The Orthotic Effect of Functional Electrical Stimulation on the Improvement of Walking in Stroke Patients with a Dropped Foot: A Systematic Review

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DOI: 10.1111/j.1525-1594.2004.07310.x · Source: PubMed
Abstract
Analysis of the available evidence on the improvement of walking in stroke patients with a dropped foot when using peroneus stimulation. A systematic review was performed to identify trials that investigated the orthotic effect of functional electrical stimulation (FES) on walking in stroke patients with a dropped foot. Two independent raters scored the methodological quality of the included articles. Walking speed and physiological cost index (PCI) were selected as the primary outcome measures. Studies that measured walking speed were pooled and a pooled difference including confidence interval was calculated. Eight studies were included in the review, of which one was a randomized controlled trial. Methodological score ranged from 8 to 18 out of 19. Six studies measured walking speed. The pooled improvement in walking speed was 0.13 m/s (0.07-0.2) or 38% (22.18-53.8). The present review suggests a positive orthotic effect of functional electrical stimulation on walking speed.

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Blackwell Science, LtdOxford, UKAORArtificial Organs0160-564X2004 International Society for Artificial Organs286577586Original Article
ELECTRICAL STIMULATION TO IMPROVE WALKING IN STROKE PATIENTSA.I.R. KOTTINK Et al.
Received July 2003; revised December 2003.
Address correspondence and reprint requests to Dr. A.I.R.
Kottink, Roessingh Research and Development, PO Box 310,
7500 AH, Enschede, The Netherlands. E-mail: a.kottink@rrd.nl
The Orthotic Effect of Functional Electrical Stimulation on
the Improvement of Walking in Stroke Patients with a
Dropped Foot: A Systematic Review
*Anke I.R. Kottink, *Linda J.M. Oostendorp, *†Jacob H. Buurke, *†Anand V. Nene,
*Hermanus J. Hermens, and *Maarten J. IJzerman
*Roessingh Research and Development; and †Roessingh Rehabilitation Center, Enschede, The Netherlands
Abstract:
Objective
Analysis of the available evidence on
the improvement of walking in stroke patients with a
dropped foot when using peroneus stimulation.
Methods
A
systematic review was performed to identify trials that
investigated the orthotic effect of functional electrical stim-
ulation (FES) on walking in stroke patients with a dropped
foot. Two independent raters scored the methodological
quality of the included articles. Walking speed and physio-
logical cost index (PCI) were selected as the primary out-
come measures. Studies that measured walking speed were
pooled and a pooled difference including confidence inter-
val was calculated.
Results
Eight studies were included in
the review, of which one was a randomized controlled trial.
Methodological score ranged from 8 to 18 out of 19. Six
studies measured walking speed. The pooled improvement
in walking speed was 0.13 m/s (0.07–0.2) or 38% (22.18–
53.8).
Conclusions
The present review suggests a positive
orthotic effect of functional electrical stimulation on walk-
ing speed.
Key Words:
Equinovarus—Peroneal nerve—
Electrical stimulation—Hemiplegia—Gait.
Stroke is a major illness in Western countries with
huge disabling consequences. The incidence of stroke
in the Netherlands is approximately 30 000 (1 : 542)
per year and the prevalence is 120 000 patients (1).
A stroke causes impairment of the cognitive, sensory,
perceptive, and motor functions. A rather common
motor impairment is a dropped foot, which is char-
acterized by the inability to dorsiflex the ankle, lead-
ing to insufficient toe clearance during walking. This
impairment, in combination with commonly seen low
selectivity of hip and knee in this patient group
results in an abnormal gait, consisting of hip hitching,
circumduction, and toe catch, also called equine gait
(2). Walking speed is impaired and there is a higher
chance of stumbling and falling.
An estimated 20% of the population with partial
recovery have a dropfoot (2). Out of 120 000 stroke
survivors in the Netherlands, 75% recover only par-
tially, that is 90 000 patients. This group of 90 000
includes approximately 18 000 patients with a
dropped foot.
The conventional treatment of drop foot is a splint,
usually a custom fitted ankle-foot orthosis (AFO),
which is a plastic support worn inside the shoe to
maintain the ankle joint in a neutral position, and
occasionally a more substantial splint attached to
the shoe. This treatment has limitations, being both
uncomfortable and awkward to use (3).
In 1961, a new method for correction of dropfoot
by means of electrical stimulation was introduced by
Liberson (4). The stimulation was applied via elec-
trodes on the skin and was synchronized with the gait
phase by a heel-switch worn in the shoe. Stimulation
was turned on when the heel was lifted at the begin-
ning of the swing phase. It then produced dorsiflex-
ion and eversion of the ankle joint. Stimulation was
turned off when the heel was on the floor again.
A number of (theoretical) advantages of FES in
comparison to an orthosis can be mentioned. The
active contraction of the muscles stimulates the
blood circulation, there is better afferent feedback,
walking distance is increased, the stimulator is not
custom made like an AFO and thus more applicable
578 A.I.R. KOTTINK ET AL.
Artif Organs, Vol. 28, No. 6, 2004
to a wide range of people, and finally the stimulator
is cosmetically better accepted (5). In addition, Mer-
letti mentions that walking with FES implies a more
energy efficient use of the hip and knee muscles by
avoiding the need for compensatory movements (6).
However, the FES system is more sensitive to distur-
bance and its application requires more time because
of the placement of surface electrodes.
FES is not appropriate for all stroke patients with
a dropped foot. The patient has to be well motivated,
able to stand and walk either alone or with minimal
assistance, and the muscles that raise the foot should
not be denervated. Contraindications are communi-
cation disorders, irritation of the skin, and limited
range of movement. The use of FES is not wide-
spread and the total number of patients being treated
remains quite small. This can be attributed to several
reasons, such as technical limitations and unfamiliar-
ity with FES in many countries. Technical limitations
associated with the use of surface stimulators con-
cern the lack of selectivity over the muscles and
nerves recruited, the sensitivity of muscle recruit-
ment to electrode placement, and pain and tissue
irritation associated with the passage of current
through the skin (7).
In order to improve the selectivity upon stimula-
tion responses, implantable systems are being de-
veloped (7–9). In contrast to the one-channel
implantable stimulator, the two-channel stimulator
provides separate control of the dorsiflexion and
eversion movement by stimulating both deep and
superficial peroneal nerves, respectively. For more
information about technical developments the
reader is referred to a review by Lyons et al. (10).
