1 Toronto
Rehabilitation Institute, Canada
2 Institute of
Biomaterials and Biomedical Engineering, University of Toronto, Canada
Introduction
In this study functional electrical
stimulation (FES) was used with patients with complete and incomplete spinal cord
injuries (SCI) in an effort to facilitate improved hand function. By improving
a patient’s ability to grasp and release everyday objects we hoped to see
increased independence in activities of daily living (ADL). It was anticipated
that the application of daily FES training, in addition to regular occupational therapy (OT) and
physiotherapy (PT), would facilitate the restoration of neurological function
in the wrist or fingers. We were examining the carryover effect of using a neuroprosthesis for grasping in our patients. The results
were compared to controls that received regular physiotherapy and occupational
therapy which included electrical stimulation for muscle strengthening without
the functional component. By doing this study we hoped to answer the following
questions: What is the best way to apply FES to restore hand function and maximize functional independence?
1. Materials and Methods
1.1 Participants
Patients were either complete or
incomplete SCI, ranging from C4 to C7. At admission to the study participants
had no functional hand movement. They either had no voluntarily movement in
their wrist and/or fingers, or may demonstrated flickers of movement up to
grade 2- . The participants were recruited to the program within seven months
of their date of injury.
Patients were randomly divided into two
groups: Group A - patients that were trained with the neuroprosthesis; or Group B - the control
group which received standard occupational therapy and physiotherapy
without FES. To date seven patients have signed a letter of consent and have
been recruited. Six were assigned to Group A and one
to Group B. This study is in the preliminary stages and we plan to have 40
patients in total. This research received ethics approval from the University of Toronto and
Toronto Rehabilitation Institute ethics boards in 2002.
1.2 Neuroprosthesis Hardware used in the Study
The Compex
Motion electric stimulator, developed by Popovic and
Keller in collaboration with Compex SA [1], was used
as a hardware platform for the neuroprosthesis for
grasping. This programmable FES system has four channels and applies surface stimulation technology
and provides the means to develop custom-made neuroprostheses.
In our study each patient had individualized stimulation protocol to facilitate
grasping function. Stimulation was triggered by a push button which the patient
controlled. The FES program evolved during the treatment and was adjusted according to
patient’s progress, typically every two weeks.
1.3 Stimulation
Protocols used in the Study
The neuroprosthesis
treatment consisted of a strengthening phase followed by a functional
training phase. The strengthening phase was required in the early stages
of the program for patients who demonstrated a very weak and inefficient
response to FES. This period often lasted a few weeks. Once a sufficient response
was achieved functional training began and the patient was asked to grasp and
release everyday objects, such as a can of pop, using the neuroprosthesis.
The participant repeated the same hand task 30 to 50 times during a 60-minute
treatment session. Patients had one or two treatment sessions per day, five
days per week. During the intervention, the OT adjusted the placement of
electrodes and guided the hand movements. The OT ensured that all movements
were functional, efficient and used normal movement patterns. An independent
hand strengthening and stretching program was provided as needed to facilitate
normal hand function.
Self-adhesive surface stimulation
electrodes were applied above the following muscles and nerves: 1) flexor
digitorum superficialis m. and the flexor digitorum profundus m.; 2) median
nerve, flexor pollicis brevis and opponens pollicis m.; 3) extensor digitorum
m.; 4) radial nerve, extensor carpi radialis longus and brevis, m. and extensor
capri ulnaris m. Stimulation parameters used were: 1)
balanced, biphasic, current regulated electrical pulses; 2) pulse amplitude
from 8 to 50 mA (typical values 17-26mA); 3) pulse width 250 µs; and 4) pulse
frequency from 20 to 70 Hz (typical value 40 Hz).
As soon as the patient showed signs of
recovery of the either voluntary extension or flexion in a muscle group they
were encouraged to make an effort in producing the movements voluntarily, which
were previously facilitated by the FES. The stimulation protocol promoted occasional wrist extension with
the desired finger extension. Since the majority of patients with quadriplegia
demonstrate upper extremity paralysis with spasticity in the finger flexors,
the occasional wrist extension caused by the stimulation did not disrupt the
tenodesis function. During the treatment period patients were observed to have
a decrease in spasticity in the fingers allowing better control of finger
flexion and extension.
1.4 Tests
Assessments were conducted on all seven
subjects.
Administrative test: demographic information and participants’ medical history was
collected at admission
Functional tests: Conducted pre and post injury: 1) Functional
Independence Measure (FIM); 2) Spinal Cord Independence Measure (SCIM); 3)
Passive and active range of motion; 4) Manual muscle testing; 5) Grip and pinch strength using dynamometers; 6) Nine
hole peg test; 7) Rehabilitation Engineering Laboratory Hand Function Test for
Functional Electrical Stimulation Assisted Grasping (REL)[2];
and 8) A writing sample.
Qualitative interview: interviews conducted with an independent assessor to explore
patients’ experience with FES and their perceptions of its impact on daily functioning.
2. Results
Group A:
Patient No. 1: 58-year-old male patient with C5-6
motor complete quadriplegia began the FES program approximately six months post-injury with a weak wrist
extension and no active finger movements in right arm. After three months of
daily treatments he was able to use a tenodesis grasp functionally due to
increased wrist extension strength. He also demonstrated flickers of movement
in individual finger extension. Functionally, the patient was able to grasp and
release various objects such as grapes and popcorn without use of the neuroprosthesis.
