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WALKING PERFORMANCE, MEDICAL OUTCOMES AND PATIENT

TRAINING IN FES OF ENERVATED MUSCLES FOR AMBULATION BY

THORACIC-LEVEL COMPLETE PARAPLEGICS

Daniel Graupe*, Humberto Cerrel-Bazo**, Helmut Kern*** and Ugo Carraro****

* University of Illinois, 851 South Morgan St., Room 1117, Chicago, IL 60607-7053 , USA, EMAIL:

graupe@ece.uic.edu

**Scuola di Specialità in Medicina Fisica e Riabilitazione, Università di Verona, Borgo Roma, Verona, Italy,

EMAIL : hcb57@yahoo.com

***Ludwig Boltzmann Institute of Electrostimulation and Physical Rehabilitation, Department of Physical

Medicine, Wilhelminenspital. A-1171 Vienna, Austria, EMAIL: helmut.kern@wienkav.at

**** Laboratory of Translational Myology of the Interdepartmental Research Institute of Myology & C.N.R.

Institute of Neuroscience, University of Padua Medical School, Padova, Italy, EMAIL:. ugo.carraro@unipd.it

ABSTRACT

Below is a discussion of an FDA-approved noninvasive Functional Electrical Neuromuscular Stimulation (FES)

System for ambulation by traumatic T1 to T12 paraplegics having no sensation and no motor function below their

SCI lesion. The system’s ambulation training, its ambulation performance evaluation and its medical evaluation

are summarized. Light microscopy muscle morphometry is included to explain ambulation performance based on

sound myology foundations of FES in enervated (upper motoneuron lesion) as compared with denervated (lower

motoneuron lesion) muscles.

KEY WORDS

FES (functional electrical stimulation), upper-motoneuron paraplegia, thoracic SCI, training, walking

performance, medical evaluation, myology, enervated muscle

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1. INTRODUCTION:

The paper discusses ambulation training and

performance and medical outcomes via transcutaneous

FES using the PARASTEP FES system for ambulation

by thoracic-level paraplegics with traumatic complete

upper-motoneuron lesions of the spinal cord, namely

where stimulation is applied to peripheral nerves to

elicit motor function in enervated muscles. The FES

system considered is the Parastep system, presently the

only one approved by FDA1 , 1994 and approved by

US Medicare and Medicaid for reimbursement of

equipment cost and of training cost2, 2003. This FES

system (Graupe and Kohn3, 1994), which is shown to

trigger action potentials in the stimulated peripheral

nerves, allows paraplegics with traumatic complete

T1-T12 paraplegia (having no sensation or motor

function below the SCI lesion) and who are trained in

its used to walk short distances. Walking distances

vary with intensity of training protocol from an

average of 115 meters per walk after a 32-session 3

months training program (Klose et al.4, 1997) to 450

meters/walk average after a 4-months daily training

program (Cerrel-Bazoet al.5, 1997). The system allows

full patient independence in standing, walking, and in

donning/doffing the system.

Among the medical benefits beyond mobility, most

important is the improvement in blood flow at below

the lesion by 50%-60% average, to near normal pre-

injury levels.

The Parastep system is based on principles

stemming from Luigi Galvani’s work6 on exciting a

frog’s leg (1791). Noninvasive (transcutaneous)

functional electrical stimulation (FES, or FNS: functional

neuromuscular stimulation) of peripheral nerves for

eliciting function enervated muscles in humans was

reported in 1960 by Lieberson7 and was applied to

hemiplegic subject to correct heel-drop. Trascutaneous

FES stimulator of thoracic-level paraplegic patients was

first reported by Kralj et al8 (1980) to allow standing and

the taking a few steps. Graupe et al9, 10

have extended

Lieberson’s and Kralj’s earlier noninvasive FES systems

to a patient-borne patient-controlled FES system for

thoracic-level complete paraplegics (with upper

motoneuron paraplegia), aiming at maximizing patient’s

independence in ambulation and in the control of the

system (see Graupe, et al.9

1982 , Graupe and Kohn

10

1983) and designing the stimulation pulses and their

coordination and control accordingly. This design was

subsequently implemented in the (now commercially

available) Parastep system (Graupe and Kohn3 1994),

which is considered throughout this paper and is further

discussed in11

. Also, some modifications of this design

are considered.

