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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.