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9th Annual Conference of the International FES Society A Pilot Study to investigate the effects of Functional Electrical Stimulation on gait in Parkinson’s Disease Mann GE 1, Finn SM 1, Taylor PN 1
1 Department of Medical Physics & Biomedical Engineering, Salisbury District Hospital, Salisbury,Wiltshire SP2 8BJ.
Abstract
1 Introduction
Parkinson’s Disease (PD) is a progressive
Parkinson’s Disease (PD) is a progressive neurological condition resulting in motor
neurological condition which gives rise to and functional disability. Walking
motor and functional disability as a result of becomes slower, and frequently a
reduced production of the neurotransmitter,dopamine, through degeneration of the basal shuffling gait develops with reduced stride
ganglia and substantia nigra. Parkinson’s length and cadence. There are difficulties
initiating and maintaining movement and
an increased incidence of falls. Ten
slower, with reduced stride length and cadence subjects with idiopathic PD were recruited
giving rise to a shuffling gait. As the disease to the 16 week study. Following a 4 week
progresses there are difficulties initiating and baseline period each subject received
Functional Electrical Stimulation (FES)
blocks (freezing), which occur particularly in for 8 weeks to the common peroneal nerve
confined spaces. Symptoms may be relieved by of the more severely affected side.
Levodopa - based drugs, which increase the Stimulation was withdrawn for the
amount of dopamine in the body. These drugs following 4 weeks. Assessments were
become less effective as the disease progresses made of stride length, time and number of
steps to complete a 20 metre walk with a
Effect of External Cues
turn and walking distance over 3 minutes.
There is evidence that external ‘cues’– visual, Episodes of ‘freezing’ and quality of life
auditory, cognitive or sensory, may be able tocompensate for the defective internal ‘cueing measures were also recorded. Each subject
kept a falls diary.
movement, usually facilitated by dopamine Results indicate that there is no immediate
orthotic effect of electrical stimulation on
1 . 2 T h e O d s t o c k D r o p p e d F o o t
gait but that there is a significant learning
Stimulator
effect on unstimulated walking at the end
of the trea tm ent per iod wh ich is
The Odstock Dropped Foot Stimulator (ODFS) maintained for at least a month after
is a single channel footswitch controlled stimulation has been withdrawn.
neuromuscular device used to correct droppedfoot during walking. Stimulation is applied tothe dorsiflexion and eversion during the swingphase of walking.
Study hypothesis
It is hypothesised that use of electrical
stimulation of the common peroneal nerve in
patients with PD may act to provide an
appropriate external sensory cue to maintain or
improve the normal gait pattern and reduce
episodes of ‘freezing’ during gait.
9th Annual Conference of the International FES Society 2 Methods
10 subjects, 6 male and 4 female, aged 41 to 80 Subjects
years (mean = 66.7) and PD of 2 to 25 years(mean = 8.7) duration were recruited to the 10 subjects with Parkinson’s Disease who were study. Three were excluded as their primary problem was a dropped foot rather than more recruited to the study. Each subject exhibited commonly recognised symptoms of idiopathic reduced stride length and heel strike during gait and most experienced both motor blocks andepisodes of falling.
Subjects required significantly fewer steps andless time to complete the 20 metre walk at the Stimulation treatment
end of the treatment period than during the 4 Subjects received single channel FES of the week baseline period both with and without common peroneal nerve of the lower limb of stimulation. This effect was maintained at the the more severely affected side. Stimulation end of the follow up period (Tables 1&2). A was delivered by the Odstock Dropped Foot similar pattern was seen in the shuffle ratio and Stimulator (ODFS), a neuromuscular stimulator step index for the 3 minute walk (Tables 3&4).
powered by a 9 volt battery, producing a train of pulses of 300 microseconds duration at a frequency of 40Hz. Stimulation was appliedthrough PALS adhesive electrodes and assessments
Wilcoxon
triggered by a pressure sensitive switch placed Assessments
The 16 week study period comprised a 4 week baseline period without stimulation, 8 weeks with stimulation and a 4 week follow up period conducted at weeks 0, 2, 4, 8, 12, 14 and 16.
Subjects completed a 20 metre walk which Table 1: Number of steps to complete 20m Walk
included walking through a doorway, turning and walking back to the start. Two high backed assessments
Wilcoxon
chairs were placed in the walkway as obstacles to be negotiated. Subjects also completed a timed 3 minute walk over the same walkway. A video recording was made of each walk for Assessments included the motor examination of the Unified Parkinson’s Disease Rating Scale (UPDRS), the Mini-Mental State Examination(MMSE), and the PDQ 39 quality of life Table 2: Time taken to complete 20m Walk With
questionnaire. Subjects completed a falls diary assessments
Wilcoxon
The number and length of steps and time to complete the 20 metre and 3 minute walks were recorded with and without stimulation from the distinguished from the number of shuffling step movements in which the foot moved forwardbut did not clear the floor. This is referred to as The average stride length is referred to as the Table 3: Shuffle ratio – 3 minute walk.
‘step index’. This is the number of steps taken
over the distance covered in 3 minutes.
3 Results
9th Annual Conference of the International FES Society assessments
Wilcoxon
effect at all but one stage of the study. It may be that a greater distance was necessary for the effect of the stimulation to be shown with such small number of subjects. This training effect is reinforced by results showing the benefits to be maintained to the end of the follow up period The training effect may have implication for the way in which stimulation is used in this patient Table 4: Step index – 3 minute walk
group. Most subjects reported that the devicetrained them to improve gait features such asheel strike and stride length. One user reported Step index 3 min endurance walk - no stimulation
that the improvement in his unassisted walkingwas maintained through periodic use of the TREATMENTPERIOD
Subjects may have benefited from the gait re- education as an adjunct to the study. Further work is necessary to establish the mechanisms of the effects of stimulation in patients with PD and to identify which patients are likely to Figure 1: Step index – 3 minute walk, no
maintained for the period of this trial. A trialwith a control group is needed to verify thisconclusion.
Step index 3 min endurance walk - with
stimulation
References
TREATMENTPERIOD
Bagley S, Kelly B, Tunnicliffe N, Turnbull G.I., Walker G.M. The effect of visual cues Parkinson’s disease. Physiotherapy. 77(6).
facilitation of gait patterns in patient’s withParkinson’s Disease. Journal of Neurology, Figure 2: Step index – 3 minute walk, with
Neurosurgery and Psychiatry. 62(1). 22– 4 Discussion and Conclusions
Summers J.J. Ability to modulate walkingcadence remains intact in Parkinson’s For the results presented in this paper there was found to be a significant carry over effect at the Neurosurgery, and Psychiatry. 57. 1532- Jacobs A.B., Horak F.B., Nutt J.G., Obeso withdrawn. This agrees with anecdotal evidence J.A. Step initiation in Parkinson’s Disease: from study participants who reported that the stimulator acted as a training device. This Sensory Triggers. Movement Disorders.
suggests an improvement in stride length and Acknowledgements
improvement in gait pattern. Interestingly there The authors acknowledge the Parkinson’s Disease was no immediate orthotic effect for most of the 20m Walk With Turn tests at any stage ofthe study. However, the step index for the 3minute walk did reveal an immediate orthotic

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