Amyotrophic Lateral Sclerosis
A Challenge for Speech-Language Pathology
By Pamela Mathy
Amyotrophic Lateral Sclerosis (ALS), first identified in 1869
by the French neurologist, Jean-Martin Charcot, is a relentlessly
progressive degenerative motor neuron disease that primarily
affects the motor neurons of the brain and spinal cord. Lou
Gehrig, with whom the disease is often associated, brought
international attention to ALS in 1939, when it caused him to
retire from baseball. More recently, a variety of public figures
from actors (Michael Zaslow) to physicists (Stephen W. Hawking)
to retired university professors interviewed on Nightline (Morrie
Schwartz) to senators (Jacob Javits) have focused attention on
this-devastating disease.
Symptoms
The early symptoms of ALS are varied. For some it begins with
speech slurring, difficulties with swallowing, and/or hoarseness.
Others may experience uncharacteristic clumsiness or tripping.
Difficulty lifting may be the initial symptom for others.
Clinically, the signs and symptoms are divided into two
areas-spinal functions and bulbar functions. Three-quarters of
people report initial spinal symptoms (weakness in the upper
and/or lower extremities) and about one-quarter present with
bulbar symptoms (weakness with changes in both speech and
swallowing). Both upper and lower motor neurons
characteristically become involved as the disease progresses.
Incidence
ALS strikes in the prime of life. The average age of diagnosis
is 55 years with a range of 40 to 70 years. It is possible,
however, to find individuals in their 20s and 30s diagnosed with
ALS. Men are 20% more likely to develop ALS than women.
Population studies estimate two cases per 100,000 population. In
the U.S., approximately 5,000 individuals per year receive a
diagnosis of ALS and nearly 30,000 people residing in the U.S. at
any time are living with ALS.
Cause
The vast majority of ALS cases diagnosed in the U.S. each year
(90%-95%) are not associated with genetic inheritance. Results of
worldwide epidemiological research examining the population-based
risk factors for ALS suggest increasing incidence (Yorkston,
Strand, & Miller, 1995). There is also a positive trend
linking ALS with occupations involving heavy labor, exposure to
heavy metals, or a history of traumatic injury. With the
exception of an unusually high frequency of cases occurring in
specific regions of the western Pacific, particularly Guam, there
is no pattern of geographic clustering of ALS. Nor is ALS
associated with a particular race or educational level.
Prognosis
The prognosis for individuals diagnosed with ALS varies from
person to person. Small percentages of people show very slow
disease progression and may live 10 to 20 years following
diagnosis. However, the average life span from the time of
diagnosis is three to five years. In their review of the
literature on survival duration, Mathy, Yorkston, and Gutmann (in
press) found a number of predictors including age at time of
onset, classification of initial symptoms (spinal, bulbar), and
pulmonary function. The older the individual at the time of
diagnosis the shorter the life span with the disease. Patients
who present with initial spinal symptoms have a three times
greater survival rate at the end of five years than those with
initial bulbar symptoms. Respiratory status is an important
predictor of survival duration.
Although current published data indicate that only between 5%
and 20% of individuals choose to prolong their lives using
mechanical ventilation, anecdotal evidence suggests that this
proportion may be rising. The suggested reasons for this trend
include the greater feasibility of home ventilation, the
increasing number of people opting for non-invasive ventilatory
support, and progress in the field of augmentative and
alternative communication (AAC).
Diagnosis
There is no specific laboratory test for ALS, making it
complex to diagnose. The diagnosis is made using clinical
findings in conjunction with results of electrodiagnostic studies
and the absence of evidence of other disorders. According to the
diagnostic guidelines of the World Federation of Neurology
(1994), there must be lower motor neuron (LMN) degeneration
detected by clinical electrophysiological or neuropathologic
examination, signs of upper motor neuron (UMN) degeneration by
clinical examination, and progressive spread of signs within a
region of the body or to other regions.
Treatment
Presently there is no cure for ALS. However, the accelerated
pace of research in the neurosciences over the last decade has
yielded several promising theories regarding its pathogenesis.
These include autoimmunity, glutamate excitotoxicity, free
radical oxidative stress, and neurofilament accumulation (Jackson
& Bryan, 1998). Increased understanding of the neuropathology
of ALS has yielded numerous clinical trials of drugs such as
antiexcitotoxic agents, antioxidants, immunosuppressants, and
neurotrophic factors (Louvel, Hugon, & Doble, 1997).