Carraro12

, 2002 and Kern13

, 2005 have studied

extensively the myology of enervated and denervated

muscles and his results, which provide myological

understating of the long term performance of FES in

upper-motor-neuron paralysis and its applicability many

years post injury.

We note that parallel work on FES in upper-

motoneuron paralysis, based on implanted (invasive) FES

systems also began in the 1980’s, for the same purpose of

ambulation by thoracic-level paraplegics. The main

groups working on percutaneous (implanted) FES

systems were and still are those of Marsolais, et al.14

,

1983 and of Holle, et al.15

, 1984.

2. FES IN UPPER-MOTONEURON

PARALYSIS:

The FES Parastep system of Fig. 1, is limited

thoracic level paraplegics, to exclude patients with

lumbar-level lesions, namely, where the paralyzed

muscles are denervated. It also requires full upper-

extremity function to exclude patients with cervical-

level lesions. The system’s design is reported in detail

in Graupe and Kohn3 1994

and will therefore not be

repeated here. It employs 12 surface electrodes at 6 sites

(quadriceps, common peroneal nerve and paraspinals at

right and left side each). The stimulation signals to each

stimulation site are designed to maximize

standing/walking time, by proper selection of stimuli

generation, including coordination and synchronization of

signal amplitude variation over time and distribution

between stimulation sites, while using very short pulses

(individually adjustable, usually from 80 to 150

microseconds) and lowest possible pulse frequency and

amplitude. They are coordinated in time and amplitude

throughout stimulation by a microprocessor that resides

in the patient-borne system, in terms of 3 menus (stand,

right step, left step). These menus are selectable by a

single finger touch on a walker-mounted switch and the

full time-evolution of the stimuli throughout each menu

resides on the above microcomputer.

Walker-support, that usually carries only

approximately 5% of body weight, is required for

balance and for safe and independent stand-up and sit-

down. Furthermore, since the patients have no

sensation, the only information (but for visual) that

they have on their ground contact comes from

sensation of pressure through the walker on their arms.

Else they claim that they “feel like walking on air”.

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Shoe-insert AFOs (ankle-foot orthoses) are useful for

providing ankle-foot stability. Since the system is noninvasive, patients may don

the system each morning and doff it in the evening.

Donning and doffing can be done by the patients

themselves without help and in short time (5-10 minutes

for donning, and 3-5 minutes for doffing).

2(a) Action Potential in the Stimulated Peripheral

Nerve

It is important to comment that FES

(transcutaneous or implanted) in upper-motoneuron

paralysis should only trigger action potential in the

stimulated peripheral nerve. This implies that the

stimulus should be of duration and level that suffice to

trigger an action potential (AP) that in turn, will travel

down the axon to the neuromuscular junction to

activate contraction in the neighboring enervated

muscle fibers. Fig. 1 shows the AP resulting from a

stimulation pulse measured at the quadriceps, as was

obtained from measuring the response-EMG at the

stimulation site with 3.75” x 1.75” surface electrodes.

We note that without FES there is no EMG at below

the SCI lesion and therefore any EMG at the

stimulated site is in response to FES. Furthermore,

with surface-FES all neurons that are being stimulated

respond simultaneously in a synchronized manner.

Hence, the APs at all the many hundreds of peripheral

neurons (that are affected by these quadriceps

electrodes) add-up to one strong signal, as in Fig. 1.

