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Sponsor: Institute of Spinal Cord Injury, Iceland



1) Introduction

2)Therapeutic Exercise

3) Standing/Ambulation

4) Manual Grasping Control

5) Bladder/Bowel Management

6) Respiratory Support

7) Epidural Electrical Stimulation

1) Introduction: Functional Electrical Stimulation (FES) uses low levels of electrical current to stimulate physical or bodily functions lost through nervous system impairment (1-7). FES is applied to peripheral nerves that control specific muscles or muscle groups.

Because FES is an involved area with extensive history, the summaries below provide only a superficial overview of the technology. Various FES applications have moved to the forefront as they evolved and then receded in priority. This ebb and flow will undoubtedly continue in the future. As such, readers interested in learning more about the subject are encouraged to consult the referenced resources.

FES is not a cure but a tool to regain specific functions. Although in some cases FES can promote limited functional recovery, it does not repair or regenerate the damaged spinal cord. FES is ineffective if target muscles become denervated, which can be slight or extensive, depending on the nature of the injury.

FES applications include standing, ambulation, cycling, grasping, bowel-and-bladder control, male sexual assistance, and respiratory control. Potential benefits include improved venous return from lower limbs, osteoporosis prevention, fewer urinary infections, muscle mass retention, and cardiovascular health. Psychological benefits can result from improved functionality and greater independence.

FES components include an electronic stimulator, a feedback or control unit, leads, and electrodes. Electrical stimulators can have one or multiple channels (outputs), which are activated in unison or in sequence to produce desired movements.

Therapist-operated FES systems use switches or dials to control activation. Control mechanisms for subject-controlled FES include joysticks, buttons, switches, joint positions sensors, heel switches, sip-and-puff devices, EMG electrodes, and voice activation.

Subject-controlled FES can be open- or closed loop. In open-loop FES, the electrical stimulator controls the output. Closed-loop FES employs joint or muscle position sensors to facilitate greater responsiveness to muscle fatigue, or to irregularities in the environment.

Electrodes act as interfaces between the electrical stimulator and the nervous system and can be external (surface) or surgically implanted depending on the application, device, and the patient's needs.

2) Therapeutic Exercise: Individuals with SCI can suffer further health impairment through the chronic lack of physically balanced exercise. FES-assisted therapeutic exercise (TE) can help in this regard.

FES TE routinely uses ergometers of some sort (e.g., stationary cycles, hand cranks, rowing devices) to exercise upper or lower extremities. Physical benefits include improved cardiac output, peripheral venous (blood) return, and muscle oxidative capacity. FES TE can decrease spasticity, while increasing plasma endorphins, muscle bulk, range of motion, and bone mineral density. Furthermore, it can improve glucose tolerance and insulin sensitivity, cortisol levels, wound healing, and self image.

FES TE devices include 1) the ERGYS 2 system, 2) the RT300 motorized FES ergometer, 3) Concept 2 indoor rowing machine, and 4) the BerkelBike, a hybrid between a recumbent bike and a hand-cycle.

3) Standing/Ambulation: In addition to the physical effects of exercise, FES for standing, transfer, and ambulation provides functional and psychological benefits. Potential benefits include improved digestion, bowel-and-bladder function, retardation of bone-density loss, decreased spasticity, reduced pressure-sore risk, improved cardiovascular health, and improved skin and muscle tone. FES-assisted ambulation allows greater access to inaccessible locations and facilitates face-to-face interactions.

Systems for standing and ambulation can be strictly FES, or combine FES with various braces, including foot-and-ankle, knee, and long-leg braces. FES standing or ambulation systems use walkers, parallel bars, or elbow canes for balance and support. Depending on the system being used and its application, physical requirements and contraindications can vary:

bulletUpper extremities needed for balance and support.
bullet Intact lumbar and sacral spinal cord so stimulation can reach target muscles.
bulletTrunk stability for support and control.
bulletArm strength to use walker.
bullet Commitment to intensive training and consistent use.
bullet Sufficient finger or voice control to select menus.
bulletNo cardiac or respiratory problems.
bulletNo history of long-bone stress fractures, osteoporosis, or severe hip or joint disease.
bulletDue to effort involved in FES, not pregnant.
bulletNo severe scoliosis.
bulletNo morbid obesity.
bulletNo irreversible contractures.
bulletNo stimulation-preventing skin problems at stimulated sites.

