consideration for use.

Breathing and Cough Assistance: Current neurotechnology alternatives to mechanical ventilation are hybrid systems that include either a phrenic nerve stimulator or diaphragmatic stimulator. Unlike ventilator systems, which use mechanical pressure to force air into the lungs, the stimulation system pulls air into the lungs by stimulating the diaphragm muscle or the phrenic nerve. As the diaphragm contracts, the chest cavity expands and air is pulled into the lungs. As the diaphragm relaxes, the chest cavity retracts and air pushes out of the lungs. The use of a breathing stimulation system is only possible if the diaphragm, lungs, and/or phrenic nerves are intact and responsive to stimulation, thus allowing the system to work using these body parts.

Persons with cervical and high thoracic levels of injury often have paralysis of the muscles responsible for coughing. Cough assistance systems (CAS) are vital to reduce the frequent respiratory complications that can occur. CAS that are currently available use different pressures to clear the lungs through an external breathing mask attached to a separate control unit. It applies pressure to the airway and then rapidly changes the pressure to create a high outflow from the lungs. Under investigation is a new hybrid system that uses an external controller and implanted electrodes to achieve a cough. There is also a epidural stimulation system with electrodes on the surface of the skin that is also under clinical investigation. The goal of these electrical stimulation systems is to create a ‘cough on demand’, reduce the need for frequent patient suctioning and allow the person with SCI to clear secretions more easily. Ideally, there would be a reduction in the frequency of respiratory complications.

Hand Grasp and Rehabilitation for the Upper Extremities: The loss of hand and arm function due to a cervical level SCI can severely restrict an individual’s ability to independently perform activities such as eating and personal hygiene. Regaining hand function is a high priority for persons with cervical level injuries. Although neurotechnology devices cannot reverse the damage to the spinal cord, they have the potential to provide increased function. Hand control systems can enhance rehabilitation or provide function to the upper extremities which include the hand, wrist or arm. These systems rely on the peripheral nervous system to contact muscles. There are two major components the these systems: stimulation or the stimulator and the control. The stimulation of the paralyzed muscles is what produces the desired movement, such as hand opening or closing for grasp, or elbow extension for reaching. The control describes the way that the user directs the movement; for instance, through a switch or a shoulder motion. In most cases, it is possible to customize both the stimulation and control to meet the needs of the user.

Upper extremity systems can generally be classified as either external or hybrid systems. External systems use electrodes that are attached to the skin over the muscles to be stimulated or the use of robotics to aid the movements. These systems are often used for exercise, muscle conditioning and limited function. Some external systems use repetitive motion therapy or combine external electrodes and EMG sensing signals to enhance the rehabilitation process. Other options include hybrid systems that have an implanted stimulator and an external control method. Hybrid systems are for long-term functional use. The first commercial implanted system, the Freehand System, was available through NeuroControl Corporation in the late 1990’s. Unfortunately, although the system was successful in producing hand function, the company could not maintain profitability and, in 2001, left the SCI market. Today, researchers are developing second generations of the implanted hand control systems. New investigations are also underway to use epidural stimulation (stimulation of the space within the spinal column) to restore hand and arm function. Other research projects are exploring the use of brain stimulation and/or robotics with traditional therapy These upper extremity systems are being designed with a goal to provide hand and arm function with control that is as natural as possible, cosmetically acceptable, practical to use, and adaptable to new activities and environments.

Pain and Spasticity Management: Neuropathic (nervous system generated) pain is a significant problem for some people with SCI. Discussion with your physician can help you better understand where the pain is coming from, and with that understanding, what can be done about it. Pain from SCI can come from an area of the spinal cord, a nerve close to the spinal cord or a fluid filled cavity within the injured spinal cord, referred to as a syrinx. Additionally, pain can be related to the disability of spinal paralysis; it includes over-use of joints or body parts, muscle spasm pain, or instability of the spine or other body organs. Conservative medical management (CMM) for people with SCI should not only include therapies directed toward relief of pain, but also include conventional physical therapies and rehabilitation, psychological and behavioral interventions. There are many areas of neurotechnology in the treatment of pain and/or spasticity including transcutaneous electrical nerve stimulation (TENS), percutaneous electrical stimualtion, implanted drug delivery systems (IDDS), transcranial magnetic stimulation and spinal cord stimulators (SCS). There are also many areas under investigation including deep brain stimulation, transcranial direct or alternative stimulation, or stimulating nerve block technology. An appropriate referral to a medical specialist trained in the field of interventional pain medicine may offer you help.

