What is Dysarthria (Slurred Speech)?
Dysarthria is a condition impacting the muscles that help us speak. It can cause issues with the speed, strength, accuracy, range, tone, or length needed for clear speech. The main feature of this disorder is difficulty speaking clearly, although the person’s understanding and usage of language remain unaffected, meaning they can understand and write language just fine. A severe form of this condition, known as anarthria, completely removes the ability to produce speech.
Speaking is a complex task that involves the coordination of five different muscle groups or ‘subsystems’. These include our breathing (respiration), voice production (phonation), sound quality (resonance), pronunciation (articulation), and rhythm of speech (prosody). Any muscle issues impacting these subsystems can result in reduced loudness, naturalness, and clarity of speech, and affects efficient communication. Dysarthria can have a significant impact on the patient and their families because communication is a crucial part of expressing our personalities and maintaining social relationships. It’s also worth noting that people with dysarthria often have trouble with eating and swallowing since the same muscles are involved in both tasks.
What Causes Dysarthria (Slurred Speech)?
Dysarthria is a condition that can be caused by various disorders affecting the nerves and muscles involved in speech. These might include brain areas like the cerebral cortex, areas for movement such as the basal ganglia, the cerebellum, cranial nerves, or the tongue, larynx, and pharynx.
There’s a classification from Mayo Clinic which groups dysarthria based on where it originates:
– Flaccid dysarthria: Caused by issues with certain cranial nerves or lower motor neurons which control the muscles for speech.
– Spastic dysarthria: Due to problems in areas involved in controlling voluntary muscles, like following a stroke or primary lateral sclerosis.
– Hypokinetic dysarthria: Often seen in Parkinson’s disease.
– Hyperkinetic dysarthria: Associated with Huntington’s disease.
– Ataxic dysarthria: Caused by strokes in the cerebellum, cerebellum tumors, or degenerative diseases such as Friedreich ataxia.
– Mixed dysarthria: Tends to occur following severe brain injury, multiple sclerosis, and amyotrophic lateral sclerosis (ALS).
Different conditions that lead to dysarthria include:
1. Infections: Diseases like Creutzfeldt–Jakob disease or AIDS.
2. Blood vessel disorders: Strokes or malformations of arteries and veins.
3. Neoplasm: Both primary and metastatic brain tumors.
4. Demyelinating diseases: Conditions like multiple sclerosis and Guillain–Barre syndrome, which damage protective nerve covers.
5. Degenerative disorders: Neurological disorders which cause progressive brain damage like Parkinson’s disease, Huntington’s disease, and ataxia telangiectasia.
6. Trauma: From brain injuries or cerebral palsy.
7. Toxins: Including heavy metal poisoning or from excessive alcohol/drug use.
There are also genetic causes like a condition called sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) caused by a gene mutation.
Lastly, there are also non-neurological causes that can lead to speech difficulty like cleft lip or palate and laryngeal tumors, but these wouldn’t be classified as dysarthria.
Risk Factors and Frequency for Dysarthria (Slurred Speech)
Dysarthria, a condition that affects speech, is common in many illnesses, but the exact number of people it affects is unknown. This is mainly because the number varies depending on what’s causing the problem.
- About 90% of people with Parkinson’s Disease (PD) develop dysarthria during their illness.
- In people with Amyotrophic Lateral Sclerosis (ALS), dysarthria can appear 3 to 5 years before weakness in the arms and legs. It affects about 70% of ALS patients who have this weakness.
- In a study of stroke patients, 28% had both aphasia (difficulty with language) and dysarthria, while 24% had only dysarthria.
- In children with neuromuscular diseases, about 31.5% had dysarthria.
- It’s estimated that between 10% to 60% of patients with Traumatic Brain Injury (TBI) have dysarthria.
Signs and Symptoms of Dysarthria (Slurred Speech)
Dysarthria, a medical condition that affects speech, can be caused by different neurological conditions. People with dysarthria may notice their symptoms right away such as in a stroke, or the symptoms may develop over time as with diseases like ALS (Amyotrophic Lateral Sclerosis).
Broadly, dysarthria can show up in multiple forms. Here’s how the Mayo Clinic classifies them:
- Flaccid dysarthria: In this form, speech tends to be slow, nasally, and breathy. Common conditions that can cause this include idiopathic peripheral facial paralysis (which causes facial paralysis and drooling) and Guillain–Barre syndrome.
- Spastic dysarthria: People with spastic dysarthria often have harsh speech that’s low in pitch and includes frequent mistakes. Symptoms can also include nasally speech, difficulty swallowing, a jaw that’s overly reactive to sudden movements, and inappropriate laughter or crying (known as pseudobulbar affect). This is often seen in people with a condition called “dysarthria-clumsy hand syndrome,” which also involves facial weakness and coordination issues.
