Dysarthria - causes, symptoms, types and treatment

The pronunciation problems of some people are due to lesions and alterations in the brain.

Communication disorders include disorders such as dyslalia, stuttering and phonological disorder, better known as dysarthria. phonological disorder, better known as dysarthria.. The basic sign that leads to the diagnosis of dysarthria is the presence of a marked difficulty in articulating phonemes adequately due to muscular problems.

In this article we will describe the causes and symptoms of the main types of dysarthria.. In addition we will explain in a synthetic form in what consist the most habitual treatments of this disorder.

What is dysarthria?

Dysarthria is a disorder that affects the muscles of speechthe lips, the tongue, the vocal cords and/or the diaphragm. The difficulty in controlling these muscles or their weakness means that people with dysarthria cannot articulate phonemes correctly, so they have pronunciation problems or speak more slowly than normal. Unlike motor aphasia, it is a pronunciation disorder and not a speech disorder.

The term "dysarthria" comes from Greek and can be literally translated as "articulatory malfunction". It is a speech disorder and not a language disorder; this means that the problem does not occur at the cognitive level but at later stages of sound production. When the person is completely unable to articulate sounds we speak of anarthria.

The DSM-IV lists dysarthria under the label "phonological disorder".while in the DSM-5 it is called "Speech sounds disorder". The basic criterion for diagnosis according to these classifications is that the person is unable to utter phonemes that would be expected to have learned to articulate at a given age.

Causes of the disorder

Dysarthria can have many different causes. Among the most common are disorders of the nervous system, such as lesions and tumors in the brain or strokes that paralyze the face or tongue. paralyzing the face or tongue. When it occurs from birth, it is usually a consequence of cerebral palsy or muscular dystrophy.

Certain disorders favor the appearance of dysarthria symptoms in adulthood, such as amyotrophic lateral sclerosis or Parkinson's, Huntington's and Wilson's diseases. Some drugs can also cause dysarthria, especially sedatives and powerful narcotics.In these cases, discontinuation of use alleviates the disorder.

Symptoms and signs

The symptoms and signs of this disorder may vary depending on the cause and type of dysarthria. Among the most common are the following:

• Difficulty moving the muscles of the face, lips and tongue.
• Poor pronunciation.
• Monotonous prosody.
• Altered timbre.
• Speech too slow or too fast.
• Nasal or hoarse voice.
• Excessively high or low volume.
• Irregular rhythm (e.g. choppy speech).
• Associated respiratory difficulties.

In relation to pronunciation difficulties, four main types of errors are usually detected: substitution, omission, insertion and distortion.. Substitution, which consists of replacing the correct phoneme with the wrong one, is the most frequent, especially when pronouncing "d" or "g" instead of "r".

While consonant articulation is affected in all cases of dysarthria, inadequate vowel pronunciation is considered an indicator of severity..

Types of dysarthria

The types of dysarthria discussed in this section differ from each other mainly in the location of the lesion in the central nervous system.

1. Spastic

Spastic dysarthria is due to lesions in the pyramidal tractsrelated to the fine motor control of the muscles of the face and neck.

In this type of dysphasia, hypernasality and sudden increases in speech volume occur. Vocalization tends to be tense and forced.

2. Ataxic

Lesions in the cerebellum cause ataxic dysarthria, whose most characteristic signs are the presence of a flat and monotonous prosody. presence of flat, monotonous prosody and slow, uncoordinated vocalization, similar to the and uncoordinated vocalization, similar to that produced in a state of drunkenness. Speech typical of this type of dysarthria has sometimes been described as "explosive".

3. Flaccid

In this type of dysarthria the vagus nerve is affectedwhich allows the movement of the larynx and therefore of the vocal cords. Dysfunctions also occur in other facial muscles.

In cases of flaccid dysarthria, the muscles may atrophy or become partially paralyzed, causing spasms, drooling and Muscle tension.

4. Hyperkinetic

Hyperkinetic dysarthria is usually caused by lesions in the basal ganglia, subcortical structures involved in involuntary movements.

The symptoms of this type of dysarthria are similar to those of spastic dysarthria: the voice tends to have a rough quality and hypernasality is also present. hypernasality is also present..

5. Hypokinetic

In general hypokinetic dysarthria appears as a consequence of Parkinson's diseasealthough it is also common that the cause is the continued use of antipsychotic drugs.

In this case the volume is usually very low, the timbre flat and the prosody monotonous. The reduction in the speed of movements caused by damage in the region known as substantia nigra explains these symptoms.

6. Mixed

This category is used when the clinical features are a combination of more than one of the types of dysarthria described above. Mixed dysarthrias are due to involvement of different motor systems.

Treatment and intervention

The treatment of dysarthria depends to a large extent on the alteration that causes the disorder since, when it is possible, correcting the ultimate cause eliminates the symptoms. However, interventions are available to improve speech in cases where the underlying problem cannot be modified.

The main objectives of speech therapy and speech therapy and speech therapy in cases of dysarthria are to strengthen the muscles involved in speech, improve breathing, achieve proper pronunciation and facilitate communication between the affected person and those close to him or her.

In cases of severe speech impairment, external aids such as speech synthesizers and alphabet boards are very useful. Learning gestures and even sign language can also be used to some extent to can also serve to some extent to compensate for the communication deficits of dysarthria.