Preliminary trials have shown that it is possible to
balance the foot well between inversion and eversion
(8). The principle aim of implantable systems is to
establish an orthotic effect rather than producing
motor relearning effects. When motor relearning is
the main goal, surface stimulators are more indi-
cated.
Although the concept of FES of the peroneus
nerve has existed for more than 40 years, there is no
hard evidence for the positive clinical effects of this
treatment.
Glanz et al. (11) performed a meta-analysis to
assess the efficacy of FES on the force of the paretic
muscles in the rehabilitation of stroke patients. They
concluded that pooling from randomized trials sup-
ports FES as promoting recovery of muscle strength
after stroke. A second review was carried out by
Burridge et al. (12), who focussed on the orthotic
and/or therapeutic effect of FES for the correction
of dropped foot in subjects suffering from upper
motor neuron lesions. However, their review had a
descriptive character and study data were not
pooled. Another aspect is that only surface stimula-
tors to correct dropped foot were included. Their
conclusion was that patients who benefit from FES,
experience sufficient improvement in the speed
and quality of walking to increase independence
significantly.
The present systematic review was carried out to
establish the available evidence of the orthotic effect
of peroneus nerve stimulation on walking speed. All
types of stimulation approaches were included,
i.e., surface and one- and two-channel implants. The
orthotic effect is defined as the effect that occurs
during stimulation while the therapeutic (carry-over)
effect is the effect that remains even after the stimu-
lator has been removed (12). The primary outcome
measures selected from the present study are walking
speed and Physiological Cost Index (PCI), which is
a measure for energy cost.
METHODS
Literature search
A literature search was performed in PubMed, in
the Database of Abstracts of Reviews of Effective-
ness (DARE), Cochrane database, NHS Economic
Evaluation Database (NHS EED), and the Health
Technology Assessment Database (HTA) from the
NHS Centre for Reviews and Dissemination of the
University of York, U.K. The PubMed database in-
cludes literature from 1966 up to 2003. The following
keywords were used separately and combined in
PubMed: cerebrovascular accident, electric stimula-
tion, electric stimulation therapy, rehabilitation,
recovery of function, peroneal nerve, muscle spastic-
ity, walking, comparative study, cost-benefit analysis,
and evaluation study. In the other databases, the pre-
vious terms and the following additional terms were
used: dropfoot, dropped foot, ankle dorsiflexion,
hemiplegia, FES, functional electric stimulation, per-
oneus, and stroke.
Studies were included if they met the following
criteria: (1) functional electrical stimulation of the
peroneal nerve should be applied to stroke patients
with a dropped foot to improve walking; (2) transcu-
taneous or implantable stimulators should have been
used; (3) comparative trial design, comparing FES
with either another treatment or baseline status; (4)
studies examining an orthotic effect or both an
orthotic and therapeutic effect; and (5) full-length
articles in English or Dutch language published
between 1966 up to 2003. To support our evidence
we also looked for suitable proceedings of FES con-
ELECTRICAL STIMULATION TO IMPROVE WALKING IN STROKE PATIENTS 579
Artif Organs, Vol. 28, No. 6, 2004
ferences that reported on the effect of peroneal
nerve stimulation on improving walking. Because
proceedings have not passed a peer-review process,
it was decided not to include them in the pooled
analysis. However, suitable proceedings will be
described in the discussion section of the present
review.
Assessment of methodological quality
As almost no randomized controlled trials with
regard to peroneal nerve stimulation have been per-
formed it was not possible to adopt the standard set
of methodological criteria. Instead, we adapted the
set in order to be able to summarize both controlled
and uncontrolled trials. Eventually, a list of 16 criteria
was used concerning patient selection, intervention,
outcome measurement, and statistics (Appendix 1).
Two raters assessed the methodological quality of the
included studies independently (AK, LO). In case of
disagreement, consensus was reached by consulting
a third rater (MY). All criteria that were answered
with yes scored 1 point, with the exception of criteria
3, where the score varied from 1 to 3 points. When
criteria 3a, b, or c was answered with yes they, respec-
tively, scored 3, 2, and 1 point. By doing so, we
accounted for the difference in methodological supe-
riority of controlled vs. noncontrolled trials. This was
done because, from a methodological point of view,
a randomized controlled trial is better than a cross-
over design and a crossover design is better than an
observational study design. The maximum score that
could be reached was 19. Because proceedings failed
to meet the criteria that they should be full-length
publications, methodological scores were not deter-
mined for them.
Data extraction
Data was extracted from the articles and catego-
rized using the following items: study design,
patients, intervention, training, variables, measure-
ments, statistics, and miscellaneous. Then an inven-
tory was made of the different outcome measures. A
selection was made between clinical measures, i.e.,
walking speed, PCI, and intermediate outcome mea-
sures, e.g., gait kinematics and spasticity.
Data analysis
Walking speed at a self-selected pace and PCI
were considered to be the primary outcome mea-
sures. Walking speed changes in each of the articles
were summarized and a pooled difference was esti-
mated using a “random effects”-model (13). This sta-
tistical model is used in meta-analyses when both
within-study sampling error (variance) and between-
studies variation are included in the assessment of
the uncertainty (confidence interval) of the results.
Random effects models give wider confidence inter-
vals than fixed effects models when there is signifi-
cant heterogeneity among the results of the included
studies.
RESULTS
Selection of literature
The systematic literature search in PubMed
resulted in the identification of 33 articles. The search
in the other databases did not yield additional arti-
cles. Twenty-five studies were excluded from this
review. Reasons for exclusion were that the study
was not specifically about stroke patients (14–21), the
study was not specifically about dropfoot (11,22–27),
the study did not report on FES (28,29), and the
study was not a comparative trial (3,30–32). Two arti-
cles were about the same study and the second article
did not yield additional information (33). The publi-
cations from Liberson, Buurke, and Zilvold (4,5,34)
failed to meet the inclusion criteria that it should
have been full-length publications written in Dutch
or English between 1966 and 2003.
Eight studies fulfilled the selection criteria and
were included in the present review (Table 1)
(2,6–8,35–38).
In addition, three proceedings from the IFESS
conference (2000) were found that report the effect
of peroneal nerve stimulation on walking speed in
chronic stroke patients (9,39,40).
