Speech disorders affect the way people talk. Dysarthria is one type of speech disorder that affects the function of muscles involved in speech, leading to loss of control of those muscles and difficulty verbally communicating.
Definition & Facts
Dysarthria, literally meaning “difficult articulation,” is a motor speech disorder in which the muscles required to produce speech are impaired. These muscles include the diaphragm, tongue, larynx, lips, and vocal folds.
There are several different classifications of dysarthria that depend on the cause of the disorder. Spastic, ataxic, flaccid, hypokinetic and hyperkinetic are all classifications of dysarthria. It’s difficult to assess how common the condition is since there are so many different types.
Symptoms & Complaints
Some may have a breathy or hoarse voice due to challenges with breath control. Hypernasal speech may also occur, resulting in a voice that sounds like the speaker’s nose is stuffy from a common cold. Speech may be slower than normal or it may be faster with a mumbling quality. Poor pronunciation can result in distorted vowels and slurring.
The pitching of the voice may be abnormal, and some people may speak in a monotone. There may be limited movement of the articulators, namely the jaw, lips and tongue. Sometimes people with dysarthria have trouble chewing or difficulty swallowing due to lack of control of certain muscles, which may also result in drooling. Symptoms of dysarthria can occur suddenly, or they can progress slowly.
Dysarthria has many possible causes, but in general, it results from a neurological injury to whichever part of the motor-speech system is affected. Brain injuries, strokes, and certain degenerative diseases can cause lesions in the parts of the brain that plan and execute movement of the skeletal muscles, which would include head and neck muscles involved in speech.
Causes of dysarthria fall into three categories: brain damage, nerve injury, and neuromuscular diseases. Brain damage can be caused by brain tumors, Huntington’s disease, strokes, multiple sclerosis, amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease), Parkinson’s disease, and traumatic brain injuries.
Nerves that supply muscles involved in speech could be damaged due to head or neck trauma or surgery. Neuromuscular diseases like muscular dystrophy, cerebral palsy, and myasthenia gravis can also cause dysarthria.
The timing of dysarthria somewhat depends on the cause. Those with disorders like muscular dystrophy or cerebral palsy will present dysarthria at birth (congenital), while it could occur much later due to many of the conditions already mentioned.
Other miscellaneous causes of dysarthria include Lyme disease, alcohol intoxication, intracranial hypertension (high pressure within the skull), dentures that don’t fit well, hypothermia, and even side effects from medications that work on the central nervous system.
Diagnosis & Tests
Either a doctor or a certified speech-language pathologist will be called in to diagnose a possible case of dysarthria. At a typical exam, the patient will give a health care provider their medical history, which should include a list of all medications currently being taken. A physical examination will then be conducted to determine the problem and its severity. A speech-language pathologist would look at the movement of several muscles and structures involved in speech such as the tongue, lips and face. They would also look at the diaphragm and breath support that might be affecting voice quality.
Other procedures, like a laryngoscopy in which a tube is placed in the throat to observe the voice box, may be undergone to determine if speech structures are working properly. More tests are needed to understand the cause of the dysarthria. Swallowing studies, along with X-rays and the ingestion of particular liquids, are used to view certain structures and their functions. Blood tests and clinical urine tests are used to check for inflammatory or infectious diseases that can cause dysarthria symptoms.
Imaging tests, including CT scan and MRIs of the brain and neck, help ascertain the cause of the problem through detailed pictures. A brain biopsy may be done if it’s possible a brain tumor is causing the problem.
Brain and nerve studies, including electroencephalograms (EEGs) and electromyograms, are done to evaluate electrical signals that are conducted from nerves to muscles. A lumbar puncture can be used to diagnose cancers, central nervous system disorders, and severe infections. All of these tests can help determine the underlying cause of dysarthria.
Treatment & Therapy
Once dysarthria is diagnosed, a speech-language pathologist will work with the patient to treat the condition and improve communication. Treatment will be tailored to the individual’s own specific case of dysarthria, depending on the cause of the condition and severity of the symptoms. Occasionally surgery may be justified to fix certain problems, but often it’s a simple matter of speech therapy. Some skills must be learned or relearned. Speech therapy will involve repetition of sounds so that specific mouth movements can be learned and involved muscles can be strengthened.
Individuals will learn to avoid conversations when they are tired, chew or swallow a certain way, improve breath support so they can speak with more volume, slow down speech and leave pauses to see if listeners have understood, and deal with frustration while attempting to communicate. In serious cases, some individuals will have to learn alternative forms of communication using computers or hand gestures.
It’s also important that people with dysarthria learn to teach others how to communicate with them. They should teach listeners to reduce distractions and try to find a quiet environment, observe the speaker while they talk, pay close attention, inform the speaker of any difficulties with understanding, repeat the parts they did understand, and ask the speaker to write what they mean to say if they still can’t understand.
Prevention & Prophylaxis
Stroke is one such cause of dysarthria that has known lifestyle risk factors. To prevent the chances of having a stroke, individuals can adopt a low sodium diet and a low-fat diet, exercise regularly, avoid or quit smoking, check blood pressure regularly, eat lots of fruits and vegetables, maintain a healthy weight, and control other chronic conditions.
With a doctor’s recommendation, a low dose of aspirin may be taken as well. Since alcohol intoxication is a possible cause of dysarthria, it’s a good idea to seek help in the case of alcohol abuse or addiction. It’s also wise to check medications for side effects that could cause dysarthria.