The physical effort of FES-assisted ambulation is six to eight times that of able-bodied walking. For this reason, less than five percent of FES users walk more than 1,500 meters without rest, and, therefore, FES ambulation is generally not a practical replacement for wheelchairs.

A well-known FES-standing/ambulation system the Parastep® stimulates the quadriceps muscles for leg extension, the peroneal nerve for hip flexion, and the paraspinal muscles (or the gluteus maximus) for trunk stability. Its belt-attached stimulator connects via wire leads to self-adhesive electrodes. Fairly effort- and time-consuming training programs are recommended for new users.

Over the years, the Parastep system has been the focus of numerous studies, including the following:

1) Dr. P. Gallien and colleagues (France) evaluated Parastep’s ambulation-fostering potential in 13 individuals (11 men, 2 women) with clinically complete injuries ranging from the T4-T10 thoracic level. Age ranged from 17 to 42 years (average 27), and the time since injury varied from 5 to 240 months (average 5 years). Motor vehicle accidents caused all but one injury. After 30 or less two-hour training sessions three to five times a week, 12 of the 13 subjects were able to ambulate. Walking distance averaged 76 meters. Although one individual obtained 350 meters, only three exceed 100 meters. Walking speed averaged 0.2 meters/second (normal walking speed ~ 1.5 meters/second). Parastep training increased the size and strength of quadriceps.

The investigators stated that Parastep “is not used to increase ambulation autonomy in daily life, but is used as an active means of exercise, in order to prevent complications of immobilization, and to answer the desire to stand and walk.” They concluded that “the psychological benefits of the device are remarkable.”

2) In a series of studies assessing different outcomes, Miami Project investigators (USA) evaluated the Parastep training program. The first examined the effects of training on walking ability, strength, and various body measurements in 16 individuals (13 men, 3 women; average age 29) with complete T4-T11 injuries sustained an average of 3.8 years earlier. Subjects trained three times weekly for a total of 32 sessions. The distance covered, the time spent standing and walking, and gait speed steadily improved over the course of training, although there was considerable performance variability between subjects. For example, six subjects were able to ambulate more than 300 meters, but four could not exceed 100 meters. Both thigh and calf girth increased, as well as the amount of lean tissue (i.e., muscle).

In the second study in this series, the investigators assessed the effect of the 32-session, Parastep, ambulation program on overall body and cardiovascular fitness. In other words, does this program have fitness benefits above and beyond the improvements immediately associated with walking? In this investigation, subjects were tested before and after training by exercising with an arm ergometer, a device designed to measure muscle power. Various fitness parameters were evaluated, including the time it took to fatigue, peak workload, heart rate, upper body strength, and various metabolic measures (e.g., oxygen uptake).  Training increased the time it took to fatigue, peak workload, and oxygen uptake; and decreased heart rate. Upper extremity strength did not significantly change.

The third study in this series examined the effect of the Parastep training program on bone density. The loss of bone density or osteoporosis is a common consequence of SCI, aggravated, it is thought, by the individual no longer being able to participate in weight-bearing activities. This loss predisposes the SCI population to bone fractures. Researchers measured bone density in several locations before and after subjects completed the 32 Parastep training sessions. Although the training program substantially increased weight-bearing activity, no increase in bone density was observed.

The fourth study looked at the exercise-related psychological effects that may result from carrying out this 32-session Parastep program. These effects were measured before and after training using a self-concept scale designed to assess self worth and esteem, a depression measurement, and individual subjective interviews. The results suggested that training improved self concept and alleviated depression. In addition to the psychological benefits often accruing from any intense exercise program, the individual interviews suggested that participants were upbeat about visible body changes, such as increase in girth and tone of quadriceps; establishing a sense of connection with the lower half of the body; and the restoration of a sense of normalcy by being able, for example, to stand upright, even briefly, and interact with others face-to-face.  