Characteristics of the included studies
Patients
The number of patients included in the selected
studies ranges from 2 to 56, with a total of 203
patients. In five studies, chronic patients were
included (2,7,8,36,38), in one study both chronic and
subacute patients were included (6), and in two stud-
ies, chronic, subacute, and acute patients were
included (35,37). The first 2 weeks after the cere-
brovascular accident has been defined as the acute
phase, the period between 2 weeks and 6 months
after the accident as the subacute phase, and the
period after 6 months has been defined as the chronic
phase. In total, 10 patients were in the acute stage,
17 patients in the subacute stage, and 176 patients in
the chronic stage after stroke.
Two of the studies were carried out in hospitalized
patients (35,38). Three patients dropped out in two
studies each (37,38). Of 203 patients, 101 were males,
44 were females, and in 58 cases the gender was not
580 A.I.R. KOTTINK ET AL.
Artif Organs, Vol. 28, No. 6, 2004
TABLE 1.
Characteristics of included studies
Author Waters (7) Merletti (6) Stefanovska (38) Bogataj (35) Granat (37) Burridge (36) Burridge (2) Kenney (8)
Study design Before/with Before/with Before/with Crossover Crossover With and without FES Experimental (RCT) Before/with
Patients
Number (dropout) 16 50 (3) 8 20 19 (3) 56 32 2 (0)
Type 12/16 CVA CVA 5/8 CVA CVA CVA 50/56 CVA CVA CVA
Age (sd) (range) 49.3 (11.3) 57.3 (12.9) 45.4 (5.9) 56.3 (10.4) 57.8 (9.4) 54 (12) 56.8 (16.6) [31–48]
Stage after stroke Chronic Chronic Subacute + chronic Acute + subacute +
chronic
Acute + subacute +
chronic
Chronic Chronic Chronic
Gender 8 male 8 female 36 male 14 female 7 male 1 female 11 male 9 female 16 male 3 female Not mentioned 23 male 9 female Not mentioned
Paretic side Not mentioned 14 right 36 left 5 right 3 left 9 right 11 left 12 right, 7 left 27 right 29 left 1 bi 17 right 15 left Not mentioned
Intervention
Treatment FES: implanted FES: transcutaneous FES: implanted FES: transcutaneous FES: transcutaneous FES: transcutaneous FES: transcutaneous FES: implanted
Control No control group No control group No control group Conventional therapy Physiotherapy No control group Physiotherapy No control group
Compared to AFO No aid No aid No aid No aid No aid No aid No aid
Training
Location At home Hospital At home Hospital At home At home At home At home
Duration 6 months 1–9 weeks 6 months 3 weeks 4 weeks 3 months 12–13 weeks 20 weeks
Intensity Daily,
individually
5 days/week,
mean 14 h
2 h/day 5
¥/
week 30min-1 h Daily, individually Daily, individually Daily, individually Daily, individually
Outcome measure
Clinical endpoint Walking speed Walking speed Walking speed Walking speed
PCI
Walking speed
PCI
Walking speed
Other outcome Stride length Spasticity
plantarflexors
Max. isometr. torque: Distance Heel strike,
inversion
Functional mobility Endurance
Cadence, EMG O
2
consumption Dorsal/plantarflexion Number of strides,
mean stride time
Symmetry Isometric torque
Kendall scale:
dorsiflexion,
eversion
Resistive torque
pas.mov.
Temporal symmetry,
mean stance time,
Fugl-Meyer ground
reaction forces
Measurements
Moments Every 3 months Every 2 weeks Every 6 months Every 3 weeks 0, 6 weeks,
11 weeks
6 weeks, 3 months,
every 6 months
0, 4–5 weeks,
12–13 weeks
0, 32 weeks
Baseline With + without
orthosis
Without aids Surf. stim. 30 min/day,
2–3 week
Not mentioned Usual aids With and without FES Usual aids + FES With/without
Usual aids
Follow-up With + without
FES
With + without FES Without FES After MFES + conv
therapy
With + without
FES
With and without FES With + without FES With FES
Statistics Not mentioned Student’s
t
-test Not mentioned MANOVA
Friedmans’ ANOVA
ANOVA, paired
t
-test Wilcoxon
Paired
t
-test
Fisher’s exact test
Wilcoxon,
Mann–Whitney,
Chi-square,
Spearman
Not mentioned
ELECTRICAL STIMULATION TO IMPROVE WALKING IN STROKE PATIENTS 581
Artif Organs, Vol. 28, No. 6, 2004
mentioned. Paretic side was mentioned in six studies
(2,6,35–38). Right hemiparesis was mentioned in 84
patients, left hemiparesis in 101 patients, and in 18
cases the side was not mentioned.
Study designs
Three different designs were used: one random-
ized controlled trial (RCT) (2), two crossover studies
(35,37), and five times a within-subject comparison
(6–8,36,38).
The method of FES varied between the studies. In
five studies transcutaneous stimulation was used
(2,35–38) and in the other three studies implantable
stimulation was applied (6–8).
In five studies, the patient could use the stimulator
every day at home (2,7,8,36,37). In three studies this
was not the case. In the study of Stefanovska patients
had a limit of 2 h/day to use the stimulator, Bogataj
used treatment sessions of 30 min to 1 h for 5 days
per week and the patients in the study of Merletti
used the stimulator for 1–4 h for 5 days per week.
Outcome measures
In the eight included studies a total of 20 different
outcome measures were used. Walking speed was
measured in six studies (2,7,8,35–37) and PCI was
measured in two studies (2,36). Both Merletti and
Stefanovska do not have walking speed or PCI as
outcome parameters in their study.
In the present study, walking speed and PCI are
considered to be the primary clinical endpoints. The
other outcome measures like endurance, gait kine-
matics, gait kinetics, torque measurements, spasticity,
EMG, and O
2
consumption are considered interme-
diate outcome measures.
Methodological quality
Scores for methodological quality ranged from 9
to 18 out of 19 (Table 2). There was a disagreement
between both raters in 9.9% of the items. Consensus
on these items was reached by a third rater. The RCT
of Burridge (2) and the cross-over study by Granat
(37) were methodologically the best articles both
with a score of 18 points. The cross-over study of
Bogataj (35) reached the next highest score, which
scored 15 out of 19 points.