Urinary function for bladder management: Most people living with SCI have reduced bladder control that requires the use of either an external or internal catheter. Neurotechnology devices offer an alternative method of bladder management that use electrical stimulation to control urination or “voiding”. Several different approaches have been developed to treat the hyper-reflexive or flaccid bladder. Hybrid devices may stimulate the sacral, tibial, or pudendal nerves or the bladder muscle itself in order to provide bladder function. The external pelvic stimulator uses electrical stimulation delivered by a vaginal or anal probe. The appropriateness of each specific device or treatment depends on the level of injury and bladder condition. However, these approaches should be discussed with your urologist. There are many neurotechnology modalities under investigation to improve or restore bladder function; such as genital or peripheral nerve stimulation. Please Note: In some instances, bowel function may coincidently exhibit benefits from the use of stimulators for urinary function.

Sexual Function: The majority of people living with spinal cord injuries experience alterations in sexual function. Men will experience dysfunction that involves erection and/or ejaculation, semen quality and sexual satisfaction. Women may experience alterations in the degree of sexual sensation and the type of injury may influence a woman’s sexual satisfaction. Electrical stimulation may be a treatment option for males but research, although promising, is inconclusive as to the role of electrical stimulation for women’s sexual function. For an anatomical male living with SCI, the use of electrical stimulation to induce ejaculation may be possible. Fertility clinics have limited success with the use of electro-ejaculation. It is known that some couples have been able to conceive using this method. Further, it is reported that selected research using a bladder stimulation system (for bladder function) has resulted in some limited return of sexual function.

Pressure Sore Prevention and Wound Therapy: Most people with spinal cord injury (SCI) are at high risk for developing pressure ulcers due to muscle atrophy, decreased mobility and altered sensation. The prevention of pressure ulcers is a lifetime health issue. Daily use of electrical stimulation can help maintain the bulk or mass of paralyzed muscles. External electrical stimulation has some practical problems because electrode placement in the upper buttock region can be difficult for users to achieve but surface electrical stimulation is commercially available in the form of neuromuscular electrical stimulation (NMES). Implanted stimulation systems for long-term therapeutic use is under investigation. Electrical stimulation (ES) for pressure ulcer treatment is one of only two therapeutic options to be recommended by the Agency for Health Care Policy and Research for severe chronic wounds. A wide variety of external stimulation devices, approved by the Food and Drug Administration (FDA) for other purposes, may be adapted for use in wound therapy. Currently approved clinical use is limited to application of electrotherapy only after there are no measurable signs of healing for at least 30 days of treatment using conventional wound treatments. New devices specifically for wound therapy are being developed and one is approved by the FDA.

Assisted Standing and Ambulation Systems: The neurotechnology systems available for assisted standing and ambulation are wide and varied. Standing allows persons with SCI additional function and improved quality of life such as the ability to reach objects from high shelves, gain entry to places inaccessible from the wheelchair, and participate in social or work situations on eye level with their peers. Ambulation systems can provide basic standing and stepping in the vicinity of the wheelchair; these provide additional or further assistance for those with voluntary movement, such as persons with incomplete spinal cord injuries. Similar to the hand systems, electrical stimulation relies on the peripheral nervous system to activate a muscle. Advantages over other assistive devices such as standing frames or ankle-foot orthotics include easy application, increased versatility and prevention of muscle atrophy by using the body’s own muscle power. There are many commercially available options for assisted stepping for persons with walking ability but who need assistance with ankle and foot control. Using external electrical stimulation, these small systems stimulate the calf muscles in coordination with the gait of the user, thus, eliminating the need for ankle-foot orthotic bracing. Implanted assisted stepping systems are also being studied. These systems do not cure the paralysis but make possible functional use of the paralyzed muscle.

New neurotechnology devices that facilitate ambulation are available for those with paraplegia or incomplete injuries in which voluntary movement is present in the lower extremities. As with standing, devices are available that use external stimulation and custom bracing with the support of a walker. Exoskeleton technology has come a long way in the development pathway and several systems have regulatory approval. These exoskeletal suits fitted to the lower extremities and designed to boost mobility and standing as well as provide ambulation. For those with complete paralysis, implanted systems to enable steps in the vicinity of the wheelchair are undergoing clinical trials. For those persons with partial paralysis due to incomplete injuries, implanted and hybrid systems are being tested in the clinic to improve baseline walking ability and achieve faster, more symmetric walking for longer distances.