Note that the initial peak at the left-side of Fig. 1

(repeated after the flat section of the signal) is the

chopped artifact of the stimulus, while the far stronger

stimulus is gated off due its far higher (order of

hundreds) amplitude. Since with the progression of

muscle fatigue, many of the neurons that were

stimulated cease to fire, it was shown in Graupe and

Kohn3 that the level of the above response-EMG signal

goes down towards zero, the response-EMG has been

used in research versions of the Parastep to adjust

stimuli-level in order to recruit deeper neurons not

stimulated earlier in order to extend duration of

standing or of walking.

3. MYOLOGY OF THE ENERVATED MUSCLE

By means of needle biopsies of the vastus

lateralis muscle of long term enervated muscles of

thoracic-level complete paraplegics, we recently

showed that, after an initial period of rapid reduction

of muscle mass, the progression of atrophy is

extremely slow for many years (up to 20). After the

first few months in which muscle mass is well known

to decrease significantly; see: Scelsi et al. (1991)16

,

Lieber et al. (2004)17

, Kern et al. (2004)18

, the atrophy

reaches a steady state, that is likely maintained by the

residual spontaneous activity (spasms) of the lower

motor neuron that still innervates the myofibers. These

results are actually quite important for because they

suggest that, contrary to what described for lower

motor neuron lesion patients19

, 2004, severe atrophy

and degeneration of muscle tissue never occur in these

patients.

Figure 2.A, shows that in normal human

muscle the myofiber profiles are separated by minimal

interstitial tissue, fibers have a large diameter and

appear closely packed. In the long-term enervated

muscle (Fig. 2. B) the interstitial space between fibers

is slightly enlarged. Fiber size is more variable than in

normal muscle, with some fibers appearing unusually

large (asterisks) while a small percentage of them

present an extremely small diameter (pointed by

arrows). On the other hands, Fig. 2.C shows that the

muscle tissue is almost fully substituted by loose and

adipose connective tissue in the denervated

degenerated muscle of lower-motoneuron-lesioned

subjects. Indeed the long series of muscle biopsies of

the RISE trial allow to conclude that: (i) while human

skeletal muscles survive longer (years) than generally

accepted on the basis of experiments in rodents; see:

Kern et al. (2005)12

, Carraro20

2002, Midrio21

2005;

(ii) recovery to clinically significant muscle size and

function occurs in mid-term (3 to 5 years) lower motor

neuron SCI subjects (Carlson et al.19

2004, Carraro et

al.22

2005). However: (iii) starting FES within the first

year post-lesion results in a better recovery of muscle

function than when started many years after SCI

(Modlin et al.23

2005). Interestingly, the denervated

human muscle one-year after SCI appears much more

similar to that displayed in Fig. 2.B, than the expected

degenerated muscle of long term lower motoneuron

injured muscle (Figures 2.C and 2.F).

In conclusion, all together our morphometry findings

scientifically support the notion that also during the

late stage of upper motoneuron paraplegia there are no

upper-time limits to start successfully a training

program by Functional Electrical Stimulation of

enervated muscles.

In Figure 2, Myofiber profiles in normal

muscle (A) are separated by minimal interstitial tissue,

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fibers have a large diameter and appear closely packed.

In the enervated muscle (B) the interstitial space

between fibers is slightly enlarged. Fiber size is more

variable with some fibers appearing unusually large

(asterisks) and a small percentage of them presenting

an extremely small diameters (pointed by arrows),

while in C the denervated muscle fibers are substituted

by adipocytes and loose connective tissue. Bars:

100µm. Tissue type morphometry: D, E, F. D, Normal

human muscle; E, Long-term enervated and F, Long-

term denervated paraplegics. The most significant

difference between normal (D), enervated (E) muscles

shows a slight increase (about 20%) in loose

connective tissue with a comparable loss of muscle

mass. On the other hand, the percentages of muscle

(15%) and connective tissue (85%, xx% of adipose

tissue included) are

reversed in the denervated muscle (F).

