Amyotrophic lateral sclerosis (ALS) is a progressive neurological disorder. It specifically affects the nerve cells in the brain and spinal cord that control voluntary muscle movement. As these motor neurons degenerate, they stop sending messages to the muscles, leading to muscle weakness and eventual paralysis.
Understanding Dysarthria
Dysarthria is a motor speech disorder that makes it difficult to form and pronounce words. It arises from damage to the nervous system, which weakens or paralyzes the muscles responsible for producing speech. These muscles include those in the face, tongue, voice box, and jaw, as well as those involved in breathing.
The specific way dysarthria manifests depends on the location of the neurological damage. This can lead to various forms, such as flaccid, spastic, ataxic, hypokinetic, hyperkinetic, or mixed dysarthria. Each type presents with distinct speech characteristics.
The Dysarthria Most Associated with ALS
ALS affects both upper motor neurons (originating in the brain and spinal cord) and lower motor neurons (connecting the spinal cord to muscles). This widespread degeneration leads to a “mixed” dysarthria, which is the most common type seen in individuals with ALS. Specifically, it combines features of both spastic and flaccid dysarthria.
Spastic dysarthria results from damage to upper motor neurons and is characterized by muscle stiffness and increased tone. Speech may sound strained, harsh, or effortful, with a slow speaking rate and reduced pitch variability. The voice can be described as tight, breathy, or hoarse.
Conversely, flaccid dysarthria arises from damage to lower motor neurons, leading to muscle weakness and reduced muscle tone. This can cause speech to sound breathy and nasal, with imprecise articulation and a weak or quiet voice.
Recognizing Speech Changes in ALS
The mixed spastic-flaccid dysarthria in ALS manifests through several recognizable speech changes. Individuals often experience slow, slurred, and difficult-to-understand speech. Articulation becomes imprecise, particularly for consonants, and the voice may have a harsh, strained, or breathy quality.
Hypernasality, where too much air escapes through the nose during speech, is also common. Speech may lack normal pitch and loudness variations, resulting in a monotone sound. People may speak in short, choppy bursts due to reduced breath support and find speaking physically tiring.
These symptoms collectively impact speech intelligibility, making it challenging for others to understand. Speech impairment can significantly hinder daily communication as the disease advances.
Strategies for Communication Support
To manage speech changes in ALS and maintain effective communication, various strategies and assistive techniques are available. Behavioral approaches include speaking slowly, over-articulating words, and using shorter sentences to conserve breath and improve clarity. Ensuring a quiet environment and gaining the listener’s attention before speaking can also aid understanding.
When natural speech becomes challenging, augmentative and alternative communication (AAC) methods become important. These range from low-tech options like whiteboards or alphabet boards, to high-tech solutions. High-tech devices include speech-generating devices (SGDs) that convert text into synthesized speech, or eye-tracking technology that allows users to control a computer with their gaze.
Speech-language pathologists (SLPs) play a significant role in assessing speech changes, recommending appropriate strategies, and facilitating the use of AAC devices. They can also help with voice banking, which allows individuals to record their own voice for use with an SGD before their speech deteriorates significantly.