Effect of functional electrical stimulation on
walking speed
Table 3 shows the measured walking speeds with
and without FES and the difference between both
measurements. Six of the eight studies measured
comfortable walking speed (2,7,8,35–37). It was not
possible to calculate differences in walking speed
for all studies due to insufficient data presentation
(8,36). Correspondence with the authors failed to
provide the missing data.
In both studies performed by Burridge (2,36) a 10-
m walking test was used to measure walking speed.
One meter was allowed at the start and finish of the
walkway for acceleration and deceleration. In the
study of Granat (37) the length of the recorded walk
path was either 6 or 10 m, dependent on the ability
of the participating patient. They used a 1.5 m lead-
in and run-out of the test walk path instead of 1 m.
Also in the study of Kenney (8), a 6-m test was used
in both included patients. Bogataj (35) measured
walking speed over a distance of 20 m and Waters (7)
did not mention how they measured walking speed.
All studies measured walking speed three times, with
the exception of the study of Granat (37), who mea-
sured walking speed five times. Waters (7) again did
not give information about this.
In three studies, a significant improvement in
walking speed was found (2,7,35). Two other studies
only reported the percentage difference without
providing a measure of variability (8,36) and the last
study did not show a significant change (37). This
study, performed by Granat and colleagues, was the
only study that found a small decrease in walking
speed after the treatment period, from 0.94 to
0.93 m/s.
TABLE 2.
Overview of methodological scores of each of the articles. The scores are separated for each part of the list
(maximum methodological score)
Author Total (19) Part 1* (5) Part 2
(4) Part 3
(6) Part 4
§
(4) Disagreement
Waters (7) 12 2 3 4 3 2
Merletti (6) 14 3 3 4 4 1
Stefanovska (38) 9 1 3 4 1 2
Bogataj (35) 15 4 3 4 4 1
Granat (37) 18 5 3 6 4 2
Burridge I (36) 13 3 1 6 3 2
Burridge II (2) 18 5 3 6 4 2
Kenney (8) 9 1 2 5 1 3
*Patient selection;
Intervention;
Outcome measures;
§
Statistics.
582 A.I.R. KOTTINK ET AL.
Artif Organs, Vol. 28, No. 6, 2004
The pooled improvement in walking speed was
0.13 m/s (0.07–0.2) or 38% (22.18–53.8).
Figure 1 shows the effect of the stimulator on
walking speed for each of the articles with its mean
and the 95% confidence interval. The methodologi-
cal score is included in brackets. There seems to be
no clear relation between methodological quality
of the studies and the reported effect of functional
electrical stimulation.
Effect of functional electrical stimulation on
Physiological Cost Index (PCI)
Two of eight studies, both carried out by Burridge,
measured PCI (2,36). The first study showed a
decrease of 39.5% in PCI, comparing PCI with and
without stimulation after 3 months. There was no sig-
nificant change in PCI over 3 months either with or
without the stimulator. The second study, which was
a RCT, showed an improvement of 24.9% in the FES
group when the stimulator was used, in a period of
12–13 weeks. Improvement was also measured in the
control group with a reduction of 1% in PCI.
DISCUSSION
In the present review, the results of eight studies
were analyzed in order to assess the orthotic effect
of FES on the improvement of walking in stroke
patients with a dropped foot. Six of the eight studies
measured walking speed and five of them suggest a
positive effect of FES on walking. These studies, with
the exception of the study performed by Waters,
made a comparison between walking with and with-
out stimulation. Waters and associates made a com-
parison between walking speed preoperative with an
orthosis and walking speed after surgery with stimu-
lation. They found that walking speed was increased
significantly (36%) by stimulation (7).
In conclusion, FES seems to have a positive
orthotic effect on walking, also when compared with
the conventional treatment. The type of stimulator
(i.e., transcutaneous or implanted) seems not to influ-
ence the walking speed.
Also the proceedings, which were not included in
the pooled analysis, showed a positive effect of per-
oneal nerve stimulation on walking speed. Haugland
and colleagues (9) found that the orthotic effect on
walking speed seen with an external stimulator was
variable, probably depending on the exact placement
of the electrodes, but for an implanted stimulator was
almost constant and at the level of the strongest
effect obtained with the external stimulator. No ther-
apeutic effect was found.
In a study performed by Matsunaga et al. (39), all
six patients were able to walk faster and longer when
using the stimulator system. Their patients showed a
mean improvement of 14.8% in walking speed.
Mann and colleagues (40) also measured the effect
of peroneal nerve stimulation alone, but then also in
TABLE 3.
Walking speed
Author
n
Methodological
quality Stimulator
Before (m/s)
mean (sd)
After (m/s)
mean (sd)
Difference (m/s)
mean (sd)
Difference (%)
mean (95% CI)
Waters (7)* 16 12 Implanted 0.58 (0.25) 0.79 (0.26) 0.21 (0.1) 36 (16.7–55.7)
Bogataj (35)
C 10 15 Transcutaneous 0.23 (0.13) 0.26 (0.11) 0.20 (0.07) 104 (59.4–149.2)
I 10 0.19 (0.09) 0.41 (0.21)
Granat (37)
16 18 Transcutaneous 0.94 (0.63) 0.93 (0.59)
-
0.01 (0.21)
-
0.8 (
-
46.2–44.6)
Burridge I (36)
§
56 13 Transcutaneous 14
Burridge II (2)
#
C 16 18 Transcutaneous 0.48 (0.25) 0.51 (0.27) 0.1 (0.04) 14 (
-
36.4–64.5)
I 16 0.64 (0.46) 0.77 (0.43)
Kenney (8)
2 9 Implanted 27
*Before with orthosis, after with stimulation.
Difference between assessment 1 (baseline) and 2 (C: conv. therapy, I: conv. therapy and FES).
Linoleum surface, session 2 is used as before, session 3 with PS as after.
§
After 3 months, difference between with and without stimulation.
#
Before FES group without stimulation, after FES group with stimulation.
Mean of two subjects.
C, control group; I, intervention group.
FIG. 1.
Methodological quality and difference in walking speed
(%). Mean and 95% confidence interval is presented.
–100 50 0 50 100 150 200
Difference in walking speed (%)
Author and methodological
quality
Kenney (9)
Waters (12)
Burridge I (13)
Bogataj (15)
Granat (18)
Burridge II (18)
Pooled
ELECTRICAL STIMULATION TO IMPROVE WALKING IN STROKE PATIENTS 583
Artif Organs, Vol. 28, No. 6, 2004
combination with stimulating a second channel.