The final study showed that the increased leg mass generated by the program was associated with greater blood flow to the legs. This enhanced blood flow was attributable to both exercise-catalyzed vascular structural changes, such as increased blood-vessel diameter, and improved vascular control mechanisms.

3) Dr. Regine Brissot and colleagues (France) evaluated the Parastep system in 15 individuals (11 men, 4 women) with T3-T11 thoracic injuries. All but two had complete injuries, age ranged from 16-47 years, and the time since injury averaged 53 months. Thirteen patients completed an average of 30 training sessions. Average walking distance without rest was 53 meters (range 1-350 meters) with an average speed of 0.15 meters/second. As with the previously discussed studies, all patients increased the strength and girth of their quadriceps. One individual with an incomplete injury was able to walk voluntarily without FES stimulation after five training sessions. Psychosocially, patients noted a definite improvement in self esteem and some progress in social integration. Three years after training, five patients still used the device for physical exercise but not for walking in a social setting.

The investigators concluded that although “the Parastep approach has very limited applications in daily life, because of its modest performance associated with high metabolic cost and cardiovascular strain…it can be a resource to keep physical and psychological fitness in patients with spinal cord injury.”

4) Manual Grasping Control:

Over the years, various FES devices have been developed to enhance grasping in individuals with upper extremity impairment. These devices also can be used as a rehabilitation tool to improve voluntary manual control in some when used soon after injury.

Individuals with quadriplegia who use FES to facilitate grasping report greater independence from adaptive equipment, a reduced need for personal assistance, and improved self-image. FES-grasping assistance can increase the number of activities an individual can perform or improve existing abilities.

FES can facilitate both the lateral or key-pinch grasp, effective for handling small objects, such as a spoon or a pen; and the palmar grasp, used to hold a glass or a book.

Physical requirements for upper-extremity FES include:

bulletHand and forearm muscles must be sufficiently innervated. Too much denervation results in FES-initiated muscle contractions that are too weak or fatigue too quickly for functional use.
bulletBicep, deltoid, and rotator cuff muscles must have enough voluntary strength to control hand placement.
bulletSubjects must be able to see well enough to direct their movements, especially if the hand lacks sensation.
bulletTruck support must provide a sufficient base for controlled arm movements and object lifting.

FES grasping devices can be subdivided in those 1) that use surface stimulators that send current through the skin (i.e., transcutaneous), and 2) that require the implantation of stimulators that deliver current directly to the targeted nerves.

Surface-stimulating devices include the following:

1) The Handmaster or Ness H200 is comprised of a hinged wrist-forearm splint with a stimulator box electrically connected to the splint via a cable. Electrodes inside the splint deliver stimulus to key muscle points necessary for movement. Ideally, candidates for this device should have sufficient shoulder and biceps functioning with limited wrist extensors. One potential disadvantage is that the device’s rigid splint design with integrated electrodes may prevent the optimal placement of electrodes for muscle stimulation.

Several studies have documented the benefits gained from using the device in individuals with quadriplegia. For example, one study evaluated the clinical experience of using it in 10 individuals with cervical injuries ranging from the C4 to C6 level. These subjects sustained their injuries 0.5 to 6 years before being recruited; their age ranged from 21 to 65 years, and eight were men. In three subjects, the splint could not be fitted due to, for example, size restrictions. In six subjects, the device stimulated grasping and releasing, and four subjects were able to do various grasping tasks (e.g., pouring water from a can, putting a tape in a VCR, etc) that they could not do otherwise.

Another study evaluated the use of the device in seven individuals with C5 to C6 injuries sustained 3 to 17 years earlier. In addition to various grasp and release assessments, outcome measures included activities of daily living (ADL), such as picking up a telephone, eating food with a fork, and lifting a videocassette.  The investigators reported significant improvements in hand function and strength after subjects used the device for three weeks.

