Design of a Neck Brace for Patients with ALS
Sarah Calano1, Maneesha Kumar1, Amy McNeal1, Brooke Odle2
1
BS Bioengineering (April 2006), Department of Bioengineering, University of
Pittsburgh, Pittsburgh, PA 15261, USA
2
BS Bioengineering (December 2006), Department of Bioengineering, University of
Pittsburgh, Pittsburgh, PA 15261, USA
Corresponding Author:
Mark Gartner
Phone: (412) 828-5209 ext. 200
Fax: (412) 828-5229
mgartner@enison.com
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ABSTRACT
“Dropped head syndrome” is a condition found in the elderly and individuals
suffering from several neuromuscular degenerative disorders such as amyotrophic lateral
sclerosis (ALS). Although they remain able to rotate their head laterally, weakened neck
extensor muscles do not allow them to support their head, causing them to turn to neck
brace support. ALS is a progressive disease and affects different parts of the body at
differing points in time. Thus, an individual with dropped head syndrome may be
functioning normally in nearly every other respect. No commercially available neck brace
is customized for patients suffering from ALS – instead they are normally designed for
victims of neck trauma. Thus, these braces are designed to completely immobilize the
head and specifically not allow any lateral mobility. As a result of these shortcomings,
an ALS specific neck brace was designed based on reviews of orthotists, clinicians, and
patients. Our purpose was to create a neck brace with adequate vertical support, lateral
mobility, and an open design for patients suffering from dropped head syndrome.
Keywords: dropped head syndrome, amyotrophic lateral sclerosis, neck brace
INTRODUCTION
Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a
progressive, degenerative, fatal neuromuscular disease. The disease is caused by the
degeneration of upper neurons in the motor cortex and lower motor neurons in the
brainstem and spinal cord.1 The characteristic symptoms of this disease include muscle
weakness and wasting, fasciculations, and increased reflexes. Eventually, those suffering
from ALS lose motor function in their limbs, respiratory control as a result of diaphragm
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weakness, or paralysis leading to issues with speech and swallowing. About 30,000
Americans have been diagnosed with ALS, a disease that typically affects older adults,
with a peak age of onset between 55 and 75 years2. ALS occurs in three forms: bulbar,
upper limb onset, and lower limb onset. For the purposes of our neck brace design and
its treatment for dropped head syndrome, this paper will only address the upper limb
onset.
Dropped head syndrome is caused by neck extensor weakness, and is seen in the
elderly and those suffering from one of many neuromuscular disorders such as
myasthenia gravis and ALS.3 ALS patients that suffer from dropped head syndrome are
unable to lift their chin off of their neck due to the extent of weakness in the extensors.
Generally, there are tears in the extensors that lead to the weakness. Over time, the
muscles in the front of the neck shorten, while the muscles in the back of the neck
lengthen (“R Mawhinney, personal communication, 2005”).
However, ALS does not
have only physical effects, but it also affects patients emotionally since they have no
knowledge of prevention or cure. To many patients, they feel that their condition makes
them appear mentally disabled, when there has often been no effect on their sensory
function or intellectual integrity.
To promote a more normal lifestyle for the patients and to counteract social
embarrassment, physicians have recommended that patients wear a neck brace (Figure 1).
However, for many patients it is difficult to accept the fact that they need such support,
and using one often means that they finally need to accept the fact that they suffer from
the disease (“L Talmon, personal communication, 2005”). Initially, many patients
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choose soft cervical collars, and wait to purchase more specialized neck braces like the
Headmaster Wire Frame Collar (Figure 2) when the disease further progresses.
However, none of the current neck braces out on the market are customized for
ALS patients. Upon first fitting, most braces seem to be comfortable and supportive, but
after a few hours, the patient often finds them extremely uncomfortable and takes them
off. Not only do these braces cause discomfort, but they also do not provide adequate
support for ALS patients. Therefore, the goal of our project was to create a neck brace
that was capable of restoring proper head position for individuals with decreased neck
muscle strength, allowing normal interaction with their environment. A special attempt
was made to ensure that the neck brace was comfortable and allowed lateral mobility.