Selection of the second muscle group was based on
clinical observation. Their results indicate a signifi-
cant therapeutic and orthotic effect on walking speed
from using a second channel of stimulation, greater
than that achieved with single channel stimulation
alone.
Choice of patients
Only 6 of 203 patients dropped out, which is quite
remarkable. Two studies described how almost all
patients continued to use the stimulator after the trial
had ended (2,36). These findings might indicate that
the use of the stimulator is not too difficult and
patients are satisfied with the effects. Another expla-
nation might be that the selection procedure for
patients was successful. It is well known from the
literature that “FES” is a useful orthotic device
for a selected subpopulation of hemiplegic patients.
According to Merletti and colleagues (6) and Graca-
nin (41), about 20% of the ambulant hemiplegic
population benefits from common peroneal nerve
stimulation during the rehabilitation period. Granat
(37) concludes that a stimulator applied in the late
stage of rehabilitation would be helpful to a few
patients (2%), particularly in patients with mediolat-
eral instability of the foot and reduced ground clear-
ance in swing leading to forefoot contact. According
to Burridge (2) and Waters (7) the stimulator does
not work for everyone, although they did not men-
tion which criteria a patient should fulfill to be suit-
able. Carnstam et al. (14) found that careful selection
led to a 94% success rate.
In conclusion, there seems to be no consensus
about subgroup-specific effects of peroneal nerve
stimulation. There is an idea that people with higher
initial walking speed perform better than people with
lower initial walking speed. However, this could not
be confirmed in the present study, because individual
walking speed data was not mentioned in the
included studies. Only the study performed by
Bogataj and associates (35) reported the individual
walking speed data of all participants. These data
showed no distinct relation between the initial walk-
ing speed of patients and their improvement after the
use of FES.
Included studies
Unfortunately, literature justifying the use of stim-
ulation to correct dropped foot is mainly based on
case studies, uncontrolled trials, and retrospective
reviews. In the present review only one RCT was
included (2), which is obviously the most reliable
design to separate specific from nonspecific effects.
They have become the gold standard for the evalua-
tion of treatment efficacy (42–44). Five of the eight
included studies were open label studies, which
means that there was no control group (6–8,36,38).
The two remaining studies were crossover studies
(35,37), whose designs could be a problem in com-
parative trials using FES, because of a possible carry-
over effect (45).
For the present review it was assumed that
although nonrandomized studies have methodologi-
cal problems, they could actually produce effect
sizes as generated in randomized studies. In this
review, most of the patients (176/203) were in the
chronic stage after stroke. The chance of spontane-
ous recovery in these patients is negligible so an
observed effect can not easily be attributed to this.
Therefore, correction for natural recovery by ran-
domization does not seem to be essential. Two stud-
ies measured not only chronic stroke patients, but
also acute and subacute patients (35,37). Particularly
remarkable is the difference in walking speed mea-
sured at baseline between both studies. The dif-
ference between Bogataj (35) and Granat (37) is
0.73 m/s or 3.5 times faster (Table 3). Bogataj did
not mention details of baseline measurements so the
difference cannot be explained by baseline measure-
ment or selection procedure.
The pooled analysis of both controlled and un-
controlled trials showed an improvement of 38%
in walking speed with a confidence interval of
22.18–53.8%.
Perry et al. (46) made a classification of walking
handicap in the stroke population. They described
how the least limited community walkers should
walk with a mean velocity of 0.58 m/s. Unlimited
community walkers should walk with a mean velocity
of 0.8 m/s. So, an improvement of 0.22 m/s is clini-
cally relevant according to Perry. Stroke patients who
normally use a peroneus stimulator, especially those
who use an implantable stimulator, are relatively
good patients and are not very limited in their daily
activities. The studies performed by Waters (7) and
Bogataj (35) managed to approach this size of im-
provement. They measured a mean improvement of,
respectively, 0.21 m/s and 0.20 m/s.
An alternative way of looking at the results is to
consider the percentage change. Burridge et al. (2)
decided that a 10% improvement in walking speed
was considered to be functionally relevant. In the
present study, this improvement is reached by all
studies, with the exception of the study performed by
Granat (37), who measured a worsening in walking
speed of
-
0.8%.
584 A.I.R. KOTTINK ET AL.
Artif Organs, Vol. 28, No. 6, 2004
Orthotic vs. therapeutic benefit
The present review was only focussed on the
orthotic effect of FES on walking speed in stroke
patients with a dropped foot.
Another interesting aspect to investigate is the
possible therapeutic or carryover effect of FES,
which can be defined as the benefit gained following
a period of stimulation. Liberson and associates
noted that when footdrop was corrected in hemiple-
gic patients by means of electrical stimulation using
cutaneous electrodes, some retained the ability to
dorsiflex for varying lengths of time after stimulation
was stopped (4). Waters et al. (7) observed the same
phenomenon in some of their patients. They found
an improvement in gait velocity without stimulation,
compared with the velocity without an orthosis
before surgery. The testing of these patients took
place immediately after walking with stimulation.
The review of Burridge et al. (12) also concluded that
some studies (14,47,48) reported a carryover effect,
which consisted of increased voluntary movement
and reduced spasticity, but that it is unclear how this
occurs, whether this effect is permanent, or how suit-
able patients can be identified. Many of the included
studies were with small samples and few used con-
vincing methodology.
Overall, the literature shows no convincing thera-
peutic effect of peroneal nerve stimulation. When
realization of a therapeutic effect is the main goal,
which might especially be the case in acute stroke
patients, surface stimulators are more indicated than
implantable stimulators. Surface stimulators are
therefore useful devices for gait training in acute
patients at rehabilitation centers. Due to the difficul-
ties involved in proper electrode placement, training
in the home situation is often cumbersome in the
beginning. Good instructions from a care profes-
sional are needed for this. Another advantage of
using the stimulator at home is that therapy duration
is not limited, so that patients can practice as much
as they want. The prescription of an implantable per-
oneal nerve stimulator is only a treatment option
when the main goal is to realize an orthotic effect for
the longterm in drop foot patients. In these patients,
an implantable stimulator offers greater comfort
when compared to a surface stimulator.