4. PATIENT TRAINING

Patient-training should start within a few years

after injury for best outcome. However, in one case, a

62-years old male T3/4 complete paraplegic, 40-years

post-injury, trained by one of the authors (DG), was

able to stand up (for approximately 2 minutes) within 6

minutes of start of training and to take his first 3 steps

3 days later24

. This outcome is not surprising in view

of the mycological discussion in Section 3 above.

The training preparatory to the use of the Parastep

system needs to contemplate the advent of derivative

factors resulting from the SCI, such as the consequent

rigidity, contracture, spasticity, metabolic fatigue (due

to lack of muscle force and endurance), energy

inefficiency, bad postural alignment, poor upper body

control and lack of motivation. All these factors may

be responsible, at least partly, from preventing SCI

subjects from the ability to properly stand and/or walk

under FES.

Generally speaking, traditional rehabilitation of

complete paraplegic subjects focuses on improving the

strength of the above-lesion muscles that are still under

voluntary control and on teaching living skills that will

lead to maximum self-sufficiency per level of injury.

Passive range of motion is given to the paralyzed

extremities with the objective of facilitating ADL

(activities of daily living) on a wheelchair but not with

the intent of achieving standing and/or walking. From

our experience with non-denervated or degenerated

paralyzed muscle, the time of acceptance to an FES

walking training program may be only limited by the

factors related to the non- inclusion criteria of the SCI

candidates (Chapter 6 in Graupe and Kohn3, Grraupe

and Kohn25

). It can be speculated that the earlier the

gait training is starthed (followowing the injury), the

better is the outcome of FES training. This rationale

may be supported in those cases in which spasticity,

rigidity and contractures can jeopardize the action of

achieving a proven ROM (range of motion) to achieve

standing. In any case, useful start of initiating a gait

training program preparatory for the use of the

Parastep walking system can be after medical

stabilization and up to 40 years post injury (see above

in this secction) if the SCI characteristics of these

subjects correspond to the inclusion criteria of the

Parastep program As an example in one case, a 62-

years old male (Chapter 6 in Graupe and Kohn3,

Graupe and Kohn25

).

On the basis of the experience of one of the

authors (HCB), it is recommended that prior to

entering a gait training program, and in order to

maximize walking performance of the Parastep users,

the patients become involved in a basic conditioning

program. This may consist in passive and active

ROM, standing, progressive upper body weight lifting,

and upper body cycle ergometry26,,27 to condition the

cardiovascular and respiratory systems to perform at

75 % of the maximum heart rate for 20-30 minutes.

All training participants must be evaluated for the

degree of rigidity, spasticity and spasms and treated

accordingly to facilitate for hip and knee full ROM and

to reach at least 90° degree of the ankle joint necessary

to stand and walk. Muscle force and endurance of the

paralyzed muscles are obtained through an active

physical training program. This program takes into

account the use of the FES computer-controlled

systems. Muscle force training for the Quadriceps,

Hamstrings and Gluteus muscles is developed through

FES-based muscle contraction against a gradual and

progressive increase of load appropriately selected on

an isokinetic chair (for exercising leg

extension/flexion, hip abduction/adduction and muscle

force exercise). The FES weight lifting program starts

at 0 Kg and is gradually progressed, if no sign of

fatigue are encounter, to reach up to 10-15 Kilograms

for the quadriceps and hamstring muscles, and as much

as 5-10 Kg for the gluteus muscles. The training

protocol is set to train the above-mentioned muscles up

to 30 minutes at least three times per week. Once the

SCI subjects achieve the set weight lifting goals for

muscle reinforcement, the subjects are ready to switch

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to the muscle endurance training program. An FES

cycle ergometry program is used and SCI subjects are

trained for 30 minutes five times per week. Load

resistance is increased gradually, starting at 0

kilopound reaching 3 kilopound four to eight weeks

later28. This protocol of training has demonstrated to

be superior to ameliorate gait performance on SCI

subjects willing to stand and walk with the Parastep

system. Following this initial conditioning program

the standing and walking program is initiated. To achieve FES-based standing and/or walking in