METHODS
To determine the essential performance requirements of an ideal ALS specific
neck brace, clinicians and patients were consulted about important requirements and
features. Patients were interviewed about their current neck brace, the amount of time
per day that they wore the brace, the issues with their current brace, and their idea of an
ideal neck brace. Based on their suggestions, initial sketches were drawn and taken to
Hanger Orthotics and Prosthetics (Pittsburgh, PA) to be prototyped. After several design
iterations based on the feedback of Hanger personnel and ALS clinicians, prototypes
were created. In order to evaluate the effectiveness of our design solution, the prototype
was reviewed by an orthotist, multiple clinicians, and ALS patients. No prototype was
reviewed or worn by a patient until it had received approval from the clinicians.
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Design Considerations: Clinicians find that ALS patients who currently wear neck
braces encounter five main hazards: suffocation, skin irritation, overheating, difficulty
swallowing, and neck soreness/pain. Suffocation can occur when the collar material is
either collapsible or too stiff. In the first case, the head drops over the brace constricting
the neck, while in the second case, the head falls down into the brace blocking the nose
and mouth. In some cases, patients were found slumped over and their brace had cut off
their air circulation thus causing suffocation (“L Talmon, personal communication,
2005”). Skin irritation becomes an issue when patients wear the neck brace on a daily
basis. Because the neck brace is used constantly, it tends to rub against the skin, causing
breakdown. Overheating occurs when there is a lack of ventilation in the design of the
neck brace. Soft cervical collars and closed designs completely cover the neck.
Difficulty swallowing can be a result of the chin being positioned too high or because of
pressure applied to the neck area. Positioning errors can be caused by patient use errors
or by the inherent non-adjustability of the design. Pressure on the neck area is due to
neck braces that lack girth adjustability in their design and do not accommodate larger
patients. The additional neck soreness and pain encountered is due to the improper
positioning of the neck brace. Our goal was to create a neck brace that would minimize
all of these problems.
Human Factors Considerations: Because patients wear the brace while walking,
driving, and during most daily activities, it was important to consider the effects on the
user using human factors analyses.
For example, a neck brace that allows for lateral
rotation of the head is very beneficial to patients who walk with the aid of a cane. Since
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current neck braces immobilize the neck, it is difficult see when they are walking.
Because the amount of time that the brace is worn greatly depends upon how it feels,
special considerations for comfort were necessary. In order to create a brace that is
durable, effort was made to include washable or easily replaceable components.
Regulatory Considerations: This neck brace would be classified as a Class I device and
considered a “cervical orthotic”. The current neck braces, and specifically those with
wire frame designs, possess the same classification. Patent and patent application
searches were performed to make sure that no feature of the brace would infringe upon
any other product. Patients would receive access to this device through physician
recommendations and orthotic companies. According to Medicare reimbursement
protocols, patients would most likely not have to pay for the device, as it would be
covered by insurance.
Design Equipment & Materials: In addition to hand sketches, SolidWorks 2005, a 3-D
solid modeling computer aided engineering (CAE) software program, was used to
generate final drawings. This allowed for modeling the sketches in three-dimensions, so
that each prototype could be analyzed from different views.
A VICON motion tracking system was used to three-dimensionally locate a point
on the chin. Signals from a reflective marker on the chin were recorded as the head was
laterally rotated. These points were then used to trace the chin’s path of motion during
head rotation.
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Material choices for the final design were based upon low weight, high strength,
and the ability to be molded. For prototyping purposes, a stereolithography (SLA) rapid
prototyping system was used to create the sliding track mechanism from resin. The other
components of the prototype were fabricated at Hanger Orthotics and Prosthetics;
however for mass production, a casting process would most likely be used.
RESULTS
After five design iterations, our final prototype resulted in a wire frame base and
sliding track mechanism (Figure 3). Vertical support bars were place in the front, but as
far to the sides as possible. The sliding track allowed a chin piece to move within a tgroove over a total range of 60 degrees (30 degrees of head rotation to each side). The
outer chin piece was made with closed cell polyethylene foam and lined with open cell
foam (memory foam) to shape to the anatomical contours of individual users. The
posterior neck support was made from closed cell foam and was supported with low
density polyethylene plastic to prevent buckling and breakdown. Padding was placed
along the wire frame to cover the sternum and to distribute the forces evenly. Materials
chosen for the prototype were based upon availability and do not necessarily represent
final production materials (Table 1).