2) The Bionic Glove is a fingerless flexible garment with a built-in stimulator and electrode contacts. The device is controlled by wrist position to assist in grasping and releasing. A pilot study in nine individuals with C6-7 injuries evaluated the effect of using the Bionic Glove for at least a year as part of daily living activities. Grasping strength increased four times, and the ability to carry out most manual tasks improved substantially.

Another study evaluated the benefits gained from six-months of using the Bionic Glove in 12 individuals with C5-7 injuries. The investigators concluded that the device increased both grasping power and range of movement. The ability to carry out most manual tasks improved significantly. However, individuals who already had some dexterity were more reluctant to use the device.

3) The ETHZ-ParaCare, evolving into the Compex Motion, device, is another flexible system that improves grasping ability and strength in individuals with quadriplegia. The rehabilitation benefit accruing by using the device relatively soon after injury was the focus of a study with 11 subjects (age 15-70; 9 men and 2 women) with C4-7 complete or incomplete injuries. All but two sustained their injuries within eight months of initiating the program; six started within three months. The investigators concluded that that the technology can be used during early rehabilitation for different purposes, including 1) for muscle training, 2) to support activities of daily living, and 3) to facilitate the development of voluntary hand movements. Some subjects discontinued using the device because the device had increased voluntary grasping ability sufficiently so that they no longer needed it. Others stopped because they required assistance to place the electrodes at home or it took too long to put on or take off.

4) The Belgrade Grasping System, evolving into the ActiGrip System, initiates not only grasping but also reaching through stimulating the triceps. This system allows flexibility in electrode positioning to maximize muscle stimulation, but, as a consequence, requires more time for the individual to place the electrodes compared to the more rigid Handmaster device.

FES implantation grasping devices include the following:

1) The Implantable Functional Neuromuscular Stimulator or Freehand system probably was the most extensively researched and evaluated FES-grasping device. It was implanted in 200+ individuals with C4-C5 injuries, obtained FDA approval, and was commercially marketed by the NeuroControl Corporation. Unfortunately, in spite of demonstrated effectiveness, it was withdrawn from the market in 2002 due to apparently economic reasons.

Basically, with this system, a joystick-like device placed on the left shoulder is controlled through shoulder movement, which, in turn, sends electrical signals to a nearby external controller. This controller then sends signals to a transmitting coil which is relayed to a receiver-stimulator that has been implanted near the right shoulder. Finally, movement-generating impulse signals are sent to eight electrodes implanted on the muscles of the right arm and hand that are used for grasping.

To further augment hand function, various surgical procedures are often carried out in conjunction with the implantation of components, such as tendon transfers and joint fusions.

Because one must wait 18-24 months after injury before all of these components can be surgically implanted, the Freehand system can’t be used in efforts to regain voluntary hand movements in the early stage of rehabilitation, as is the case with the aforementioned surface-stimulation devices. Sometimes additional surgeries are often needed to replace failed components and to reposition stimulation electrodes.

The Freehand was evaluated in 51 subjects with C5-6 injuries recruited from eight SCI centers in the U.S., and one each in the UK and Australia. Eighty-two percent of the subjects were men, time sustained since injury averaged 4.6 years, and age averaged 32 years. Subjects were followed at least three years. The device substantially increased pinch force and grasp-release abilities in virtually all patients. In addition, all subjects became more independent in carrying out activities of daily living, such as eating with utensils, brushing teeth, shaving, etc. Over 90% of the subjects used the device at home and reported high satisfaction.

2) Myoelectrically-Controlled System: Based on the Freehand system, a more powerful, less cumbersome, second-generation device has been developed and studied in individuals with SCI. Because the device eliminates the need to wear a shoulder joystick as required with the Freehand, it is easier to put on and take of.