SCI subjects, it is necessary to understand the

kinematics of standing or walking. This may differ for

different SCI subjects and it may be related to the level

of injury, residual locomotor force and to the non-

linear components above mentioned. As in any

training activity, lack of motivation may play an

important role. Kinematic considerations imply that

we must emphasize that the Parastep users are allowed

to stand and walk against gravity, due to both active

and passive forces provided by the FES system. This

system is compound of two elements; the first element

is a computerized electrical stimulator that delivers to

the lower extremities (lower trunk and paralyzed

muscles extremities) FES synthesized and coordinated

trains of electrical impulses to produce the muscle

contraction for “locking-in” the hip and knee for

stability and to relax other such muscles when needed

in a coordinated manner. FES muscle contractions

anchor the lower trunk and hip through artificial FES

muscle activity, decreasing C shape lumbar curvature

and improving stability. Other coordinated stimuli

simulate the common peroneal nerve to produce a

coordinated hip-flexion reflex to facilitate the swing

phase of the gait movement.. The second component is

the AFO which, through a ground reaction sub-patellar

push, generates passive forces making the foot-ankle

joint stable and contributes to “lock-in” the knee for

stability. As a whole, this neuroprosthesis prevents the

body from falling and facilitates a stepping pattern

through the peroneal reflex (lower extremity

synergistic flexor activity) as above.

Standing and walking training implies several

acquired skills of motor control and the integration of

the FES neuroprosthesis to the residual components of

voluntary motor control at above the level of injury

and to the derivative factors resulting from the SCI.

When first learning a new motor skill (like

standing and walking), movements may be slow,

vacillating and poorly coordinated. Each trail is an

attempt to achieve a target or a goal. At this stage,

learning relies heavily on feedback to control each

action. The unskilled performer pauses between

movement as visual information, above-lesion posture

information and ground-contact information obtained

through the arms while holding and leaning (even if

with only 3% to 5% of body weight) on the walker, are

absorbed and evaluated. Subsequently, the movement

is attempted again with a revised plan.. Eventually, the

sequencing and timing of the movement becomes

automated, shifting from direct visual control to a

more internalized form of control 29

.

The Vicenza gait-training procedure with the

Parastep system starts at the first achievement of the

upright position by neuro-modulating the FES currents

to useful lower-extremities muscle contraction and by

cuing the subjects for good postural alignment. This

postural behavior can also be helped through by using

mirror-feedback training. Gait training follows and

walking is allowed at first on a flat surface. In the

beginning, fuzzy behavior (slow, vacillating, and

poorly coordinated movements) is evidenced. Each

trail is an attempt to achieve a target or a goal of good

performance, until the learned movement becomes

smooth and coordinated, and requires little attention.

Learning this new behavior relies also in repetition

and, as such, treadmill training has allowed the SCI

subjects to repeat movement hundreds of times more

than on ground surface, thus improving performance

(see Tables 1 and 2).

5. RESULTS

Ambulation performance, concerning average

walking distances (meters-per-walk) were reported by

Klose et al.4 and by Cerrel-Bazo et al.

5 and are given in

Table 3 below. These relate to two different training

methods, one, at Vicenza, Italy of 4 months of daily

training5, including considerable muscle-strengthening

routines using treadmill exercises (see Fig. 3), the

second24

, at the University of Miami school of

Medicine, being of 11 weeks of training (3 one-hour

sessions per week). Medical and psychological evaluation results were

published in References 3, 11, 29, 30, 31, 32, 33 and are

summarized in Table 4 below. A 15 minute movie (T9

and T10 complete traumatic SCI paraplegics) is

accessible in Graupe34

.