- Hypokinetic dysarthria: People with Parkinson’s disease often have this form of dysarthria. Their speech can be monotonous, poorly pronounced, and soft. Other signs can include facial stiffness, tremors, rigid movements, and hurried walking.
- Hyperkinetic dysarthria: This form can occur from lesions in a part of the brain known as the basal ganglia or when there’s excessively uncontrolled movement as seen in Huntington’s Disease(HD). Speech can be harsh and inconsistent in both volume and tempo. Speech may unexpectedly stop from time to time.
- Ataxic dysarthria: This is often seen with conditions that affect the cerebellum in the brain. Symptoms include a “scanning” speech quality or uneven rhythm, slow pronunciation of syllables, and pauses after each syllable. There might also be a lack of motor coordination depending on the part of the cerebellum affected.
- Mixed dysarthria: This includes aspects of two or more types of dysarthria and can occur when two or more parts of the central nervous system are affected. This is usually seen in diseases like ALS and multiple sclerosis, where speech is slow, rhythmic speech patterns (prosody) are disrupted, the voice is strained, and there is significant nasality.
Testing for Dysarthria (Slurred Speech)
When a patient shows signs of dysarthria, or difficulty speaking, doctors gather a detailed medical history and carry out certain examinations. The examination process can involve five steps: history taking, oral motor or speech mechanism testing, checking various aspects of speech such as breathing, voice quality, clarity of speech, volume, and rate, observing speech performance, and finally, understanding how well others can understand their speech.
A simple test called the water glass manometer test can be used to broadly examine people’s capability of generating pressure for speech production. The patient is asked to blow bubbles through a straw into a glass of water. If they can maintain a stream of bubbles for 5 seconds, their breath support is considered adequate for speech.
Doctors also use a range of texts like the passage “My grandfather” and “Caterpillar passage”, which helps doctors evaluate the various subsystems involved in speech. For example, the Caterpillar passage is a narrative about a memorable trip to the amusement park and a thrilling roller coaster ride. Reading this passage allows doctors to evaluate the patient’s word pronunciation, their grasp of everyday vocabulary and sentence structure, and their pronunciation of complex word forms.
Doctors also use different tools to evaluate how understandable the patient’s speech is to others. Assessment of Intelligibility in Dysarthric Speakers (AIDS) is one common tool, which includes tasks of reading or repeating words and sentences. The Sentence Intelligibility Test (SIT) examines the clarity of words and sentences and checks how quickly intelligible words can be spoken in a minute.
Doctors are also interested in the onset and progression of dysarthria and other neurological issues that might be related, such as tremors or issues with swallowing and walking. They may also review the patient’s medications to see if overdoses or exposure to toxins, such as alcohol and cocaine, might be contributing factors. Quick bedside tests like having the patient count from 1 to 100 can sometimes highlight issues with respiratory muscles. Also, asking the patient to sustain the sound “ah” can help assess laryngeal or vocal cord function.
Imaging techniques like CT scans of the head or MRI scans of the brain can also be useful. Blood and urine tests, as well as electromyography (EMG), and nerve conduction studies might also be needed, depending on the patient’s symptoms and medical history. If the doctors suspect something like Guillain-Barré syndrome, which affects the nerves, they will use tests to measure lung function.
Tools like the Frenchay Dysarthria Assessment can also be used, which involve specific tasks to identify different types of dysarthria. Speech pathologists rate many areas of the patient’s speech, from breathing to tongue movement to clarity of speech, plus other influencing factors. For a more subjective assessment, they might use self-report questionnaires that help the patient express their experience with their speech difficulties. It is important to remember that the severity of dysarthria may not always match the extent of perceived difficulties in communication.
Treatment Options for Dysarthria (Slurred Speech)
The main objectives of speech and language therapy are to help recover communication abilities, teach patients coping strategies for communication disorders, and provide education and support for caregivers and others in the patient’s life on how to assist with their communication challenges. This therapy can help reduce feelings of isolation and better meet the wants and needs of the patient.
Developing a treatment plan requires careful consideration of the cause and severity of the communication disorder, as well as any other conditions the patient might have. Speech therapists and doctors collaborate to design a plan tailored to the patient’s needs. Research shows that speech therapy significantly improves speech in adults who have communication challenges due to stroke. Some specific treatments, like the Lee Silverman Voice Treatment, have proved effective for certain conditions like Parkinson’s disease.
The therapy can be categorized into five main types:
- Targeting the speech-production systems
- Communication strategies
- Adapting the environment
- Augmentative and alternative communication (AAC)
- Medical or surgical interventions
Therapists can focus on the five individual elements that underlie speech production. Some techniques improve the loudness and clarity of speech or the use of the voice. Breathing can be supported by adjusting posture.