With 12 stimulation electrodes, this system can activate 12 muscles compared to only eight for the Freehand system, allowing more refined hand function, forearm rotational movement, and elbow extension. In addition to the stimulation electrodes, two recording electrodes are implanted near muscles in which the individual can still voluntarily control. Often, one recording electrode is implanted on the muscle furthest down the arm that still has some voluntary control, and the other is implanted in the neck or shoulder region. In theory, however, even if the patient can voluntarily control only one muscle, he still can use the device.

When the individual contracts the targeted voluntary muscles, the recording electrodes pick up the electrical signals (i.e., myoelectrical) the muscles generate and transmit them out of the body to an external control unit. This unit transforms these signals and relays them back into the body to the 12 electrodes that stimulate the desired hand and arm function. In a nutshell, the voluntary movement of controllable muscles send signals through the device that stimulate paralysis-affected muscles.

In a typical procedure, like turning on a car ignition with a key, the individual activates the system by moving the shoulder or neck. Next, like shifting the car into gear to get it moving, contracting and relaxing a forearm muscle with retained function causes the hand to close and open, respectively.

One study looked at the functional gains accruing by implanting the device into nine arms of seven individuals with C5-6 injuries sustained one to four years earlier (i.e., the device implanted in both arms of two individuals). In all subjects, the device substantially improved pinch force, grasp function, and ability to carry out activities of daily living.

In a later study by the same investigators, three individuals with C5-6 injuries using the device were followed for two to four years. Augmentative surgeries, such as tendon transfers, were carried out at the same time that the device was implanted. As before, improvements were noted in pinch force, grasp function, and activities of daily living. Several of the recording electrodes needed to be surgical adjusted or repositioned.

3) The STIMuGRIP system is being developed by Finetech Medical. With this technology, a receiver is implanted under the skin of the forearm that relays signals to two electrodes connected to grip-controlling muscles. Like a wristwatch, an external controller is strapped around the forearm directly over the implanted receiver.  The controller detects arm acceleration somewhat similarly to a computer game sensing a forearm swing to hit an imaginary tennis ball. This movement generates signals which are sent to the internal receiver and, in turn, the electrodes that trigger the stimulation or relaxation of various muscles used to pick-up, hold, and release an item.


5) Bladder/Bowel Management: FES offers a potential bladder and bowel control mechanism for individuals with SCI. Devices have included the Brindley (also called Finetech-Brindley, Brindley Vocare) and the InterStim systems. Both surgically implanted devices stimulate sacral nerves to achieve desired effects.

The Interstim was not specifically designed for SCI use. Unlike the Brindley device, implantation of the InterStim does not involve the cutting of nerves. Therefore the InterStim can be used to treat urinary incontinence in individuals with complete and incomplete SCI. Clinical results using Interstim – not specifically for those with SCI – indicate that reliable continence is achieved by 45%.  An additional 34% of users report that incontinence is reduced by 50% or greater.

The ideal Brindley candidate is an individual with complete SCI who suffers incontinence and frequent urinary tract infections. The system drains the bladder’s volume to less than 50 milliliters, which eliminates catheterization, reducing infections.

Brindley use is restricted to those with complete SCI because it often requires the cutting of sacral sensory nerves and bladder nerve roots, which block sensations needed for reflex erections and precludes spontaneous improvements in voluntary bladder control.

Surgically implanted Brindley components include an electrical stimulator, wire leads, and cuff electrodes. The stimulator is implanted in the abdomen under the skin, usually beneath the ribs. Silicon-coated electrodes are implanted around surgically exposed spinal sacral roots. Implanted wire leads connect the components.

Using separate frequencies and pulse durations, an external radio-frequency control device directs the Brindley system to stimulate lower bowel contractions or reflex erections.  

To use the Brindley system, patients must:

bulletBe physically mature (skeletal growth after implantation can dislodge implanted components);
bulletPossess a complete spinal-cord lesion;
bulletBe neurologically stable (in order to manipulate the device and establish the right time to use it);
bulletPossess intact, peripheral nerves to bladder and sphincter muscles, which can be stimulated;
bulletHave reflex bladder contractions, which generate adequate bladder pressures.