Patient No. 2: 18-year-old male with C7 incomplete quadriplegia. Admitted to FES
program one month post injury. Presented with grade 4 wrist extension, flickers of finger
flexion/extension and thumb flexion and abduction. Used
tenodesis for grasp. After 2.5 months of FES training: 1) grade 3-4
voluntary flexion, extension of all digits; 2) right
hand was stronger in finger flexion and left hand was stronger in finger
extension; and 3) fully independent in ADL.
Patient No. 3: 19-year-old male patient with C6
incomplete quadriplegia started FES treatment two months after onset of SCI. At admission he only
demonstrated a weak left tenodesis grasp and was fully dependent in ADL. After
three months of neuroprosthesis treatment he
demonstrated: 1) voluntary finger flexion, opposition and finger extension in
left arm; 2) used a power grasp voluntarily to grasp and release objects; and
3) complete independence in ADL.
Patient No. 4: 24-year-old male diagnosed with C4 complete quadriplegia started FES treatment three months post
injury. Following two months of treatment he was able to flex his left elbow
against gravity in order to assist with eating, drinking and brushing his teeth
while using a universal cuff. While wearing the neuroprosthesis
he was able to place his left hand around small objects and raise them to mouth
level. No neurological recovery was observed in the left wrist or fingers.
Patients who were not yet
discharged from the FES program at the time this article was written:
Patient No. 5: 63-year-old male with central cord syndrome (C4 incomplete quadriplegia)
admitted to the FES program one month post injury. He was fully dependent in ADL and
demonstrated no functional grasp, very weak (2-)
finger flexion, extension and thumb flexion/abduction bilaterally. After a
month of FES training the following recovery was observed in both arms: 1)
grade 4 finger flexion/extension, and thumb opposition in right hand enabling a
power grasp and fine motor control; 2) left hand was weaker than the right,
patient was able to manage gross motor activities with left hand; and 3)
increased independence in self-care.
Patient No.6: 22-year-old male with C5 complete
quadriplegia. FES was initiated three months after injury once patient demonstrated a
flicker of right wrist extension. The goal of the FES was to increase strength
and develop a tenodesis grasp. After 2 months of FES training: 1) increase
strength in wrist extension to grade 2-; and 2) able to use the neuroprosthesis independently to grasp and release objects,
unable to grasp without the neuroprosthesis.
The results can be summarized into five
points: 1) following the initial sessions with FES patients appeared motivated
to continue participating in the program; 2) objective increases in hand
flexibility, strength and dexterity were observed following FES; 3) decreased
spasticity further facilitated independent grasping abilities; 4) post FES
treatment patients increased their level of independence in ADL; and 5) the
result of the qualitative interviews indicated four main themes: patients
reported increases in hand function, greater independence in activities of
daily living, a sense of satisfaction, and reported long term commitment to the
technology to facilitate recovery. It should be noted that patients without
large functional changes in independent muscle activity could use the neuroprosthesis for functional tasks. In Figures 1 and 2
assessment scores obtained for patients 1 through 4 are presented.
Group B:
Patient No. 7: 46-year-old, male patient with C6
complete quadriplegia started standard OT and PT treatments in a rehabilitation
centre seven months after onset of SCI. After anther two months of standard
therapy his hand function remained unchanged.
3. Discussion
The study presented
suggests that a treatment consisting of repetitive execution of the grasping
tasks assisted with FES, promotes recovery of grasping function in both
complete and incomplete SCI patients. However, the recovery in incomplete SCI
patients is significantly greater compared to complete SCI patients. This
result suggests that FES may cause reorganisation in the central nervous
system after SCI, and that it promotes function recovery.
Currently we are in
the preliminary stages of this study. Our objective is to have 40 participants
(20 intervention, 20 controls). As the evidence for FES is building our goal is to apply the findings to daily
occupational therapy practice. The results of our research to date indicate the
following practices are useful to maximizing recovery: 1) individualized
stimulation programs that are monitored and adjusted by an OT; 2) a
strengthening program followed by functional training increases likelihood of
carryover; 3) FES is best complimented with regular PT and OT which includes
hand stretching and strengthening; and 4) FES treatment is an excellent therapy
that can be applied for a short period of time and can facilitate durable
results in maximizing grasping function and increasing independent living
skills.
References:
[1] Keller T., et al, Transcutaneous
Functional Electrical Stimulator “Compex Motion”,
Artificial Organs, 2002. 26(3): p. 219-223.
[2] Popovic
M.R, et al, Rehabilitation Engineering Laboratory
Hand Function Test for Functional Electrical Stimulation Assisted Grasping,
submitted to International Functional Electrical Stimulation Society
Conference, Australia, 2003
Acknowledgments: The authors wish to
acknowledge the Toronto Rehabilitation Institute, Natural Sciences and
Engineering Research Council of Canada, Connaught Foundation and McAllister Foundation
sponsorship of this research.
Figure 1: Average REL test results for
Group A before and after the treatment
Figure 2: Average FIM and SCIM test
results for Group A before and after the treatment