Throughout the design progression, clinicians and patients were interviewed on
the design and gave input and suggestions. For the two prototyped designs, formal
surveys were given to clinicians and patients to quantify the success of the design and to
clarify what features required improvement. The brace was ranked on comfort,
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functionality, appearance, and overall design and the results are represented in Tables 2
and 3.
DISCUSSION
Design Solutions
Hazards: To provide a comfortable patient interface, padding was made from
non-abrasive, non-allergenic material to prevent skin breakdown. Additionally, all
padding was designed to be easily replaceable or washable. To prevent overheating, an
open design was incorporated and the weight of the brace was minimized to less than one
pound. Non collapsible materials and adjustability were incorporated to prevent
suffocation and additional neck soreness/pain.
Human Factors: The 60 degree range of motion allowed the users to accomplish
daily activities by permitting them to rotate their head while walking or eating. To allow
easy maintenance of the device, the soft goods were designed to be replaceable or
washable every six months, resulting in a very durable design.
Design Evolution
The design progression of the ALS specific neck brace can be seen in Figure 4.
Initially, the lateral mobility was incorporated through ball and socket pivot joints at the
base of the brace (Figure 4a). However, it became clear that pivot joints do not provide
adequate support as they tend to collapse from side to side.
Through the use of the VICON motion tracking system, we were able to
determine that the chin’s arc of motion was constant and circular for 60 degrees. This
circular motion led to the design based upon a simple pivot joint at the chin (Figure 4b).
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However, the radius required for this pivot was 3.25 inches and was therefore too large to
fit underneath the chin.
Instead of the pivot design, the chin’s path of motion was used to create a tracking
system (Figure 4c). In this iteration, a chin support piece was designed to move along a
recessed track, providing up to 60 degrees of rotation. This track was attached to the wire
frame base through height adjustable bars. However, the design was deemed unfeasible
since the bars were slanted, and any adjustment would cause the chin piece to move
outward and protrude from the neck.
Design four, also our first prototype, maintained the concept of the chin track for
lateral motion (Figure 4d). The t-groove track system was instead supported through
non-adjustable front supports. Alternatively, we decided that height adjustability could
occur through various device sizes and heights of the chin piece itself. However, the
stability of this brace was an issue since the Velcro straps attached to the front supports at
an angle and pulled back at an upward angle. This angle destabilized the brace and did
not allow proper girth adjustment. Additionally, the entire pressure of the brace and head
concentrated on one point at the sternum. The pressure on this bony prominence was
unbearable for long periods of time and the brace did not have enough padding to
distribute the load.
The fifth design iteration was created after receiving the feedback of the
clinicians. In this final design, the support bars in the front of the brace were positioned
vertically and further to the sides (Figure 5). Thus, the Velcro straps attached vertically,
and pulled back directly, stabilizing the brace. At the point of pressure on the sternum,
memory foam padding was added to distribute the weight of the brace. This greatly
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increased the comfort of the device, and removed the direct pressure point on the bone.
Lastly, the chin piece was lined with memory foam to fit the anatomical contours of the
user, and to provide a more comfortable and stable support for the chin.
Conclusion
Thus, overall this neck brace design provides full vertical support while allowing for
lateral mobility. Design features including an open design, non-collapsible material, nonabrasive skin contact surfaces, and adjustability were incorporated to prevent hazards and
provide ease of use. This customized design will allow patients with amyotrophic lateral
sclerosis (ALS) and other neuromuscular degenerative diseases to participate in normal
daily activities and increase their quality of life.
