Switch-Activated Electrically Controlled Prosthesis Following aClosed Head Injury: A Case Study
David Berbrayer, FRCP(c)
Wallis T. Farraday, CP(C), CP(N.Z.)
ABSTRACT
This article discusses the upper-extremity prosthetic treatment of a 31-year-old
male with a closed head trauma and
mild spastic quadriparesis. He demonstrated good cognition, spastic dysarthria, a right transradial (below-elbow)
amputation, left transtibial (below-knee) amputation and right ankle disarticulation (Syme) amputation. Mobility
was provided by a powered wheelchair
with a right joystick control, and he was
dependent in feeding, dressing, grooming, washing and transfers. His right
transradial residual limb was successfully fitted with a custom switch-activated prosthesis using the left index finger,
which was laterally posted, to activate
the switch and thereby open and close
the terminal device. The prosthesis allowed the patient to independently feed
with modified utensils and improved his
ability with grooming. The authors believe this is the first case report of a
powered prosthesis used in a closed
head injury.
Introduction
Reiter first demonstrated the concept
of myoelectric control of artificial
limbs (1). Presently, the advantages of
myoelectric prostheses are thought to
include improved cosmesis, function,
range of functional position, and freedom from or reduction of harnessing.
Scott proposed that existing myoelectric prostheses still demonstrate deficiencies with lack of adequate multifunction control systems, powered
components for shoulder function, and
proprioception and sensory feedback
(2).
Patients with closed head injuries
may have with a variety of neurological
deficits, including visual/speech impairments, spasticity, weakness, incoordination, and sensory and cognitive
deficits. In patients with closed head
injuries and spastic quadriparesis, the
usual outcome consists of wheelchair
mobility and dependence on an external care-giver.
The following discussion describes a
young man with intact cognition but
impaired speech and multiple limb amputations, who was successfully fitted
with a switch-activated, electrically
controlled, transradial (below-elbow)
prosthesis. It enabled him to feed and
groom himself, improving his quality
of life.
Case Report
A 28-year-old male fabric maker underwent triple-extremity amputation,
including a left transtibial (below
knee) amputation, a right ankle disarticulation (Syme) amputation and a
right transradial (below-elbow) amputation. lie remained in an acute care
rehabilitation facility for 10 months
and then was transferred to his parents
home.
He was fitted with a right transtibial
prosthesis, patellar tendon bearing
(PTB) with solid ankle cushion heel
(SACH) foot and a right ankle disarticulation prosthesis, but he was unable
to walk due to spasticity. He was
trained to drive a powered wheelchair
with a right joystick control using a passive transradial prosthesis and terminal
ring (see Figure 1
). The terminal device
acted with passive control and did not
provide any precision or coordinated
grip force that would allow him to hold
objects like a modified spoon or fork.
The left upper-extremity had severe
spasticity, preventing any isolated
movement at the shoulder, elbow and
hand. He remained totally dependent
in feeding, dressing, grooming, washing and transfers. His mother assisted,
particularly with feeding, which was a
source of frustration due to the patient's desire to become less dependent.
Trials of reducing spasticity with
physiotherapy and medication were
made over several years. It was concluded that the left upper extremity
was unable to function independently
to allow feeding, grooming and washing. Attempts to learn a one-hand technique were not possible due to spasticity. He remained dependent on attendant care and his parents for self-care.
The spasticity was more marked on his
left arm and leg and milder on his right
side. Range of motion of the right
shoulder and elbow demonstrated
good passive functional range.
Three years after the injury, a request was made to the Amputee Clinic
to provide a prosthetic device that
would improve independence with
feeding and self-grooming. The prosthetic assessment and prescription
were based on the following questions:
- Was there any motor neuron control of the right transradial residual
limb?
- Could flexors and/or extensors be
used to operate an externally controlled terminal device?
- Did the individual have the ability
to not only isolate the control functions
of the electrode sites, but to actually
position the terminal device in the correct orientation to use it?
- What options would best suit the
individual's needs?
Method
The initial prescription was an electric
switch control system for opening and
closing the terminal device, using a
Greifera terminal device with friction
control for pronation and supination.
A Muenster socket with a semi-flexible
brim was designed to allow for easy
donning (see Figure 2
). A lubricated
donning technique was used to allow
for all distal redundant tissue to be
properly contained within this interface.
Initially, a nonconventional harness
system was applied to activate the
switch control and, ultimately, the
Greifer. The harness used a waist belt,
held in place by perineal straps, with a
strap and cable leading to the activation switch. Shoulder extension and/or
elevation caused the cable to shorten,
thus activating the switch and delivering a response to the terminal device.
After a trial with this harness system, it
was found too cumbersome and awkward to operate, so it was decided to
seek an alternative control source.