Many articles have been published on the use of the Brindley device, including the following summarized below:

Dr. Johannes Kutzenberger et al (Germany) summarized 16 years of experience treating 464 patients with paraplegia (220 female, 244 male) with the Brindley device. Specifically, sensory nerve roots at the sacral S2-5 level were completely transected – a procedure called sacral deafferentiation. This selective cutting eliminates the sensory input from key bladder muscles into the spinal cord, and, in turn stops the reflex contraction of the bladder muscles, which may otherwise lead to uncontrolled bladder emptying. The second step was the implantation of the Brindley stimulator on the still intact motor nerve roots which innervate the muscles needed for bladder control. Through the use of an external transmitter, the stimulator allowed the patients to void voluntarily. Hence, in a nutshell, bladder control was achieved by 1) cutting the input nerves that trigger uncontrolled bladder emptying, and 2) establishing external control over the nerves that stimulate bladder contraction.

Of the 464 treated patients, 440 have been continuously followed for 0.5 to 17 years. Continence was achieved in 83% of them. Frequency of voluntary voiding averaged 4.7 times per day, and voluntary defecation averaged 4.9 times per week. In addition, urinary tract infections decreased from an average of 6.3 per year before the procedure to 1.2 afterwards.

Dr. H.E. van der Aa and colleagues (Netherlands) reported the treatment of 38 patients with SCI with the Brindley system. Of these patients, 33 were men, and age ranged from 15 to 59. All patients had either thoracic or cervical injuries sustained at least a year before treatment. Of the 38 treated patients, 37 were retrospectively evaluated. All demonstrated an increase in bladder capacity and a decrease in residual urine volume. Thirty-one were fully continent. Patients also reported a decreased infection rate and improved social life.

6) Respiratory Support: FES has provided respiratory assistance for individuals with higher-level, respiration-compromising injuries. Although mechanical ventilation provides respiratory support, it distorts the voice, limits mobility, and increase infection risks. Using FES to stimulate diaphragmatic contractions, called phrenic-nerve pacing, allows users to minimize ventilator use. This can improve the subject’s mobility and speech, while reducing respiratory secretions, respiratory infections, and personal care needs.

Basically, these pacing devices consist of surgically implanted receivers and electrodes and an external transmitter and antenna. The transmitter and antenna send a signal to receivers just under the skin. The receivers transform the radio waves to pulses, which then stimulate the phrenic nerves via electrodes. This nerve stimulation triggers the diaphragm to contract and, as a result inhalation. When the pulse stops, the diaphragm relaxes and exhalation occurs. Appropriate pulsing will produce normal breathing (see www.averylabs.com). 

However, SCI between C3-5 can damage the diaphragm-controlling phrenic nerves that FES stimulates. Therefore, phrenic nerve functionality must be confirmed before phrenic-nerve pacing is considered.

Dr. S. Hirschfield and colleagues (Germany and Finland) compared the outcomes of treating over a 20-year period 32 patients with functioning phrenic nerves with pacing devices with 32 patients who were mechanically ventilated. The mechanically ventilated patients were not randomized to this group but rather could not use pacing devices because their phrenic nerves were damaged.  All patients had cervical C3-level or above injuries.

Although this was not a controlled study due to the inherently different composition of the two treatment groups, the investigators observed that treatment of respiratory insufficiency after cervical SCI with a pacing device instead of mechanical ventilation resulted in the following benefits:

·         Significantly reduces upper airway infections,

·         Reduces cumulative health-care cost,

·         Improves quality of speech,

·         Improves quality of life,

·         Reduces mortality and prolongs life.

As demonstrated by Drs. Lloyd and Abbott Krieger (USA), those with denervated phrenic nerves may be able to overcome this obstacle through the surgical rerouting of one of the 11 rib-cage-associated intercostal nerves to the dysfunctional phrenic nerve. At the same time, a phrenic nerve pacemaker is implanted. Of the 10 surgical nerve transfers, eight resulted in successful diaphragmatic pacing. An average of nine months was required for transferred nerves to innervate the diaphragms of these eight and respond to electrical stimulation.

