Cerebral palsy (CP) is an umbrella term describing a group of permanent disorders that affect movement and posture, resulting from non-progressive disturbances in the developing brain. Because the brain areas controlling movement also manage the muscles used for speech, the ability to talk varies widely among individuals with CP. CP affects the brain’s ability to control muscles, which can impact speech production. However, this does not equate to an inability to communicate or a lack of clear thought.
Understanding the Impact on Speech Muscles
Talking is a complex physical act requiring the precise coordination of numerous muscles, including those in the lips, tongue, jaw, vocal cords, and the diaphragm for breath support. In people with cerebral palsy, damage to the brain’s motor control centers often disrupts the signals sent to these muscles, leading to difficulties in motor control, posture, and muscle tone. This impaired control over the oral-motor structures makes the fine adjustments necessary for clear articulation challenging.
The specific type of muscle tone issue associated with CP directly interferes with speech mechanics. Spasticity, the most common type, involves stiff, tight muscles and exaggerated reflexes, making rapid, accurate movements of the tongue and lips difficult. Dyskinetic CP causes involuntary, fluctuating muscle movements that disrupt the steady flow of air and sound production. Ataxia, characterized by a lack of muscle coordination, results in unsteady and imprecise movements, breaking down the rhythm and timing required for speaking.
Motor control issues often result in dysarthria, the most common speech impairment in CP, affecting up to 88% of individuals. Dysarthria stems from weakness or poor coordination of the speech muscles, impacting the breath stream, voice production, and articulation. Lack of respiratory control can lead to speaking on short bursts of air, resulting in a quiet voice during longer sentences.
Specific Communication Difficulties
The challenges stemming from muscle control manifest in several distinct ways, affecting the clarity of sounds and the entire communication process. Dysarthria can cause slurred or mumbled speech, a delayed rate of speech, and difficulties forming syllables due to poor oral-motor control. This results in reduced speech intelligibility, making communication difficult for others to understand.
Beyond articulation, the voice itself can be affected, leading to voice disorders. These include problems with volume control (too soft or too loud) and issues with quality, such as hoarseness or a breathy sound. Irregularities in pitch and the inability to sustain voicing also occur due to difficulty coordinating the laryngeal muscles and the breath stream. CP can sometimes involve developmental verbal apraxia, which is separate from dysarthria. Apraxia is a difficulty in the neurological planning and sequencing of muscle movements needed for speech, even if the muscles are not weak.
Communication difficulties extend to fluency, resulting in interruptions like stuttering, or problems with prosody (the rhythm, stress, and intonation of speech). Co-occurring language processing difficulties or cognitive-communication disorders may also be present, making it hard to understand spoken language or organize thoughts. Approximately a quarter of people with CP are non-verbal, highlighting the wide spectrum of communication needs.
Utilizing Alternative Communication Methods
For individuals whose verbal speech is difficult to understand or non-functional, Augmentative and Alternative Communication (AAC) systems offer a robust pathway for expression. Speech-Language Pathologists (SLPs) play a central role, assessing an individual’s unique abilities and needs to recommend the most suitable AAC approach. Early intervention with AAC is highly beneficial, as it supports language development and can even help to increase verbal speech, while reducing frustration.
AAC encompasses a variety of tools, ranging from no-tech to high-tech options. Low-tech solutions require no batteries and include communication boards or books where the user points to pictures, symbols, or words. These boards are customized and easily transportable, providing a reliable way to communicate in any environment. Mid-tech options often involve simple electronic devices that play pre-recorded messages when a button is pressed.
High-tech AAC systems are more sophisticated, utilizing specialized speech-generating devices, tablets, or computers with text-to-speech capabilities. For those with severe physical limitations, these devices can be accessed through alternative methods like eye-gaze technology, head pointers, or specialized switches. These tools provide a voice, allowing individuals with CP to express their ideas, needs, and feelings effectively and participate fully in their communities.