Riluzole, an antiglutamate agent, is the first FDA-approved drug
for the treatment of patients with ALS. Although Riluzole is not
a cure, results of clinical trials indicate some promise in
prolonging life, especially with bulbar patients. The current
trend is to evaluate potential additive or synergistic effects of
drug combinations.
As with any incurable disease, the state of the art in
treatment for ALS is symptom management (also referred to as
"palliative care"). According to the World Health
Organization, palliative care is active care of the total
patient. Individuals with ALS receive the best treatment from
multidisciplinary clinical teams that specialize in neuromuscular
disorders. Intervention deals with symptoms that occur over the
course of the disease process. The ALS Association (ALSA) and the
Muscular Dystrophy Association (MDA) sponsor clinics in many U.
S. cities (information can be obtained from their Web sites-see
reference list).
Role of Speech-Language Pathology
Individuals with ALS and their families must face the
challenge of adjusting to an avalanche of losses. The diagnosis
of a rapidly progressive disease with no cure presents the loss
of control of one's future. The loss of control of movement
brings the realization of the need to depend on others for even
the most basic of life's functions. Perhaps most devastating
is the prospect of losing the ability to speak. Although current
medical and rehabilitation technology cannot offer a way to
prevent any of these losses, speech-language pathologists can
assist individuals with ALS to maintain their ability to
communicate using compensatory strategies and AAC aids and
techniques.
As speech intelligibility begins to decline, intervention
focuses on maintaining functional communication versus attempting
to reduce speech impairment (Yorkston, Miller, & Strand,
1995). Direct speech intervention is not recommended for a number
of reasons. First, exercise to fatigue may hasten neurological
deterioration. Speech drills may be so tiring that speech
adequacy for functional use in other settings would be
compromised. Finally, speech exercises emphasizing optimum
performance can only prove to be a discouraging reminder of
increasing loss of ability.
Cognitive Functioning
Because ALS is classified as a motor neuron disease, the
typical assumption is that cognitive functioning is spared.
However, studies examining the results of neuropsychological
functioning have found that as many as one-third of individuals
with ALS show clinically significant cognitive impairments.
Unlike the diffuse cognitive changes associated with
Alzheimer's disease, the pattern of deficits in some
individuals with ALS is consistent with frontal lobe involvement
(e.g., impairments in tasks demanding sustained attention and the
ability to shift quickly from topic to topic, confrontation
naming, judgment, insight, verbal fluency).
Our understanding of the timing of cognitive changes as the
disease progresses, the extent of changes based on individual
characteristics, and the implications of these changes on
functional abilities is in its infancy. Speech-language
pathologists (SLPs) who work with these individuals should be
aware of the potential cognitive deficits in their patients with
ALS as they plan their treatment. For example, complex AAC
devices that require extensive new learning may be a poor choice
for some individuals.
Speech Functioning
Due to the effects of upper and lower motor neuron changes,
the speech of individuals with ALS is classified as mixed
(spastic and flaccid) dysarthria (Duffy, 1995). In addition to
the perceptual features observed in both types of dysarthria
(imprecise consonants, hypernasality, harsh voice), features
associated primarily with spastic dysarthria (low pitch, reduced
stress, and strained-strangled voice quality) and indicators of
flaccid dysarthria (audible inspiration and nasal emission) are
evident in some speakers with ALS. With disease progression and
increased muscle wasting and atrophy, flaccidity symptoms
predominate.
The literature examining changes in speech functioning in ALS
reveals two major thrusts. One area focuses on measuring how the
progression of ALS impairs the components of the speech mechanism
including respiratory, laryngeal, and lingual function (see
Duffy, 1995; and Mathy, Yorkston, & Gutmann, in press).
Although knowledge regarding the underlying impairment is
important, effective intervention planning in ALS requires an
understanding of the impact of speech impairment on
speech/communicative functioning. Work by Yorkston and her
colleagues (see references) has described five stages of speech
decline in ALS. For each stage, interventions are provided to
deal with immediate needs, and suggestions for future planning
are given. Research delineating predictors of changes in speech
functioning is also important. Yorkston, Strand, Miller, Hillel,
and Smith (1993) found reduction in speaking rate to be the
strongest predictor of decreases in speech intelligibility.