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ACKNOWLEDGEMENTS
The authors would like to thank Mr. Robert Mawhinney of Hanger Orthotics and
Prosthetics, Inc for his assistance in the design and prototyping process of the neck
braces, Ms. Linda Talmon of the ALS Society of Pittsburgh for serving as our mentor and
presenting us with our design problem, Dr. Sandeep Rana and Dr. Barbara Swan of the
ALS Clinic at Allegheny General Hospital in Pittsburgh, PA for allowing us to meet with
their patients and giving us a clinician’s point of view regarding our designs, Mr. James
Joyce, an ALS patient who provided us with ample feedback on our prototype, Mr. Mike
Rose of the ALS Society of Pittsburgh for his neck brace design insight, Mr. Mark
Gartner, Professor of the University of Pittsburgh’s Bioengineering Senior Design
Course, for his continuous feedback on the progress and documentation of our project,
and the Bioengineering Department at the University, Dr. Hal Wrigley, and Dr. Linda
Baker for their generous financial gift used to fund this project.
REFERENCES
1. Charles T, Swash M. Amyotrophic lateral sclerosis: current
understanding. Journal of Neuroscience Nursing 2001; 33(5): 24553.[PubMed]
2. Walling, A, MD. Amyotrophic Lateral Sclerosis: Lou Gehrig’s Disease.
American Family Physician March 15, 1999:59(6). Retrieved November
28, 2005 from http://www.aafp.org/afp/990315ap/1489.html.
3. Gourie-Devi M, MD, Nalini A, Sandhya S. Early or late appearance of
“dropped head syndrome” in amyotrophic lateral sclerosis. Journal of
Neurology and Psychiatry 2003; 74: 683-686.[PubMed]
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Note: This appendix page will not appear in the actual article. It’s just here for
reviewing purposes because the tables, figures, and figure legends must be on
separate pages, but referenced in the article.
Appendix
1.
2.
3.
4.
5.
6.
7.
Figure 1
Figure 2
Figure 3
Figure 4
Figure Legend
Table 1
Table 2
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(a)
(b)
(c)
Figure 1. Current Neck Braces used by ALS patients.
(a) Philadelphia C-Breeze Collar
(b) Executive Collar
(c) Aspen Cervical Collar
Figure 2. Headmaster Cervical Collar.
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(a)
(b)
(c)
(d)
Figure 3. Final Prototype of the ALS Neck Brace.
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(a) Design Iteration 1
(b) Design Iteration 2
(c) Design Iteration 3
(d) Design Iteration 4
Figure 4. Neck brace design progression
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Figure Legend
Figure 1. Current Neck Braces used by ALS patients.
(a) Philadelphia C-Breeze Collar
(b) Executive Collar
(c) Aspen Cervical Collar
Figure 2. Headmaster Cervical Collar.
Figure 3. Final Prototype of the ALS Specific Neck Brace.
(a) Front view of the final prototype
(b) Side view of the final prototype
(c) View of the posterior support of the neck brace
(d) View of the chin piece of the neck brace
Figure 4. Evolution of the Neck Brace
(a) Design Iteration 1 of the neck brace
(b) The results of the motion test (left); Design Iteration 2 of the neck brace (right)
(c) The track mechanism (left); Design Iteration 3 of the neck brace (right)
(d) Front view (left) and side view (right) of the first prototyped neck brace
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Table 1. Materials used for the current prototype and ideal materials for
manufacturing
Brace Component
Wire Frame Base
Prototyped Brace
Steel
Actual Brace
Aluminum wire or High
Density polyethylene
Track
WaterShed 11120 Resin
Any material with a low
coefficient of friction
that can be cast
Padding
Temperfoam, Plastazote,
Closed cell foam,
Surgical tubing
Temperfoam, Plastazote,
Closed cell foam,
Surgical tubing
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Table 2. Clinician survey (n=2) results for Design 4 (Prototype 1)
Topic
Functionality
Comfort
Appearance
Overall Design
Clinician Score
19/20
17/20
9.5/10
10/10
Table 2. Clinician (n=3) and patient (n=1) survey results for Design 5 (Prototype 2)
Topic
Functionality
Comfort
Appearance
Overall Design
Clinician Score
19.7/20
19.7/20
9.5/10
10/10
Patient Score
20/20
20/20
7/10
10/10
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