As noted earlier, the left arm had
severe spasticity, restricting any isolated active control of the patient's shoulder, elbow or hand. However, the left
index finger was capable of 20 degrees
of isolated flexion and extension. Control was poor due to increased tone. A
custom orthosis with a lateral post of
the index finger was fabricated for the
left wrist, hand and fingers. The orthosis housed both an activating device and a battery for the externally powered prothesis used on his right forearm (see Figure 3
).
The lateral posting of the index finger allowed flexion and extension of
the digit while controlling transverse
motion. The flexion and extension
movements of the index finger were
capable of operating the activating device for the terminal device (see Figures 4 and 5). The activating device
consisted of two micro switches, which
opened the Greifer with partial depression of the activating device, and
closed the Greifer with full depression
of the activating device (see Figure 4
and Figure 5
). The orthosis was fabricated
from a flexible carbon acrylic composite, allowing easy donning by an assistant. The orthosis was secured to the
forearm with one inch Velcrob webbing.
After three months of training using
the Greifer, the patient was able to
hold a cup and bowl as well as a swivel
spoon and adapted fork, independently and safely. He was able to hold solid
objects, such as fruit and sandwiches,
as well as wash his face with a sponge
and assist in combing his hair with a
modified comb. His mother and the
nursing staff were incorporated into
the teaching sessions with the occupational therapist, physical therapist and
physician. The prosthetist continually
re-evaluated the prosthesis' fit and the
terminal device's degree of opening
and closing.
The patient has since returned home
and reports continued success with the
prosthesis. The Greifer was chosen to
control grip force and provide maximal
stability and precision with modified
utensils and cups. The Greifer also provides coordinated grip force for large
objects, such as sandwiches. Previously, he was unable to control any objects
with a dysfunctional contralateral left
upper extremity and a passive terminal
device on the right upper extremity.
He has achieved more self-confidence
and is retraining with a computer
course.
Discussion
Myoelectric prostheses have now become an accepted prescription in amputee clinics in North America. Millstein, et al., reported the advantages
and disadvantages of electric prostheses and compared them to body-powered prostheses (3).
Kritter suggested that 5,000 myoelectric prostheses were fitted in the
United States by 1985 and between
10,000 to 20,000 worldwide (4). Single
muscle, switch and servo-type cable
controls are now available and provide
options for external power when the
traditional two-muscle site control cannot be used (5). Recently, further advances have resulted in the development of proportional myoelectric control in which the motor voltage of a
prosthetic hand varies in direct proportion to the EMG signal, giving the amputee control over speed and force of
grip (6). Patient training requires specific expertise with team members familiar with externally powered prostheses and skilled with EMG signals
and adaptive devices (7,8). Further advances are currently being undertaken
to promote adequate proprioceptive
and sensory feedback (2).
Acquired limb loss in patients with
traumatic brain injury has been described by Stone, et. al., (9). Patients
with acquired head injuries present a
unique challenge for prosthetic fitting
due to cognitive impairment, spasticity
and communication disorders. This article describes the successful fitting of a
young multi-limb amputee with an external powered prosthesis that provided him with independence in feeding
and continued success in using
powered mobility.
It is important to consider the degree
of comprehension and underlying spasticity following a closed head trauma
that will influence the final prosthetic
fitting. Careful evaluation must determine if any remaining function of the
existing upper extremity may be used
to control an externally powered terminal device.
To achieve success, the amputee
should have intact cognition, a supportive family or attendant care system
and access to a specialized amputee facility. The presence of spasticity and
communication disorder does not necessarily preclude the prescription of a
powered upper-extremity prosthesis.
Specific goals and function must be realistic and evaluated regularly throughout the fitting process.
Acknowledgements
The authors wish to acknowledge the contribution of the Sunnybrook Centre for Independent Living amputee team for the development and training with the prosthesis. The
authors would also like to thank Carol
Knapton, secretary, Rehabilitation Department, Sunnybrook Health Science Centre,
for typing the manuscript.
Financial Disclosure Statement
In accordance with rules from the Archives,
the authors present the following disclosure
of financial statement: No commercial party having a direct or indirect interest in the
subject matter of this article has conferred
or will confer a benefit upon the authors or
upon any organization with which the authors are associated.
DAVID BERBRAYER, FRCP(C), is an
assistant professor in the department of rehabilitation medicine at the University of
Toronto, Sunnybrook Health Science Centre, 2075 Bayview Ave., North York, Ontario, Canada M4N 3M5.
WALLIS T. FARRADAY, CP(C),
CP(N. Z.), is director of prosthetics and orthotics at Sunnybrook Centre for Independent Living in Toronto, Ontario.
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