Conventional treatment
In the present review, only three of the eight stud-
ies included a control group (2,35,37). The control
group in the study of Burridge (2) and Granat (37)
both received physiotherapy. As only Granat
described the patients as receiving their normal phys-
iotherapy during the control period, it was not
possible to examine if there was a difference in treat-
ment intensity between both studies. The conven-
tional treatment in the study of Bogataj (35) was
much more comprehensive, consisting of physical
therapy, medical treatment, occupational therapy,
speech therapy, sessions with a psychologist, sessions
with a social worker, and a cultural program. These
studies show that different conventional treatments
exist with a large variation in intensity to treat stroke
patients with a dropped foot, which makes it difficult
to compare their results.
Dropped foot is conventionally corrected by splint-
ing. As far as we know, only one (placebo-controlled)
randomized clinical trial (49) has been performed to
examine the effect of an AFO on walking ability in
stroke patients. Beckerman et al. included 60 patients
and they combined treatment with a polypropylene
AFO, thermocoagulation (TH), placebo-AFO, and
placebo-TH treatment, which resulted in four groups.
The results show that the efficacy of both therapeutic
interventions appears to be neither statistically
significant nor clinically relevant. Only in the AFO
group was there a small but clinically irrelevant
increase of 0.1 m/s in comfortable and maximum
walking speed in comparison with the placebo-AFO
group. Also, two thirds of all included patients were
unsatisfied with the use of the AFO, as measured with
the Sickness Impact Profile.
An
interesting
aspect
that
has
not
been
clarified
yet
is the additional value of a peroneus stimulator in
comparison with an AFO. Numerous (observational)
studies have reported the effect of using an AFO or
FES separately, but Mann et al. (50) has made a
comparison between both treatments. In this study
chronic stroke patients were randomly assi-gned to
use either an AFO or a surface stimulator for 12
weeks to manage their dropped foot. Significant im-
provements in walking speed, endurance, and mo-
bility were observed after 12 weeks in both groups.
The FES group showed a significant carryover effect
in their unaided walking past 12 weeks, which was
not observed in the AFO group. Also a larger trend
towards improved PCI was observed in the FES
group compared to the AFO group. These results
support the hypothesis that FES may have a greater
training effect than simply using an AFO to correct
a dropped foot in chronic stroke patients. However,
further work is required to investigate this more
comprehensively.
CONCLUSION
FES seems to have a positive orthotic effect on
walking speed and PCI. The pooled effect size for
ELECTRICAL STIMULATION TO IMPROVE WALKING IN STROKE PATIENTS 585
Artif Organs, Vol. 28, No. 6, 2004
walking speed was 0.13 m/s (0.07–0.2 m/s) or
38%(22.18–53.8%).
Walking speed seems also to increase when FES is
compared with an AFO. In the literature it is not clear
what proportion might benefit from FES. Future stu-
dies should report on suitability criteria for patients.
PCI was found to decrease in two studies (2,36). In
one study, there was a significant decrease in PCI
with and without stimulation after 3 months (36). No
significant changes were found when comparing PCI
before and after treatment. Although patients often
reported that walking was less fatiguing, this seemed
to be a psychological effect.
Acknowledgments:
The authors acknowledge sta-
tistical advice from Mrs. Karin Groothuis, Roessingh
Research and Development.
REFERENCES
1. Available at: http://www.hartstichting.nl/go/default.asp?mID
=
5558. Accessed April 2, 2004.
2. Burridge JH, Taylor PN, Hagan SA, Wood DE, Swain ID. The
effects of common peroneal stimulation on the effort and
speed of walking: a randomized controlled trial with chronic
hemiplegic patients.
Clin Rehabil
1997;11:201–10.
3. Taylor PN, Burridge JH, Dunkerley AL, et al. Patients’ per-
ceptions of the Odstock Dropped Foot Stimulator (ODFS).
Clin Rehabil
1999;13:439–46.
4. Liberson WT, Holmquest ME, Scot D, Dow M. Functional
electrotherapy: stimulation of the peroneal nerve synchro-
nized with the swing phase of the gait of hemiplegic patients.
Arch Phys Med Rehabil
1961;42:101–5.
5. Buurke JH, Schlecht M, Bouwman R. Ist der peronaeus-
stimulator eine sinnvolle alternative zur unterschenkelor-
these? Technik, anwendung und ergebnisse.
Med Orth Tech
1990;110:60–3.
6. Merletti R, Andina A, Galante M, Furlan I. Clinical experi-
ence of electronic peroneal stimulators in 50 hemiparetic
patients.
Scand J Rehabil Med
1979;11:111–21.
7. Waters RL, McNeal D, Perry J. Experimental corrrection of
footdrop by electrical stimulation of the peroneal nerve.
J Bone Joint Surg Am
1975;57:1047–54.
8. Kenney L, Bultstra G, Buschman R, et al. An implantable two
channel drop foot stimulator: initial clinical results.
Artif
Organs
2002;26:267–70.
9. Haugland M, Childs C, Ladouceur M, Haase J, Sinkjaer T. An
implantable foot drop stimulator. Proceedings of the 5th
Annual Conference of IFESS, Aalborg, Denmark, 2000;59–62.
10. Lyons GM, Sinkjær T, Burridge JH, Wilcox DJ. A review of
portable FES-based neural orthoses for the correction of
drop foot.
IEEE Trans Neural Syst Rehabil Eng
2002;10:260–
79.
11. Glanz M, Klawansky S, Stason W, Berkey C, Chalmers TC.
Functional electrostimulation in poststroke rehabilitation: a
meta-analysis of the randomized controlled trials.
Arch Phys
Med Rehabil
1996;77:549–53.
12. Burridge JH, Swain ID, Taylor PN. Functional electrical stim-
ulation. a review of the literature published on common per-
oneal nerve stimulation for the correction of dropped foot.
Rev Clin Gerontol
1998;8:155–61.
13. DerSimonian R, Laird NM. Meta-analysis in clinical trials.
Control Clin Trials
1986;7:177–88.
14. Carnstam B, Larsson LE, Prevec TS. Improvement of gait
following functional electrical stimulation. I. Investigations on
changes in voluntary strength and proprioceptive reflexes.
Scand J Rehabil Med
1977;9:7–13.
15. Kljajic M, Malezic M, Acimovic R, et al. Gait evaluation in
hemiparetic patients using subcutaneous peroneal electrical
stimulation.
Scand J Rehabil Med
1992;24:121–6.