For individuals with one functioning phrenic nerve, they may able to regain substantial respiratory capability by combining the stimulation of inhalation-assisting intercostal muscles with unilateral phrenic-nerve pacing. For example, Dr. Anthony DiMarco et al (USA) did this combination procedure on for four individuals with ventilator-dependent quadriplegia who still had a single functional phrenic nerve. The intercostal muscles were activated by the electrical stimulation of nerve roots through an electrode surgically placed in the spinal cord’s thoracic area. After treatment, the subjects were able to stay off mechanical ventilation for at least 16 hours per day. In addition, improvements were noted in sense of smell, quality of speech, and overall well being.

A less invasive procedure is intramuscular-diaphragm pacing, a procedure which does not require the cutting of phrenic nerves or the surgical opening of the chest (i.e., thoracotomy) usually required with conventional phrenic-nerve pacing. Under this procedure, electrodes are laparoscopically placed in the diaphragm near where the phrenic nerve connects to it. Because of the method’s visualization capability, laparoscopic procedures only require small incisions. After evaluating this approach in five ventilator-dependent subjects with quadriplegia, Dr. Anthony DiMarco and colleagues concluded that this technology provides comparable ventilatory support and clinical benefit as conventional, much more invasive, phrenic-nerve pacing.

FES-Assisted Cough: SCI-related abdominal muscle impairment can affect coughing ability needed to clear airways of secretions and irritants. In addition to clogging breathing airways, coughing inability increases respiratory-infection risk and can lead to atelectasis (a collapsed or airless state of the lungs). FES-assisted cough is one mechanism by which coughing ability can be enhanced. Basically, it involves taking a deep breath and then coordinating FES-stimulated abdominal contractions with forced expiration.

In an illustrative case study, Dr. P.N. Taylor et al (United Kingdom) evaluated the impact of electrical stimulation on blood-pressure control and cough augmentation in a 40-year-old, ventilator-dependent male with a C3-4 level injury.  Before starting the stimulation program, the patient couldn’t cough on his own and required manual assistance and tracheal suction to maintain his airways. After initiating the program, he became independent in coughing and no longer required suction or manual assistance.


7) EPIDURAL ELECTRICAL STIMULATION In research reported in 2011, Dr. Susan Harkema and colleagues (USA) used epidural electrical stimulation to improve functioning in a 23-year-old male with a C7-T1 injury sustained 3.4 years before device implantation.  Although possessing no motor function in trunk and leg muscles, he had retained some below-injury sensation. Modified from an existing device used to treat pain, an epidural spinal cord stimulation unit was placed over the outer dura membrane of the patient’s spinal-cord L1-S1 segments. The implantation intervention was combined with a rigorous rehabilitation program involving body-weight-supported treadmill training.

The theory is that with a motor-complete cervical injury of this nature, epidural stimulation can modulate “spinal cord circuitry into a physiological state that enables sensory input, derived from standing and stepping movements, to serve as a source of neural control to perform these tasks.” In other words, the intact neural networks remaining within the spinal-cord’s lumbosacral segments can be reactivated with the right input. Basically, the implanted device will generate signals that to some degree substituted for those normally sent by the brain, and when these signals are combined with the sensory input from the legs, uninjured neural networks can direct the movements required to stand and step.

With epidural stimulation, the patient was able to stand, supporting his full weight for periods ranging from 4-25 minutes, feats he could not do before device implantation even with the extensive locomotor training and rehabilitation he had undertaken. In addition, the patient was eventually able to voluntarily move toe, ankle, and leg muscles during epidural stimulation sessions. Finally, improvements were noted in bladder, bowel, and sexual functioning, as well as temperature regulation. The investigators concluded that “Task specific training with epidural stimulation may have reactivated previously silent spared neural circuits or promoted plasticity”