Therapy may involve using constructive approaches like reinforcing, clarifying, encouraging. Patients can benefit from techniques such as slowing down their speech, repeating phrases, and using non-verbal cues such as eye contact and facial expressions.
There are also sophisticated techniques like biofeedback which were found to improve speech clarity. Creating a quiet background, arranging suitable seating, and encouraging face-to-face interaction can also enhance speech understanding.
In addition to these, AAC tools can be used. These can be low-tech aids like picture boards or pen and paper, or high-tech aids like smartphones and speech-generating devices.
Exciting progress has been made in computer-based interventions for managing communication disorders. Some small studies on mobile apps and computer-assisted therapy have shown promising results and potential for further advancements.
Medical or surgical treatment should focus on addressing the root cause of the communication disorder. For example, in conditions like Parkinson’s disease, medication can help manage the symptoms. Surgery can also be an option, although the outcomes vary.
Since the COVID-19 pandemic, telehealth has been used more and more to provide speech therapy, proving to be not only cost-effective but also equally effective as traditional rehab. Despite the positive feedback received so far, more research is needed to continue improving these remote therapy methods.
What else can Dysarthria (Slurred Speech) be?
When you struggle to pronounce words, this could be due to a medical problem known as dysarthria. However, other similar conditions need to be ruled out. These include aphasia, apraxia of speech, and aphemia.
Apraxia of speech is like a hiccup in the brain’s control over the muscles that create speech. People with this condition tend to have difficulty starting to speak or moving between sounds. Their way of speaking might seem like it’s full of trial and error, making inconsistent mistakes. Interestingly, when asked to repeat a complicated word, such as “television,” the error made each time will be a little different. Usually, apraxia of speech does not exist on its own; it’s mostly seen alongside aphasia. On imaging tests, doctors might spot damage in the speech and language areas of the brain.
Aphasia is when an individual has trouble dealing with language. It can affect either the understanding or the creation of speech, and can even make reading and writing a challenge depending on where it is located in the brain.
On the other hand, aphemia is a condition that hampers your speech motor control to the point of almost making you mute. However, it enables you to understand, read, and write normally.
What to expect with Dysarthria (Slurred Speech)
Dysarthria is categorized as chronic when it lasts more than 5 years, and it’s considered stable in patients whose underlying conditions do not progress over time.
Recovery from dysarthria significantly depends on the cause. For example, one study on recovery after stroke-related dysarthria showed a recovery in about half of the patients. Unfortunately, we don’t have any specific long-term predictions for various diseases. Still, it seems clear from several individual reports that dysarthria usually worsens in most neurodegenerative diseases.
Functional Communication Measures, or FCMs, are rating scales used to gauge a person’s communication capabilities. These scales range from 1 to 7, with 1 being the least functional and 7 being the most functional. These measures help assess a patient’s ability to communicate and swallow during speech-language therapy.
Possible Complications When Diagnosed with Dysarthria (Slurred Speech)
Speech difficulties can greatly affect a person’s mental and social well-being. After a stroke, some patients report changes in their self-identity, feeling stigmatized, and dealing with emotional and social issues due to dysarthria, a condition that hinders speech. This can be particularly damaging for children, who may experience behavioral problems, difficulty accessing education, and fewer future job opportunities as a result.
There are tools, like the Dysarthria Impact Profile (DIP), designed to measure the mental and social impacts of this condition. These tools are key in deciding the best interventions and tracking their outcomes. For example, patients may indicate how their speech has affected their life in various situations, such as talking to unfamiliar people or ordering food at a restaurant.
Another tool, the Communicative Participation Item Bank (CPIB), is used by adults with different communication disorders. This tool has valuable clinical and research applications. Again, patients share how their condition affects them in everyday situations, providing vital information for treatment planning and outcome measurement.
Preventing Dysarthria (Slurred Speech)
If a person or their family member notices problems with their speech (known as dysarthria), they should immediately inform a medical professional. A sudden onset might indicate a stroke, necessitating a quick check-up at the hospital. For symptoms that develop slowly over time, the initial evaluation is usually done by a family doctor, who would then refer the patient to a specialist. There are various strategies that the patient and those caring for them can employ during their recovery.
For instance, caregivers should focus on the speaker, converse in a quiet well-lit area, repeat misunderstood phrases, and confirm unclear statements by asking questions that require a yes or no answer. The patient, on the other hand, should start by speaking one word or phrase before moving on to complete sentences. Speaking slowly and pausing frequently can aid understanding. It’s a good idea to consistently check if listeners understand and involves using pictures and written words if necessary. Care should be taken to prevent fatigue and frustration, as these can exacerbate the unclear speech. If necessary, alternate means of communication should be explored. Educating others about dysarthria can improve their understanding of the condition and their interactions with those affected.