16. Stefanovska A, Vodovnik L, Gros N, Rebersek S, Acimovic-
Janezic R. FES and spasticity.
IEEE Trans Biomed Eng
1989;36:738–45.
17. Tabeke K, Basmaijan JV. Gait analysis in stroke patients to
assess treatments of foot-drop.
Arch Phys Med Rehabil
1976;57:305–10.
18. Tabeke K, Kukulka C, Narayan MG, Milner M, Basmaijan JV.
Peroneal nerve stimulator in rehabilitation of hemiplegic
patients.
Arch Phys Med Rehabil
1975;56:237–9.
19. Taylor PN, Burridge JH, Dunkerley AL, et al. Clinical use of
the Odstock Dropped Foot Stimulator: its effect on the speed
and effort of walking.
Arch Phys Med Rehabil
1999;80:1577–
83.
20. Taylor P, Burridge J, Dunkerley A, et al. Clinical audit of 5
years provision of the Odstock Dropped Foot Stimulator.
Artif Organs
1999;23:440–2.
21. Voigt M, Sinkjaer T. Kinematic and kinetic analysis of the
walking pattern in hemiplegic patients with foot-drop using a
peroneal nerve stimulator.
Clin Biomech (Bristol, Avon)
2000;15:340–51.
22. Bogataj U, Gros N, Malezic M, Kelih B, Kljajic M, Acimovic
R. Restoration of gait during two to 3 weeks of therapy with
multichannel electrical stimulation.
Phys Ther
1989;69:319–27.
23. Daly JJ, Ruff RL, Haycook K, Strasshofer B, Marsolais EB,
Dobos L. Feasibility of gait training for acute stroke patients
using FNS with implanted electrodes.
J Neurol Sci
2000;
179(Suppl 1–2):103–7.
24. Daly JJ, Ruff RL. Electrically induced recovery of gait com-
ponents for older patients with chronic stroke.
Am J Phys Med
Rehabil
2000;79:349–60.
25. Malezic M, Bogataj U, Gros N, Kelih B, Kljajic M, Acimovic-
Janezic R. Evaluation of gait with multichannel electrical stim-
ulation.
Orthopedics
1987;10:769–72.
26. Malezic M, Bogataj U, Gros N, et al. Application of a pro-
grammable dual-channel adaptive electrical stimulation sys-
tem for the control and analysis of gait.
J Rehabil Res Dev
Fall
1992;29: 41–53.
27. Strojnik P, Acimovic R, Vavken E, Simic V, Stanic U. Treat-
ment of drop foot using an implantable peroneal underknee
stimulator.
Scand J Rehabil Med
1987;19:37–43.
28. Levin MF, Hui-Chan CW. Relief of hemiparetic spasticity by
TENS is associated with improvement in reflex and voluntary
motor functions.
Electroencephalogr Clin Neurophysio
1992;
85:131–42.
29. Veltink PH, Ladouceur M, Sinkjaer T. Inhibition of the triceps
surae stretch reflex by stimulation of the deep peroneal nerve
in persons with spastic stroke.
Arch Phys Med Rehabil
2000;81:1016–24.
30. Burridge JH, McLellan DL. Relation between abnormal pat-
terns of muscle activation and response to common peroneal
nerve stimulation in hemiplegia.
J Neurol Neurosurg Psychia-
try
2000;69:353–61.
31. Kumar VP, Lau HK, Liu J, Pereira BP, Pho RW. Clinical
applications of functional electrical stimulation.
Ann Acad
Med Singapore
1995;24:428–35.
32. Rozman J, Acimovic-Janezic R, Tekavcic I, Kljajic M, Trlep
M. Implantable stimulator for selective stimulation of the
common peroneal nerve: a preliminary report.
J Med Eng
Technol
1994;18:47–53.
33. Waters RL, McNeal DR, Faloon W, Clifford B. Functional
electrical stimulation of the peroneal nerve for hemiplegia.
Long-term clinical follow-up.
J Bone Joint Surg Am
1985;67:
792–3.
586 A.I.R. KOTTINK ET AL.
Artif Organs, Vol. 28, No. 6, 2004
34. Zilvold G.
Functionele Electrostimulatie Van De Nervus Pero-
neus.
Meppel: Krips Repro, 1976.
35. Bogataj U, Gros N, Kljajic M, Acimovic R, Malezic M.
The rehabilitation of gait in patients with hemiplegia: a
comparison between conventional therapy and multichan-
nel functional stimulation therapy.
Phys Ther
1995;75:490–
502.
36. Burridge J, Taylor P, Hagan S, Swain I. Experience of clinical
use of the Odstock Dropped Foot Stimulator.
Artif Organs
1997;21:254–60.
37. Granat MH, Maxwell DJ, Ferguson AC, Lees KR, Barbenel
JC. Peroneal stimulator; evaluation for the correction of spas-
tic drop foot in hemiplegia.
Arch Phys Med Rehabil
1996;77:
19–24.
38. Stefanovska A, Gros N, Vodovnik L, Rebersek S, Acimovic-
Janezic R. Chronic electrical stimulation for the modification
of spasticity in hemiplegic patients.
Scand J Rehabil Med
Suppl
1988;17:115–21.
39. Matsunaga T, Shimada Y, Sato M, et al. The akita heel sensor
system (AHSS) for the correction of dropped foot gait in
hemiplegic patients. Proceedings of the 5th Annual Confer-
ence of IFESS, Aalborg, Denmark, 2000;394–5.
40. Mann GE, Burridge JH, Ewins DJ, et al. Optimising two
channel stimulation to improve walking following stroke. Pro-
ceedings of the 5th Annual Conference of IFESS, Aalborg,
Denmark, 2000;452–5.
41. Vodovnik L, Bajd T, Kralj A, Gracanin F, Strojnik P. Func-
tional electrical stimulation for control of locomotor systems.
Crit Rev Bioeng
1981;6:63–131.
42. Byar DP, Simon RM, Friedewald WT, et al. Randomized
clinical trials: perspectives on some recent ideas.
N Engl J Med
1976;295:74–80.
43. Feinstein AR. Current problems and future challenges in ran-
domized clinical trials.
Circulation
1984;70:767–74.
44. Abel U, Koch A. The role of randomization in clinical studies:
myths and beliefs.
J Clin Epidemiol
1999;52:487–97.