Augmentative and Alternative Communication
AAC aids ranging from light-tech alphabet boards to high-tech
micro computer-based systems that provide speech and writing
augmentation offer means for people with ALS to maintain their
communicative functioning. Because most individuals with ALS are
adults with intact literacy skills, they benefit most from AAC
aids and strategies that provide the ability to generate messages
through spelling.
Patterns of AAC technology use by individuals with ALS are
just beginning to be examined. Differences in use have been found
based on such factors as initial symptom presentation (bulbar,
spinal), communicative activity (e.g., face-to-face conversation,
indication of basic wants or needs, indication of detailed wants
or needs, etc.), and partner familiarity. For example, both
individuals with initial bulbar presentation and those with
initial spinal presentation preferred light tech AAC aids (e.g.,
handwriting, alphabet board, gesture, vocalization) to convey
basic needs or wants to familiar caregivers whereas they used
high-tech aids to communicate detailed needs or wants (messages
requiring extensive explanation). Further, when communicating
with unfamiliar partners, both groups preferred to use high-tech
aids to communicate basic as well as detailed needs. People with
ALS, therefore, need access to both light- and high-tech systems
to best maintain their communicative functioning.
Future Direction
Over the last decade, the level of hope of individuals with
ALS, their families, and advocates has been bolstered by an
increased understanding of the disease and by the results of
initial clinical drug trials. Many hurdles remain to be overcome,
however, for the dream of a cure to become reality. In the
meantime, individuals with ALS and their families need SLPs with
expertise in AAC to assist them to maintain vital human
communication.
. . . . . . . . . .
Pamela Mathy
is director of Clinical Services in the Department of Speech and
Hearing Science at Arizona State University. In addition to her
administrative duties, she engages in clinical teaching, with a
focus on adults and children with neurogenic and neuromuscular
disorders, and she teaches the graduate course in AAC. Before
moving to Arizona, she directed the AAC clinical program at
Munroe Meyer Institute, University of Nebraska Medical
Center.
. . . . . . . . . .
References
ALS Association
Duffy, J. R.
(1995).
Motor speech disorders: Substrates, differential diagnosis,
and management. St. Louis: Mosby.
Jackson, C. E., & Bryan, W. W.
(1998). Amyotrophic lateral sclerosis.
Seminars in Neurology, 18
(1), 27-39.
Louvel, E., Hugon, J., & Doble, A.
(1997). Therapeutic advances in amyotrophic lateral sclerosis.
Trends in Pharmacological Sciences, 18
(6), 196-203.
Mathy, P., Yorkston, K. M., & Gutmann, M.
(in press). Augmentative communication for individuals with
amyotrophic lateral sclerosis. In D. R. Beukelman, K .M.
Yorkston, & J. Reichle (Eds.).
Augmentative communication for adults with neurogenic and
neuromotor disabilities
(Vol. 2). Baltimore: Paul H. Brookes.
Muscular Dystrophy Association
World Federation of Neurology Research Group on
Neuromuscular Disease.
(1994). El Escorial World Federation of Neurology criteria for
the diagnosis of amyotrophic lateral sclerosis.
Journal of the Neurological Sciences, 124
(Suppl.), 96-107.
World Health Organization of Palliative Care
Yorkston, K. M., Miller, R. M., & Strand, E.
A.
(1995).
Management of speech and swallowing disorders in degenerative
disease. Tucson, AZ: Communication Skill Builders.
Yorkston, K. M., Strand, E. A., & Hume, J.
(1998). The relationship between motor function and speech
-function in amyotrophic lateral sclerosis. In M. Cannito, K. M.
Yorkston, & D. R. Beukelman (Eds.),
Neuromotor speech disorders: Nature, assessment, and
management
(pp. 85-98). Baltimore: Paul H. Brookes.
Yorkston, K. M., Strand, E. A., & Kennedy, M. R.
T.
(1996). Comprehensibility of dysarthric speech: Implications for
assessment and treatment planning.
American Journal of Speech-Language Pathology, 5
(1), 55- 66.
Yorkston, K. M., Strand, E., Miller, R., Hillel, A.,
& Smith, K.
(1993). Speech deterioration in amyotrophic lateral sclerosis:
Implications for the timing of intervention.
Journal of Medical Speech-Language Pathology, 1
(1), 35-46.