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6. STOCHASTIC MODULATION OF FES

PULSES TO REDUCE RATE OF FATIGUE

When considering future improvements in FES,

we briefly discuss one possible approach that should

be examined, as follows:

A study by Graupe et al.35

reports very

preliminary results (one patient only) of a 36.6%

reduction (+/- 10.2% at 95% confidence level ) in the

rate of muscle fatigue when the FES stimulation signal

undergoes a 12% stochastic modulation of the time of

arrival (frequency) of the stimuli at the quadriceps, as

shown in Table 5. Whereas many more tests are

needed before definite conclusions can be reached,

these results point to a possible and simple way to

reduce the rate of muscle fatigue and increase of

walking range in upper motoneuron paraplegia, thus

making FES more efficient. This may be worth

testing also when FES is employed in denervated

muscles.

The motivation for these tests is that it can be

observed36

that the natural rate of action potentials in

healthy individuals varies in what appears (to the

outside observer who has no access to the regulation

carried out in the CNS), to be random at about 10%-

20% around some average rate. Also, in the

mathematical analysis of nonlinear systems it is known

that stochastic modulation improves stability37

and it is

possible that the neuromuscular loops (which are

certainly highly nonlinear) “take advantage” of this

feature.

The results above were carried out by stimulating

the quadriceps of a complete T7 (traumatic) paraplegic

patient, while seated at a fixed (marked) position

repeatedly, over 25 test sessions, at an average inter-

pulse interval of 42 milliseconds (average 24 Hz) and

with stochastic modulation of 0, +/-5, +/-10 , +/-20

milliseconds. Time to fatigue was measured from start

of stimulation (Leg lifting) to when the heel touched

the floor. Stimulation level and all other parameter

were held constant and patient had no knowledge

which (if any) modulation was applied. There was a 5

minutes rest between each stimulation test and sessions

were held at same time each day, with approximately

10 stimulation runs, each of a different (randomly

selected) modulation unknown to the patient.

7. CONCLUSIONS

In this paper we described a non-invasive

FDA-approved readily available FES system for

ambulation by persons with complete thoracic-level

upper motoneuron SCI, together with a description of

the Vicenza procedure for patient- training when using

that system, with ambulation results and medical

outcomes and with the mycological foundations for its

performance even when training is started many years

after injury. We note that the very rigorous Vicenza

training procedure, results in average ambulation

distances of several hundreds of meters (aver 400 m.)

per walk, since it first monitors and treats the

derivative factors discussed in Sect. 4. It continues to

monitor address these factors throughout actual

training of standing/walking rather than concentrating

on muscle contraction force. The mycological tissue

slides that are shown (Section 3) serve to explain how

training can be initiated many years (40 years in one

case that is reported) post injury. The results indicate

that the Parastep FES system, which is presently also

approved for reimbursement of both equipment cost

and training cost by Medicare and Medicaid in the

USA, is not a futuristic or experimental system, but a

valid system to allow SCI patients with complete

lesions between T1 an T12 (no sensation and no motor

function below the lesion) for independent walking of

reasonable distances at reasonable though low speeds

(ave. 14.5 m/sec). Furthermore, cardiovascular

parameters are improved such that blood flow to the

lower extremities (which drops significantly after SCI

– by about 30% to 49%) is essentially restored to near

post-injury levels (ave. 56% increase).

The system can be donned by the patient without

assistance in 5 to 19 minutes and doffed without

assistance. in 3 to 5 minutes.

Concerning future possible improvements, we

discussed (Set. 2.a) the possibility of using response

EMG for automatic feedback to adjust stimulation

level with the progression of muscle fatigue, We also

outlined (Sect. 5) the possibility that stochastically

modulated stimulation signals may significantly

enhance performance. Whereas this possibility is

presently only confirmed in one patient (36.6%

improvement in time to fatigue) requires more study, it

is based on theoretical foundations and on parallelity to

rate of action potential in intact animal data . It should

also be noted that whereas our experiments employ

only stochastic rate modulation, stochastic amplitude

modulation and even stochastic pulse rate modulation

should also be investigated for the same purpose. If

confirmed, such stochastic modulation may have

benefit in other electrical stimulation applications, say,

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to denervated muscles (with or without stem cell

implantation) and beyond.