Rehabilitation and Exercise Systems: For people living with spinal cord injury, exercise and rehabiliation is vital but must be accomplished differently than prior to injury. This section describes exercise of paralyzed limbs and rehabilitation of muscles that even have a trace of voluntary movement. Exercise is essential to prevent the development of secondary conditions in the cardiovascular and pulmonary systems of the body. These systems move nutrients, gases, and wastes to and from cells helping to fight diseases, stabilize the body and prevent obesity. An additional important consideration for persons with SCI is restoring the condition of the affected muscles. After the onset of SCI, the muscles below the level of injury generally atrophy, potential problems with osteoporosis or brittle bones may develop and circulation become impaired due to inactivity.

Exercise can be achieved using Electrical Muscle Stimulation (EMS) which relies on the peripheral nervous system. The surface EMS devices send pulses of electricity into the user’s skin that result in a contraction of the muscles. For those with incomplete SCI and voluntary movement, exercising a muscle using EMS can slowly build muscle mass to potentially gain functional movement. For those with paralysis but who have intact peripheral nerves, electrical stimulation may be used to help maintain the condition of muscles. EMS devices have long been used by physical therapists not only for rehabilitation of atrophied muscles, but to achieve relaxation of muscle spasms or increase range of motion. Such devices as external stimulation or FES cycling may reduce the number of medical complications resulting from immobility and lead to an improved and healthier lifestyle. It is vital to understand that results produced while using EMS devices may not show immediately. There are a variety of EMS devices available with or without a prescription. Before starting an EMS exercise regime, you should consult a physician or professional therapist.

For those with incomplete SCI and/or some voluntary movement below the level of injury, muscles may be reconditioned through rehabilitation. Movement enhancement systems are devices that are used to assist with the exercise or work of muscles in a limb. They reinforce the belief behind rehabilitation therapy which is to improve the function of a weakened muscle or to “boost” the voluntary function that already exists. It has been proven that treadmill systems and robotics technology may improve locomotor (movement) skills and upper extremity function with repetitive motion therapy. These tools go beyond traditional therapy to push the body toward more potential movement and improved exercise.

Neurotech Network offers a directory of devices with further details on specific technologies.

Technology under Investigation and Research

There are some encouraging results from research for spinal cord injury. This are some highlights in this every changing field.

Stimulation of the Spine: Translating current spinal cord stimulation technology to spinal cord injury has been a theme for several researchers to help restore functional movement. SCS has been applied and is commercially available to treat chronic pain. Most recently, the technique has been under investigation for lower and upper extremity movements as well as respiratory, bladder and cardiovascular functions. Some research labs are using current implanted commercial devices while others are developing their own specially designed technology specifically for this application. There have also been developments in the use of transcutaneous spinal stimulation which using surface electrodes over the spine as a potential therapeutic treatment.

Tapping into the Brain: Brain Computer Interfaces (BCI) or Brain Machine Interface (BMI) are a type of neurotechnology in development in several laboratories around the world as well as some commercial entities. There are a variety of potential applications such as restoring communication, control of robotics and augmenting mobility to those with neurologic disease, high level injuries, or limb loss. Electrodes that are implanted in or placed over the motor cortex of the brain act as sensors that record neural activity of the user. The idea is that if a user simply thinks about movement, the brain signals generated can be sensed and translated by a BCI/BMI, and in turn used to control an external device, such as a computer cursor, robotic arm, or other stimulation modalities. The potential of such research may be the ability to provide stable, flexible and natural control over assistive devices using brain activity.

Merging Brain Power and Electrical Stimulation: An emerging rehabilitation technique is the use of stimulation to the brain while coupling this will rehabilitation techniques. Several research laboratories are using a variety of brain stimulation modalities such as repetitive transcranial magnetic stimulation (rTMS) or trancranial direct current stimulation. The stimulation is applied at various times (before, during or after) rehabilitation techniques to help facilitate improvements in the rehabilitation process. This promising field may change the way rehabilitation is practiced in the future.

To learn more about current clinical trials, the North American Spinal Cord Injury Consortium offers an easy way to find trials that may be right for you. Visit SCItrials.org to create a profile and search for clinical trials.

This is an overview of applications of neurotechnology for spinal cord injury. Devices are commercially available and there are also many new technologies being investigated in research centers. These are tools that can be used to combat secondary conditions, foster or encourage further independence and/or potentially improve quality of life. These technologies are not a one-size-fits-all and not everyone is appropriate for a particular technology.

Neurotech Network offers free resources and a directory of devices specifically for spinal cord injury as well as related symptoms. Check out our resource page here

The content for this article was provided by Neurotech Network. The source of references include the National Institutes of Health, United Spinal Association and and scitrails.org.

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