45. IJzerman MJ, Baardman G, Hermens HJ, Veltink PH, Boom
HBK, Zilvold G. Comparative trials on hybrid walking sys-
tems for people with paraplegia: an analysis of study method-
ology.
Prosthet Orthot Int
1999;23:260–73.
46. Perry J, Garrett M, Gronley JK, Mulroy SJ. Classification of
walking handicap in the stroke population.
Stroke
1995;26:
982–9.
47. Stefancic M, Rebersek M, Merletti R. The therapeutic effects
of the Ljubljana functional electronic brace.
Eur Medicophys
1976;12:1–9.
48. Merletti R, Zelaschi F, Latella D, Galli M, Angeli S, Sessa
MB. A control study of muscle force recovery in hemiparetic
patients during treatment with functional electrical stimula-
tion.
Scand J Rehabil Med
1978;10:147–54.
49. Beckerman H, Becher J, Lankhorst GJ, Verbeek AL. Walking
ability of stroke patients: efficacy of tibial nerve blocking and
a polypropylene ankle-foot orthosis.
Arch Phys Med Rehabil
1996;77:1144–51.
50. Mann GE, Wright PA, Swain ID. Training effects of electrical
stimulation and the conventional ankle foot orthosis in the
correction of drop foot following stroke. FESnet Abstract
Submission 2000.
APPENDIX I. CRITERIA LIST FOR ASSESSMENT OF METHODOLOGICAL QUALITY
Patient selection
1. Were the eligibility criteria specified? Yes/No/Don’t know
2. Was the selection procedure described? Yes/No/Don’t know
3. Was the design of the study:
a) a randomized controlled trial? Yes: score 3
No
b) a crossover? Yes: score 2
No
c) open label? Yes: score 1
Intervention
4. Was the index intervention explicitly described? Yes/No/Don’t know
5. Were cointerventions avoided of comparable? Yes/No/Don’t know
6. Was the compliance acceptable in all groups? Yes/No/Don’t know
7. Was the baseline described? Yes/No/Don’t know
Outcome measurements
8. Were the outcome measures relevant? Yes/No/Don’t know
9. Were adverse effects described? Yes/No/Don’t know
10. Was the withdrawal/dropout rate described and acceptable? Yes/No/Don’t know
11. 1) Was a short-term follow-up measurement described? Yes/No/Don’t know
Short-term
£
2 months
2) Was a long-term follow-up measurement described? Yes/No/Don’t know
Long-term
2 months
12. Were outcomes standardized? Yes/No/Don’t know
Statistics
13. Was the sample size for each group described? Yes/No/Don’t know
14. Is the number of patients at least 15? Yes/No/Don’t know
15. Were point estimates and measures of variability presented for the primary outcome measures? Yes/No/Don’t know
16. Were statistical tests performed and described? Yes/No/Don’t know
    • "The primary outcome parameter of this study was achievement of voluntary ankle dorsiflexion at the paretic side, which represents selective motor control. Previous studies have shown that FES has a positive orthotic effect on walking ability in chronic stroke subjects [9,13,24] . The application of electrical stimulation via surface electrodes restores motor functions, reduces muscle tonicity via the reduction of the stretching reflex, causing lower spasticity and allowing a larger range of motion [26][27][28]and preventing soft tissue stiffness and contracture [29]. "
    Full-text · Dataset · May 2016
    • "Today, FES is the main choice to help foot drop patient walk. There are many FES for foot drop available in the market, varying from removable to surgical FES system [7]. Conventional Functional Electric Stimulation (FES) systems available in the market basically consist of electronic stimulators, sensors and stimulation electrodes. "
    [Show abstract] [Hide abstract] ABSTRACT: This paper describes the initial concept of functional electrical stimulation (FES) for foot drop injury based on the arm swing motion. The prototype was an effort to improve the existing FES available in the market that are facing problems due to the error of detecting a step intention, especially in the acute stage of foot drop injury due to stroke. The development of the device was divided into two main phases: hardware design and testing. Hardware phases consisted of the design of the electronic structure and parts such as accelerometer ADXL335 and programming for PIC18F4520. Initial testing was conducted with six normal subjects and one foot drop patient subject in order to identify the functional performance of the prototype. The result shows that the gait sensing placement of the prototype FES was successfully controlled by using the arm swing movement.
    Full-text · Article · Dec 2015
    • "Through electrical stimulation of the ankle dorsiflexors and evertors during the swing phase and early stance phase of gait, foot clearance, heel loading and roll off are almost normally regulated . The use of FES does not limit passive or active ankle movements and, thus, promotes normal sensory feedback, dynamic balance (especially on uneven terrain), and push-off (Fatone et al., 2009; Kottink et al., 2004; Ring et al., 2009). Three recent, large randomised controlled trials (Bethoux et al., 2014; Everaert et al., 2013; Kluding et al., 2013) have shown that surface-based peroneal FES is at least as effective as an AFO for improving walking velocity and various other aspects of balance and mobility in people with drop foot in the chronic phase of stroke. "
    [Show abstract] [Hide abstract] ABSTRACT: Purpose: To investigate whether an implantable functional electrical stimulation (FES) system of the common peroneal nerve (ActiGait®) improves relevant aspects of gait in chronic stroke patients with a drop foot typically using an ankle-foot orthosis (AFO). Methods: Ten community-dwelling patients participated, of whom eight patients could be analysed. Gait quality (kinematic, kinetic, and spatiotemporal characteristics) during a 10-meter comfortable walk test, normalised net energy expenditure during a 6-minute walk test, participation (physical activity and stroke impact) and user satisfaction were tested before implantation and at various moments after FES-system activation up to 26 weeks. Results: Walking with FES yielded increased maximum paretic ankle plantarflexion (FES: -0.12; AFO: -4.79°, p < 0.01), higher paretic peak ankle power (FES: 1.46; AFO: 0.98 W/kg, p < 0.05) and better step length symmetry (FES: 14.90; AFO: 21.45% , p < 0.05). User satisfaction was higher for FES, but was unrelated to objective gait improvements. Energy expenditure and participation did not change. Conclusion: Implantable FES improved the use of residual ankle plantarflexion motion, ankle power of the paretic leg and step length symmetry compared to using an AFO, however, not resulting in decreased energy expenditure or improved participation. User satisfaction was highest with FES, but this was not related to the observed gait improvements.
    Full-text · Article · Oct 2015
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