A minor improvement that was recently designed

by one of the present authors (DG) involves wireless

(RF) links between walker and the body of the FES

unit, to avoid wiring between these components, to

further enhance patient independence.

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25. Graupe D, Kohn KH, Neurol. Res., 19: pp. 323-333.

1997.

26. Ragnarsson, KT, Physiological effects of functional

electrical stimulation-induced exercises in spinal cord

injures individuals. Clinical Orthopeadics,1998; 233: 53-63

, 1998.

27. Faghri PD, Glaser RM, Figoni SF. Functional Electrical

Stimulation Leg Cycle Ergometer Exercise: Training Effects

on Cardiorespiratory Responses of Spinal Cord Injured

Subjects at Rest and During Submaximal Exercise. Arch

Phys Med Rehabil, 1992; 73: 1085-93, 1992.

28. Cerrel Bazo H., Petrofsky JS, Brown SW. Recent

Advances in the Applications of Computer Controlled

Exercise. Ambulation and Functional Electrical Stimulation

in the Rehabilitation of Spinal Cord Injury Patients. Proc.

Fifth Congress of SOMIPAR [Società Medica Italiana di

Paraplegia], Perugia, Italy, Oct. 1992.

29. Schmidt RA. Motor control and learning: a behavioral

emphasis, second edition, Champaign, Illinois: Humans

Kinetics, 1998.

30. Nash MS, Jacobs PL, Montalvo PM, Klose KJ, Guest

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RS, Needham-Shropshire BM, Arch. Phys. Med. Rehab.,

78:808-814, 1997.

31. Jacobs PL, Nash MS, Klose KJ, Guest RS, Needham-

Shrpshire BM, Green BA, Arch. Phys. Med. Rehab., 78:794-

798, 1997.

32. Needham-Shropshire BM, Broton GJ, Klose KJ ,

Lebwohl N, Guest RS, Jacobs PL, Arch. Phys. Med.

Rehab., 78:799-803, 1997

33. Guest RL, Klose KJ, Needham-Shropshire BM, Jacobs

PL, Arch. Phys. Med and Rehab., 78:804-807, 1997.

34. Graupe D, www.ece.uic.edu/~graupe, 1994

35. Graupe D, Suliga P, Prudian C and Kohn KH,

Stochastically modulated stimulation to slow down muscle

fatigue at stimulated sites in paraplegics using FES for leg

extension, Neurol. Res., 22, 703-704, Oct. 2000

36. Stalberg E, Trontelj I V, Single Fiber

Electromyography, Mirvale Press, Old Woking, UK, 1979.

37. Chung, H.S.-H. Hui, S.Y.R. Tang, S.C. Wu, A. On

the use of current control scheme for switched-capacitor

DC/DC converters, IEEE Trans. Industrial Electronics, 47,

2, 238-244, Apr. 2000.

Figure 1: Response-EMG as measured at quadriceps of complete thoracic-level paraplegic

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Figure 2: Morphological appearance and distribution of tissue types of human normal and paraplegic muscle: H-E Stained: (A) Normal adult human muscle; (B) Upper motor neuron lesion (enervated) muscle; (C), lower motor neuron

lesion (denervated) paraplegic muscles; (D) Normal human muscle; (E) Long-term enervated; (F) Long-term

denervated paraplegics.

FIGURE 3: Parastep Users, trained at Vicenza’s Villa Margherita Neurorehabilitation and Research Center

(under the direction of Dr. H. Cerrel-Bazo) - shown at the finish of 1.5 kilometer walk in Carpi, Italy, part of

the city's "Marathon Run" celebration.

Research

Subjects

SEX A

GE

Height

meters

Weight

kg

TYPE

Of SCI

SCI - LEVEL

(Thoracic)

MF 1 M 20 1,75 70 Motor Car Accid. 8

SM 2 M 23 1,75 65 MCA 10

TC 3 M 22 1,80 67 MCA 5

RB 4 M 25 1,83 75 Gun Shot 10

LL 5 F 25 1,60 53 FALL-horse 8

MG 6 M 32 1,77 62 MCA 7

MEAN 24,5 1,75 65,3 8

SD 4,14 0,08 7,5011 1,8973

TABLE 1: Demographics characteristics of some SCI gait train in Vicenza, Italy.

Research

Subjects

Months

after SCI

METERs

Continuous walk

M/MIN

speed

Minutes of

Continuous walk

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MF 1 28 600 20 30

SM 2 57 600 15 40

TC 3 10 675 15 45

RB 4 72 675 15 45

LL 5 20 650 13 50

MG 6 22 900 15 60

MEAN 34,83 683,33 15,5 45

SD 24,175 111,43 2,345 10

TABLE 2: SCI walking Performance (Parastep gait training in Vicenza, Italy)

Ave. Distance m/walk Ave speed m/sec

Approx 85 sessions daily over 4 months Vicenza (Cerrel-Bazo et al. [5]):

14 patients 444.3 14.5

32 sessions 3/week, 12 weeks Univ. of Miami (Klose et al. [4] ):

16 patients (13 male, 3 female) 115 5.0

TABLE 3: Ambulation Performance Results (Parastep Users) COMMENT: For most USA patients, 4 -months training program that first concentrates on the SCI derivative factors

(see Sect. 4) programs as in Vicenza are impractical. On completing a 32 session program, performance may

reach that of a 4-month program in 6-12 months if patients continue ambulating at least 30 Min./day for some patients

Pre-FES-Training

(Ave)

Post-FES-Training

(Ave)

Lower-extremity Blood Flow 417 mL/min 650 mL/min (improv.) (Nash et al. [29] )12 patient data/ U. of Miami

Heart Rate 70.1 63.2 (improv.) (Nash et al. [29]) 12 patients/Miami

Time to fatigue (at peak arm ergometry test) 15.3min 19.2min (impr.) (Jacobs et al. [30]) 15 patients/Miami

Peak Workload Heart Rate (pk arm ergom. test) 188.5 183.1 (impr.) (Jacobs et al. [30] 15 patients/Miami

Oxyg. Uptake (pk Arm ergom. test) 20mL/Kg/min 23mL/Kg/min (improv.) (Jacobs et al. [30) 15 patients/Miami

Spasticity usually improvement especially

for very spastic pre-training

(Graupe, Kohn [3], [9], [31])

Michael Reese Hospital, Chicago

Bone Density No follow-up data except for 11 weeks after start of

training, where no significant change was reported (Needham-Shropshire et al.[32)

Physical Self Concept (TSCS scores) 43.2 TSCS 52 TSCS (improv.) (Guest et al. [33]) 15 patients/Miami

Depression Scores (BDI scores) 8.8 BDI 5.4 BDI (impr.) (Guest et al. [33]) 15 patient data

TABLE 4: Medical and Psychological Evaluation Outcomes (Parastep Users) Notation: TSCS: Tennessee Self Concept Scale; BDI: Beck Depression Inventory score

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Pulse interval )m.sec) 42+/- 0 42+/-5 42+/-10 42+/- 20_

Ave. extension time (m.sec) 82.22 112.33 97.42 94.78

% improvement 0 +36.62 +18.5 +15.3

Stand. Dev. (m.sec) 11.43 18.06 16.8 13.2

95% conf. range (t-test) (m.sec) +/-8.8 +/-11.45 +/-10.7 +/-10.2___

Table 5: Leg extension times with stochastically modulated stimulation inter-pulse intervals:

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